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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:16:40 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-28 13:16:40 +0000
commit47ab3d4a42e9ab51c465c4322d2ec233f6324e6b (patch)
treea61a0ffd83f4a3def4b36e5c8e99630c559aa723 /src/fmt
parentInitial commit. (diff)
downloadgolang-1.18-upstream.tar.xz
golang-1.18-upstream.zip
Adding upstream version 1.18.10.upstream/1.18.10upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/fmt')
-rw-r--r--src/fmt/doc.go343
-rw-r--r--src/fmt/errors.go43
-rw-r--r--src/fmt/errors_test.go77
-rw-r--r--src/fmt/example_test.go365
-rw-r--r--src/fmt/export_test.go8
-rw-r--r--src/fmt/fmt_test.go1898
-rw-r--r--src/fmt/format.go593
-rw-r--r--src/fmt/gostringer_example_test.go59
-rw-r--r--src/fmt/print.go1172
-rw-r--r--src/fmt/scan.go1238
-rw-r--r--src/fmt/scan_test.go1331
-rw-r--r--src/fmt/stringer_example_test.go29
-rw-r--r--src/fmt/stringer_test.go61
13 files changed, 7217 insertions, 0 deletions
diff --git a/src/fmt/doc.go b/src/fmt/doc.go
new file mode 100644
index 0000000..c584cc9
--- /dev/null
+++ b/src/fmt/doc.go
@@ -0,0 +1,343 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+ Package fmt implements formatted I/O with functions analogous
+ to C's printf and scanf. The format 'verbs' are derived from C's but
+ are simpler.
+
+
+ Printing
+
+ The verbs:
+
+ General:
+ %v the value in a default format
+ when printing structs, the plus flag (%+v) adds field names
+ %#v a Go-syntax representation of the value
+ %T a Go-syntax representation of the type of the value
+ %% a literal percent sign; consumes no value
+
+ Boolean:
+ %t the word true or false
+ Integer:
+ %b base 2
+ %c the character represented by the corresponding Unicode code point
+ %d base 10
+ %o base 8
+ %O base 8 with 0o prefix
+ %q a single-quoted character literal safely escaped with Go syntax.
+ %x base 16, with lower-case letters for a-f
+ %X base 16, with upper-case letters for A-F
+ %U Unicode format: U+1234; same as "U+%04X"
+ Floating-point and complex constituents:
+ %b decimalless scientific notation with exponent a power of two,
+ in the manner of strconv.FormatFloat with the 'b' format,
+ e.g. -123456p-78
+ %e scientific notation, e.g. -1.234456e+78
+ %E scientific notation, e.g. -1.234456E+78
+ %f decimal point but no exponent, e.g. 123.456
+ %F synonym for %f
+ %g %e for large exponents, %f otherwise. Precision is discussed below.
+ %G %E for large exponents, %F otherwise
+ %x hexadecimal notation (with decimal power of two exponent), e.g. -0x1.23abcp+20
+ %X upper-case hexadecimal notation, e.g. -0X1.23ABCP+20
+ String and slice of bytes (treated equivalently with these verbs):
+ %s the uninterpreted bytes of the string or slice
+ %q a double-quoted string safely escaped with Go syntax
+ %x base 16, lower-case, two characters per byte
+ %X base 16, upper-case, two characters per byte
+ Slice:
+ %p address of 0th element in base 16 notation, with leading 0x
+ Pointer:
+ %p base 16 notation, with leading 0x
+ The %b, %d, %o, %x and %X verbs also work with pointers,
+ formatting the value exactly as if it were an integer.
+
+ The default format for %v is:
+ bool: %t
+ int, int8 etc.: %d
+ uint, uint8 etc.: %d, %#x if printed with %#v
+ float32, complex64, etc: %g
+ string: %s
+ chan: %p
+ pointer: %p
+ For compound objects, the elements are printed using these rules, recursively,
+ laid out like this:
+ struct: {field0 field1 ...}
+ array, slice: [elem0 elem1 ...]
+ maps: map[key1:value1 key2:value2 ...]
+ pointer to above: &{}, &[], &map[]
+
+ Width is specified by an optional decimal number immediately preceding the verb.
+ If absent, the width is whatever is necessary to represent the value.
+ Precision is specified after the (optional) width by a period followed by a
+ decimal number. If no period is present, a default precision is used.
+ A period with no following number specifies a precision of zero.
+ Examples:
+ %f default width, default precision
+ %9f width 9, default precision
+ %.2f default width, precision 2
+ %9.2f width 9, precision 2
+ %9.f width 9, precision 0
+
+ Width and precision are measured in units of Unicode code points,
+ that is, runes. (This differs from C's printf where the
+ units are always measured in bytes.) Either or both of the flags
+ may be replaced with the character '*', causing their values to be
+ obtained from the next operand (preceding the one to format),
+ which must be of type int.
+
+ For most values, width is the minimum number of runes to output,
+ padding the formatted form with spaces if necessary.
+
+ For strings, byte slices and byte arrays, however, precision
+ limits the length of the input to be formatted (not the size of
+ the output), truncating if necessary. Normally it is measured in
+ runes, but for these types when formatted with the %x or %X format
+ it is measured in bytes.
+
+ For floating-point values, width sets the minimum width of the field and
+ precision sets the number of places after the decimal, if appropriate,
+ except that for %g/%G precision sets the maximum number of significant
+ digits (trailing zeros are removed). For example, given 12.345 the format
+ %6.3f prints 12.345 while %.3g prints 12.3. The default precision for %e, %f
+ and %#g is 6; for %g it is the smallest number of digits necessary to identify
+ the value uniquely.
+
+ For complex numbers, the width and precision apply to the two
+ components independently and the result is parenthesized, so %f applied
+ to 1.2+3.4i produces (1.200000+3.400000i).
+
+ Other flags:
+ + always print a sign for numeric values;
+ guarantee ASCII-only output for %q (%+q)
+ - pad with spaces on the right rather than the left (left-justify the field)
+ # alternate format: add leading 0b for binary (%#b), 0 for octal (%#o),
+ 0x or 0X for hex (%#x or %#X); suppress 0x for %p (%#p);
+ for %q, print a raw (backquoted) string if strconv.CanBackquote
+ returns true;
+ always print a decimal point for %e, %E, %f, %F, %g and %G;
+ do not remove trailing zeros for %g and %G;
+ write e.g. U+0078 'x' if the character is printable for %U (%#U).
+ ' ' (space) leave a space for elided sign in numbers (% d);
+ put spaces between bytes printing strings or slices in hex (% x, % X)
+ 0 pad with leading zeros rather than spaces;
+ for numbers, this moves the padding after the sign
+
+ Flags are ignored by verbs that do not expect them.
+ For example there is no alternate decimal format, so %#d and %d
+ behave identically.
+
+ For each Printf-like function, there is also a Print function
+ that takes no format and is equivalent to saying %v for every
+ operand. Another variant Println inserts blanks between
+ operands and appends a newline.
+
+ Regardless of the verb, if an operand is an interface value,
+ the internal concrete value is used, not the interface itself.
+ Thus:
+ var i interface{} = 23
+ fmt.Printf("%v\n", i)
+ will print 23.
+
+ Except when printed using the verbs %T and %p, special
+ formatting considerations apply for operands that implement
+ certain interfaces. In order of application:
+
+ 1. If the operand is a reflect.Value, the operand is replaced by the
+ concrete value that it holds, and printing continues with the next rule.
+
+ 2. If an operand implements the Formatter interface, it will
+ be invoked. In this case the interpretation of verbs and flags is
+ controlled by that implementation.
+
+ 3. If the %v verb is used with the # flag (%#v) and the operand
+ implements the GoStringer interface, that will be invoked.
+
+ If the format (which is implicitly %v for Println etc.) is valid
+ for a string (%s %q %v %x %X), the following two rules apply:
+
+ 4. If an operand implements the error interface, the Error method
+ will be invoked to convert the object to a string, which will then
+ be formatted as required by the verb (if any).
+
+ 5. If an operand implements method String() string, that method
+ will be invoked to convert the object to a string, which will then
+ be formatted as required by the verb (if any).
+
+ For compound operands such as slices and structs, the format
+ applies to the elements of each operand, recursively, not to the
+ operand as a whole. Thus %q will quote each element of a slice
+ of strings, and %6.2f will control formatting for each element
+ of a floating-point array.
+
+ However, when printing a byte slice with a string-like verb
+ (%s %q %x %X), it is treated identically to a string, as a single item.
+
+ To avoid recursion in cases such as
+ type X string
+ func (x X) String() string { return Sprintf("<%s>", x) }
+ convert the value before recurring:
+ func (x X) String() string { return Sprintf("<%s>", string(x)) }
+ Infinite recursion can also be triggered by self-referential data
+ structures, such as a slice that contains itself as an element, if
+ that type has a String method. Such pathologies are rare, however,
+ and the package does not protect against them.
+
+ When printing a struct, fmt cannot and therefore does not invoke
+ formatting methods such as Error or String on unexported fields.
+
+ Explicit argument indexes
+
+ In Printf, Sprintf, and Fprintf, the default behavior is for each
+ formatting verb to format successive arguments passed in the call.
+ However, the notation [n] immediately before the verb indicates that the
+ nth one-indexed argument is to be formatted instead. The same notation
+ before a '*' for a width or precision selects the argument index holding
+ the value. After processing a bracketed expression [n], subsequent verbs
+ will use arguments n+1, n+2, etc. unless otherwise directed.
+
+ For example,
+ fmt.Sprintf("%[2]d %[1]d\n", 11, 22)
+ will yield "22 11", while
+ fmt.Sprintf("%[3]*.[2]*[1]f", 12.0, 2, 6)
+ equivalent to
+ fmt.Sprintf("%6.2f", 12.0)
+ will yield " 12.00". Because an explicit index affects subsequent verbs,
+ this notation can be used to print the same values multiple times
+ by resetting the index for the first argument to be repeated:
+ fmt.Sprintf("%d %d %#[1]x %#x", 16, 17)
+ will yield "16 17 0x10 0x11".
+
+ Format errors
+
+ If an invalid argument is given for a verb, such as providing
+ a string to %d, the generated string will contain a
+ description of the problem, as in these examples:
+
+ Wrong type or unknown verb: %!verb(type=value)
+ Printf("%d", "hi"): %!d(string=hi)
+ Too many arguments: %!(EXTRA type=value)
+ Printf("hi", "guys"): hi%!(EXTRA string=guys)
+ Too few arguments: %!verb(MISSING)
+ Printf("hi%d"): hi%!d(MISSING)
+ Non-int for width or precision: %!(BADWIDTH) or %!(BADPREC)
+ Printf("%*s", 4.5, "hi"): %!(BADWIDTH)hi
+ Printf("%.*s", 4.5, "hi"): %!(BADPREC)hi
+ Invalid or invalid use of argument index: %!(BADINDEX)
+ Printf("%*[2]d", 7): %!d(BADINDEX)
+ Printf("%.[2]d", 7): %!d(BADINDEX)
+
+ All errors begin with the string "%!" followed sometimes
+ by a single character (the verb) and end with a parenthesized
+ description.
+
+ If an Error or String method triggers a panic when called by a
+ print routine, the fmt package reformats the error message
+ from the panic, decorating it with an indication that it came
+ through the fmt package. For example, if a String method
+ calls panic("bad"), the resulting formatted message will look
+ like
+ %!s(PANIC=bad)
+
+ The %!s just shows the print verb in use when the failure
+ occurred. If the panic is caused by a nil receiver to an Error
+ or String method, however, the output is the undecorated
+ string, "<nil>".
+
+ Scanning
+
+ An analogous set of functions scans formatted text to yield
+ values. Scan, Scanf and Scanln read from os.Stdin; Fscan,
+ Fscanf and Fscanln read from a specified io.Reader; Sscan,
+ Sscanf and Sscanln read from an argument string.
+
+ Scan, Fscan, Sscan treat newlines in the input as spaces.
+
+ Scanln, Fscanln and Sscanln stop scanning at a newline and
+ require that the items be followed by a newline or EOF.
+
+ Scanf, Fscanf, and Sscanf parse the arguments according to a
+ format string, analogous to that of Printf. In the text that
+ follows, 'space' means any Unicode whitespace character
+ except newline.
+
+ In the format string, a verb introduced by the % character
+ consumes and parses input; these verbs are described in more
+ detail below. A character other than %, space, or newline in
+ the format consumes exactly that input character, which must
+ be present. A newline with zero or more spaces before it in
+ the format string consumes zero or more spaces in the input
+ followed by a single newline or the end of the input. A space
+ following a newline in the format string consumes zero or more
+ spaces in the input. Otherwise, any run of one or more spaces
+ in the format string consumes as many spaces as possible in
+ the input. Unless the run of spaces in the format string
+ appears adjacent to a newline, the run must consume at least
+ one space from the input or find the end of the input.
+
+ The handling of spaces and newlines differs from that of C's
+ scanf family: in C, newlines are treated as any other space,
+ and it is never an error when a run of spaces in the format
+ string finds no spaces to consume in the input.
+
+ The verbs behave analogously to those of Printf.
+ For example, %x will scan an integer as a hexadecimal number,
+ and %v will scan the default representation format for the value.
+ The Printf verbs %p and %T and the flags # and + are not implemented.
+ For floating-point and complex values, all valid formatting verbs
+ (%b %e %E %f %F %g %G %x %X and %v) are equivalent and accept
+ both decimal and hexadecimal notation (for example: "2.3e+7", "0x4.5p-8")
+ and digit-separating underscores (for example: "3.14159_26535_89793").
+
+ Input processed by verbs is implicitly space-delimited: the
+ implementation of every verb except %c starts by discarding
+ leading spaces from the remaining input, and the %s verb
+ (and %v reading into a string) stops consuming input at the first
+ space or newline character.
+
+ The familiar base-setting prefixes 0b (binary), 0o and 0 (octal),
+ and 0x (hexadecimal) are accepted when scanning integers
+ without a format or with the %v verb, as are digit-separating
+ underscores.
+
+ Width is interpreted in the input text but there is no
+ syntax for scanning with a precision (no %5.2f, just %5f).
+ If width is provided, it applies after leading spaces are
+ trimmed and specifies the maximum number of runes to read
+ to satisfy the verb. For example,
+ Sscanf(" 1234567 ", "%5s%d", &s, &i)
+ will set s to "12345" and i to 67 while
+ Sscanf(" 12 34 567 ", "%5s%d", &s, &i)
+ will set s to "12" and i to 34.
+
+ In all the scanning functions, a carriage return followed
+ immediately by a newline is treated as a plain newline
+ (\r\n means the same as \n).
+
+ In all the scanning functions, if an operand implements method
+ Scan (that is, it implements the Scanner interface) that
+ method will be used to scan the text for that operand. Also,
+ if the number of arguments scanned is less than the number of
+ arguments provided, an error is returned.
+
+ All arguments to be scanned must be either pointers to basic
+ types or implementations of the Scanner interface.
+
+ Like Scanf and Fscanf, Sscanf need not consume its entire input.
+ There is no way to recover how much of the input string Sscanf used.
+
+ Note: Fscan etc. can read one character (rune) past the input
+ they return, which means that a loop calling a scan routine
+ may skip some of the input. This is usually a problem only
+ when there is no space between input values. If the reader
+ provided to Fscan implements ReadRune, that method will be used
+ to read characters. If the reader also implements UnreadRune,
+ that method will be used to save the character and successive
+ calls will not lose data. To attach ReadRune and UnreadRune
+ methods to a reader without that capability, use
+ bufio.NewReader.
+*/
+package fmt
diff --git a/src/fmt/errors.go b/src/fmt/errors.go
new file mode 100644
index 0000000..4f4daf1
--- /dev/null
+++ b/src/fmt/errors.go
@@ -0,0 +1,43 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt
+
+import "errors"
+
+// Errorf formats according to a format specifier and returns the string as a
+// value that satisfies error.
+//
+// If the format specifier includes a %w verb with an error operand,
+// the returned error will implement an Unwrap method returning the operand. It is
+// invalid to include more than one %w verb or to supply it with an operand
+// that does not implement the error interface. The %w verb is otherwise
+// a synonym for %v.
+func Errorf(format string, a ...any) error {
+ p := newPrinter()
+ p.wrapErrs = true
+ p.doPrintf(format, a)
+ s := string(p.buf)
+ var err error
+ if p.wrappedErr == nil {
+ err = errors.New(s)
+ } else {
+ err = &wrapError{s, p.wrappedErr}
+ }
+ p.free()
+ return err
+}
+
+type wrapError struct {
+ msg string
+ err error
+}
+
+func (e *wrapError) Error() string {
+ return e.msg
+}
+
+func (e *wrapError) Unwrap() error {
+ return e.err
+}
diff --git a/src/fmt/errors_test.go b/src/fmt/errors_test.go
new file mode 100644
index 0000000..481a7b8
--- /dev/null
+++ b/src/fmt/errors_test.go
@@ -0,0 +1,77 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt_test
+
+import (
+ "errors"
+ "fmt"
+ "testing"
+)
+
+func TestErrorf(t *testing.T) {
+ // noVetErrorf is an alias for fmt.Errorf that does not trigger vet warnings for
+ // %w format strings.
+ noVetErrorf := fmt.Errorf
+
+ wrapped := errors.New("inner error")
+ for _, test := range []struct {
+ err error
+ wantText string
+ wantUnwrap error
+ }{{
+ err: fmt.Errorf("%w", wrapped),
+ wantText: "inner error",
+ wantUnwrap: wrapped,
+ }, {
+ err: fmt.Errorf("added context: %w", wrapped),
+ wantText: "added context: inner error",
+ wantUnwrap: wrapped,
+ }, {
+ err: fmt.Errorf("%w with added context", wrapped),
+ wantText: "inner error with added context",
+ wantUnwrap: wrapped,
+ }, {
+ err: fmt.Errorf("%s %w %v", "prefix", wrapped, "suffix"),
+ wantText: "prefix inner error suffix",
+ wantUnwrap: wrapped,
+ }, {
+ err: fmt.Errorf("%[2]s: %[1]w", wrapped, "positional verb"),
+ wantText: "positional verb: inner error",
+ wantUnwrap: wrapped,
+ }, {
+ err: fmt.Errorf("%v", wrapped),
+ wantText: "inner error",
+ }, {
+ err: fmt.Errorf("added context: %v", wrapped),
+ wantText: "added context: inner error",
+ }, {
+ err: fmt.Errorf("%v with added context", wrapped),
+ wantText: "inner error with added context",
+ }, {
+ err: noVetErrorf("%w is not an error", "not-an-error"),
+ wantText: "%!w(string=not-an-error) is not an error",
+ }, {
+ err: noVetErrorf("wrapped two errors: %w %w", errString("1"), errString("2")),
+ wantText: "wrapped two errors: 1 %!w(fmt_test.errString=2)",
+ }, {
+ err: noVetErrorf("wrapped three errors: %w %w %w", errString("1"), errString("2"), errString("3")),
+ wantText: "wrapped three errors: 1 %!w(fmt_test.errString=2) %!w(fmt_test.errString=3)",
+ }, {
+ err: fmt.Errorf("%w", nil),
+ wantText: "%!w(<nil>)",
+ wantUnwrap: nil, // still nil
+ }} {
+ if got, want := errors.Unwrap(test.err), test.wantUnwrap; got != want {
+ t.Errorf("Formatted error: %v\nerrors.Unwrap() = %v, want %v", test.err, got, want)
+ }
+ if got, want := test.err.Error(), test.wantText; got != want {
+ t.Errorf("err.Error() = %q, want %q", got, want)
+ }
+ }
+}
+
+type errString string
+
+func (e errString) Error() string { return string(e) }
diff --git a/src/fmt/example_test.go b/src/fmt/example_test.go
new file mode 100644
index 0000000..5962834
--- /dev/null
+++ b/src/fmt/example_test.go
@@ -0,0 +1,365 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt_test
+
+import (
+ "fmt"
+ "io"
+ "math"
+ "os"
+ "strings"
+ "time"
+)
+
+// The Errorf function lets us use formatting features
+// to create descriptive error messages.
+func ExampleErrorf() {
+ const name, id = "bueller", 17
+ err := fmt.Errorf("user %q (id %d) not found", name, id)
+ fmt.Println(err.Error())
+
+ // Output: user "bueller" (id 17) not found
+}
+
+func ExampleFscanf() {
+ var (
+ i int
+ b bool
+ s string
+ )
+ r := strings.NewReader("5 true gophers")
+ n, err := fmt.Fscanf(r, "%d %t %s", &i, &b, &s)
+ if err != nil {
+ fmt.Fprintf(os.Stderr, "Fscanf: %v\n", err)
+ }
+ fmt.Println(i, b, s)
+ fmt.Println(n)
+ // Output:
+ // 5 true gophers
+ // 3
+}
+
+func ExampleFscanln() {
+ s := `dmr 1771 1.61803398875
+ ken 271828 3.14159`
+ r := strings.NewReader(s)
+ var a string
+ var b int
+ var c float64
+ for {
+ n, err := fmt.Fscanln(r, &a, &b, &c)
+ if err == io.EOF {
+ break
+ }
+ if err != nil {
+ panic(err)
+ }
+ fmt.Printf("%d: %s, %d, %f\n", n, a, b, c)
+ }
+ // Output:
+ // 3: dmr, 1771, 1.618034
+ // 3: ken, 271828, 3.141590
+}
+
+func ExampleSscanf() {
+ var name string
+ var age int
+ n, err := fmt.Sscanf("Kim is 22 years old", "%s is %d years old", &name, &age)
+ if err != nil {
+ panic(err)
+ }
+ fmt.Printf("%d: %s, %d\n", n, name, age)
+
+ // Output:
+ // 2: Kim, 22
+}
+
+func ExamplePrint() {
+ const name, age = "Kim", 22
+ fmt.Print(name, " is ", age, " years old.\n")
+
+ // It is conventional not to worry about any
+ // error returned by Print.
+
+ // Output:
+ // Kim is 22 years old.
+}
+
+func ExamplePrintln() {
+ const name, age = "Kim", 22
+ fmt.Println(name, "is", age, "years old.")
+
+ // It is conventional not to worry about any
+ // error returned by Println.
+
+ // Output:
+ // Kim is 22 years old.
+}
+
+func ExamplePrintf() {
+ const name, age = "Kim", 22
+ fmt.Printf("%s is %d years old.\n", name, age)
+
+ // It is conventional not to worry about any
+ // error returned by Printf.
+
+ // Output:
+ // Kim is 22 years old.
+}
+
+func ExampleSprint() {
+ const name, age = "Kim", 22
+ s := fmt.Sprint(name, " is ", age, " years old.\n")
+
+ io.WriteString(os.Stdout, s) // Ignoring error for simplicity.
+
+ // Output:
+ // Kim is 22 years old.
+}
+
+func ExampleSprintln() {
+ const name, age = "Kim", 22
+ s := fmt.Sprintln(name, "is", age, "years old.")
+
+ io.WriteString(os.Stdout, s) // Ignoring error for simplicity.
+
+ // Output:
+ // Kim is 22 years old.
+}
+
+func ExampleSprintf() {
+ const name, age = "Kim", 22
+ s := fmt.Sprintf("%s is %d years old.\n", name, age)
+
+ io.WriteString(os.Stdout, s) // Ignoring error for simplicity.
+
+ // Output:
+ // Kim is 22 years old.
+}
+
+func ExampleFprint() {
+ const name, age = "Kim", 22
+ n, err := fmt.Fprint(os.Stdout, name, " is ", age, " years old.\n")
+
+ // The n and err return values from Fprint are
+ // those returned by the underlying io.Writer.
+ if err != nil {
+ fmt.Fprintf(os.Stderr, "Fprint: %v\n", err)
+ }
+ fmt.Print(n, " bytes written.\n")
+
+ // Output:
+ // Kim is 22 years old.
+ // 21 bytes written.
+}
+
+func ExampleFprintln() {
+ const name, age = "Kim", 22
+ n, err := fmt.Fprintln(os.Stdout, name, "is", age, "years old.")
+
+ // The n and err return values from Fprintln are
+ // those returned by the underlying io.Writer.
+ if err != nil {
+ fmt.Fprintf(os.Stderr, "Fprintln: %v\n", err)
+ }
+ fmt.Println(n, "bytes written.")
+
+ // Output:
+ // Kim is 22 years old.
+ // 21 bytes written.
+}
+
+func ExampleFprintf() {
+ const name, age = "Kim", 22
+ n, err := fmt.Fprintf(os.Stdout, "%s is %d years old.\n", name, age)
+
+ // The n and err return values from Fprintf are
+ // those returned by the underlying io.Writer.
+ if err != nil {
+ fmt.Fprintf(os.Stderr, "Fprintf: %v\n", err)
+ }
+ fmt.Printf("%d bytes written.\n", n)
+
+ // Output:
+ // Kim is 22 years old.
+ // 21 bytes written.
+}
+
+// Print, Println, and Printf lay out their arguments differently. In this example
+// we can compare their behaviors. Println always adds blanks between the items it
+// prints, while Print adds blanks only between non-string arguments and Printf
+// does exactly what it is told.
+// Sprint, Sprintln, Sprintf, Fprint, Fprintln, and Fprintf behave the same as
+// their corresponding Print, Println, and Printf functions shown here.
+func Example_printers() {
+ a, b := 3.0, 4.0
+ h := math.Hypot(a, b)
+
+ // Print inserts blanks between arguments when neither is a string.
+ // It does not add a newline to the output, so we add one explicitly.
+ fmt.Print("The vector (", a, b, ") has length ", h, ".\n")
+
+ // Println always inserts spaces between its arguments,
+ // so it cannot be used to produce the same output as Print in this case;
+ // its output has extra spaces.
+ // Also, Println always adds a newline to the output.
+ fmt.Println("The vector (", a, b, ") has length", h, ".")
+
+ // Printf provides complete control but is more complex to use.
+ // It does not add a newline to the output, so we add one explicitly
+ // at the end of the format specifier string.
+ fmt.Printf("The vector (%g %g) has length %g.\n", a, b, h)
+
+ // Output:
+ // The vector (3 4) has length 5.
+ // The vector ( 3 4 ) has length 5 .
+ // The vector (3 4) has length 5.
+}
+
+// These examples demonstrate the basics of printing using a format string. Printf,
+// Sprintf, and Fprintf all take a format string that specifies how to format the
+// subsequent arguments. For example, %d (we call that a 'verb') says to print the
+// corresponding argument, which must be an integer (or something containing an
+// integer, such as a slice of ints) in decimal. The verb %v ('v' for 'value')
+// always formats the argument in its default form, just how Print or Println would
+// show it. The special verb %T ('T' for 'Type') prints the type of the argument
+// rather than its value. The examples are not exhaustive; see the package comment
+// for all the details.
+func Example_formats() {
+ // A basic set of examples showing that %v is the default format, in this
+ // case decimal for integers, which can be explicitly requested with %d;
+ // the output is just what Println generates.
+ integer := 23
+ // Each of these prints "23" (without the quotes).
+ fmt.Println(integer)
+ fmt.Printf("%v\n", integer)
+ fmt.Printf("%d\n", integer)
+
+ // The special verb %T shows the type of an item rather than its value.
+ fmt.Printf("%T %T\n", integer, &integer)
+ // Result: int *int
+
+ // Println(x) is the same as Printf("%v\n", x) so we will use only Printf
+ // in the following examples. Each one demonstrates how to format values of
+ // a particular type, such as integers or strings. We start each format
+ // string with %v to show the default output and follow that with one or
+ // more custom formats.
+
+ // Booleans print as "true" or "false" with %v or %t.
+ truth := true
+ fmt.Printf("%v %t\n", truth, truth)
+ // Result: true true
+
+ // Integers print as decimals with %v and %d,
+ // or in hex with %x, octal with %o, or binary with %b.
+ answer := 42
+ fmt.Printf("%v %d %x %o %b\n", answer, answer, answer, answer, answer)
+ // Result: 42 42 2a 52 101010
+
+ // Floats have multiple formats: %v and %g print a compact representation,
+ // while %f prints a decimal point and %e uses exponential notation. The
+ // format %6.2f used here shows how to set the width and precision to
+ // control the appearance of a floating-point value. In this instance, 6 is
+ // the total width of the printed text for the value (note the extra spaces
+ // in the output) and 2 is the number of decimal places to show.
+ pi := math.Pi
+ fmt.Printf("%v %g %.2f (%6.2f) %e\n", pi, pi, pi, pi, pi)
+ // Result: 3.141592653589793 3.141592653589793 3.14 ( 3.14) 3.141593e+00
+
+ // Complex numbers format as parenthesized pairs of floats, with an 'i'
+ // after the imaginary part.
+ point := 110.7 + 22.5i
+ fmt.Printf("%v %g %.2f %.2e\n", point, point, point, point)
+ // Result: (110.7+22.5i) (110.7+22.5i) (110.70+22.50i) (1.11e+02+2.25e+01i)
+
+ // Runes are integers but when printed with %c show the character with that
+ // Unicode value. The %q verb shows them as quoted characters, %U as a
+ // hex Unicode code point, and %#U as both a code point and a quoted
+ // printable form if the rune is printable.
+ smile := '😀'
+ fmt.Printf("%v %d %c %q %U %#U\n", smile, smile, smile, smile, smile, smile)
+ // Result: 128512 128512 😀 '😀' U+1F600 U+1F600 '😀'
+
+ // Strings are formatted with %v and %s as-is, with %q as quoted strings,
+ // and %#q as backquoted strings.
+ placeholders := `foo "bar"`
+ fmt.Printf("%v %s %q %#q\n", placeholders, placeholders, placeholders, placeholders)
+ // Result: foo "bar" foo "bar" "foo \"bar\"" `foo "bar"`
+
+ // Maps formatted with %v show keys and values in their default formats.
+ // The %#v form (the # is called a "flag" in this context) shows the map in
+ // the Go source format. Maps are printed in a consistent order, sorted
+ // by the values of the keys.
+ isLegume := map[string]bool{
+ "peanut": true,
+ "dachshund": false,
+ }
+ fmt.Printf("%v %#v\n", isLegume, isLegume)
+ // Result: map[dachshund:false peanut:true] map[string]bool{"dachshund":false, "peanut":true}
+
+ // Structs formatted with %v show field values in their default formats.
+ // The %+v form shows the fields by name, while %#v formats the struct in
+ // Go source format.
+ person := struct {
+ Name string
+ Age int
+ }{"Kim", 22}
+ fmt.Printf("%v %+v %#v\n", person, person, person)
+ // Result: {Kim 22} {Name:Kim Age:22} struct { Name string; Age int }{Name:"Kim", Age:22}
+
+ // The default format for a pointer shows the underlying value preceded by
+ // an ampersand. The %p verb prints the pointer value in hex. We use a
+ // typed nil for the argument to %p here because the value of any non-nil
+ // pointer would change from run to run; run the commented-out Printf
+ // call yourself to see.
+ pointer := &person
+ fmt.Printf("%v %p\n", pointer, (*int)(nil))
+ // Result: &{Kim 22} 0x0
+ // fmt.Printf("%v %p\n", pointer, pointer)
+ // Result: &{Kim 22} 0x010203 // See comment above.
+
+ // Arrays and slices are formatted by applying the format to each element.
+ greats := [5]string{"Kitano", "Kobayashi", "Kurosawa", "Miyazaki", "Ozu"}
+ fmt.Printf("%v %q\n", greats, greats)
+ // Result: [Kitano Kobayashi Kurosawa Miyazaki Ozu] ["Kitano" "Kobayashi" "Kurosawa" "Miyazaki" "Ozu"]
+
+ kGreats := greats[:3]
+ fmt.Printf("%v %q %#v\n", kGreats, kGreats, kGreats)
+ // Result: [Kitano Kobayashi Kurosawa] ["Kitano" "Kobayashi" "Kurosawa"] []string{"Kitano", "Kobayashi", "Kurosawa"}
+
+ // Byte slices are special. Integer verbs like %d print the elements in
+ // that format. The %s and %q forms treat the slice like a string. The %x
+ // verb has a special form with the space flag that puts a space between
+ // the bytes.
+ cmd := []byte("a⌘")
+ fmt.Printf("%v %d %s %q %x % x\n", cmd, cmd, cmd, cmd, cmd, cmd)
+ // Result: [97 226 140 152] [97 226 140 152] a⌘ "a⌘" 61e28c98 61 e2 8c 98
+
+ // Types that implement Stringer are printed the same as strings. Because
+ // Stringers return a string, we can print them using a string-specific
+ // verb such as %q.
+ now := time.Unix(123456789, 0).UTC() // time.Time implements fmt.Stringer.
+ fmt.Printf("%v %q\n", now, now)
+ // Result: 1973-11-29 21:33:09 +0000 UTC "1973-11-29 21:33:09 +0000 UTC"
+
+ // Output:
+ // 23
+ // 23
+ // 23
+ // int *int
+ // true true
+ // 42 42 2a 52 101010
+ // 3.141592653589793 3.141592653589793 3.14 ( 3.14) 3.141593e+00
+ // (110.7+22.5i) (110.7+22.5i) (110.70+22.50i) (1.11e+02+2.25e+01i)
+ // 128512 128512 😀 '😀' U+1F600 U+1F600 '😀'
+ // foo "bar" foo "bar" "foo \"bar\"" `foo "bar"`
+ // map[dachshund:false peanut:true] map[string]bool{"dachshund":false, "peanut":true}
+ // {Kim 22} {Name:Kim Age:22} struct { Name string; Age int }{Name:"Kim", Age:22}
+ // &{Kim 22} 0x0
+ // [Kitano Kobayashi Kurosawa Miyazaki Ozu] ["Kitano" "Kobayashi" "Kurosawa" "Miyazaki" "Ozu"]
+ // [Kitano Kobayashi Kurosawa] ["Kitano" "Kobayashi" "Kurosawa"] []string{"Kitano", "Kobayashi", "Kurosawa"}
+ // [97 226 140 152] [97 226 140 152] a⌘ "a⌘" 61e28c98 61 e2 8c 98
+ // 1973-11-29 21:33:09 +0000 UTC "1973-11-29 21:33:09 +0000 UTC"
+}
diff --git a/src/fmt/export_test.go b/src/fmt/export_test.go
new file mode 100644
index 0000000..14163a2
--- /dev/null
+++ b/src/fmt/export_test.go
@@ -0,0 +1,8 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt
+
+var IsSpace = isSpace
+var Parsenum = parsenum
diff --git a/src/fmt/fmt_test.go b/src/fmt/fmt_test.go
new file mode 100644
index 0000000..a4c65b8
--- /dev/null
+++ b/src/fmt/fmt_test.go
@@ -0,0 +1,1898 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt_test
+
+import (
+ "bytes"
+ . "fmt"
+ "internal/race"
+ "io"
+ "math"
+ "reflect"
+ "runtime"
+ "strings"
+ "testing"
+ "time"
+ "unicode"
+)
+
+type (
+ renamedBool bool
+ renamedInt int
+ renamedInt8 int8
+ renamedInt16 int16
+ renamedInt32 int32
+ renamedInt64 int64
+ renamedUint uint
+ renamedUint8 uint8
+ renamedUint16 uint16
+ renamedUint32 uint32
+ renamedUint64 uint64
+ renamedUintptr uintptr
+ renamedString string
+ renamedBytes []byte
+ renamedFloat32 float32
+ renamedFloat64 float64
+ renamedComplex64 complex64
+ renamedComplex128 complex128
+)
+
+func TestFmtInterface(t *testing.T) {
+ var i1 any
+ i1 = "abc"
+ s := Sprintf("%s", i1)
+ if s != "abc" {
+ t.Errorf(`Sprintf("%%s", empty("abc")) = %q want %q`, s, "abc")
+ }
+}
+
+var (
+ NaN = math.NaN()
+ posInf = math.Inf(1)
+ negInf = math.Inf(-1)
+
+ intVar = 0
+
+ array = [5]int{1, 2, 3, 4, 5}
+ iarray = [4]any{1, "hello", 2.5, nil}
+ slice = array[:]
+ islice = iarray[:]
+)
+
+type A struct {
+ i int
+ j uint
+ s string
+ x []int
+}
+
+type I int
+
+func (i I) String() string { return Sprintf("<%d>", int(i)) }
+
+type B struct {
+ I I
+ j int
+}
+
+type C struct {
+ i int
+ B
+}
+
+type F int
+
+func (f F) Format(s State, c rune) {
+ Fprintf(s, "<%c=F(%d)>", c, int(f))
+}
+
+type G int
+
+func (g G) GoString() string {
+ return Sprintf("GoString(%d)", int(g))
+}
+
+type S struct {
+ F F // a struct field that Formats
+ G G // a struct field that GoStrings
+}
+
+type SI struct {
+ I any
+}
+
+// P is a type with a String method with pointer receiver for testing %p.
+type P int
+
+var pValue P
+
+func (p *P) String() string {
+ return "String(p)"
+}
+
+var barray = [5]renamedUint8{1, 2, 3, 4, 5}
+var bslice = barray[:]
+
+type byteStringer byte
+
+func (byteStringer) String() string {
+ return "X"
+}
+
+var byteStringerSlice = []byteStringer{'h', 'e', 'l', 'l', 'o'}
+
+type byteFormatter byte
+
+func (byteFormatter) Format(f State, _ rune) {
+ Fprint(f, "X")
+}
+
+var byteFormatterSlice = []byteFormatter{'h', 'e', 'l', 'l', 'o'}
+
+type writeStringFormatter string
+
+func (sf writeStringFormatter) Format(f State, c rune) {
+ if sw, ok := f.(io.StringWriter); ok {
+ sw.WriteString("***" + string(sf) + "***")
+ }
+}
+
+var fmtTests = []struct {
+ fmt string
+ val any
+ out string
+}{
+ {"%d", 12345, "12345"},
+ {"%v", 12345, "12345"},
+ {"%t", true, "true"},
+
+ // basic string
+ {"%s", "abc", "abc"},
+ {"%q", "abc", `"abc"`},
+ {"%x", "abc", "616263"},
+ {"%x", "\xff\xf0\x0f\xff", "fff00fff"},
+ {"%X", "\xff\xf0\x0f\xff", "FFF00FFF"},
+ {"%x", "", ""},
+ {"% x", "", ""},
+ {"%#x", "", ""},
+ {"%# x", "", ""},
+ {"%x", "xyz", "78797a"},
+ {"%X", "xyz", "78797A"},
+ {"% x", "xyz", "78 79 7a"},
+ {"% X", "xyz", "78 79 7A"},
+ {"%#x", "xyz", "0x78797a"},
+ {"%#X", "xyz", "0X78797A"},
+ {"%# x", "xyz", "0x78 0x79 0x7a"},
+ {"%# X", "xyz", "0X78 0X79 0X7A"},
+
+ // basic bytes
+ {"%s", []byte("abc"), "abc"},
+ {"%s", [3]byte{'a', 'b', 'c'}, "abc"},
+ {"%s", &[3]byte{'a', 'b', 'c'}, "&abc"},
+ {"%q", []byte("abc"), `"abc"`},
+ {"%x", []byte("abc"), "616263"},
+ {"%x", []byte("\xff\xf0\x0f\xff"), "fff00fff"},
+ {"%X", []byte("\xff\xf0\x0f\xff"), "FFF00FFF"},
+ {"%x", []byte(""), ""},
+ {"% x", []byte(""), ""},
+ {"%#x", []byte(""), ""},
+ {"%# x", []byte(""), ""},
+ {"%x", []byte("xyz"), "78797a"},
+ {"%X", []byte("xyz"), "78797A"},
+ {"% x", []byte("xyz"), "78 79 7a"},
+ {"% X", []byte("xyz"), "78 79 7A"},
+ {"%#x", []byte("xyz"), "0x78797a"},
+ {"%#X", []byte("xyz"), "0X78797A"},
+ {"%# x", []byte("xyz"), "0x78 0x79 0x7a"},
+ {"%# X", []byte("xyz"), "0X78 0X79 0X7A"},
+
+ // escaped strings
+ {"%q", "", `""`},
+ {"%#q", "", "``"},
+ {"%q", "\"", `"\""`},
+ {"%#q", "\"", "`\"`"},
+ {"%q", "`", `"` + "`" + `"`},
+ {"%#q", "`", `"` + "`" + `"`},
+ {"%q", "\n", `"\n"`},
+ {"%#q", "\n", `"\n"`},
+ {"%q", `\n`, `"\\n"`},
+ {"%#q", `\n`, "`\\n`"},
+ {"%q", "abc", `"abc"`},
+ {"%#q", "abc", "`abc`"},
+ {"%q", "日本語", `"日本語"`},
+ {"%+q", "日本語", `"\u65e5\u672c\u8a9e"`},
+ {"%#q", "日本語", "`日本語`"},
+ {"%#+q", "日本語", "`日本語`"},
+ {"%q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+ {"%+q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+ {"%#q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+ {"%#+q", "\a\b\f\n\r\t\v\"\\", `"\a\b\f\n\r\t\v\"\\"`},
+ {"%q", "☺", `"☺"`},
+ {"% q", "☺", `"☺"`}, // The space modifier should have no effect.
+ {"%+q", "☺", `"\u263a"`},
+ {"%#q", "☺", "`☺`"},
+ {"%#+q", "☺", "`☺`"},
+ {"%10q", "⌘", ` "⌘"`},
+ {"%+10q", "⌘", ` "\u2318"`},
+ {"%-10q", "⌘", `"⌘" `},
+ {"%+-10q", "⌘", `"\u2318" `},
+ {"%010q", "⌘", `0000000"⌘"`},
+ {"%+010q", "⌘", `00"\u2318"`},
+ {"%-010q", "⌘", `"⌘" `}, // 0 has no effect when - is present.
+ {"%+-010q", "⌘", `"\u2318" `},
+ {"%#8q", "\n", ` "\n"`},
+ {"%#+8q", "\r", ` "\r"`},
+ {"%#-8q", "\t", "` ` "},
+ {"%#+-8q", "\b", `"\b" `},
+ {"%q", "abc\xffdef", `"abc\xffdef"`},
+ {"%+q", "abc\xffdef", `"abc\xffdef"`},
+ {"%#q", "abc\xffdef", `"abc\xffdef"`},
+ {"%#+q", "abc\xffdef", `"abc\xffdef"`},
+ // Runes that are not printable.
+ {"%q", "\U0010ffff", `"\U0010ffff"`},
+ {"%+q", "\U0010ffff", `"\U0010ffff"`},
+ {"%#q", "\U0010ffff", "`􏿿`"},
+ {"%#+q", "\U0010ffff", "`􏿿`"},
+ // Runes that are not valid.
+ {"%q", string(rune(0x110000)), `"�"`},
+ {"%+q", string(rune(0x110000)), `"\ufffd"`},
+ {"%#q", string(rune(0x110000)), "`�`"},
+ {"%#+q", string(rune(0x110000)), "`�`"},
+
+ // characters
+ {"%c", uint('x'), "x"},
+ {"%c", 0xe4, "ä"},
+ {"%c", 0x672c, "本"},
+ {"%c", '日', "日"},
+ {"%.0c", '⌘', "⌘"}, // Specifying precision should have no effect.
+ {"%3c", '⌘', " ⌘"},
+ {"%-3c", '⌘', "⌘ "},
+ // Runes that are not printable.
+ {"%c", '\U00000e00', "\u0e00"},
+ {"%c", '\U0010ffff', "\U0010ffff"},
+ // Runes that are not valid.
+ {"%c", -1, "�"},
+ {"%c", 0xDC80, "�"},
+ {"%c", rune(0x110000), "�"},
+ {"%c", int64(0xFFFFFFFFF), "�"},
+ {"%c", uint64(0xFFFFFFFFF), "�"},
+
+ // escaped characters
+ {"%q", uint(0), `'\x00'`},
+ {"%+q", uint(0), `'\x00'`},
+ {"%q", '"', `'"'`},
+ {"%+q", '"', `'"'`},
+ {"%q", '\'', `'\''`},
+ {"%+q", '\'', `'\''`},
+ {"%q", '`', "'`'"},
+ {"%+q", '`', "'`'"},
+ {"%q", 'x', `'x'`},
+ {"%+q", 'x', `'x'`},
+ {"%q", 'ÿ', `'ÿ'`},
+ {"%+q", 'ÿ', `'\u00ff'`},
+ {"%q", '\n', `'\n'`},
+ {"%+q", '\n', `'\n'`},
+ {"%q", '☺', `'☺'`},
+ {"%+q", '☺', `'\u263a'`},
+ {"% q", '☺', `'☺'`}, // The space modifier should have no effect.
+ {"%.0q", '☺', `'☺'`}, // Specifying precision should have no effect.
+ {"%10q", '⌘', ` '⌘'`},
+ {"%+10q", '⌘', ` '\u2318'`},
+ {"%-10q", '⌘', `'⌘' `},
+ {"%+-10q", '⌘', `'\u2318' `},
+ {"%010q", '⌘', `0000000'⌘'`},
+ {"%+010q", '⌘', `00'\u2318'`},
+ {"%-010q", '⌘', `'⌘' `}, // 0 has no effect when - is present.
+ {"%+-010q", '⌘', `'\u2318' `},
+ // Runes that are not printable.
+ {"%q", '\U00000e00', `'\u0e00'`},
+ {"%q", '\U0010ffff', `'\U0010ffff'`},
+ // Runes that are not valid.
+ {"%q", int32(-1), `'�'`},
+ {"%q", 0xDC80, `'�'`},
+ {"%q", rune(0x110000), `'�'`},
+ {"%q", int64(0xFFFFFFFFF), `'�'`},
+ {"%q", uint64(0xFFFFFFFFF), `'�'`},
+
+ // width
+ {"%5s", "abc", " abc"},
+ {"%5s", []byte("abc"), " abc"},
+ {"%2s", "\u263a", " ☺"},
+ {"%2s", []byte("\u263a"), " ☺"},
+ {"%-5s", "abc", "abc "},
+ {"%-5s", []byte("abc"), "abc "},
+ {"%05s", "abc", "00abc"},
+ {"%05s", []byte("abc"), "00abc"},
+ {"%5s", "abcdefghijklmnopqrstuvwxyz", "abcdefghijklmnopqrstuvwxyz"},
+ {"%5s", []byte("abcdefghijklmnopqrstuvwxyz"), "abcdefghijklmnopqrstuvwxyz"},
+ {"%.5s", "abcdefghijklmnopqrstuvwxyz", "abcde"},
+ {"%.5s", []byte("abcdefghijklmnopqrstuvwxyz"), "abcde"},
+ {"%.0s", "日本語日本語", ""},
+ {"%.0s", []byte("日本語日本語"), ""},
+ {"%.5s", "日本語日本語", "日本語日本"},
+ {"%.5s", []byte("日本語日本語"), "日本語日本"},
+ {"%.10s", "日本語日本語", "日本語日本語"},
+ {"%.10s", []byte("日本語日本語"), "日本語日本語"},
+ {"%08q", "abc", `000"abc"`},
+ {"%08q", []byte("abc"), `000"abc"`},
+ {"%-8q", "abc", `"abc" `},
+ {"%-8q", []byte("abc"), `"abc" `},
+ {"%.5q", "abcdefghijklmnopqrstuvwxyz", `"abcde"`},
+ {"%.5q", []byte("abcdefghijklmnopqrstuvwxyz"), `"abcde"`},
+ {"%.5x", "abcdefghijklmnopqrstuvwxyz", "6162636465"},
+ {"%.5x", []byte("abcdefghijklmnopqrstuvwxyz"), "6162636465"},
+ {"%.3q", "日本語日本語", `"日本語"`},
+ {"%.3q", []byte("日本語日本語"), `"日本語"`},
+ {"%.1q", "日本語", `"日"`},
+ {"%.1q", []byte("日本語"), `"日"`},
+ {"%.1x", "日本語", "e6"},
+ {"%.1X", []byte("日本語"), "E6"},
+ {"%10.1q", "日本語日本語", ` "日"`},
+ {"%10.1q", []byte("日本語日本語"), ` "日"`},
+ {"%10v", nil, " <nil>"},
+ {"%-10v", nil, "<nil> "},
+
+ // integers
+ {"%d", uint(12345), "12345"},
+ {"%d", int(-12345), "-12345"},
+ {"%d", ^uint8(0), "255"},
+ {"%d", ^uint16(0), "65535"},
+ {"%d", ^uint32(0), "4294967295"},
+ {"%d", ^uint64(0), "18446744073709551615"},
+ {"%d", int8(-1 << 7), "-128"},
+ {"%d", int16(-1 << 15), "-32768"},
+ {"%d", int32(-1 << 31), "-2147483648"},
+ {"%d", int64(-1 << 63), "-9223372036854775808"},
+ {"%.d", 0, ""},
+ {"%.0d", 0, ""},
+ {"%6.0d", 0, " "},
+ {"%06.0d", 0, " "},
+ {"% d", 12345, " 12345"},
+ {"%+d", 12345, "+12345"},
+ {"%+d", -12345, "-12345"},
+ {"%b", 7, "111"},
+ {"%b", -6, "-110"},
+ {"%#b", 7, "0b111"},
+ {"%#b", -6, "-0b110"},
+ {"%b", ^uint32(0), "11111111111111111111111111111111"},
+ {"%b", ^uint64(0), "1111111111111111111111111111111111111111111111111111111111111111"},
+ {"%b", int64(-1 << 63), zeroFill("-1", 63, "")},
+ {"%o", 01234, "1234"},
+ {"%o", -01234, "-1234"},
+ {"%#o", 01234, "01234"},
+ {"%#o", -01234, "-01234"},
+ {"%O", 01234, "0o1234"},
+ {"%O", -01234, "-0o1234"},
+ {"%o", ^uint32(0), "37777777777"},
+ {"%o", ^uint64(0), "1777777777777777777777"},
+ {"%#X", 0, "0X0"},
+ {"%x", 0x12abcdef, "12abcdef"},
+ {"%X", 0x12abcdef, "12ABCDEF"},
+ {"%x", ^uint32(0), "ffffffff"},
+ {"%X", ^uint64(0), "FFFFFFFFFFFFFFFF"},
+ {"%.20b", 7, "00000000000000000111"},
+ {"%10d", 12345, " 12345"},
+ {"%10d", -12345, " -12345"},
+ {"%+10d", 12345, " +12345"},
+ {"%010d", 12345, "0000012345"},
+ {"%010d", -12345, "-000012345"},
+ {"%20.8d", 1234, " 00001234"},
+ {"%20.8d", -1234, " -00001234"},
+ {"%020.8d", 1234, " 00001234"},
+ {"%020.8d", -1234, " -00001234"},
+ {"%-20.8d", 1234, "00001234 "},
+ {"%-20.8d", -1234, "-00001234 "},
+ {"%-#20.8x", 0x1234abc, "0x01234abc "},
+ {"%-#20.8X", 0x1234abc, "0X01234ABC "},
+ {"%-#20.8o", 01234, "00001234 "},
+
+ // Test correct f.intbuf overflow checks.
+ {"%068d", 1, zeroFill("", 68, "1")},
+ {"%068d", -1, zeroFill("-", 67, "1")},
+ {"%#.68x", 42, zeroFill("0x", 68, "2a")},
+ {"%.68d", -42, zeroFill("-", 68, "42")},
+ {"%+.68d", 42, zeroFill("+", 68, "42")},
+ {"% .68d", 42, zeroFill(" ", 68, "42")},
+ {"% +.68d", 42, zeroFill("+", 68, "42")},
+
+ // unicode format
+ {"%U", 0, "U+0000"},
+ {"%U", -1, "U+FFFFFFFFFFFFFFFF"},
+ {"%U", '\n', `U+000A`},
+ {"%#U", '\n', `U+000A`},
+ {"%+U", 'x', `U+0078`}, // Plus flag should have no effect.
+ {"%# U", 'x', `U+0078 'x'`}, // Space flag should have no effect.
+ {"%#.2U", 'x', `U+0078 'x'`}, // Precisions below 4 should print 4 digits.
+ {"%U", '\u263a', `U+263A`},
+ {"%#U", '\u263a', `U+263A '☺'`},
+ {"%U", '\U0001D6C2', `U+1D6C2`},
+ {"%#U", '\U0001D6C2', `U+1D6C2 '𝛂'`},
+ {"%#14.6U", '⌘', " U+002318 '⌘'"},
+ {"%#-14.6U", '⌘', "U+002318 '⌘' "},
+ {"%#014.6U", '⌘', " U+002318 '⌘'"},
+ {"%#-014.6U", '⌘', "U+002318 '⌘' "},
+ {"%.68U", uint(42), zeroFill("U+", 68, "2A")},
+ {"%#.68U", '日', zeroFill("U+", 68, "65E5") + " '日'"},
+
+ // floats
+ {"%+.3e", 0.0, "+0.000e+00"},
+ {"%+.3e", 1.0, "+1.000e+00"},
+ {"%+.3x", 0.0, "+0x0.000p+00"},
+ {"%+.3x", 1.0, "+0x1.000p+00"},
+ {"%+.3f", -1.0, "-1.000"},
+ {"%+.3F", -1.0, "-1.000"},
+ {"%+.3F", float32(-1.0), "-1.000"},
+ {"%+07.2f", 1.0, "+001.00"},
+ {"%+07.2f", -1.0, "-001.00"},
+ {"%-07.2f", 1.0, "1.00 "},
+ {"%-07.2f", -1.0, "-1.00 "},
+ {"%+-07.2f", 1.0, "+1.00 "},
+ {"%+-07.2f", -1.0, "-1.00 "},
+ {"%-+07.2f", 1.0, "+1.00 "},
+ {"%-+07.2f", -1.0, "-1.00 "},
+ {"%+10.2f", +1.0, " +1.00"},
+ {"%+10.2f", -1.0, " -1.00"},
+ {"% .3E", -1.0, "-1.000E+00"},
+ {"% .3e", 1.0, " 1.000e+00"},
+ {"% .3X", -1.0, "-0X1.000P+00"},
+ {"% .3x", 1.0, " 0x1.000p+00"},
+ {"%+.3g", 0.0, "+0"},
+ {"%+.3g", 1.0, "+1"},
+ {"%+.3g", -1.0, "-1"},
+ {"% .3g", -1.0, "-1"},
+ {"% .3g", 1.0, " 1"},
+ {"%b", float32(1.0), "8388608p-23"},
+ {"%b", 1.0, "4503599627370496p-52"},
+ // Test sharp flag used with floats.
+ {"%#g", 1e-323, "1.00000e-323"},
+ {"%#g", -1.0, "-1.00000"},
+ {"%#g", 1.1, "1.10000"},
+ {"%#g", 123456.0, "123456."},
+ {"%#g", 1234567.0, "1.234567e+06"},
+ {"%#g", 1230000.0, "1.23000e+06"},
+ {"%#g", 1000000.0, "1.00000e+06"},
+ {"%#.0f", 1.0, "1."},
+ {"%#.0e", 1.0, "1.e+00"},
+ {"%#.0x", 1.0, "0x1.p+00"},
+ {"%#.0g", 1.0, "1."},
+ {"%#.0g", 1100000.0, "1.e+06"},
+ {"%#.4f", 1.0, "1.0000"},
+ {"%#.4e", 1.0, "1.0000e+00"},
+ {"%#.4x", 1.0, "0x1.0000p+00"},
+ {"%#.4g", 1.0, "1.000"},
+ {"%#.4g", 100000.0, "1.000e+05"},
+ {"%#.4g", 1.234, "1.234"},
+ {"%#.4g", 0.1234, "0.1234"},
+ {"%#.4g", 1.23, "1.230"},
+ {"%#.4g", 0.123, "0.1230"},
+ {"%#.4g", 1.2, "1.200"},
+ {"%#.4g", 0.12, "0.1200"},
+ {"%#.4g", 10.2, "10.20"},
+ {"%#.4g", 0.0, "0.000"},
+ {"%#.4g", 0.012, "0.01200"},
+ {"%#.0f", 123.0, "123."},
+ {"%#.0e", 123.0, "1.e+02"},
+ {"%#.0x", 123.0, "0x1.p+07"},
+ {"%#.0g", 123.0, "1.e+02"},
+ {"%#.4f", 123.0, "123.0000"},
+ {"%#.4e", 123.0, "1.2300e+02"},
+ {"%#.4x", 123.0, "0x1.ec00p+06"},
+ {"%#.4g", 123.0, "123.0"},
+ {"%#.4g", 123000.0, "1.230e+05"},
+ {"%#9.4g", 1.0, " 1.000"},
+ // The sharp flag has no effect for binary float format.
+ {"%#b", 1.0, "4503599627370496p-52"},
+ // Precision has no effect for binary float format.
+ {"%.4b", float32(1.0), "8388608p-23"},
+ {"%.4b", -1.0, "-4503599627370496p-52"},
+ // Test correct f.intbuf boundary checks.
+ {"%.68f", 1.0, zeroFill("1.", 68, "")},
+ {"%.68f", -1.0, zeroFill("-1.", 68, "")},
+ // float infinites and NaNs
+ {"%f", posInf, "+Inf"},
+ {"%.1f", negInf, "-Inf"},
+ {"% f", NaN, " NaN"},
+ {"%20f", posInf, " +Inf"},
+ {"% 20F", posInf, " Inf"},
+ {"% 20e", negInf, " -Inf"},
+ {"% 20x", negInf, " -Inf"},
+ {"%+20E", negInf, " -Inf"},
+ {"%+20X", negInf, " -Inf"},
+ {"% +20g", negInf, " -Inf"},
+ {"%+-20G", posInf, "+Inf "},
+ {"%20e", NaN, " NaN"},
+ {"%20x", NaN, " NaN"},
+ {"% +20E", NaN, " +NaN"},
+ {"% +20X", NaN, " +NaN"},
+ {"% -20g", NaN, " NaN "},
+ {"%+-20G", NaN, "+NaN "},
+ // Zero padding does not apply to infinities and NaN.
+ {"%+020e", posInf, " +Inf"},
+ {"%+020x", posInf, " +Inf"},
+ {"%-020f", negInf, "-Inf "},
+ {"%-020E", NaN, "NaN "},
+ {"%-020X", NaN, "NaN "},
+
+ // complex values
+ {"%.f", 0i, "(0+0i)"},
+ {"% .f", 0i, "( 0+0i)"},
+ {"%+.f", 0i, "(+0+0i)"},
+ {"% +.f", 0i, "(+0+0i)"},
+ {"%+.3e", 0i, "(+0.000e+00+0.000e+00i)"},
+ {"%+.3x", 0i, "(+0x0.000p+00+0x0.000p+00i)"},
+ {"%+.3f", 0i, "(+0.000+0.000i)"},
+ {"%+.3g", 0i, "(+0+0i)"},
+ {"%+.3e", 1 + 2i, "(+1.000e+00+2.000e+00i)"},
+ {"%+.3x", 1 + 2i, "(+0x1.000p+00+0x1.000p+01i)"},
+ {"%+.3f", 1 + 2i, "(+1.000+2.000i)"},
+ {"%+.3g", 1 + 2i, "(+1+2i)"},
+ {"%.3e", 0i, "(0.000e+00+0.000e+00i)"},
+ {"%.3x", 0i, "(0x0.000p+00+0x0.000p+00i)"},
+ {"%.3f", 0i, "(0.000+0.000i)"},
+ {"%.3F", 0i, "(0.000+0.000i)"},
+ {"%.3F", complex64(0i), "(0.000+0.000i)"},
+ {"%.3g", 0i, "(0+0i)"},
+ {"%.3e", 1 + 2i, "(1.000e+00+2.000e+00i)"},
+ {"%.3x", 1 + 2i, "(0x1.000p+00+0x1.000p+01i)"},
+ {"%.3f", 1 + 2i, "(1.000+2.000i)"},
+ {"%.3g", 1 + 2i, "(1+2i)"},
+ {"%.3e", -1 - 2i, "(-1.000e+00-2.000e+00i)"},
+ {"%.3x", -1 - 2i, "(-0x1.000p+00-0x1.000p+01i)"},
+ {"%.3f", -1 - 2i, "(-1.000-2.000i)"},
+ {"%.3g", -1 - 2i, "(-1-2i)"},
+ {"% .3E", -1 - 2i, "(-1.000E+00-2.000E+00i)"},
+ {"% .3X", -1 - 2i, "(-0X1.000P+00-0X1.000P+01i)"},
+ {"%+.3g", 1 + 2i, "(+1+2i)"},
+ {"%+.3g", complex64(1 + 2i), "(+1+2i)"},
+ {"%#g", 1 + 2i, "(1.00000+2.00000i)"},
+ {"%#g", 123456 + 789012i, "(123456.+789012.i)"},
+ {"%#g", 1e-10i, "(0.00000+1.00000e-10i)"},
+ {"%#g", -1e10 - 1.11e100i, "(-1.00000e+10-1.11000e+100i)"},
+ {"%#.0f", 1.23 + 1.0i, "(1.+1.i)"},
+ {"%#.0e", 1.23 + 1.0i, "(1.e+00+1.e+00i)"},
+ {"%#.0x", 1.23 + 1.0i, "(0x1.p+00+0x1.p+00i)"},
+ {"%#.0g", 1.23 + 1.0i, "(1.+1.i)"},
+ {"%#.0g", 0 + 100000i, "(0.+1.e+05i)"},
+ {"%#.0g", 1230000 + 0i, "(1.e+06+0.i)"},
+ {"%#.4f", 1 + 1.23i, "(1.0000+1.2300i)"},
+ {"%#.4e", 123 + 1i, "(1.2300e+02+1.0000e+00i)"},
+ {"%#.4x", 123 + 1i, "(0x1.ec00p+06+0x1.0000p+00i)"},
+ {"%#.4g", 123 + 1.23i, "(123.0+1.230i)"},
+ {"%#12.5g", 0 + 100000i, "( 0.0000 +1.0000e+05i)"},
+ {"%#12.5g", 1230000 - 0i, "( 1.2300e+06 +0.0000i)"},
+ {"%b", 1 + 2i, "(4503599627370496p-52+4503599627370496p-51i)"},
+ {"%b", complex64(1 + 2i), "(8388608p-23+8388608p-22i)"},
+ // The sharp flag has no effect for binary complex format.
+ {"%#b", 1 + 2i, "(4503599627370496p-52+4503599627370496p-51i)"},
+ // Precision has no effect for binary complex format.
+ {"%.4b", 1 + 2i, "(4503599627370496p-52+4503599627370496p-51i)"},
+ {"%.4b", complex64(1 + 2i), "(8388608p-23+8388608p-22i)"},
+ // complex infinites and NaNs
+ {"%f", complex(posInf, posInf), "(+Inf+Infi)"},
+ {"%f", complex(negInf, negInf), "(-Inf-Infi)"},
+ {"%f", complex(NaN, NaN), "(NaN+NaNi)"},
+ {"%.1f", complex(posInf, posInf), "(+Inf+Infi)"},
+ {"% f", complex(posInf, posInf), "( Inf+Infi)"},
+ {"% f", complex(negInf, negInf), "(-Inf-Infi)"},
+ {"% f", complex(NaN, NaN), "( NaN+NaNi)"},
+ {"%8e", complex(posInf, posInf), "( +Inf +Infi)"},
+ {"%8x", complex(posInf, posInf), "( +Inf +Infi)"},
+ {"% 8E", complex(posInf, posInf), "( Inf +Infi)"},
+ {"% 8X", complex(posInf, posInf), "( Inf +Infi)"},
+ {"%+8f", complex(negInf, negInf), "( -Inf -Infi)"},
+ {"% +8g", complex(negInf, negInf), "( -Inf -Infi)"},
+ {"% -8G", complex(NaN, NaN), "( NaN +NaN i)"},
+ {"%+-8b", complex(NaN, NaN), "(+NaN +NaN i)"},
+ // Zero padding does not apply to infinities and NaN.
+ {"%08f", complex(posInf, posInf), "( +Inf +Infi)"},
+ {"%-08g", complex(negInf, negInf), "(-Inf -Inf i)"},
+ {"%-08G", complex(NaN, NaN), "(NaN +NaN i)"},
+
+ // old test/fmt_test.go
+ {"%e", 1.0, "1.000000e+00"},
+ {"%e", 1234.5678e3, "1.234568e+06"},
+ {"%e", 1234.5678e-8, "1.234568e-05"},
+ {"%e", -7.0, "-7.000000e+00"},
+ {"%e", -1e-9, "-1.000000e-09"},
+ {"%f", 1234.5678e3, "1234567.800000"},
+ {"%f", 1234.5678e-8, "0.000012"},
+ {"%f", -7.0, "-7.000000"},
+ {"%f", -1e-9, "-0.000000"},
+ {"%g", 1234.5678e3, "1.2345678e+06"},
+ {"%g", float32(1234.5678e3), "1.2345678e+06"},
+ {"%g", 1234.5678e-8, "1.2345678e-05"},
+ {"%g", -7.0, "-7"},
+ {"%g", -1e-9, "-1e-09"},
+ {"%g", float32(-1e-9), "-1e-09"},
+ {"%E", 1.0, "1.000000E+00"},
+ {"%E", 1234.5678e3, "1.234568E+06"},
+ {"%E", 1234.5678e-8, "1.234568E-05"},
+ {"%E", -7.0, "-7.000000E+00"},
+ {"%E", -1e-9, "-1.000000E-09"},
+ {"%G", 1234.5678e3, "1.2345678E+06"},
+ {"%G", float32(1234.5678e3), "1.2345678E+06"},
+ {"%G", 1234.5678e-8, "1.2345678E-05"},
+ {"%G", -7.0, "-7"},
+ {"%G", -1e-9, "-1E-09"},
+ {"%G", float32(-1e-9), "-1E-09"},
+ {"%20.5s", "qwertyuiop", " qwert"},
+ {"%.5s", "qwertyuiop", "qwert"},
+ {"%-20.5s", "qwertyuiop", "qwert "},
+ {"%20c", 'x', " x"},
+ {"%-20c", 'x', "x "},
+ {"%20.6e", 1.2345e3, " 1.234500e+03"},
+ {"%20.6e", 1.2345e-3, " 1.234500e-03"},
+ {"%20e", 1.2345e3, " 1.234500e+03"},
+ {"%20e", 1.2345e-3, " 1.234500e-03"},
+ {"%20.8e", 1.2345e3, " 1.23450000e+03"},
+ {"%20f", 1.23456789e3, " 1234.567890"},
+ {"%20f", 1.23456789e-3, " 0.001235"},
+ {"%20f", 12345678901.23456789, " 12345678901.234568"},
+ {"%-20f", 1.23456789e3, "1234.567890 "},
+ {"%20.8f", 1.23456789e3, " 1234.56789000"},
+ {"%20.8f", 1.23456789e-3, " 0.00123457"},
+ {"%g", 1.23456789e3, "1234.56789"},
+ {"%g", 1.23456789e-3, "0.00123456789"},
+ {"%g", 1.23456789e20, "1.23456789e+20"},
+
+ // arrays
+ {"%v", array, "[1 2 3 4 5]"},
+ {"%v", iarray, "[1 hello 2.5 <nil>]"},
+ {"%v", barray, "[1 2 3 4 5]"},
+ {"%v", &array, "&[1 2 3 4 5]"},
+ {"%v", &iarray, "&[1 hello 2.5 <nil>]"},
+ {"%v", &barray, "&[1 2 3 4 5]"},
+
+ // slices
+ {"%v", slice, "[1 2 3 4 5]"},
+ {"%v", islice, "[1 hello 2.5 <nil>]"},
+ {"%v", bslice, "[1 2 3 4 5]"},
+ {"%v", &slice, "&[1 2 3 4 5]"},
+ {"%v", &islice, "&[1 hello 2.5 <nil>]"},
+ {"%v", &bslice, "&[1 2 3 4 5]"},
+
+ // byte arrays and slices with %b,%c,%d,%o,%U and %v
+ {"%b", [3]byte{65, 66, 67}, "[1000001 1000010 1000011]"},
+ {"%c", [3]byte{65, 66, 67}, "[A B C]"},
+ {"%d", [3]byte{65, 66, 67}, "[65 66 67]"},
+ {"%o", [3]byte{65, 66, 67}, "[101 102 103]"},
+ {"%U", [3]byte{65, 66, 67}, "[U+0041 U+0042 U+0043]"},
+ {"%v", [3]byte{65, 66, 67}, "[65 66 67]"},
+ {"%v", [1]byte{123}, "[123]"},
+ {"%012v", []byte{}, "[]"},
+ {"%#012v", []byte{}, "[]byte{}"},
+ {"%6v", []byte{1, 11, 111}, "[ 1 11 111]"},
+ {"%06v", []byte{1, 11, 111}, "[000001 000011 000111]"},
+ {"%-6v", []byte{1, 11, 111}, "[1 11 111 ]"},
+ {"%-06v", []byte{1, 11, 111}, "[1 11 111 ]"},
+ {"%#v", []byte{1, 11, 111}, "[]byte{0x1, 0xb, 0x6f}"},
+ {"%#6v", []byte{1, 11, 111}, "[]byte{ 0x1, 0xb, 0x6f}"},
+ {"%#06v", []byte{1, 11, 111}, "[]byte{0x000001, 0x00000b, 0x00006f}"},
+ {"%#-6v", []byte{1, 11, 111}, "[]byte{0x1 , 0xb , 0x6f }"},
+ {"%#-06v", []byte{1, 11, 111}, "[]byte{0x1 , 0xb , 0x6f }"},
+ // f.space should and f.plus should not have an effect with %v.
+ {"% v", []byte{1, 11, 111}, "[ 1 11 111]"},
+ {"%+v", [3]byte{1, 11, 111}, "[1 11 111]"},
+ {"%# -6v", []byte{1, 11, 111}, "[]byte{ 0x1 , 0xb , 0x6f }"},
+ {"%#+-6v", [3]byte{1, 11, 111}, "[3]uint8{0x1 , 0xb , 0x6f }"},
+ // f.space and f.plus should have an effect with %d.
+ {"% d", []byte{1, 11, 111}, "[ 1 11 111]"},
+ {"%+d", [3]byte{1, 11, 111}, "[+1 +11 +111]"},
+ {"%# -6d", []byte{1, 11, 111}, "[ 1 11 111 ]"},
+ {"%#+-6d", [3]byte{1, 11, 111}, "[+1 +11 +111 ]"},
+
+ // floates with %v
+ {"%v", 1.2345678, "1.2345678"},
+ {"%v", float32(1.2345678), "1.2345678"},
+
+ // complexes with %v
+ {"%v", 1 + 2i, "(1+2i)"},
+ {"%v", complex64(1 + 2i), "(1+2i)"},
+
+ // structs
+ {"%v", A{1, 2, "a", []int{1, 2}}, `{1 2 a [1 2]}`},
+ {"%+v", A{1, 2, "a", []int{1, 2}}, `{i:1 j:2 s:a x:[1 2]}`},
+
+ // +v on structs with Stringable items
+ {"%+v", B{1, 2}, `{I:<1> j:2}`},
+ {"%+v", C{1, B{2, 3}}, `{i:1 B:{I:<2> j:3}}`},
+
+ // other formats on Stringable items
+ {"%s", I(23), `<23>`},
+ {"%q", I(23), `"<23>"`},
+ {"%x", I(23), `3c32333e`},
+ {"%#x", I(23), `0x3c32333e`},
+ {"%# x", I(23), `0x3c 0x32 0x33 0x3e`},
+ // Stringer applies only to string formats.
+ {"%d", I(23), `23`},
+ // Stringer applies to the extracted value.
+ {"%s", reflect.ValueOf(I(23)), `<23>`},
+
+ // go syntax
+ {"%#v", A{1, 2, "a", []int{1, 2}}, `fmt_test.A{i:1, j:0x2, s:"a", x:[]int{1, 2}}`},
+ {"%#v", new(byte), "(*uint8)(0xPTR)"},
+ {"%#v", TestFmtInterface, "(func(*testing.T))(0xPTR)"},
+ {"%#v", make(chan int), "(chan int)(0xPTR)"},
+ {"%#v", uint64(1<<64 - 1), "0xffffffffffffffff"},
+ {"%#v", 1000000000, "1000000000"},
+ {"%#v", map[string]int{"a": 1}, `map[string]int{"a":1}`},
+ {"%#v", map[string]B{"a": {1, 2}}, `map[string]fmt_test.B{"a":fmt_test.B{I:1, j:2}}`},
+ {"%#v", []string{"a", "b"}, `[]string{"a", "b"}`},
+ {"%#v", SI{}, `fmt_test.SI{I:interface {}(nil)}`},
+ {"%#v", []int(nil), `[]int(nil)`},
+ {"%#v", []int{}, `[]int{}`},
+ {"%#v", array, `[5]int{1, 2, 3, 4, 5}`},
+ {"%#v", &array, `&[5]int{1, 2, 3, 4, 5}`},
+ {"%#v", iarray, `[4]interface {}{1, "hello", 2.5, interface {}(nil)}`},
+ {"%#v", &iarray, `&[4]interface {}{1, "hello", 2.5, interface {}(nil)}`},
+ {"%#v", map[int]byte(nil), `map[int]uint8(nil)`},
+ {"%#v", map[int]byte{}, `map[int]uint8{}`},
+ {"%#v", "foo", `"foo"`},
+ {"%#v", barray, `[5]fmt_test.renamedUint8{0x1, 0x2, 0x3, 0x4, 0x5}`},
+ {"%#v", bslice, `[]fmt_test.renamedUint8{0x1, 0x2, 0x3, 0x4, 0x5}`},
+ {"%#v", []int32(nil), "[]int32(nil)"},
+ {"%#v", 1.2345678, "1.2345678"},
+ {"%#v", float32(1.2345678), "1.2345678"},
+
+ // Whole number floats are printed without decimals. See Issue 27634.
+ {"%#v", 1.0, "1"},
+ {"%#v", 1000000.0, "1e+06"},
+ {"%#v", float32(1.0), "1"},
+ {"%#v", float32(1000000.0), "1e+06"},
+
+ // Only print []byte and []uint8 as type []byte if they appear at the top level.
+ {"%#v", []byte(nil), "[]byte(nil)"},
+ {"%#v", []uint8(nil), "[]byte(nil)"},
+ {"%#v", []byte{}, "[]byte{}"},
+ {"%#v", []uint8{}, "[]byte{}"},
+ {"%#v", reflect.ValueOf([]byte{}), "[]uint8{}"},
+ {"%#v", reflect.ValueOf([]uint8{}), "[]uint8{}"},
+ {"%#v", &[]byte{}, "&[]uint8{}"},
+ {"%#v", &[]byte{}, "&[]uint8{}"},
+ {"%#v", [3]byte{}, "[3]uint8{0x0, 0x0, 0x0}"},
+ {"%#v", [3]uint8{}, "[3]uint8{0x0, 0x0, 0x0}"},
+
+ // slices with other formats
+ {"%#x", []int{1, 2, 15}, `[0x1 0x2 0xf]`},
+ {"%x", []int{1, 2, 15}, `[1 2 f]`},
+ {"%d", []int{1, 2, 15}, `[1 2 15]`},
+ {"%d", []byte{1, 2, 15}, `[1 2 15]`},
+ {"%q", []string{"a", "b"}, `["a" "b"]`},
+ {"% 02x", []byte{1}, "01"},
+ {"% 02x", []byte{1, 2, 3}, "01 02 03"},
+
+ // Padding with byte slices.
+ {"%2x", []byte{}, " "},
+ {"%#2x", []byte{}, " "},
+ {"% 02x", []byte{}, "00"},
+ {"%# 02x", []byte{}, "00"},
+ {"%-2x", []byte{}, " "},
+ {"%-02x", []byte{}, " "},
+ {"%8x", []byte{0xab}, " ab"},
+ {"% 8x", []byte{0xab}, " ab"},
+ {"%#8x", []byte{0xab}, " 0xab"},
+ {"%# 8x", []byte{0xab}, " 0xab"},
+ {"%08x", []byte{0xab}, "000000ab"},
+ {"% 08x", []byte{0xab}, "000000ab"},
+ {"%#08x", []byte{0xab}, "00000xab"},
+ {"%# 08x", []byte{0xab}, "00000xab"},
+ {"%10x", []byte{0xab, 0xcd}, " abcd"},
+ {"% 10x", []byte{0xab, 0xcd}, " ab cd"},
+ {"%#10x", []byte{0xab, 0xcd}, " 0xabcd"},
+ {"%# 10x", []byte{0xab, 0xcd}, " 0xab 0xcd"},
+ {"%010x", []byte{0xab, 0xcd}, "000000abcd"},
+ {"% 010x", []byte{0xab, 0xcd}, "00000ab cd"},
+ {"%#010x", []byte{0xab, 0xcd}, "00000xabcd"},
+ {"%# 010x", []byte{0xab, 0xcd}, "00xab 0xcd"},
+ {"%-10X", []byte{0xab}, "AB "},
+ {"% -010X", []byte{0xab}, "AB "},
+ {"%#-10X", []byte{0xab, 0xcd}, "0XABCD "},
+ {"%# -010X", []byte{0xab, 0xcd}, "0XAB 0XCD "},
+ // Same for strings
+ {"%2x", "", " "},
+ {"%#2x", "", " "},
+ {"% 02x", "", "00"},
+ {"%# 02x", "", "00"},
+ {"%-2x", "", " "},
+ {"%-02x", "", " "},
+ {"%8x", "\xab", " ab"},
+ {"% 8x", "\xab", " ab"},
+ {"%#8x", "\xab", " 0xab"},
+ {"%# 8x", "\xab", " 0xab"},
+ {"%08x", "\xab", "000000ab"},
+ {"% 08x", "\xab", "000000ab"},
+ {"%#08x", "\xab", "00000xab"},
+ {"%# 08x", "\xab", "00000xab"},
+ {"%10x", "\xab\xcd", " abcd"},
+ {"% 10x", "\xab\xcd", " ab cd"},
+ {"%#10x", "\xab\xcd", " 0xabcd"},
+ {"%# 10x", "\xab\xcd", " 0xab 0xcd"},
+ {"%010x", "\xab\xcd", "000000abcd"},
+ {"% 010x", "\xab\xcd", "00000ab cd"},
+ {"%#010x", "\xab\xcd", "00000xabcd"},
+ {"%# 010x", "\xab\xcd", "00xab 0xcd"},
+ {"%-10X", "\xab", "AB "},
+ {"% -010X", "\xab", "AB "},
+ {"%#-10X", "\xab\xcd", "0XABCD "},
+ {"%# -010X", "\xab\xcd", "0XAB 0XCD "},
+
+ // renamings
+ {"%v", renamedBool(true), "true"},
+ {"%d", renamedBool(true), "%!d(fmt_test.renamedBool=true)"},
+ {"%o", renamedInt(8), "10"},
+ {"%d", renamedInt8(-9), "-9"},
+ {"%v", renamedInt16(10), "10"},
+ {"%v", renamedInt32(-11), "-11"},
+ {"%X", renamedInt64(255), "FF"},
+ {"%v", renamedUint(13), "13"},
+ {"%o", renamedUint8(14), "16"},
+ {"%X", renamedUint16(15), "F"},
+ {"%d", renamedUint32(16), "16"},
+ {"%X", renamedUint64(17), "11"},
+ {"%o", renamedUintptr(18), "22"},
+ {"%x", renamedString("thing"), "7468696e67"},
+ {"%d", renamedBytes([]byte{1, 2, 15}), `[1 2 15]`},
+ {"%q", renamedBytes([]byte("hello")), `"hello"`},
+ {"%x", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, "68656c6c6f"},
+ {"%X", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, "68656C6C6F"},
+ {"%s", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, "hello"},
+ {"%q", []renamedUint8{'h', 'e', 'l', 'l', 'o'}, `"hello"`},
+ {"%v", renamedFloat32(22), "22"},
+ {"%v", renamedFloat64(33), "33"},
+ {"%v", renamedComplex64(3 + 4i), "(3+4i)"},
+ {"%v", renamedComplex128(4 - 3i), "(4-3i)"},
+
+ // Formatter
+ {"%x", F(1), "<x=F(1)>"},
+ {"%x", G(2), "2"},
+ {"%+v", S{F(4), G(5)}, "{F:<v=F(4)> G:5}"},
+
+ // GoStringer
+ {"%#v", G(6), "GoString(6)"},
+ {"%#v", S{F(7), G(8)}, "fmt_test.S{F:<v=F(7)>, G:GoString(8)}"},
+
+ // %T
+ {"%T", byte(0), "uint8"},
+ {"%T", reflect.ValueOf(nil), "reflect.Value"},
+ {"%T", (4 - 3i), "complex128"},
+ {"%T", renamedComplex128(4 - 3i), "fmt_test.renamedComplex128"},
+ {"%T", intVar, "int"},
+ {"%6T", &intVar, " *int"},
+ {"%10T", nil, " <nil>"},
+ {"%-10T", nil, "<nil> "},
+
+ // %p with pointers
+ {"%p", (*int)(nil), "0x0"},
+ {"%#p", (*int)(nil), "0"},
+ {"%p", &intVar, "0xPTR"},
+ {"%#p", &intVar, "PTR"},
+ {"%p", &array, "0xPTR"},
+ {"%p", &slice, "0xPTR"},
+ {"%8.2p", (*int)(nil), " 0x00"},
+ {"%-20.16p", &intVar, "0xPTR "},
+ // %p on non-pointers
+ {"%p", make(chan int), "0xPTR"},
+ {"%p", make(map[int]int), "0xPTR"},
+ {"%p", func() {}, "0xPTR"},
+ {"%p", 27, "%!p(int=27)"}, // not a pointer at all
+ {"%p", nil, "%!p(<nil>)"}, // nil on its own has no type ...
+ {"%#p", nil, "%!p(<nil>)"}, // ... and hence is not a pointer type.
+ // pointers with specified base
+ {"%b", &intVar, "PTR_b"},
+ {"%d", &intVar, "PTR_d"},
+ {"%o", &intVar, "PTR_o"},
+ {"%x", &intVar, "PTR_x"},
+ {"%X", &intVar, "PTR_X"},
+ // %v on pointers
+ {"%v", nil, "<nil>"},
+ {"%#v", nil, "<nil>"},
+ {"%v", (*int)(nil), "<nil>"},
+ {"%#v", (*int)(nil), "(*int)(nil)"},
+ {"%v", &intVar, "0xPTR"},
+ {"%#v", &intVar, "(*int)(0xPTR)"},
+ {"%8.2v", (*int)(nil), " <nil>"},
+ {"%-20.16v", &intVar, "0xPTR "},
+ // string method on pointer
+ {"%s", &pValue, "String(p)"}, // String method...
+ {"%p", &pValue, "0xPTR"}, // ... is not called with %p.
+
+ // %d on Stringer should give integer if possible
+ {"%s", time.Time{}.Month(), "January"},
+ {"%d", time.Time{}.Month(), "1"},
+
+ // erroneous things
+ {"", nil, "%!(EXTRA <nil>)"},
+ {"", 2, "%!(EXTRA int=2)"},
+ {"no args", "hello", "no args%!(EXTRA string=hello)"},
+ {"%s %", "hello", "hello %!(NOVERB)"},
+ {"%s %.2", "hello", "hello %!(NOVERB)"},
+ {"%017091901790959340919092959340919017929593813360", 0, "%!(NOVERB)%!(EXTRA int=0)"},
+ {"%184467440737095516170v", 0, "%!(NOVERB)%!(EXTRA int=0)"},
+ // Extra argument errors should format without flags set.
+ {"%010.2", "12345", "%!(NOVERB)%!(EXTRA string=12345)"},
+
+ // Test that maps with non-reflexive keys print all keys and values.
+ {"%v", map[float64]int{NaN: 1, NaN: 1}, "map[NaN:1 NaN:1]"},
+
+ // Comparison of padding rules with C printf.
+ /*
+ C program:
+ #include <stdio.h>
+
+ char *format[] = {
+ "[%.2f]",
+ "[% .2f]",
+ "[%+.2f]",
+ "[%7.2f]",
+ "[% 7.2f]",
+ "[%+7.2f]",
+ "[% +7.2f]",
+ "[%07.2f]",
+ "[% 07.2f]",
+ "[%+07.2f]",
+ "[% +07.2f]"
+ };
+
+ int main(void) {
+ int i;
+ for(i = 0; i < 11; i++) {
+ printf("%s: ", format[i]);
+ printf(format[i], 1.0);
+ printf(" ");
+ printf(format[i], -1.0);
+ printf("\n");
+ }
+ }
+
+ Output:
+ [%.2f]: [1.00] [-1.00]
+ [% .2f]: [ 1.00] [-1.00]
+ [%+.2f]: [+1.00] [-1.00]
+ [%7.2f]: [ 1.00] [ -1.00]
+ [% 7.2f]: [ 1.00] [ -1.00]
+ [%+7.2f]: [ +1.00] [ -1.00]
+ [% +7.2f]: [ +1.00] [ -1.00]
+ [%07.2f]: [0001.00] [-001.00]
+ [% 07.2f]: [ 001.00] [-001.00]
+ [%+07.2f]: [+001.00] [-001.00]
+ [% +07.2f]: [+001.00] [-001.00]
+
+ */
+ {"%.2f", 1.0, "1.00"},
+ {"%.2f", -1.0, "-1.00"},
+ {"% .2f", 1.0, " 1.00"},
+ {"% .2f", -1.0, "-1.00"},
+ {"%+.2f", 1.0, "+1.00"},
+ {"%+.2f", -1.0, "-1.00"},
+ {"%7.2f", 1.0, " 1.00"},
+ {"%7.2f", -1.0, " -1.00"},
+ {"% 7.2f", 1.0, " 1.00"},
+ {"% 7.2f", -1.0, " -1.00"},
+ {"%+7.2f", 1.0, " +1.00"},
+ {"%+7.2f", -1.0, " -1.00"},
+ {"% +7.2f", 1.0, " +1.00"},
+ {"% +7.2f", -1.0, " -1.00"},
+ {"%07.2f", 1.0, "0001.00"},
+ {"%07.2f", -1.0, "-001.00"},
+ {"% 07.2f", 1.0, " 001.00"},
+ {"% 07.2f", -1.0, "-001.00"},
+ {"%+07.2f", 1.0, "+001.00"},
+ {"%+07.2f", -1.0, "-001.00"},
+ {"% +07.2f", 1.0, "+001.00"},
+ {"% +07.2f", -1.0, "-001.00"},
+
+ // Complex numbers: exhaustively tested in TestComplexFormatting.
+ {"%7.2f", 1 + 2i, "( 1.00 +2.00i)"},
+ {"%+07.2f", -1 - 2i, "(-001.00-002.00i)"},
+
+ // Use spaces instead of zero if padding to the right.
+ {"%0-5s", "abc", "abc "},
+ {"%-05.1f", 1.0, "1.0 "},
+
+ // float and complex formatting should not change the padding width
+ // for other elements. See issue 14642.
+ {"%06v", []any{+10.0, 10}, "[000010 000010]"},
+ {"%06v", []any{-10.0, 10}, "[-00010 000010]"},
+ {"%06v", []any{+10.0 + 10i, 10}, "[(000010+00010i) 000010]"},
+ {"%06v", []any{-10.0 + 10i, 10}, "[(-00010+00010i) 000010]"},
+
+ // integer formatting should not alter padding for other elements.
+ {"%03.6v", []any{1, 2.0, "x"}, "[000001 002 00x]"},
+ {"%03.0v", []any{0, 2.0, "x"}, "[ 002 000]"},
+
+ // Complex fmt used to leave the plus flag set for future entries in the array
+ // causing +2+0i and +3+0i instead of 2+0i and 3+0i.
+ {"%v", []complex64{1, 2, 3}, "[(1+0i) (2+0i) (3+0i)]"},
+ {"%v", []complex128{1, 2, 3}, "[(1+0i) (2+0i) (3+0i)]"},
+
+ // Incomplete format specification caused crash.
+ {"%.", 3, "%!.(int=3)"},
+
+ // Padding for complex numbers. Has been bad, then fixed, then bad again.
+ {"%+10.2f", +104.66 + 440.51i, "( +104.66 +440.51i)"},
+ {"%+10.2f", -104.66 + 440.51i, "( -104.66 +440.51i)"},
+ {"%+10.2f", +104.66 - 440.51i, "( +104.66 -440.51i)"},
+ {"%+10.2f", -104.66 - 440.51i, "( -104.66 -440.51i)"},
+ {"%+010.2f", +104.66 + 440.51i, "(+000104.66+000440.51i)"},
+ {"%+010.2f", -104.66 + 440.51i, "(-000104.66+000440.51i)"},
+ {"%+010.2f", +104.66 - 440.51i, "(+000104.66-000440.51i)"},
+ {"%+010.2f", -104.66 - 440.51i, "(-000104.66-000440.51i)"},
+
+ // []T where type T is a byte with a Stringer method.
+ {"%v", byteStringerSlice, "[X X X X X]"},
+ {"%s", byteStringerSlice, "hello"},
+ {"%q", byteStringerSlice, "\"hello\""},
+ {"%x", byteStringerSlice, "68656c6c6f"},
+ {"%X", byteStringerSlice, "68656C6C6F"},
+ {"%#v", byteStringerSlice, "[]fmt_test.byteStringer{0x68, 0x65, 0x6c, 0x6c, 0x6f}"},
+
+ // And the same for Formatter.
+ {"%v", byteFormatterSlice, "[X X X X X]"},
+ {"%s", byteFormatterSlice, "hello"},
+ {"%q", byteFormatterSlice, "\"hello\""},
+ {"%x", byteFormatterSlice, "68656c6c6f"},
+ {"%X", byteFormatterSlice, "68656C6C6F"},
+ // This next case seems wrong, but the docs say the Formatter wins here.
+ {"%#v", byteFormatterSlice, "[]fmt_test.byteFormatter{X, X, X, X, X}"},
+
+ // pp.WriteString
+ {"%s", writeStringFormatter(""), "******"},
+ {"%s", writeStringFormatter("xyz"), "***xyz***"},
+ {"%s", writeStringFormatter("⌘/⌘"), "***⌘/⌘***"},
+
+ // reflect.Value handled specially in Go 1.5, making it possible to
+ // see inside non-exported fields (which cannot be accessed with Interface()).
+ // Issue 8965.
+ {"%v", reflect.ValueOf(A{}).Field(0).String(), "<int Value>"}, // Equivalent to the old way.
+ {"%v", reflect.ValueOf(A{}).Field(0), "0"}, // Sees inside the field.
+
+ // verbs apply to the extracted value too.
+ {"%s", reflect.ValueOf("hello"), "hello"},
+ {"%q", reflect.ValueOf("hello"), `"hello"`},
+ {"%#04x", reflect.ValueOf(256), "0x0100"},
+
+ // invalid reflect.Value doesn't crash.
+ {"%v", reflect.Value{}, "<invalid reflect.Value>"},
+ {"%v", &reflect.Value{}, "<invalid Value>"},
+ {"%v", SI{reflect.Value{}}, "{<invalid Value>}"},
+
+ // Tests to check that not supported verbs generate an error string.
+ {"%☠", nil, "%!☠(<nil>)"},
+ {"%☠", any(nil), "%!☠(<nil>)"},
+ {"%☠", int(0), "%!☠(int=0)"},
+ {"%☠", uint(0), "%!☠(uint=0)"},
+ {"%☠", []byte{0, 1}, "[%!☠(uint8=0) %!☠(uint8=1)]"},
+ {"%☠", []uint8{0, 1}, "[%!☠(uint8=0) %!☠(uint8=1)]"},
+ {"%☠", [1]byte{0}, "[%!☠(uint8=0)]"},
+ {"%☠", [1]uint8{0}, "[%!☠(uint8=0)]"},
+ {"%☠", "hello", "%!☠(string=hello)"},
+ {"%☠", 1.2345678, "%!☠(float64=1.2345678)"},
+ {"%☠", float32(1.2345678), "%!☠(float32=1.2345678)"},
+ {"%☠", 1.2345678 + 1.2345678i, "%!☠(complex128=(1.2345678+1.2345678i))"},
+ {"%☠", complex64(1.2345678 + 1.2345678i), "%!☠(complex64=(1.2345678+1.2345678i))"},
+ {"%☠", &intVar, "%!☠(*int=0xPTR)"},
+ {"%☠", make(chan int), "%!☠(chan int=0xPTR)"},
+ {"%☠", func() {}, "%!☠(func()=0xPTR)"},
+ {"%☠", reflect.ValueOf(renamedInt(0)), "%!☠(fmt_test.renamedInt=0)"},
+ {"%☠", SI{renamedInt(0)}, "{%!☠(fmt_test.renamedInt=0)}"},
+ {"%☠", &[]any{I(1), G(2)}, "&[%!☠(fmt_test.I=1) %!☠(fmt_test.G=2)]"},
+ {"%☠", SI{&[]any{I(1), G(2)}}, "{%!☠(*[]interface {}=&[1 2])}"},
+ {"%☠", reflect.Value{}, "<invalid reflect.Value>"},
+ {"%☠", map[float64]int{NaN: 1}, "map[%!☠(float64=NaN):%!☠(int=1)]"},
+}
+
+// zeroFill generates zero-filled strings of the specified width. The length
+// of the suffix (but not the prefix) is compensated for in the width calculation.
+func zeroFill(prefix string, width int, suffix string) string {
+ return prefix + strings.Repeat("0", width-len(suffix)) + suffix
+}
+
+func TestSprintf(t *testing.T) {
+ for _, tt := range fmtTests {
+ s := Sprintf(tt.fmt, tt.val)
+ i := strings.Index(tt.out, "PTR")
+ if i >= 0 && i < len(s) {
+ var pattern, chars string
+ switch {
+ case strings.HasPrefix(tt.out[i:], "PTR_b"):
+ pattern = "PTR_b"
+ chars = "01"
+ case strings.HasPrefix(tt.out[i:], "PTR_o"):
+ pattern = "PTR_o"
+ chars = "01234567"
+ case strings.HasPrefix(tt.out[i:], "PTR_d"):
+ pattern = "PTR_d"
+ chars = "0123456789"
+ case strings.HasPrefix(tt.out[i:], "PTR_x"):
+ pattern = "PTR_x"
+ chars = "0123456789abcdef"
+ case strings.HasPrefix(tt.out[i:], "PTR_X"):
+ pattern = "PTR_X"
+ chars = "0123456789ABCDEF"
+ default:
+ pattern = "PTR"
+ chars = "0123456789abcdefABCDEF"
+ }
+ p := s[:i] + pattern
+ for j := i; j < len(s); j++ {
+ if !strings.ContainsRune(chars, rune(s[j])) {
+ p += s[j:]
+ break
+ }
+ }
+ s = p
+ }
+ if s != tt.out {
+ if _, ok := tt.val.(string); ok {
+ // Don't requote the already-quoted strings.
+ // It's too confusing to read the errors.
+ t.Errorf("Sprintf(%q, %q) = <%s> want <%s>", tt.fmt, tt.val, s, tt.out)
+ } else {
+ t.Errorf("Sprintf(%q, %v) = %q want %q", tt.fmt, tt.val, s, tt.out)
+ }
+ }
+ }
+}
+
+// TestComplexFormatting checks that a complex always formats to the same
+// thing as if done by hand with two singleton prints.
+func TestComplexFormatting(t *testing.T) {
+ var yesNo = []bool{true, false}
+ var values = []float64{1, 0, -1, posInf, negInf, NaN}
+ for _, plus := range yesNo {
+ for _, zero := range yesNo {
+ for _, space := range yesNo {
+ for _, char := range "fFeEgG" {
+ realFmt := "%"
+ if zero {
+ realFmt += "0"
+ }
+ if space {
+ realFmt += " "
+ }
+ if plus {
+ realFmt += "+"
+ }
+ realFmt += "10.2"
+ realFmt += string(char)
+ // Imaginary part always has a sign, so force + and ignore space.
+ imagFmt := "%"
+ if zero {
+ imagFmt += "0"
+ }
+ imagFmt += "+"
+ imagFmt += "10.2"
+ imagFmt += string(char)
+ for _, realValue := range values {
+ for _, imagValue := range values {
+ one := Sprintf(realFmt, complex(realValue, imagValue))
+ two := Sprintf("("+realFmt+imagFmt+"i)", realValue, imagValue)
+ if one != two {
+ t.Error(f, one, two)
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+}
+
+type SE []any // slice of empty; notational compactness.
+
+var reorderTests = []struct {
+ fmt string
+ val SE
+ out string
+}{
+ {"%[1]d", SE{1}, "1"},
+ {"%[2]d", SE{2, 1}, "1"},
+ {"%[2]d %[1]d", SE{1, 2}, "2 1"},
+ {"%[2]*[1]d", SE{2, 5}, " 2"},
+ {"%6.2f", SE{12.0}, " 12.00"}, // Explicit version of next line.
+ {"%[3]*.[2]*[1]f", SE{12.0, 2, 6}, " 12.00"},
+ {"%[1]*.[2]*[3]f", SE{6, 2, 12.0}, " 12.00"},
+ {"%10f", SE{12.0}, " 12.000000"},
+ {"%[1]*[3]f", SE{10, 99, 12.0}, " 12.000000"},
+ {"%.6f", SE{12.0}, "12.000000"}, // Explicit version of next line.
+ {"%.[1]*[3]f", SE{6, 99, 12.0}, "12.000000"},
+ {"%6.f", SE{12.0}, " 12"}, // // Explicit version of next line; empty precision means zero.
+ {"%[1]*.[3]f", SE{6, 3, 12.0}, " 12"},
+ // An actual use! Print the same arguments twice.
+ {"%d %d %d %#[1]o %#o %#o", SE{11, 12, 13}, "11 12 13 013 014 015"},
+
+ // Erroneous cases.
+ {"%[d", SE{2, 1}, "%!d(BADINDEX)"},
+ {"%]d", SE{2, 1}, "%!](int=2)d%!(EXTRA int=1)"},
+ {"%[]d", SE{2, 1}, "%!d(BADINDEX)"},
+ {"%[-3]d", SE{2, 1}, "%!d(BADINDEX)"},
+ {"%[99]d", SE{2, 1}, "%!d(BADINDEX)"},
+ {"%[3]", SE{2, 1}, "%!(NOVERB)"},
+ {"%[1].2d", SE{5, 6}, "%!d(BADINDEX)"},
+ {"%[1]2d", SE{2, 1}, "%!d(BADINDEX)"},
+ {"%3.[2]d", SE{7}, "%!d(BADINDEX)"},
+ {"%.[2]d", SE{7}, "%!d(BADINDEX)"},
+ {"%d %d %d %#[1]o %#o %#o %#o", SE{11, 12, 13}, "11 12 13 013 014 015 %!o(MISSING)"},
+ {"%[5]d %[2]d %d", SE{1, 2, 3}, "%!d(BADINDEX) 2 3"},
+ {"%d %[3]d %d", SE{1, 2}, "1 %!d(BADINDEX) 2"}, // Erroneous index does not affect sequence.
+ {"%.[]", SE{}, "%!](BADINDEX)"}, // Issue 10675
+ {"%.-3d", SE{42}, "%!-(int=42)3d"}, // TODO: Should this set return better error messages?
+ {"%2147483648d", SE{42}, "%!(NOVERB)%!(EXTRA int=42)"},
+ {"%-2147483648d", SE{42}, "%!(NOVERB)%!(EXTRA int=42)"},
+ {"%.2147483648d", SE{42}, "%!(NOVERB)%!(EXTRA int=42)"},
+}
+
+func TestReorder(t *testing.T) {
+ for _, tt := range reorderTests {
+ s := Sprintf(tt.fmt, tt.val...)
+ if s != tt.out {
+ t.Errorf("Sprintf(%q, %v) = <%s> want <%s>", tt.fmt, tt.val, s, tt.out)
+ } else {
+ }
+ }
+}
+
+func BenchmarkSprintfPadding(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%16f", 1.0)
+ }
+ })
+}
+
+func BenchmarkSprintfEmpty(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("")
+ }
+ })
+}
+
+func BenchmarkSprintfString(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%s", "hello")
+ }
+ })
+}
+
+func BenchmarkSprintfTruncateString(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%.3s", "日本語日本語日本語日本語")
+ }
+ })
+}
+
+func BenchmarkSprintfTruncateBytes(b *testing.B) {
+ var bytes any = []byte("日本語日本語日本語日本語")
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%.3s", bytes)
+ }
+ })
+}
+
+func BenchmarkSprintfSlowParsingPath(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%.v", nil)
+ }
+ })
+}
+
+func BenchmarkSprintfQuoteString(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%q", "日本語日本語日本語")
+ }
+ })
+}
+
+func BenchmarkSprintfInt(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%d", 5)
+ }
+ })
+}
+
+func BenchmarkSprintfIntInt(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%d %d", 5, 6)
+ }
+ })
+}
+
+func BenchmarkSprintfPrefixedInt(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("This is some meaningless prefix text that needs to be scanned %d", 6)
+ }
+ })
+}
+
+func BenchmarkSprintfFloat(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%g", 5.23184)
+ }
+ })
+}
+
+func BenchmarkSprintfComplex(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%f", 5.23184+5.23184i)
+ }
+ })
+}
+
+func BenchmarkSprintfBoolean(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%t", true)
+ }
+ })
+}
+
+func BenchmarkSprintfHexString(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("% #x", "0123456789abcdef")
+ }
+ })
+}
+
+func BenchmarkSprintfHexBytes(b *testing.B) {
+ data := []byte("0123456789abcdef")
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("% #x", data)
+ }
+ })
+}
+
+func BenchmarkSprintfBytes(b *testing.B) {
+ data := []byte("0123456789abcdef")
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%v", data)
+ }
+ })
+}
+
+func BenchmarkSprintfStringer(b *testing.B) {
+ stringer := I(12345)
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%v", stringer)
+ }
+ })
+}
+
+func BenchmarkSprintfStructure(b *testing.B) {
+ s := &[]any{SI{12345}, map[int]string{0: "hello"}}
+ b.RunParallel(func(pb *testing.PB) {
+ for pb.Next() {
+ Sprintf("%#v", s)
+ }
+ })
+}
+
+func BenchmarkManyArgs(b *testing.B) {
+ b.RunParallel(func(pb *testing.PB) {
+ var buf bytes.Buffer
+ for pb.Next() {
+ buf.Reset()
+ Fprintf(&buf, "%2d/%2d/%2d %d:%d:%d %s %s\n", 3, 4, 5, 11, 12, 13, "hello", "world")
+ }
+ })
+}
+
+func BenchmarkFprintInt(b *testing.B) {
+ var buf bytes.Buffer
+ for i := 0; i < b.N; i++ {
+ buf.Reset()
+ Fprint(&buf, 123456)
+ }
+}
+
+func BenchmarkFprintfBytes(b *testing.B) {
+ data := []byte(string("0123456789"))
+ var buf bytes.Buffer
+ for i := 0; i < b.N; i++ {
+ buf.Reset()
+ Fprintf(&buf, "%s", data)
+ }
+}
+
+func BenchmarkFprintIntNoAlloc(b *testing.B) {
+ var x any = 123456
+ var buf bytes.Buffer
+ for i := 0; i < b.N; i++ {
+ buf.Reset()
+ Fprint(&buf, x)
+ }
+}
+
+var mallocBuf bytes.Buffer
+var mallocPointer *int // A pointer so we know the interface value won't allocate.
+
+var mallocTest = []struct {
+ count int
+ desc string
+ fn func()
+}{
+ {0, `Sprintf("")`, func() { Sprintf("") }},
+ {1, `Sprintf("xxx")`, func() { Sprintf("xxx") }},
+ {2, `Sprintf("%x")`, func() { Sprintf("%x", 7) }},
+ {2, `Sprintf("%s")`, func() { Sprintf("%s", "hello") }},
+ {3, `Sprintf("%x %x")`, func() { Sprintf("%x %x", 7, 112) }},
+ {2, `Sprintf("%g")`, func() { Sprintf("%g", float32(3.14159)) }}, // TODO: Can this be 1?
+ {1, `Fprintf(buf, "%s")`, func() { mallocBuf.Reset(); Fprintf(&mallocBuf, "%s", "hello") }},
+ // If the interface value doesn't need to allocate, amortized allocation overhead should be zero.
+ {0, `Fprintf(buf, "%x %x %x")`, func() {
+ mallocBuf.Reset()
+ Fprintf(&mallocBuf, "%x %x %x", mallocPointer, mallocPointer, mallocPointer)
+ }},
+}
+
+var _ bytes.Buffer
+
+func TestCountMallocs(t *testing.T) {
+ switch {
+ case testing.Short():
+ t.Skip("skipping malloc count in short mode")
+ case runtime.GOMAXPROCS(0) > 1:
+ t.Skip("skipping; GOMAXPROCS>1")
+ case race.Enabled:
+ t.Skip("skipping malloc count under race detector")
+ }
+ for _, mt := range mallocTest {
+ mallocs := testing.AllocsPerRun(100, mt.fn)
+ if got, max := mallocs, float64(mt.count); got > max {
+ t.Errorf("%s: got %v allocs, want <=%v", mt.desc, got, max)
+ }
+ }
+}
+
+type flagPrinter struct{}
+
+func (flagPrinter) Format(f State, c rune) {
+ s := "%"
+ for i := 0; i < 128; i++ {
+ if f.Flag(i) {
+ s += string(rune(i))
+ }
+ }
+ if w, ok := f.Width(); ok {
+ s += Sprintf("%d", w)
+ }
+ if p, ok := f.Precision(); ok {
+ s += Sprintf(".%d", p)
+ }
+ s += string(c)
+ io.WriteString(f, "["+s+"]")
+}
+
+var flagtests = []struct {
+ in string
+ out string
+}{
+ {"%a", "[%a]"},
+ {"%-a", "[%-a]"},
+ {"%+a", "[%+a]"},
+ {"%#a", "[%#a]"},
+ {"% a", "[% a]"},
+ {"%0a", "[%0a]"},
+ {"%1.2a", "[%1.2a]"},
+ {"%-1.2a", "[%-1.2a]"},
+ {"%+1.2a", "[%+1.2a]"},
+ {"%-+1.2a", "[%+-1.2a]"},
+ {"%-+1.2abc", "[%+-1.2a]bc"},
+ {"%-1.2abc", "[%-1.2a]bc"},
+}
+
+func TestFlagParser(t *testing.T) {
+ var flagprinter flagPrinter
+ for _, tt := range flagtests {
+ s := Sprintf(tt.in, &flagprinter)
+ if s != tt.out {
+ t.Errorf("Sprintf(%q, &flagprinter) => %q, want %q", tt.in, s, tt.out)
+ }
+ }
+}
+
+func TestStructPrinter(t *testing.T) {
+ type T struct {
+ a string
+ b string
+ c int
+ }
+ var s T
+ s.a = "abc"
+ s.b = "def"
+ s.c = 123
+ var tests = []struct {
+ fmt string
+ out string
+ }{
+ {"%v", "{abc def 123}"},
+ {"%+v", "{a:abc b:def c:123}"},
+ {"%#v", `fmt_test.T{a:"abc", b:"def", c:123}`},
+ }
+ for _, tt := range tests {
+ out := Sprintf(tt.fmt, s)
+ if out != tt.out {
+ t.Errorf("Sprintf(%q, s) = %#q, want %#q", tt.fmt, out, tt.out)
+ }
+ // The same but with a pointer.
+ out = Sprintf(tt.fmt, &s)
+ if out != "&"+tt.out {
+ t.Errorf("Sprintf(%q, &s) = %#q, want %#q", tt.fmt, out, "&"+tt.out)
+ }
+ }
+}
+
+func TestSlicePrinter(t *testing.T) {
+ slice := []int{}
+ s := Sprint(slice)
+ if s != "[]" {
+ t.Errorf("empty slice printed as %q not %q", s, "[]")
+ }
+ slice = []int{1, 2, 3}
+ s = Sprint(slice)
+ if s != "[1 2 3]" {
+ t.Errorf("slice: got %q expected %q", s, "[1 2 3]")
+ }
+ s = Sprint(&slice)
+ if s != "&[1 2 3]" {
+ t.Errorf("&slice: got %q expected %q", s, "&[1 2 3]")
+ }
+}
+
+// presentInMap checks map printing using substrings so we don't depend on the
+// print order.
+func presentInMap(s string, a []string, t *testing.T) {
+ for i := 0; i < len(a); i++ {
+ loc := strings.Index(s, a[i])
+ if loc < 0 {
+ t.Errorf("map print: expected to find %q in %q", a[i], s)
+ }
+ // make sure the match ends here
+ loc += len(a[i])
+ if loc >= len(s) || (s[loc] != ' ' && s[loc] != ']') {
+ t.Errorf("map print: %q not properly terminated in %q", a[i], s)
+ }
+ }
+}
+
+func TestMapPrinter(t *testing.T) {
+ m0 := make(map[int]string)
+ s := Sprint(m0)
+ if s != "map[]" {
+ t.Errorf("empty map printed as %q not %q", s, "map[]")
+ }
+ m1 := map[int]string{1: "one", 2: "two", 3: "three"}
+ a := []string{"1:one", "2:two", "3:three"}
+ presentInMap(Sprintf("%v", m1), a, t)
+ presentInMap(Sprint(m1), a, t)
+ // Pointer to map prints the same but with initial &.
+ if !strings.HasPrefix(Sprint(&m1), "&") {
+ t.Errorf("no initial & for address of map")
+ }
+ presentInMap(Sprintf("%v", &m1), a, t)
+ presentInMap(Sprint(&m1), a, t)
+}
+
+func TestEmptyMap(t *testing.T) {
+ const emptyMapStr = "map[]"
+ var m map[string]int
+ s := Sprint(m)
+ if s != emptyMapStr {
+ t.Errorf("nil map printed as %q not %q", s, emptyMapStr)
+ }
+ m = make(map[string]int)
+ s = Sprint(m)
+ if s != emptyMapStr {
+ t.Errorf("empty map printed as %q not %q", s, emptyMapStr)
+ }
+}
+
+// TestBlank checks that Sprint (and hence Print, Fprint) puts spaces in the
+// right places, that is, between arg pairs in which neither is a string.
+func TestBlank(t *testing.T) {
+ got := Sprint("<", 1, ">:", 1, 2, 3, "!")
+ expect := "<1>:1 2 3!"
+ if got != expect {
+ t.Errorf("got %q expected %q", got, expect)
+ }
+}
+
+// TestBlankln checks that Sprintln (and hence Println, Fprintln) puts spaces in
+// the right places, that is, between all arg pairs.
+func TestBlankln(t *testing.T) {
+ got := Sprintln("<", 1, ">:", 1, 2, 3, "!")
+ expect := "< 1 >: 1 2 3 !\n"
+ if got != expect {
+ t.Errorf("got %q expected %q", got, expect)
+ }
+}
+
+// TestFormatterPrintln checks Formatter with Sprint, Sprintln, Sprintf.
+func TestFormatterPrintln(t *testing.T) {
+ f := F(1)
+ expect := "<v=F(1)>\n"
+ s := Sprint(f, "\n")
+ if s != expect {
+ t.Errorf("Sprint wrong with Formatter: expected %q got %q", expect, s)
+ }
+ s = Sprintln(f)
+ if s != expect {
+ t.Errorf("Sprintln wrong with Formatter: expected %q got %q", expect, s)
+ }
+ s = Sprintf("%v\n", f)
+ if s != expect {
+ t.Errorf("Sprintf wrong with Formatter: expected %q got %q", expect, s)
+ }
+}
+
+func args(a ...any) []any { return a }
+
+var startests = []struct {
+ fmt string
+ in []any
+ out string
+}{
+ {"%*d", args(4, 42), " 42"},
+ {"%-*d", args(4, 42), "42 "},
+ {"%*d", args(-4, 42), "42 "},
+ {"%-*d", args(-4, 42), "42 "},
+ {"%.*d", args(4, 42), "0042"},
+ {"%*.*d", args(8, 4, 42), " 0042"},
+ {"%0*d", args(4, 42), "0042"},
+ // Some non-int types for width. (Issue 10732).
+ {"%0*d", args(uint(4), 42), "0042"},
+ {"%0*d", args(uint64(4), 42), "0042"},
+ {"%0*d", args('\x04', 42), "0042"},
+ {"%0*d", args(uintptr(4), 42), "0042"},
+
+ // erroneous
+ {"%*d", args(nil, 42), "%!(BADWIDTH)42"},
+ {"%*d", args(int(1e7), 42), "%!(BADWIDTH)42"},
+ {"%*d", args(int(-1e7), 42), "%!(BADWIDTH)42"},
+ {"%.*d", args(nil, 42), "%!(BADPREC)42"},
+ {"%.*d", args(-1, 42), "%!(BADPREC)42"},
+ {"%.*d", args(int(1e7), 42), "%!(BADPREC)42"},
+ {"%.*d", args(uint(1e7), 42), "%!(BADPREC)42"},
+ {"%.*d", args(uint64(1<<63), 42), "%!(BADPREC)42"}, // Huge negative (-inf).
+ {"%.*d", args(uint64(1<<64-1), 42), "%!(BADPREC)42"}, // Small negative (-1).
+ {"%*d", args(5, "foo"), "%!d(string= foo)"},
+ {"%*% %d", args(20, 5), "% 5"},
+ {"%*", args(4), "%!(NOVERB)"},
+}
+
+func TestWidthAndPrecision(t *testing.T) {
+ for i, tt := range startests {
+ s := Sprintf(tt.fmt, tt.in...)
+ if s != tt.out {
+ t.Errorf("#%d: %q: got %q expected %q", i, tt.fmt, s, tt.out)
+ }
+ }
+}
+
+// PanicS is a type that panics in String.
+type PanicS struct {
+ message any
+}
+
+// Value receiver.
+func (p PanicS) String() string {
+ panic(p.message)
+}
+
+// PanicGo is a type that panics in GoString.
+type PanicGo struct {
+ message any
+}
+
+// Value receiver.
+func (p PanicGo) GoString() string {
+ panic(p.message)
+}
+
+// PanicF is a type that panics in Format.
+type PanicF struct {
+ message any
+}
+
+// Value receiver.
+func (p PanicF) Format(f State, c rune) {
+ panic(p.message)
+}
+
+var panictests = []struct {
+ fmt string
+ in any
+ out string
+}{
+ // String
+ {"%s", (*PanicS)(nil), "<nil>"}, // nil pointer special case
+ {"%s", PanicS{io.ErrUnexpectedEOF}, "%!s(PANIC=String method: unexpected EOF)"},
+ {"%s", PanicS{3}, "%!s(PANIC=String method: 3)"},
+ // GoString
+ {"%#v", (*PanicGo)(nil), "<nil>"}, // nil pointer special case
+ {"%#v", PanicGo{io.ErrUnexpectedEOF}, "%!v(PANIC=GoString method: unexpected EOF)"},
+ {"%#v", PanicGo{3}, "%!v(PANIC=GoString method: 3)"},
+ // Issue 18282. catchPanic should not clear fmtFlags permanently.
+ {"%#v", []any{PanicGo{3}, PanicGo{3}}, "[]interface {}{%!v(PANIC=GoString method: 3), %!v(PANIC=GoString method: 3)}"},
+ // Format
+ {"%s", (*PanicF)(nil), "<nil>"}, // nil pointer special case
+ {"%s", PanicF{io.ErrUnexpectedEOF}, "%!s(PANIC=Format method: unexpected EOF)"},
+ {"%s", PanicF{3}, "%!s(PANIC=Format method: 3)"},
+}
+
+func TestPanics(t *testing.T) {
+ for i, tt := range panictests {
+ s := Sprintf(tt.fmt, tt.in)
+ if s != tt.out {
+ t.Errorf("%d: %q: got %q expected %q", i, tt.fmt, s, tt.out)
+ }
+ }
+}
+
+// recurCount tests that erroneous String routine doesn't cause fatal recursion.
+var recurCount = 0
+
+type Recur struct {
+ i int
+ failed *bool
+}
+
+func (r *Recur) String() string {
+ if recurCount++; recurCount > 10 {
+ *r.failed = true
+ return "FAIL"
+ }
+ // This will call badVerb. Before the fix, that would cause us to recur into
+ // this routine to print %!p(value). Now we don't call the user's method
+ // during an error.
+ return Sprintf("recur@%p value: %d", r, r.i)
+}
+
+func TestBadVerbRecursion(t *testing.T) {
+ failed := false
+ r := &Recur{3, &failed}
+ Sprintf("recur@%p value: %d\n", &r, r.i)
+ if failed {
+ t.Error("fail with pointer")
+ }
+ failed = false
+ r = &Recur{4, &failed}
+ Sprintf("recur@%p, value: %d\n", r, r.i)
+ if failed {
+ t.Error("fail with value")
+ }
+}
+
+func TestIsSpace(t *testing.T) {
+ // This tests the internal isSpace function.
+ // IsSpace = isSpace is defined in export_test.go.
+ for i := rune(0); i <= unicode.MaxRune; i++ {
+ if IsSpace(i) != unicode.IsSpace(i) {
+ t.Errorf("isSpace(%U) = %v, want %v", i, IsSpace(i), unicode.IsSpace(i))
+ }
+ }
+}
+
+func hideFromVet(s string) string { return s }
+
+func TestNilDoesNotBecomeTyped(t *testing.T) {
+ type A struct{}
+ type B struct{}
+ var a *A = nil
+ var b B = B{}
+ got := Sprintf(hideFromVet("%s %s %s %s %s"), nil, a, nil, b, nil)
+ const expect = "%!s(<nil>) %!s(*fmt_test.A=<nil>) %!s(<nil>) {} %!s(<nil>)"
+ if got != expect {
+ t.Errorf("expected:\n\t%q\ngot:\n\t%q", expect, got)
+ }
+}
+
+var formatterFlagTests = []struct {
+ in string
+ val any
+ out string
+}{
+ // scalar values with the (unused by fmt) 'a' verb.
+ {"%a", flagPrinter{}, "[%a]"},
+ {"%-a", flagPrinter{}, "[%-a]"},
+ {"%+a", flagPrinter{}, "[%+a]"},
+ {"%#a", flagPrinter{}, "[%#a]"},
+ {"% a", flagPrinter{}, "[% a]"},
+ {"%0a", flagPrinter{}, "[%0a]"},
+ {"%1.2a", flagPrinter{}, "[%1.2a]"},
+ {"%-1.2a", flagPrinter{}, "[%-1.2a]"},
+ {"%+1.2a", flagPrinter{}, "[%+1.2a]"},
+ {"%-+1.2a", flagPrinter{}, "[%+-1.2a]"},
+ {"%-+1.2abc", flagPrinter{}, "[%+-1.2a]bc"},
+ {"%-1.2abc", flagPrinter{}, "[%-1.2a]bc"},
+
+ // composite values with the 'a' verb
+ {"%a", [1]flagPrinter{}, "[[%a]]"},
+ {"%-a", [1]flagPrinter{}, "[[%-a]]"},
+ {"%+a", [1]flagPrinter{}, "[[%+a]]"},
+ {"%#a", [1]flagPrinter{}, "[[%#a]]"},
+ {"% a", [1]flagPrinter{}, "[[% a]]"},
+ {"%0a", [1]flagPrinter{}, "[[%0a]]"},
+ {"%1.2a", [1]flagPrinter{}, "[[%1.2a]]"},
+ {"%-1.2a", [1]flagPrinter{}, "[[%-1.2a]]"},
+ {"%+1.2a", [1]flagPrinter{}, "[[%+1.2a]]"},
+ {"%-+1.2a", [1]flagPrinter{}, "[[%+-1.2a]]"},
+ {"%-+1.2abc", [1]flagPrinter{}, "[[%+-1.2a]]bc"},
+ {"%-1.2abc", [1]flagPrinter{}, "[[%-1.2a]]bc"},
+
+ // simple values with the 'v' verb
+ {"%v", flagPrinter{}, "[%v]"},
+ {"%-v", flagPrinter{}, "[%-v]"},
+ {"%+v", flagPrinter{}, "[%+v]"},
+ {"%#v", flagPrinter{}, "[%#v]"},
+ {"% v", flagPrinter{}, "[% v]"},
+ {"%0v", flagPrinter{}, "[%0v]"},
+ {"%1.2v", flagPrinter{}, "[%1.2v]"},
+ {"%-1.2v", flagPrinter{}, "[%-1.2v]"},
+ {"%+1.2v", flagPrinter{}, "[%+1.2v]"},
+ {"%-+1.2v", flagPrinter{}, "[%+-1.2v]"},
+ {"%-+1.2vbc", flagPrinter{}, "[%+-1.2v]bc"},
+ {"%-1.2vbc", flagPrinter{}, "[%-1.2v]bc"},
+
+ // composite values with the 'v' verb.
+ {"%v", [1]flagPrinter{}, "[[%v]]"},
+ {"%-v", [1]flagPrinter{}, "[[%-v]]"},
+ {"%+v", [1]flagPrinter{}, "[[%+v]]"},
+ {"%#v", [1]flagPrinter{}, "[1]fmt_test.flagPrinter{[%#v]}"},
+ {"% v", [1]flagPrinter{}, "[[% v]]"},
+ {"%0v", [1]flagPrinter{}, "[[%0v]]"},
+ {"%1.2v", [1]flagPrinter{}, "[[%1.2v]]"},
+ {"%-1.2v", [1]flagPrinter{}, "[[%-1.2v]]"},
+ {"%+1.2v", [1]flagPrinter{}, "[[%+1.2v]]"},
+ {"%-+1.2v", [1]flagPrinter{}, "[[%+-1.2v]]"},
+ {"%-+1.2vbc", [1]flagPrinter{}, "[[%+-1.2v]]bc"},
+ {"%-1.2vbc", [1]flagPrinter{}, "[[%-1.2v]]bc"},
+}
+
+func TestFormatterFlags(t *testing.T) {
+ for _, tt := range formatterFlagTests {
+ s := Sprintf(tt.in, tt.val)
+ if s != tt.out {
+ t.Errorf("Sprintf(%q, %T) = %q, want %q", tt.in, tt.val, s, tt.out)
+ }
+ }
+}
+
+func TestParsenum(t *testing.T) {
+ testCases := []struct {
+ s string
+ start, end int
+ num int
+ isnum bool
+ newi int
+ }{
+ {"a123", 0, 4, 0, false, 0},
+ {"1234", 1, 1, 0, false, 1},
+ {"123a", 0, 4, 123, true, 3},
+ {"12a3", 0, 4, 12, true, 2},
+ {"1234", 0, 4, 1234, true, 4},
+ {"1a234", 1, 3, 0, false, 1},
+ }
+ for _, tt := range testCases {
+ num, isnum, newi := Parsenum(tt.s, tt.start, tt.end)
+ if num != tt.num || isnum != tt.isnum || newi != tt.newi {
+ t.Errorf("parsenum(%q, %d, %d) = %d, %v, %d, want %d, %v, %d", tt.s, tt.start, tt.end, num, isnum, newi, tt.num, tt.isnum, tt.newi)
+ }
+ }
+}
diff --git a/src/fmt/format.go b/src/fmt/format.go
new file mode 100644
index 0000000..bd00e5a
--- /dev/null
+++ b/src/fmt/format.go
@@ -0,0 +1,593 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt
+
+import (
+ "strconv"
+ "unicode/utf8"
+)
+
+const (
+ ldigits = "0123456789abcdefx"
+ udigits = "0123456789ABCDEFX"
+)
+
+const (
+ signed = true
+ unsigned = false
+)
+
+// flags placed in a separate struct for easy clearing.
+type fmtFlags struct {
+ widPresent bool
+ precPresent bool
+ minus bool
+ plus bool
+ sharp bool
+ space bool
+ zero bool
+
+ // For the formats %+v %#v, we set the plusV/sharpV flags
+ // and clear the plus/sharp flags since %+v and %#v are in effect
+ // different, flagless formats set at the top level.
+ plusV bool
+ sharpV bool
+}
+
+// A fmt is the raw formatter used by Printf etc.
+// It prints into a buffer that must be set up separately.
+type fmt struct {
+ buf *buffer
+
+ fmtFlags
+
+ wid int // width
+ prec int // precision
+
+ // intbuf is large enough to store %b of an int64 with a sign and
+ // avoids padding at the end of the struct on 32 bit architectures.
+ intbuf [68]byte
+}
+
+func (f *fmt) clearflags() {
+ f.fmtFlags = fmtFlags{}
+}
+
+func (f *fmt) init(buf *buffer) {
+ f.buf = buf
+ f.clearflags()
+}
+
+// writePadding generates n bytes of padding.
+func (f *fmt) writePadding(n int) {
+ if n <= 0 { // No padding bytes needed.
+ return
+ }
+ buf := *f.buf
+ oldLen := len(buf)
+ newLen := oldLen + n
+ // Make enough room for padding.
+ if newLen > cap(buf) {
+ buf = make(buffer, cap(buf)*2+n)
+ copy(buf, *f.buf)
+ }
+ // Decide which byte the padding should be filled with.
+ padByte := byte(' ')
+ if f.zero {
+ padByte = byte('0')
+ }
+ // Fill padding with padByte.
+ padding := buf[oldLen:newLen]
+ for i := range padding {
+ padding[i] = padByte
+ }
+ *f.buf = buf[:newLen]
+}
+
+// pad appends b to f.buf, padded on left (!f.minus) or right (f.minus).
+func (f *fmt) pad(b []byte) {
+ if !f.widPresent || f.wid == 0 {
+ f.buf.write(b)
+ return
+ }
+ width := f.wid - utf8.RuneCount(b)
+ if !f.minus {
+ // left padding
+ f.writePadding(width)
+ f.buf.write(b)
+ } else {
+ // right padding
+ f.buf.write(b)
+ f.writePadding(width)
+ }
+}
+
+// padString appends s to f.buf, padded on left (!f.minus) or right (f.minus).
+func (f *fmt) padString(s string) {
+ if !f.widPresent || f.wid == 0 {
+ f.buf.writeString(s)
+ return
+ }
+ width := f.wid - utf8.RuneCountInString(s)
+ if !f.minus {
+ // left padding
+ f.writePadding(width)
+ f.buf.writeString(s)
+ } else {
+ // right padding
+ f.buf.writeString(s)
+ f.writePadding(width)
+ }
+}
+
+// fmtBoolean formats a boolean.
+func (f *fmt) fmtBoolean(v bool) {
+ if v {
+ f.padString("true")
+ } else {
+ f.padString("false")
+ }
+}
+
+// fmtUnicode formats a uint64 as "U+0078" or with f.sharp set as "U+0078 'x'".
+func (f *fmt) fmtUnicode(u uint64) {
+ buf := f.intbuf[0:]
+
+ // With default precision set the maximum needed buf length is 18
+ // for formatting -1 with %#U ("U+FFFFFFFFFFFFFFFF") which fits
+ // into the already allocated intbuf with a capacity of 68 bytes.
+ prec := 4
+ if f.precPresent && f.prec > 4 {
+ prec = f.prec
+ // Compute space needed for "U+" , number, " '", character, "'".
+ width := 2 + prec + 2 + utf8.UTFMax + 1
+ if width > len(buf) {
+ buf = make([]byte, width)
+ }
+ }
+
+ // Format into buf, ending at buf[i]. Formatting numbers is easier right-to-left.
+ i := len(buf)
+
+ // For %#U we want to add a space and a quoted character at the end of the buffer.
+ if f.sharp && u <= utf8.MaxRune && strconv.IsPrint(rune(u)) {
+ i--
+ buf[i] = '\''
+ i -= utf8.RuneLen(rune(u))
+ utf8.EncodeRune(buf[i:], rune(u))
+ i--
+ buf[i] = '\''
+ i--
+ buf[i] = ' '
+ }
+ // Format the Unicode code point u as a hexadecimal number.
+ for u >= 16 {
+ i--
+ buf[i] = udigits[u&0xF]
+ prec--
+ u >>= 4
+ }
+ i--
+ buf[i] = udigits[u]
+ prec--
+ // Add zeros in front of the number until requested precision is reached.
+ for prec > 0 {
+ i--
+ buf[i] = '0'
+ prec--
+ }
+ // Add a leading "U+".
+ i--
+ buf[i] = '+'
+ i--
+ buf[i] = 'U'
+
+ oldZero := f.zero
+ f.zero = false
+ f.pad(buf[i:])
+ f.zero = oldZero
+}
+
+// fmtInteger formats signed and unsigned integers.
+func (f *fmt) fmtInteger(u uint64, base int, isSigned bool, verb rune, digits string) {
+ negative := isSigned && int64(u) < 0
+ if negative {
+ u = -u
+ }
+
+ buf := f.intbuf[0:]
+ // The already allocated f.intbuf with a capacity of 68 bytes
+ // is large enough for integer formatting when no precision or width is set.
+ if f.widPresent || f.precPresent {
+ // Account 3 extra bytes for possible addition of a sign and "0x".
+ width := 3 + f.wid + f.prec // wid and prec are always positive.
+ if width > len(buf) {
+ // We're going to need a bigger boat.
+ buf = make([]byte, width)
+ }
+ }
+
+ // Two ways to ask for extra leading zero digits: %.3d or %03d.
+ // If both are specified the f.zero flag is ignored and
+ // padding with spaces is used instead.
+ prec := 0
+ if f.precPresent {
+ prec = f.prec
+ // Precision of 0 and value of 0 means "print nothing" but padding.
+ if prec == 0 && u == 0 {
+ oldZero := f.zero
+ f.zero = false
+ f.writePadding(f.wid)
+ f.zero = oldZero
+ return
+ }
+ } else if f.zero && f.widPresent {
+ prec = f.wid
+ if negative || f.plus || f.space {
+ prec-- // leave room for sign
+ }
+ }
+
+ // Because printing is easier right-to-left: format u into buf, ending at buf[i].
+ // We could make things marginally faster by splitting the 32-bit case out
+ // into a separate block but it's not worth the duplication, so u has 64 bits.
+ i := len(buf)
+ // Use constants for the division and modulo for more efficient code.
+ // Switch cases ordered by popularity.
+ switch base {
+ case 10:
+ for u >= 10 {
+ i--
+ next := u / 10
+ buf[i] = byte('0' + u - next*10)
+ u = next
+ }
+ case 16:
+ for u >= 16 {
+ i--
+ buf[i] = digits[u&0xF]
+ u >>= 4
+ }
+ case 8:
+ for u >= 8 {
+ i--
+ buf[i] = byte('0' + u&7)
+ u >>= 3
+ }
+ case 2:
+ for u >= 2 {
+ i--
+ buf[i] = byte('0' + u&1)
+ u >>= 1
+ }
+ default:
+ panic("fmt: unknown base; can't happen")
+ }
+ i--
+ buf[i] = digits[u]
+ for i > 0 && prec > len(buf)-i {
+ i--
+ buf[i] = '0'
+ }
+
+ // Various prefixes: 0x, -, etc.
+ if f.sharp {
+ switch base {
+ case 2:
+ // Add a leading 0b.
+ i--
+ buf[i] = 'b'
+ i--
+ buf[i] = '0'
+ case 8:
+ if buf[i] != '0' {
+ i--
+ buf[i] = '0'
+ }
+ case 16:
+ // Add a leading 0x or 0X.
+ i--
+ buf[i] = digits[16]
+ i--
+ buf[i] = '0'
+ }
+ }
+ if verb == 'O' {
+ i--
+ buf[i] = 'o'
+ i--
+ buf[i] = '0'
+ }
+
+ if negative {
+ i--
+ buf[i] = '-'
+ } else if f.plus {
+ i--
+ buf[i] = '+'
+ } else if f.space {
+ i--
+ buf[i] = ' '
+ }
+
+ // Left padding with zeros has already been handled like precision earlier
+ // or the f.zero flag is ignored due to an explicitly set precision.
+ oldZero := f.zero
+ f.zero = false
+ f.pad(buf[i:])
+ f.zero = oldZero
+}
+
+// truncateString truncates the string s to the specified precision, if present.
+func (f *fmt) truncateString(s string) string {
+ if f.precPresent {
+ n := f.prec
+ for i := range s {
+ n--
+ if n < 0 {
+ return s[:i]
+ }
+ }
+ }
+ return s
+}
+
+// truncate truncates the byte slice b as a string of the specified precision, if present.
+func (f *fmt) truncate(b []byte) []byte {
+ if f.precPresent {
+ n := f.prec
+ for i := 0; i < len(b); {
+ n--
+ if n < 0 {
+ return b[:i]
+ }
+ wid := 1
+ if b[i] >= utf8.RuneSelf {
+ _, wid = utf8.DecodeRune(b[i:])
+ }
+ i += wid
+ }
+ }
+ return b
+}
+
+// fmtS formats a string.
+func (f *fmt) fmtS(s string) {
+ s = f.truncateString(s)
+ f.padString(s)
+}
+
+// fmtBs formats the byte slice b as if it was formatted as string with fmtS.
+func (f *fmt) fmtBs(b []byte) {
+ b = f.truncate(b)
+ f.pad(b)
+}
+
+// fmtSbx formats a string or byte slice as a hexadecimal encoding of its bytes.
+func (f *fmt) fmtSbx(s string, b []byte, digits string) {
+ length := len(b)
+ if b == nil {
+ // No byte slice present. Assume string s should be encoded.
+ length = len(s)
+ }
+ // Set length to not process more bytes than the precision demands.
+ if f.precPresent && f.prec < length {
+ length = f.prec
+ }
+ // Compute width of the encoding taking into account the f.sharp and f.space flag.
+ width := 2 * length
+ if width > 0 {
+ if f.space {
+ // Each element encoded by two hexadecimals will get a leading 0x or 0X.
+ if f.sharp {
+ width *= 2
+ }
+ // Elements will be separated by a space.
+ width += length - 1
+ } else if f.sharp {
+ // Only a leading 0x or 0X will be added for the whole string.
+ width += 2
+ }
+ } else { // The byte slice or string that should be encoded is empty.
+ if f.widPresent {
+ f.writePadding(f.wid)
+ }
+ return
+ }
+ // Handle padding to the left.
+ if f.widPresent && f.wid > width && !f.minus {
+ f.writePadding(f.wid - width)
+ }
+ // Write the encoding directly into the output buffer.
+ buf := *f.buf
+ if f.sharp {
+ // Add leading 0x or 0X.
+ buf = append(buf, '0', digits[16])
+ }
+ var c byte
+ for i := 0; i < length; i++ {
+ if f.space && i > 0 {
+ // Separate elements with a space.
+ buf = append(buf, ' ')
+ if f.sharp {
+ // Add leading 0x or 0X for each element.
+ buf = append(buf, '0', digits[16])
+ }
+ }
+ if b != nil {
+ c = b[i] // Take a byte from the input byte slice.
+ } else {
+ c = s[i] // Take a byte from the input string.
+ }
+ // Encode each byte as two hexadecimal digits.
+ buf = append(buf, digits[c>>4], digits[c&0xF])
+ }
+ *f.buf = buf
+ // Handle padding to the right.
+ if f.widPresent && f.wid > width && f.minus {
+ f.writePadding(f.wid - width)
+ }
+}
+
+// fmtSx formats a string as a hexadecimal encoding of its bytes.
+func (f *fmt) fmtSx(s, digits string) {
+ f.fmtSbx(s, nil, digits)
+}
+
+// fmtBx formats a byte slice as a hexadecimal encoding of its bytes.
+func (f *fmt) fmtBx(b []byte, digits string) {
+ f.fmtSbx("", b, digits)
+}
+
+// fmtQ formats a string as a double-quoted, escaped Go string constant.
+// If f.sharp is set a raw (backquoted) string may be returned instead
+// if the string does not contain any control characters other than tab.
+func (f *fmt) fmtQ(s string) {
+ s = f.truncateString(s)
+ if f.sharp && strconv.CanBackquote(s) {
+ f.padString("`" + s + "`")
+ return
+ }
+ buf := f.intbuf[:0]
+ if f.plus {
+ f.pad(strconv.AppendQuoteToASCII(buf, s))
+ } else {
+ f.pad(strconv.AppendQuote(buf, s))
+ }
+}
+
+// fmtC formats an integer as a Unicode character.
+// If the character is not valid Unicode, it will print '\ufffd'.
+func (f *fmt) fmtC(c uint64) {
+ r := rune(c)
+ if c > utf8.MaxRune {
+ r = utf8.RuneError
+ }
+ buf := f.intbuf[:0]
+ w := utf8.EncodeRune(buf[:utf8.UTFMax], r)
+ f.pad(buf[:w])
+}
+
+// fmtQc formats an integer as a single-quoted, escaped Go character constant.
+// If the character is not valid Unicode, it will print '\ufffd'.
+func (f *fmt) fmtQc(c uint64) {
+ r := rune(c)
+ if c > utf8.MaxRune {
+ r = utf8.RuneError
+ }
+ buf := f.intbuf[:0]
+ if f.plus {
+ f.pad(strconv.AppendQuoteRuneToASCII(buf, r))
+ } else {
+ f.pad(strconv.AppendQuoteRune(buf, r))
+ }
+}
+
+// fmtFloat formats a float64. It assumes that verb is a valid format specifier
+// for strconv.AppendFloat and therefore fits into a byte.
+func (f *fmt) fmtFloat(v float64, size int, verb rune, prec int) {
+ // Explicit precision in format specifier overrules default precision.
+ if f.precPresent {
+ prec = f.prec
+ }
+ // Format number, reserving space for leading + sign if needed.
+ num := strconv.AppendFloat(f.intbuf[:1], v, byte(verb), prec, size)
+ if num[1] == '-' || num[1] == '+' {
+ num = num[1:]
+ } else {
+ num[0] = '+'
+ }
+ // f.space means to add a leading space instead of a "+" sign unless
+ // the sign is explicitly asked for by f.plus.
+ if f.space && num[0] == '+' && !f.plus {
+ num[0] = ' '
+ }
+ // Special handling for infinities and NaN,
+ // which don't look like a number so shouldn't be padded with zeros.
+ if num[1] == 'I' || num[1] == 'N' {
+ oldZero := f.zero
+ f.zero = false
+ // Remove sign before NaN if not asked for.
+ if num[1] == 'N' && !f.space && !f.plus {
+ num = num[1:]
+ }
+ f.pad(num)
+ f.zero = oldZero
+ return
+ }
+ // The sharp flag forces printing a decimal point for non-binary formats
+ // and retains trailing zeros, which we may need to restore.
+ if f.sharp && verb != 'b' {
+ digits := 0
+ switch verb {
+ case 'v', 'g', 'G', 'x':
+ digits = prec
+ // If no precision is set explicitly use a precision of 6.
+ if digits == -1 {
+ digits = 6
+ }
+ }
+
+ // Buffer pre-allocated with enough room for
+ // exponent notations of the form "e+123" or "p-1023".
+ var tailBuf [6]byte
+ tail := tailBuf[:0]
+
+ hasDecimalPoint := false
+ sawNonzeroDigit := false
+ // Starting from i = 1 to skip sign at num[0].
+ for i := 1; i < len(num); i++ {
+ switch num[i] {
+ case '.':
+ hasDecimalPoint = true
+ case 'p', 'P':
+ tail = append(tail, num[i:]...)
+ num = num[:i]
+ case 'e', 'E':
+ if verb != 'x' && verb != 'X' {
+ tail = append(tail, num[i:]...)
+ num = num[:i]
+ break
+ }
+ fallthrough
+ default:
+ if num[i] != '0' {
+ sawNonzeroDigit = true
+ }
+ // Count significant digits after the first non-zero digit.
+ if sawNonzeroDigit {
+ digits--
+ }
+ }
+ }
+ if !hasDecimalPoint {
+ // Leading digit 0 should contribute once to digits.
+ if len(num) == 2 && num[1] == '0' {
+ digits--
+ }
+ num = append(num, '.')
+ }
+ for digits > 0 {
+ num = append(num, '0')
+ digits--
+ }
+ num = append(num, tail...)
+ }
+ // We want a sign if asked for and if the sign is not positive.
+ if f.plus || num[0] != '+' {
+ // If we're zero padding to the left we want the sign before the leading zeros.
+ // Achieve this by writing the sign out and then padding the unsigned number.
+ if f.zero && f.widPresent && f.wid > len(num) {
+ f.buf.writeByte(num[0])
+ f.writePadding(f.wid - len(num))
+ f.buf.write(num[1:])
+ return
+ }
+ f.pad(num)
+ return
+ }
+ // No sign to show and the number is positive; just print the unsigned number.
+ f.pad(num[1:])
+}
diff --git a/src/fmt/gostringer_example_test.go b/src/fmt/gostringer_example_test.go
new file mode 100644
index 0000000..ab19ee3
--- /dev/null
+++ b/src/fmt/gostringer_example_test.go
@@ -0,0 +1,59 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt_test
+
+import (
+ "fmt"
+)
+
+// Address has a City, State and a Country.
+type Address struct {
+ City string
+ State string
+ Country string
+}
+
+// Person has a Name, Age and Address.
+type Person struct {
+ Name string
+ Age uint
+ Addr *Address
+}
+
+// GoString makes Person satisfy the GoStringer interface.
+// The return value is valid Go code that can be used to reproduce the Person struct.
+func (p Person) GoString() string {
+ if p.Addr != nil {
+ return fmt.Sprintf("Person{Name: %q, Age: %d, Addr: &Address{City: %q, State: %q, Country: %q}}", p.Name, int(p.Age), p.Addr.City, p.Addr.State, p.Addr.Country)
+ }
+ return fmt.Sprintf("Person{Name: %q, Age: %d}", p.Name, int(p.Age))
+}
+
+func ExampleGoStringer() {
+ p1 := Person{
+ Name: "Warren",
+ Age: 31,
+ Addr: &Address{
+ City: "Denver",
+ State: "CO",
+ Country: "U.S.A.",
+ },
+ }
+ // If GoString() wasn't implemented, the output of `fmt.Printf("%#v", p1)` would be similar to
+ // Person{Name:"Warren", Age:0x1f, Addr:(*main.Address)(0x10448240)}
+ fmt.Printf("%#v\n", p1)
+
+ p2 := Person{
+ Name: "Theia",
+ Age: 4,
+ }
+ // If GoString() wasn't implemented, the output of `fmt.Printf("%#v", p2)` would be similar to
+ // Person{Name:"Theia", Age:0x4, Addr:(*main.Address)(nil)}
+ fmt.Printf("%#v\n", p2)
+
+ // Output:
+ // Person{Name: "Warren", Age: 31, Addr: &Address{City: "Denver", State: "CO", Country: "U.S.A."}}
+ // Person{Name: "Theia", Age: 4}
+}
diff --git a/src/fmt/print.go b/src/fmt/print.go
new file mode 100644
index 0000000..1c37c3c
--- /dev/null
+++ b/src/fmt/print.go
@@ -0,0 +1,1172 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt
+
+import (
+ "internal/fmtsort"
+ "io"
+ "os"
+ "reflect"
+ "sync"
+ "unicode/utf8"
+)
+
+// Strings for use with buffer.WriteString.
+// This is less overhead than using buffer.Write with byte arrays.
+const (
+ commaSpaceString = ", "
+ nilAngleString = "<nil>"
+ nilParenString = "(nil)"
+ nilString = "nil"
+ mapString = "map["
+ percentBangString = "%!"
+ missingString = "(MISSING)"
+ badIndexString = "(BADINDEX)"
+ panicString = "(PANIC="
+ extraString = "%!(EXTRA "
+ badWidthString = "%!(BADWIDTH)"
+ badPrecString = "%!(BADPREC)"
+ noVerbString = "%!(NOVERB)"
+ invReflectString = "<invalid reflect.Value>"
+)
+
+// State represents the printer state passed to custom formatters.
+// It provides access to the io.Writer interface plus information about
+// the flags and options for the operand's format specifier.
+type State interface {
+ // Write is the function to call to emit formatted output to be printed.
+ Write(b []byte) (n int, err error)
+ // Width returns the value of the width option and whether it has been set.
+ Width() (wid int, ok bool)
+ // Precision returns the value of the precision option and whether it has been set.
+ Precision() (prec int, ok bool)
+
+ // Flag reports whether the flag c, a character, has been set.
+ Flag(c int) bool
+}
+
+// Formatter is implemented by any value that has a Format method.
+// The implementation controls how State and rune are interpreted,
+// and may call Sprint(f) or Fprint(f) etc. to generate its output.
+type Formatter interface {
+ Format(f State, verb rune)
+}
+
+// Stringer is implemented by any value that has a String method,
+// which defines the ``native'' format for that value.
+// The String method is used to print values passed as an operand
+// to any format that accepts a string or to an unformatted printer
+// such as Print.
+type Stringer interface {
+ String() string
+}
+
+// GoStringer is implemented by any value that has a GoString method,
+// which defines the Go syntax for that value.
+// The GoString method is used to print values passed as an operand
+// to a %#v format.
+type GoStringer interface {
+ GoString() string
+}
+
+// Use simple []byte instead of bytes.Buffer to avoid large dependency.
+type buffer []byte
+
+func (b *buffer) write(p []byte) {
+ *b = append(*b, p...)
+}
+
+func (b *buffer) writeString(s string) {
+ *b = append(*b, s...)
+}
+
+func (b *buffer) writeByte(c byte) {
+ *b = append(*b, c)
+}
+
+func (bp *buffer) writeRune(r rune) {
+ if r < utf8.RuneSelf {
+ *bp = append(*bp, byte(r))
+ return
+ }
+
+ b := *bp
+ n := len(b)
+ for n+utf8.UTFMax > cap(b) {
+ b = append(b, 0)
+ }
+ w := utf8.EncodeRune(b[n:n+utf8.UTFMax], r)
+ *bp = b[:n+w]
+}
+
+// pp is used to store a printer's state and is reused with sync.Pool to avoid allocations.
+type pp struct {
+ buf buffer
+
+ // arg holds the current item, as an interface{}.
+ arg any
+
+ // value is used instead of arg for reflect values.
+ value reflect.Value
+
+ // fmt is used to format basic items such as integers or strings.
+ fmt fmt
+
+ // reordered records whether the format string used argument reordering.
+ reordered bool
+ // goodArgNum records whether the most recent reordering directive was valid.
+ goodArgNum bool
+ // panicking is set by catchPanic to avoid infinite panic, recover, panic, ... recursion.
+ panicking bool
+ // erroring is set when printing an error string to guard against calling handleMethods.
+ erroring bool
+ // wrapErrs is set when the format string may contain a %w verb.
+ wrapErrs bool
+ // wrappedErr records the target of the %w verb.
+ wrappedErr error
+}
+
+var ppFree = sync.Pool{
+ New: func() any { return new(pp) },
+}
+
+// newPrinter allocates a new pp struct or grabs a cached one.
+func newPrinter() *pp {
+ p := ppFree.Get().(*pp)
+ p.panicking = false
+ p.erroring = false
+ p.wrapErrs = false
+ p.fmt.init(&p.buf)
+ return p
+}
+
+// free saves used pp structs in ppFree; avoids an allocation per invocation.
+func (p *pp) free() {
+ // Proper usage of a sync.Pool requires each entry to have approximately
+ // the same memory cost. To obtain this property when the stored type
+ // contains a variably-sized buffer, we add a hard limit on the maximum buffer
+ // to place back in the pool.
+ //
+ // See https://golang.org/issue/23199
+ if cap(p.buf) > 64<<10 {
+ return
+ }
+
+ p.buf = p.buf[:0]
+ p.arg = nil
+ p.value = reflect.Value{}
+ p.wrappedErr = nil
+ ppFree.Put(p)
+}
+
+func (p *pp) Width() (wid int, ok bool) { return p.fmt.wid, p.fmt.widPresent }
+
+func (p *pp) Precision() (prec int, ok bool) { return p.fmt.prec, p.fmt.precPresent }
+
+func (p *pp) Flag(b int) bool {
+ switch b {
+ case '-':
+ return p.fmt.minus
+ case '+':
+ return p.fmt.plus || p.fmt.plusV
+ case '#':
+ return p.fmt.sharp || p.fmt.sharpV
+ case ' ':
+ return p.fmt.space
+ case '0':
+ return p.fmt.zero
+ }
+ return false
+}
+
+// Implement Write so we can call Fprintf on a pp (through State), for
+// recursive use in custom verbs.
+func (p *pp) Write(b []byte) (ret int, err error) {
+ p.buf.write(b)
+ return len(b), nil
+}
+
+// Implement WriteString so that we can call io.WriteString
+// on a pp (through state), for efficiency.
+func (p *pp) WriteString(s string) (ret int, err error) {
+ p.buf.writeString(s)
+ return len(s), nil
+}
+
+// These routines end in 'f' and take a format string.
+
+// Fprintf formats according to a format specifier and writes to w.
+// It returns the number of bytes written and any write error encountered.
+func Fprintf(w io.Writer, format string, a ...any) (n int, err error) {
+ p := newPrinter()
+ p.doPrintf(format, a)
+ n, err = w.Write(p.buf)
+ p.free()
+ return
+}
+
+// Printf formats according to a format specifier and writes to standard output.
+// It returns the number of bytes written and any write error encountered.
+func Printf(format string, a ...any) (n int, err error) {
+ return Fprintf(os.Stdout, format, a...)
+}
+
+// Sprintf formats according to a format specifier and returns the resulting string.
+func Sprintf(format string, a ...any) string {
+ p := newPrinter()
+ p.doPrintf(format, a)
+ s := string(p.buf)
+ p.free()
+ return s
+}
+
+// These routines do not take a format string
+
+// Fprint formats using the default formats for its operands and writes to w.
+// Spaces are added between operands when neither is a string.
+// It returns the number of bytes written and any write error encountered.
+func Fprint(w io.Writer, a ...any) (n int, err error) {
+ p := newPrinter()
+ p.doPrint(a)
+ n, err = w.Write(p.buf)
+ p.free()
+ return
+}
+
+// Print formats using the default formats for its operands and writes to standard output.
+// Spaces are added between operands when neither is a string.
+// It returns the number of bytes written and any write error encountered.
+func Print(a ...any) (n int, err error) {
+ return Fprint(os.Stdout, a...)
+}
+
+// Sprint formats using the default formats for its operands and returns the resulting string.
+// Spaces are added between operands when neither is a string.
+func Sprint(a ...any) string {
+ p := newPrinter()
+ p.doPrint(a)
+ s := string(p.buf)
+ p.free()
+ return s
+}
+
+// These routines end in 'ln', do not take a format string,
+// always add spaces between operands, and add a newline
+// after the last operand.
+
+// Fprintln formats using the default formats for its operands and writes to w.
+// Spaces are always added between operands and a newline is appended.
+// It returns the number of bytes written and any write error encountered.
+func Fprintln(w io.Writer, a ...any) (n int, err error) {
+ p := newPrinter()
+ p.doPrintln(a)
+ n, err = w.Write(p.buf)
+ p.free()
+ return
+}
+
+// Println formats using the default formats for its operands and writes to standard output.
+// Spaces are always added between operands and a newline is appended.
+// It returns the number of bytes written and any write error encountered.
+func Println(a ...any) (n int, err error) {
+ return Fprintln(os.Stdout, a...)
+}
+
+// Sprintln formats using the default formats for its operands and returns the resulting string.
+// Spaces are always added between operands and a newline is appended.
+func Sprintln(a ...any) string {
+ p := newPrinter()
+ p.doPrintln(a)
+ s := string(p.buf)
+ p.free()
+ return s
+}
+
+// getField gets the i'th field of the struct value.
+// If the field is itself is an interface, return a value for
+// the thing inside the interface, not the interface itself.
+func getField(v reflect.Value, i int) reflect.Value {
+ val := v.Field(i)
+ if val.Kind() == reflect.Interface && !val.IsNil() {
+ val = val.Elem()
+ }
+ return val
+}
+
+// tooLarge reports whether the magnitude of the integer is
+// too large to be used as a formatting width or precision.
+func tooLarge(x int) bool {
+ const max int = 1e6
+ return x > max || x < -max
+}
+
+// parsenum converts ASCII to integer. num is 0 (and isnum is false) if no number present.
+func parsenum(s string, start, end int) (num int, isnum bool, newi int) {
+ if start >= end {
+ return 0, false, end
+ }
+ for newi = start; newi < end && '0' <= s[newi] && s[newi] <= '9'; newi++ {
+ if tooLarge(num) {
+ return 0, false, end // Overflow; crazy long number most likely.
+ }
+ num = num*10 + int(s[newi]-'0')
+ isnum = true
+ }
+ return
+}
+
+func (p *pp) unknownType(v reflect.Value) {
+ if !v.IsValid() {
+ p.buf.writeString(nilAngleString)
+ return
+ }
+ p.buf.writeByte('?')
+ p.buf.writeString(v.Type().String())
+ p.buf.writeByte('?')
+}
+
+func (p *pp) badVerb(verb rune) {
+ p.erroring = true
+ p.buf.writeString(percentBangString)
+ p.buf.writeRune(verb)
+ p.buf.writeByte('(')
+ switch {
+ case p.arg != nil:
+ p.buf.writeString(reflect.TypeOf(p.arg).String())
+ p.buf.writeByte('=')
+ p.printArg(p.arg, 'v')
+ case p.value.IsValid():
+ p.buf.writeString(p.value.Type().String())
+ p.buf.writeByte('=')
+ p.printValue(p.value, 'v', 0)
+ default:
+ p.buf.writeString(nilAngleString)
+ }
+ p.buf.writeByte(')')
+ p.erroring = false
+}
+
+func (p *pp) fmtBool(v bool, verb rune) {
+ switch verb {
+ case 't', 'v':
+ p.fmt.fmtBoolean(v)
+ default:
+ p.badVerb(verb)
+ }
+}
+
+// fmt0x64 formats a uint64 in hexadecimal and prefixes it with 0x or
+// not, as requested, by temporarily setting the sharp flag.
+func (p *pp) fmt0x64(v uint64, leading0x bool) {
+ sharp := p.fmt.sharp
+ p.fmt.sharp = leading0x
+ p.fmt.fmtInteger(v, 16, unsigned, 'v', ldigits)
+ p.fmt.sharp = sharp
+}
+
+// fmtInteger formats a signed or unsigned integer.
+func (p *pp) fmtInteger(v uint64, isSigned bool, verb rune) {
+ switch verb {
+ case 'v':
+ if p.fmt.sharpV && !isSigned {
+ p.fmt0x64(v, true)
+ } else {
+ p.fmt.fmtInteger(v, 10, isSigned, verb, ldigits)
+ }
+ case 'd':
+ p.fmt.fmtInteger(v, 10, isSigned, verb, ldigits)
+ case 'b':
+ p.fmt.fmtInteger(v, 2, isSigned, verb, ldigits)
+ case 'o', 'O':
+ p.fmt.fmtInteger(v, 8, isSigned, verb, ldigits)
+ case 'x':
+ p.fmt.fmtInteger(v, 16, isSigned, verb, ldigits)
+ case 'X':
+ p.fmt.fmtInteger(v, 16, isSigned, verb, udigits)
+ case 'c':
+ p.fmt.fmtC(v)
+ case 'q':
+ p.fmt.fmtQc(v)
+ case 'U':
+ p.fmt.fmtUnicode(v)
+ default:
+ p.badVerb(verb)
+ }
+}
+
+// fmtFloat formats a float. The default precision for each verb
+// is specified as last argument in the call to fmt_float.
+func (p *pp) fmtFloat(v float64, size int, verb rune) {
+ switch verb {
+ case 'v':
+ p.fmt.fmtFloat(v, size, 'g', -1)
+ case 'b', 'g', 'G', 'x', 'X':
+ p.fmt.fmtFloat(v, size, verb, -1)
+ case 'f', 'e', 'E':
+ p.fmt.fmtFloat(v, size, verb, 6)
+ case 'F':
+ p.fmt.fmtFloat(v, size, 'f', 6)
+ default:
+ p.badVerb(verb)
+ }
+}
+
+// fmtComplex formats a complex number v with
+// r = real(v) and j = imag(v) as (r+ji) using
+// fmtFloat for r and j formatting.
+func (p *pp) fmtComplex(v complex128, size int, verb rune) {
+ // Make sure any unsupported verbs are found before the
+ // calls to fmtFloat to not generate an incorrect error string.
+ switch verb {
+ case 'v', 'b', 'g', 'G', 'x', 'X', 'f', 'F', 'e', 'E':
+ oldPlus := p.fmt.plus
+ p.buf.writeByte('(')
+ p.fmtFloat(real(v), size/2, verb)
+ // Imaginary part always has a sign.
+ p.fmt.plus = true
+ p.fmtFloat(imag(v), size/2, verb)
+ p.buf.writeString("i)")
+ p.fmt.plus = oldPlus
+ default:
+ p.badVerb(verb)
+ }
+}
+
+func (p *pp) fmtString(v string, verb rune) {
+ switch verb {
+ case 'v':
+ if p.fmt.sharpV {
+ p.fmt.fmtQ(v)
+ } else {
+ p.fmt.fmtS(v)
+ }
+ case 's':
+ p.fmt.fmtS(v)
+ case 'x':
+ p.fmt.fmtSx(v, ldigits)
+ case 'X':
+ p.fmt.fmtSx(v, udigits)
+ case 'q':
+ p.fmt.fmtQ(v)
+ default:
+ p.badVerb(verb)
+ }
+}
+
+func (p *pp) fmtBytes(v []byte, verb rune, typeString string) {
+ switch verb {
+ case 'v', 'd':
+ if p.fmt.sharpV {
+ p.buf.writeString(typeString)
+ if v == nil {
+ p.buf.writeString(nilParenString)
+ return
+ }
+ p.buf.writeByte('{')
+ for i, c := range v {
+ if i > 0 {
+ p.buf.writeString(commaSpaceString)
+ }
+ p.fmt0x64(uint64(c), true)
+ }
+ p.buf.writeByte('}')
+ } else {
+ p.buf.writeByte('[')
+ for i, c := range v {
+ if i > 0 {
+ p.buf.writeByte(' ')
+ }
+ p.fmt.fmtInteger(uint64(c), 10, unsigned, verb, ldigits)
+ }
+ p.buf.writeByte(']')
+ }
+ case 's':
+ p.fmt.fmtBs(v)
+ case 'x':
+ p.fmt.fmtBx(v, ldigits)
+ case 'X':
+ p.fmt.fmtBx(v, udigits)
+ case 'q':
+ p.fmt.fmtQ(string(v))
+ default:
+ p.printValue(reflect.ValueOf(v), verb, 0)
+ }
+}
+
+func (p *pp) fmtPointer(value reflect.Value, verb rune) {
+ var u uintptr
+ switch value.Kind() {
+ case reflect.Chan, reflect.Func, reflect.Map, reflect.Pointer, reflect.Slice, reflect.UnsafePointer:
+ u = value.Pointer()
+ default:
+ p.badVerb(verb)
+ return
+ }
+
+ switch verb {
+ case 'v':
+ if p.fmt.sharpV {
+ p.buf.writeByte('(')
+ p.buf.writeString(value.Type().String())
+ p.buf.writeString(")(")
+ if u == 0 {
+ p.buf.writeString(nilString)
+ } else {
+ p.fmt0x64(uint64(u), true)
+ }
+ p.buf.writeByte(')')
+ } else {
+ if u == 0 {
+ p.fmt.padString(nilAngleString)
+ } else {
+ p.fmt0x64(uint64(u), !p.fmt.sharp)
+ }
+ }
+ case 'p':
+ p.fmt0x64(uint64(u), !p.fmt.sharp)
+ case 'b', 'o', 'd', 'x', 'X':
+ p.fmtInteger(uint64(u), unsigned, verb)
+ default:
+ p.badVerb(verb)
+ }
+}
+
+func (p *pp) catchPanic(arg any, verb rune, method string) {
+ if err := recover(); err != nil {
+ // If it's a nil pointer, just say "<nil>". The likeliest causes are a
+ // Stringer that fails to guard against nil or a nil pointer for a
+ // value receiver, and in either case, "<nil>" is a nice result.
+ if v := reflect.ValueOf(arg); v.Kind() == reflect.Pointer && v.IsNil() {
+ p.buf.writeString(nilAngleString)
+ return
+ }
+ // Otherwise print a concise panic message. Most of the time the panic
+ // value will print itself nicely.
+ if p.panicking {
+ // Nested panics; the recursion in printArg cannot succeed.
+ panic(err)
+ }
+
+ oldFlags := p.fmt.fmtFlags
+ // For this output we want default behavior.
+ p.fmt.clearflags()
+
+ p.buf.writeString(percentBangString)
+ p.buf.writeRune(verb)
+ p.buf.writeString(panicString)
+ p.buf.writeString(method)
+ p.buf.writeString(" method: ")
+ p.panicking = true
+ p.printArg(err, 'v')
+ p.panicking = false
+ p.buf.writeByte(')')
+
+ p.fmt.fmtFlags = oldFlags
+ }
+}
+
+func (p *pp) handleMethods(verb rune) (handled bool) {
+ if p.erroring {
+ return
+ }
+ if verb == 'w' {
+ // It is invalid to use %w other than with Errorf, more than once,
+ // or with a non-error arg.
+ err, ok := p.arg.(error)
+ if !ok || !p.wrapErrs || p.wrappedErr != nil {
+ p.wrappedErr = nil
+ p.wrapErrs = false
+ p.badVerb(verb)
+ return true
+ }
+ p.wrappedErr = err
+ // If the arg is a Formatter, pass 'v' as the verb to it.
+ verb = 'v'
+ }
+
+ // Is it a Formatter?
+ if formatter, ok := p.arg.(Formatter); ok {
+ handled = true
+ defer p.catchPanic(p.arg, verb, "Format")
+ formatter.Format(p, verb)
+ return
+ }
+
+ // If we're doing Go syntax and the argument knows how to supply it, take care of it now.
+ if p.fmt.sharpV {
+ if stringer, ok := p.arg.(GoStringer); ok {
+ handled = true
+ defer p.catchPanic(p.arg, verb, "GoString")
+ // Print the result of GoString unadorned.
+ p.fmt.fmtS(stringer.GoString())
+ return
+ }
+ } else {
+ // If a string is acceptable according to the format, see if
+ // the value satisfies one of the string-valued interfaces.
+ // Println etc. set verb to %v, which is "stringable".
+ switch verb {
+ case 'v', 's', 'x', 'X', 'q':
+ // Is it an error or Stringer?
+ // The duplication in the bodies is necessary:
+ // setting handled and deferring catchPanic
+ // must happen before calling the method.
+ switch v := p.arg.(type) {
+ case error:
+ handled = true
+ defer p.catchPanic(p.arg, verb, "Error")
+ p.fmtString(v.Error(), verb)
+ return
+
+ case Stringer:
+ handled = true
+ defer p.catchPanic(p.arg, verb, "String")
+ p.fmtString(v.String(), verb)
+ return
+ }
+ }
+ }
+ return false
+}
+
+func (p *pp) printArg(arg any, verb rune) {
+ p.arg = arg
+ p.value = reflect.Value{}
+
+ if arg == nil {
+ switch verb {
+ case 'T', 'v':
+ p.fmt.padString(nilAngleString)
+ default:
+ p.badVerb(verb)
+ }
+ return
+ }
+
+ // Special processing considerations.
+ // %T (the value's type) and %p (its address) are special; we always do them first.
+ switch verb {
+ case 'T':
+ p.fmt.fmtS(reflect.TypeOf(arg).String())
+ return
+ case 'p':
+ p.fmtPointer(reflect.ValueOf(arg), 'p')
+ return
+ }
+
+ // Some types can be done without reflection.
+ switch f := arg.(type) {
+ case bool:
+ p.fmtBool(f, verb)
+ case float32:
+ p.fmtFloat(float64(f), 32, verb)
+ case float64:
+ p.fmtFloat(f, 64, verb)
+ case complex64:
+ p.fmtComplex(complex128(f), 64, verb)
+ case complex128:
+ p.fmtComplex(f, 128, verb)
+ case int:
+ p.fmtInteger(uint64(f), signed, verb)
+ case int8:
+ p.fmtInteger(uint64(f), signed, verb)
+ case int16:
+ p.fmtInteger(uint64(f), signed, verb)
+ case int32:
+ p.fmtInteger(uint64(f), signed, verb)
+ case int64:
+ p.fmtInteger(uint64(f), signed, verb)
+ case uint:
+ p.fmtInteger(uint64(f), unsigned, verb)
+ case uint8:
+ p.fmtInteger(uint64(f), unsigned, verb)
+ case uint16:
+ p.fmtInteger(uint64(f), unsigned, verb)
+ case uint32:
+ p.fmtInteger(uint64(f), unsigned, verb)
+ case uint64:
+ p.fmtInteger(f, unsigned, verb)
+ case uintptr:
+ p.fmtInteger(uint64(f), unsigned, verb)
+ case string:
+ p.fmtString(f, verb)
+ case []byte:
+ p.fmtBytes(f, verb, "[]byte")
+ case reflect.Value:
+ // Handle extractable values with special methods
+ // since printValue does not handle them at depth 0.
+ if f.IsValid() && f.CanInterface() {
+ p.arg = f.Interface()
+ if p.handleMethods(verb) {
+ return
+ }
+ }
+ p.printValue(f, verb, 0)
+ default:
+ // If the type is not simple, it might have methods.
+ if !p.handleMethods(verb) {
+ // Need to use reflection, since the type had no
+ // interface methods that could be used for formatting.
+ p.printValue(reflect.ValueOf(f), verb, 0)
+ }
+ }
+}
+
+// printValue is similar to printArg but starts with a reflect value, not an interface{} value.
+// It does not handle 'p' and 'T' verbs because these should have been already handled by printArg.
+func (p *pp) printValue(value reflect.Value, verb rune, depth int) {
+ // Handle values with special methods if not already handled by printArg (depth == 0).
+ if depth > 0 && value.IsValid() && value.CanInterface() {
+ p.arg = value.Interface()
+ if p.handleMethods(verb) {
+ return
+ }
+ }
+ p.arg = nil
+ p.value = value
+
+ switch f := value; value.Kind() {
+ case reflect.Invalid:
+ if depth == 0 {
+ p.buf.writeString(invReflectString)
+ } else {
+ switch verb {
+ case 'v':
+ p.buf.writeString(nilAngleString)
+ default:
+ p.badVerb(verb)
+ }
+ }
+ case reflect.Bool:
+ p.fmtBool(f.Bool(), verb)
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ p.fmtInteger(uint64(f.Int()), signed, verb)
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+ p.fmtInteger(f.Uint(), unsigned, verb)
+ case reflect.Float32:
+ p.fmtFloat(f.Float(), 32, verb)
+ case reflect.Float64:
+ p.fmtFloat(f.Float(), 64, verb)
+ case reflect.Complex64:
+ p.fmtComplex(f.Complex(), 64, verb)
+ case reflect.Complex128:
+ p.fmtComplex(f.Complex(), 128, verb)
+ case reflect.String:
+ p.fmtString(f.String(), verb)
+ case reflect.Map:
+ if p.fmt.sharpV {
+ p.buf.writeString(f.Type().String())
+ if f.IsNil() {
+ p.buf.writeString(nilParenString)
+ return
+ }
+ p.buf.writeByte('{')
+ } else {
+ p.buf.writeString(mapString)
+ }
+ sorted := fmtsort.Sort(f)
+ for i, key := range sorted.Key {
+ if i > 0 {
+ if p.fmt.sharpV {
+ p.buf.writeString(commaSpaceString)
+ } else {
+ p.buf.writeByte(' ')
+ }
+ }
+ p.printValue(key, verb, depth+1)
+ p.buf.writeByte(':')
+ p.printValue(sorted.Value[i], verb, depth+1)
+ }
+ if p.fmt.sharpV {
+ p.buf.writeByte('}')
+ } else {
+ p.buf.writeByte(']')
+ }
+ case reflect.Struct:
+ if p.fmt.sharpV {
+ p.buf.writeString(f.Type().String())
+ }
+ p.buf.writeByte('{')
+ for i := 0; i < f.NumField(); i++ {
+ if i > 0 {
+ if p.fmt.sharpV {
+ p.buf.writeString(commaSpaceString)
+ } else {
+ p.buf.writeByte(' ')
+ }
+ }
+ if p.fmt.plusV || p.fmt.sharpV {
+ if name := f.Type().Field(i).Name; name != "" {
+ p.buf.writeString(name)
+ p.buf.writeByte(':')
+ }
+ }
+ p.printValue(getField(f, i), verb, depth+1)
+ }
+ p.buf.writeByte('}')
+ case reflect.Interface:
+ value := f.Elem()
+ if !value.IsValid() {
+ if p.fmt.sharpV {
+ p.buf.writeString(f.Type().String())
+ p.buf.writeString(nilParenString)
+ } else {
+ p.buf.writeString(nilAngleString)
+ }
+ } else {
+ p.printValue(value, verb, depth+1)
+ }
+ case reflect.Array, reflect.Slice:
+ switch verb {
+ case 's', 'q', 'x', 'X':
+ // Handle byte and uint8 slices and arrays special for the above verbs.
+ t := f.Type()
+ if t.Elem().Kind() == reflect.Uint8 {
+ var bytes []byte
+ if f.Kind() == reflect.Slice {
+ bytes = f.Bytes()
+ } else if f.CanAddr() {
+ bytes = f.Slice(0, f.Len()).Bytes()
+ } else {
+ // We have an array, but we cannot Slice() a non-addressable array,
+ // so we build a slice by hand. This is a rare case but it would be nice
+ // if reflection could help a little more.
+ bytes = make([]byte, f.Len())
+ for i := range bytes {
+ bytes[i] = byte(f.Index(i).Uint())
+ }
+ }
+ p.fmtBytes(bytes, verb, t.String())
+ return
+ }
+ }
+ if p.fmt.sharpV {
+ p.buf.writeString(f.Type().String())
+ if f.Kind() == reflect.Slice && f.IsNil() {
+ p.buf.writeString(nilParenString)
+ return
+ }
+ p.buf.writeByte('{')
+ for i := 0; i < f.Len(); i++ {
+ if i > 0 {
+ p.buf.writeString(commaSpaceString)
+ }
+ p.printValue(f.Index(i), verb, depth+1)
+ }
+ p.buf.writeByte('}')
+ } else {
+ p.buf.writeByte('[')
+ for i := 0; i < f.Len(); i++ {
+ if i > 0 {
+ p.buf.writeByte(' ')
+ }
+ p.printValue(f.Index(i), verb, depth+1)
+ }
+ p.buf.writeByte(']')
+ }
+ case reflect.Pointer:
+ // pointer to array or slice or struct? ok at top level
+ // but not embedded (avoid loops)
+ if depth == 0 && f.Pointer() != 0 {
+ switch a := f.Elem(); a.Kind() {
+ case reflect.Array, reflect.Slice, reflect.Struct, reflect.Map:
+ p.buf.writeByte('&')
+ p.printValue(a, verb, depth+1)
+ return
+ }
+ }
+ fallthrough
+ case reflect.Chan, reflect.Func, reflect.UnsafePointer:
+ p.fmtPointer(f, verb)
+ default:
+ p.unknownType(f)
+ }
+}
+
+// intFromArg gets the argNumth element of a. On return, isInt reports whether the argument has integer type.
+func intFromArg(a []any, argNum int) (num int, isInt bool, newArgNum int) {
+ newArgNum = argNum
+ if argNum < len(a) {
+ num, isInt = a[argNum].(int) // Almost always OK.
+ if !isInt {
+ // Work harder.
+ switch v := reflect.ValueOf(a[argNum]); v.Kind() {
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ n := v.Int()
+ if int64(int(n)) == n {
+ num = int(n)
+ isInt = true
+ }
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+ n := v.Uint()
+ if int64(n) >= 0 && uint64(int(n)) == n {
+ num = int(n)
+ isInt = true
+ }
+ default:
+ // Already 0, false.
+ }
+ }
+ newArgNum = argNum + 1
+ if tooLarge(num) {
+ num = 0
+ isInt = false
+ }
+ }
+ return
+}
+
+// parseArgNumber returns the value of the bracketed number, minus 1
+// (explicit argument numbers are one-indexed but we want zero-indexed).
+// The opening bracket is known to be present at format[0].
+// The returned values are the index, the number of bytes to consume
+// up to the closing paren, if present, and whether the number parsed
+// ok. The bytes to consume will be 1 if no closing paren is present.
+func parseArgNumber(format string) (index int, wid int, ok bool) {
+ // There must be at least 3 bytes: [n].
+ if len(format) < 3 {
+ return 0, 1, false
+ }
+
+ // Find closing bracket.
+ for i := 1; i < len(format); i++ {
+ if format[i] == ']' {
+ width, ok, newi := parsenum(format, 1, i)
+ if !ok || newi != i {
+ return 0, i + 1, false
+ }
+ return width - 1, i + 1, true // arg numbers are one-indexed and skip paren.
+ }
+ }
+ return 0, 1, false
+}
+
+// argNumber returns the next argument to evaluate, which is either the value of the passed-in
+// argNum or the value of the bracketed integer that begins format[i:]. It also returns
+// the new value of i, that is, the index of the next byte of the format to process.
+func (p *pp) argNumber(argNum int, format string, i int, numArgs int) (newArgNum, newi int, found bool) {
+ if len(format) <= i || format[i] != '[' {
+ return argNum, i, false
+ }
+ p.reordered = true
+ index, wid, ok := parseArgNumber(format[i:])
+ if ok && 0 <= index && index < numArgs {
+ return index, i + wid, true
+ }
+ p.goodArgNum = false
+ return argNum, i + wid, ok
+}
+
+func (p *pp) badArgNum(verb rune) {
+ p.buf.writeString(percentBangString)
+ p.buf.writeRune(verb)
+ p.buf.writeString(badIndexString)
+}
+
+func (p *pp) missingArg(verb rune) {
+ p.buf.writeString(percentBangString)
+ p.buf.writeRune(verb)
+ p.buf.writeString(missingString)
+}
+
+func (p *pp) doPrintf(format string, a []any) {
+ end := len(format)
+ argNum := 0 // we process one argument per non-trivial format
+ afterIndex := false // previous item in format was an index like [3].
+ p.reordered = false
+formatLoop:
+ for i := 0; i < end; {
+ p.goodArgNum = true
+ lasti := i
+ for i < end && format[i] != '%' {
+ i++
+ }
+ if i > lasti {
+ p.buf.writeString(format[lasti:i])
+ }
+ if i >= end {
+ // done processing format string
+ break
+ }
+
+ // Process one verb
+ i++
+
+ // Do we have flags?
+ p.fmt.clearflags()
+ simpleFormat:
+ for ; i < end; i++ {
+ c := format[i]
+ switch c {
+ case '#':
+ p.fmt.sharp = true
+ case '0':
+ p.fmt.zero = !p.fmt.minus // Only allow zero padding to the left.
+ case '+':
+ p.fmt.plus = true
+ case '-':
+ p.fmt.minus = true
+ p.fmt.zero = false // Do not pad with zeros to the right.
+ case ' ':
+ p.fmt.space = true
+ default:
+ // Fast path for common case of ascii lower case simple verbs
+ // without precision or width or argument indices.
+ if 'a' <= c && c <= 'z' && argNum < len(a) {
+ if c == 'v' {
+ // Go syntax
+ p.fmt.sharpV = p.fmt.sharp
+ p.fmt.sharp = false
+ // Struct-field syntax
+ p.fmt.plusV = p.fmt.plus
+ p.fmt.plus = false
+ }
+ p.printArg(a[argNum], rune(c))
+ argNum++
+ i++
+ continue formatLoop
+ }
+ // Format is more complex than simple flags and a verb or is malformed.
+ break simpleFormat
+ }
+ }
+
+ // Do we have an explicit argument index?
+ argNum, i, afterIndex = p.argNumber(argNum, format, i, len(a))
+
+ // Do we have width?
+ if i < end && format[i] == '*' {
+ i++
+ p.fmt.wid, p.fmt.widPresent, argNum = intFromArg(a, argNum)
+
+ if !p.fmt.widPresent {
+ p.buf.writeString(badWidthString)
+ }
+
+ // We have a negative width, so take its value and ensure
+ // that the minus flag is set
+ if p.fmt.wid < 0 {
+ p.fmt.wid = -p.fmt.wid
+ p.fmt.minus = true
+ p.fmt.zero = false // Do not pad with zeros to the right.
+ }
+ afterIndex = false
+ } else {
+ p.fmt.wid, p.fmt.widPresent, i = parsenum(format, i, end)
+ if afterIndex && p.fmt.widPresent { // "%[3]2d"
+ p.goodArgNum = false
+ }
+ }
+
+ // Do we have precision?
+ if i+1 < end && format[i] == '.' {
+ i++
+ if afterIndex { // "%[3].2d"
+ p.goodArgNum = false
+ }
+ argNum, i, afterIndex = p.argNumber(argNum, format, i, len(a))
+ if i < end && format[i] == '*' {
+ i++
+ p.fmt.prec, p.fmt.precPresent, argNum = intFromArg(a, argNum)
+ // Negative precision arguments don't make sense
+ if p.fmt.prec < 0 {
+ p.fmt.prec = 0
+ p.fmt.precPresent = false
+ }
+ if !p.fmt.precPresent {
+ p.buf.writeString(badPrecString)
+ }
+ afterIndex = false
+ } else {
+ p.fmt.prec, p.fmt.precPresent, i = parsenum(format, i, end)
+ if !p.fmt.precPresent {
+ p.fmt.prec = 0
+ p.fmt.precPresent = true
+ }
+ }
+ }
+
+ if !afterIndex {
+ argNum, i, afterIndex = p.argNumber(argNum, format, i, len(a))
+ }
+
+ if i >= end {
+ p.buf.writeString(noVerbString)
+ break
+ }
+
+ verb, size := rune(format[i]), 1
+ if verb >= utf8.RuneSelf {
+ verb, size = utf8.DecodeRuneInString(format[i:])
+ }
+ i += size
+
+ switch {
+ case verb == '%': // Percent does not absorb operands and ignores f.wid and f.prec.
+ p.buf.writeByte('%')
+ case !p.goodArgNum:
+ p.badArgNum(verb)
+ case argNum >= len(a): // No argument left over to print for the current verb.
+ p.missingArg(verb)
+ case verb == 'v':
+ // Go syntax
+ p.fmt.sharpV = p.fmt.sharp
+ p.fmt.sharp = false
+ // Struct-field syntax
+ p.fmt.plusV = p.fmt.plus
+ p.fmt.plus = false
+ fallthrough
+ default:
+ p.printArg(a[argNum], verb)
+ argNum++
+ }
+ }
+
+ // Check for extra arguments unless the call accessed the arguments
+ // out of order, in which case it's too expensive to detect if they've all
+ // been used and arguably OK if they're not.
+ if !p.reordered && argNum < len(a) {
+ p.fmt.clearflags()
+ p.buf.writeString(extraString)
+ for i, arg := range a[argNum:] {
+ if i > 0 {
+ p.buf.writeString(commaSpaceString)
+ }
+ if arg == nil {
+ p.buf.writeString(nilAngleString)
+ } else {
+ p.buf.writeString(reflect.TypeOf(arg).String())
+ p.buf.writeByte('=')
+ p.printArg(arg, 'v')
+ }
+ }
+ p.buf.writeByte(')')
+ }
+}
+
+func (p *pp) doPrint(a []any) {
+ prevString := false
+ for argNum, arg := range a {
+ isString := arg != nil && reflect.TypeOf(arg).Kind() == reflect.String
+ // Add a space between two non-string arguments.
+ if argNum > 0 && !isString && !prevString {
+ p.buf.writeByte(' ')
+ }
+ p.printArg(arg, 'v')
+ prevString = isString
+ }
+}
+
+// doPrintln is like doPrint but always adds a space between arguments
+// and a newline after the last argument.
+func (p *pp) doPrintln(a []any) {
+ for argNum, arg := range a {
+ if argNum > 0 {
+ p.buf.writeByte(' ')
+ }
+ p.printArg(arg, 'v')
+ }
+ p.buf.writeByte('\n')
+}
diff --git a/src/fmt/scan.go b/src/fmt/scan.go
new file mode 100644
index 0000000..d38610d
--- /dev/null
+++ b/src/fmt/scan.go
@@ -0,0 +1,1238 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt
+
+import (
+ "errors"
+ "io"
+ "math"
+ "os"
+ "reflect"
+ "strconv"
+ "sync"
+ "unicode/utf8"
+)
+
+// ScanState represents the scanner state passed to custom scanners.
+// Scanners may do rune-at-a-time scanning or ask the ScanState
+// to discover the next space-delimited token.
+type ScanState interface {
+ // ReadRune reads the next rune (Unicode code point) from the input.
+ // If invoked during Scanln, Fscanln, or Sscanln, ReadRune() will
+ // return EOF after returning the first '\n' or when reading beyond
+ // the specified width.
+ ReadRune() (r rune, size int, err error)
+ // UnreadRune causes the next call to ReadRune to return the same rune.
+ UnreadRune() error
+ // SkipSpace skips space in the input. Newlines are treated appropriately
+ // for the operation being performed; see the package documentation
+ // for more information.
+ SkipSpace()
+ // Token skips space in the input if skipSpace is true, then returns the
+ // run of Unicode code points c satisfying f(c). If f is nil,
+ // !unicode.IsSpace(c) is used; that is, the token will hold non-space
+ // characters. Newlines are treated appropriately for the operation being
+ // performed; see the package documentation for more information.
+ // The returned slice points to shared data that may be overwritten
+ // by the next call to Token, a call to a Scan function using the ScanState
+ // as input, or when the calling Scan method returns.
+ Token(skipSpace bool, f func(rune) bool) (token []byte, err error)
+ // Width returns the value of the width option and whether it has been set.
+ // The unit is Unicode code points.
+ Width() (wid int, ok bool)
+ // Because ReadRune is implemented by the interface, Read should never be
+ // called by the scanning routines and a valid implementation of
+ // ScanState may choose always to return an error from Read.
+ Read(buf []byte) (n int, err error)
+}
+
+// Scanner is implemented by any value that has a Scan method, which scans
+// the input for the representation of a value and stores the result in the
+// receiver, which must be a pointer to be useful. The Scan method is called
+// for any argument to Scan, Scanf, or Scanln that implements it.
+type Scanner interface {
+ Scan(state ScanState, verb rune) error
+}
+
+// Scan scans text read from standard input, storing successive
+// space-separated values into successive arguments. Newlines count
+// as space. It returns the number of items successfully scanned.
+// If that is less than the number of arguments, err will report why.
+func Scan(a ...any) (n int, err error) {
+ return Fscan(os.Stdin, a...)
+}
+
+// Scanln is similar to Scan, but stops scanning at a newline and
+// after the final item there must be a newline or EOF.
+func Scanln(a ...any) (n int, err error) {
+ return Fscanln(os.Stdin, a...)
+}
+
+// Scanf scans text read from standard input, storing successive
+// space-separated values into successive arguments as determined by
+// the format. It returns the number of items successfully scanned.
+// If that is less than the number of arguments, err will report why.
+// Newlines in the input must match newlines in the format.
+// The one exception: the verb %c always scans the next rune in the
+// input, even if it is a space (or tab etc.) or newline.
+func Scanf(format string, a ...any) (n int, err error) {
+ return Fscanf(os.Stdin, format, a...)
+}
+
+type stringReader string
+
+func (r *stringReader) Read(b []byte) (n int, err error) {
+ n = copy(b, *r)
+ *r = (*r)[n:]
+ if n == 0 {
+ err = io.EOF
+ }
+ return
+}
+
+// Sscan scans the argument string, storing successive space-separated
+// values into successive arguments. Newlines count as space. It
+// returns the number of items successfully scanned. If that is less
+// than the number of arguments, err will report why.
+func Sscan(str string, a ...any) (n int, err error) {
+ return Fscan((*stringReader)(&str), a...)
+}
+
+// Sscanln is similar to Sscan, but stops scanning at a newline and
+// after the final item there must be a newline or EOF.
+func Sscanln(str string, a ...any) (n int, err error) {
+ return Fscanln((*stringReader)(&str), a...)
+}
+
+// Sscanf scans the argument string, storing successive space-separated
+// values into successive arguments as determined by the format. It
+// returns the number of items successfully parsed.
+// Newlines in the input must match newlines in the format.
+func Sscanf(str string, format string, a ...any) (n int, err error) {
+ return Fscanf((*stringReader)(&str), format, a...)
+}
+
+// Fscan scans text read from r, storing successive space-separated
+// values into successive arguments. Newlines count as space. It
+// returns the number of items successfully scanned. If that is less
+// than the number of arguments, err will report why.
+func Fscan(r io.Reader, a ...any) (n int, err error) {
+ s, old := newScanState(r, true, false)
+ n, err = s.doScan(a)
+ s.free(old)
+ return
+}
+
+// Fscanln is similar to Fscan, but stops scanning at a newline and
+// after the final item there must be a newline or EOF.
+func Fscanln(r io.Reader, a ...any) (n int, err error) {
+ s, old := newScanState(r, false, true)
+ n, err = s.doScan(a)
+ s.free(old)
+ return
+}
+
+// Fscanf scans text read from r, storing successive space-separated
+// values into successive arguments as determined by the format. It
+// returns the number of items successfully parsed.
+// Newlines in the input must match newlines in the format.
+func Fscanf(r io.Reader, format string, a ...any) (n int, err error) {
+ s, old := newScanState(r, false, false)
+ n, err = s.doScanf(format, a)
+ s.free(old)
+ return
+}
+
+// scanError represents an error generated by the scanning software.
+// It's used as a unique signature to identify such errors when recovering.
+type scanError struct {
+ err error
+}
+
+const eof = -1
+
+// ss is the internal implementation of ScanState.
+type ss struct {
+ rs io.RuneScanner // where to read input
+ buf buffer // token accumulator
+ count int // runes consumed so far.
+ atEOF bool // already read EOF
+ ssave
+}
+
+// ssave holds the parts of ss that need to be
+// saved and restored on recursive scans.
+type ssave struct {
+ validSave bool // is or was a part of an actual ss.
+ nlIsEnd bool // whether newline terminates scan
+ nlIsSpace bool // whether newline counts as white space
+ argLimit int // max value of ss.count for this arg; argLimit <= limit
+ limit int // max value of ss.count.
+ maxWid int // width of this arg.
+}
+
+// The Read method is only in ScanState so that ScanState
+// satisfies io.Reader. It will never be called when used as
+// intended, so there is no need to make it actually work.
+func (s *ss) Read(buf []byte) (n int, err error) {
+ return 0, errors.New("ScanState's Read should not be called. Use ReadRune")
+}
+
+func (s *ss) ReadRune() (r rune, size int, err error) {
+ if s.atEOF || s.count >= s.argLimit {
+ err = io.EOF
+ return
+ }
+
+ r, size, err = s.rs.ReadRune()
+ if err == nil {
+ s.count++
+ if s.nlIsEnd && r == '\n' {
+ s.atEOF = true
+ }
+ } else if err == io.EOF {
+ s.atEOF = true
+ }
+ return
+}
+
+func (s *ss) Width() (wid int, ok bool) {
+ if s.maxWid == hugeWid {
+ return 0, false
+ }
+ return s.maxWid, true
+}
+
+// The public method returns an error; this private one panics.
+// If getRune reaches EOF, the return value is EOF (-1).
+func (s *ss) getRune() (r rune) {
+ r, _, err := s.ReadRune()
+ if err != nil {
+ if err == io.EOF {
+ return eof
+ }
+ s.error(err)
+ }
+ return
+}
+
+// mustReadRune turns io.EOF into a panic(io.ErrUnexpectedEOF).
+// It is called in cases such as string scanning where an EOF is a
+// syntax error.
+func (s *ss) mustReadRune() (r rune) {
+ r = s.getRune()
+ if r == eof {
+ s.error(io.ErrUnexpectedEOF)
+ }
+ return
+}
+
+func (s *ss) UnreadRune() error {
+ s.rs.UnreadRune()
+ s.atEOF = false
+ s.count--
+ return nil
+}
+
+func (s *ss) error(err error) {
+ panic(scanError{err})
+}
+
+func (s *ss) errorString(err string) {
+ panic(scanError{errors.New(err)})
+}
+
+func (s *ss) Token(skipSpace bool, f func(rune) bool) (tok []byte, err error) {
+ defer func() {
+ if e := recover(); e != nil {
+ if se, ok := e.(scanError); ok {
+ err = se.err
+ } else {
+ panic(e)
+ }
+ }
+ }()
+ if f == nil {
+ f = notSpace
+ }
+ s.buf = s.buf[:0]
+ tok = s.token(skipSpace, f)
+ return
+}
+
+// space is a copy of the unicode.White_Space ranges,
+// to avoid depending on package unicode.
+var space = [][2]uint16{
+ {0x0009, 0x000d},
+ {0x0020, 0x0020},
+ {0x0085, 0x0085},
+ {0x00a0, 0x00a0},
+ {0x1680, 0x1680},
+ {0x2000, 0x200a},
+ {0x2028, 0x2029},
+ {0x202f, 0x202f},
+ {0x205f, 0x205f},
+ {0x3000, 0x3000},
+}
+
+func isSpace(r rune) bool {
+ if r >= 1<<16 {
+ return false
+ }
+ rx := uint16(r)
+ for _, rng := range space {
+ if rx < rng[0] {
+ return false
+ }
+ if rx <= rng[1] {
+ return true
+ }
+ }
+ return false
+}
+
+// notSpace is the default scanning function used in Token.
+func notSpace(r rune) bool {
+ return !isSpace(r)
+}
+
+// readRune is a structure to enable reading UTF-8 encoded code points
+// from an io.Reader. It is used if the Reader given to the scanner does
+// not already implement io.RuneScanner.
+type readRune struct {
+ reader io.Reader
+ buf [utf8.UTFMax]byte // used only inside ReadRune
+ pending int // number of bytes in pendBuf; only >0 for bad UTF-8
+ pendBuf [utf8.UTFMax]byte // bytes left over
+ peekRune rune // if >=0 next rune; when <0 is ^(previous Rune)
+}
+
+// readByte returns the next byte from the input, which may be
+// left over from a previous read if the UTF-8 was ill-formed.
+func (r *readRune) readByte() (b byte, err error) {
+ if r.pending > 0 {
+ b = r.pendBuf[0]
+ copy(r.pendBuf[0:], r.pendBuf[1:])
+ r.pending--
+ return
+ }
+ n, err := io.ReadFull(r.reader, r.pendBuf[:1])
+ if n != 1 {
+ return 0, err
+ }
+ return r.pendBuf[0], err
+}
+
+// ReadRune returns the next UTF-8 encoded code point from the
+// io.Reader inside r.
+func (r *readRune) ReadRune() (rr rune, size int, err error) {
+ if r.peekRune >= 0 {
+ rr = r.peekRune
+ r.peekRune = ^r.peekRune
+ size = utf8.RuneLen(rr)
+ return
+ }
+ r.buf[0], err = r.readByte()
+ if err != nil {
+ return
+ }
+ if r.buf[0] < utf8.RuneSelf { // fast check for common ASCII case
+ rr = rune(r.buf[0])
+ size = 1 // Known to be 1.
+ // Flip the bits of the rune so it's available to UnreadRune.
+ r.peekRune = ^rr
+ return
+ }
+ var n int
+ for n = 1; !utf8.FullRune(r.buf[:n]); n++ {
+ r.buf[n], err = r.readByte()
+ if err != nil {
+ if err == io.EOF {
+ err = nil
+ break
+ }
+ return
+ }
+ }
+ rr, size = utf8.DecodeRune(r.buf[:n])
+ if size < n { // an error, save the bytes for the next read
+ copy(r.pendBuf[r.pending:], r.buf[size:n])
+ r.pending += n - size
+ }
+ // Flip the bits of the rune so it's available to UnreadRune.
+ r.peekRune = ^rr
+ return
+}
+
+func (r *readRune) UnreadRune() error {
+ if r.peekRune >= 0 {
+ return errors.New("fmt: scanning called UnreadRune with no rune available")
+ }
+ // Reverse bit flip of previously read rune to obtain valid >=0 state.
+ r.peekRune = ^r.peekRune
+ return nil
+}
+
+var ssFree = sync.Pool{
+ New: func() any { return new(ss) },
+}
+
+// newScanState allocates a new ss struct or grab a cached one.
+func newScanState(r io.Reader, nlIsSpace, nlIsEnd bool) (s *ss, old ssave) {
+ s = ssFree.Get().(*ss)
+ if rs, ok := r.(io.RuneScanner); ok {
+ s.rs = rs
+ } else {
+ s.rs = &readRune{reader: r, peekRune: -1}
+ }
+ s.nlIsSpace = nlIsSpace
+ s.nlIsEnd = nlIsEnd
+ s.atEOF = false
+ s.limit = hugeWid
+ s.argLimit = hugeWid
+ s.maxWid = hugeWid
+ s.validSave = true
+ s.count = 0
+ return
+}
+
+// free saves used ss structs in ssFree; avoid an allocation per invocation.
+func (s *ss) free(old ssave) {
+ // If it was used recursively, just restore the old state.
+ if old.validSave {
+ s.ssave = old
+ return
+ }
+ // Don't hold on to ss structs with large buffers.
+ if cap(s.buf) > 1024 {
+ return
+ }
+ s.buf = s.buf[:0]
+ s.rs = nil
+ ssFree.Put(s)
+}
+
+// SkipSpace provides Scan methods the ability to skip space and newline
+// characters in keeping with the current scanning mode set by format strings
+// and Scan/Scanln.
+func (s *ss) SkipSpace() {
+ for {
+ r := s.getRune()
+ if r == eof {
+ return
+ }
+ if r == '\r' && s.peek("\n") {
+ continue
+ }
+ if r == '\n' {
+ if s.nlIsSpace {
+ continue
+ }
+ s.errorString("unexpected newline")
+ return
+ }
+ if !isSpace(r) {
+ s.UnreadRune()
+ break
+ }
+ }
+}
+
+// token returns the next space-delimited string from the input. It
+// skips white space. For Scanln, it stops at newlines. For Scan,
+// newlines are treated as spaces.
+func (s *ss) token(skipSpace bool, f func(rune) bool) []byte {
+ if skipSpace {
+ s.SkipSpace()
+ }
+ // read until white space or newline
+ for {
+ r := s.getRune()
+ if r == eof {
+ break
+ }
+ if !f(r) {
+ s.UnreadRune()
+ break
+ }
+ s.buf.writeRune(r)
+ }
+ return s.buf
+}
+
+var complexError = errors.New("syntax error scanning complex number")
+var boolError = errors.New("syntax error scanning boolean")
+
+func indexRune(s string, r rune) int {
+ for i, c := range s {
+ if c == r {
+ return i
+ }
+ }
+ return -1
+}
+
+// consume reads the next rune in the input and reports whether it is in the ok string.
+// If accept is true, it puts the character into the input token.
+func (s *ss) consume(ok string, accept bool) bool {
+ r := s.getRune()
+ if r == eof {
+ return false
+ }
+ if indexRune(ok, r) >= 0 {
+ if accept {
+ s.buf.writeRune(r)
+ }
+ return true
+ }
+ if r != eof && accept {
+ s.UnreadRune()
+ }
+ return false
+}
+
+// peek reports whether the next character is in the ok string, without consuming it.
+func (s *ss) peek(ok string) bool {
+ r := s.getRune()
+ if r != eof {
+ s.UnreadRune()
+ }
+ return indexRune(ok, r) >= 0
+}
+
+func (s *ss) notEOF() {
+ // Guarantee there is data to be read.
+ if r := s.getRune(); r == eof {
+ panic(io.EOF)
+ }
+ s.UnreadRune()
+}
+
+// accept checks the next rune in the input. If it's a byte (sic) in the string, it puts it in the
+// buffer and returns true. Otherwise it return false.
+func (s *ss) accept(ok string) bool {
+ return s.consume(ok, true)
+}
+
+// okVerb verifies that the verb is present in the list, setting s.err appropriately if not.
+func (s *ss) okVerb(verb rune, okVerbs, typ string) bool {
+ for _, v := range okVerbs {
+ if v == verb {
+ return true
+ }
+ }
+ s.errorString("bad verb '%" + string(verb) + "' for " + typ)
+ return false
+}
+
+// scanBool returns the value of the boolean represented by the next token.
+func (s *ss) scanBool(verb rune) bool {
+ s.SkipSpace()
+ s.notEOF()
+ if !s.okVerb(verb, "tv", "boolean") {
+ return false
+ }
+ // Syntax-checking a boolean is annoying. We're not fastidious about case.
+ switch s.getRune() {
+ case '0':
+ return false
+ case '1':
+ return true
+ case 't', 'T':
+ if s.accept("rR") && (!s.accept("uU") || !s.accept("eE")) {
+ s.error(boolError)
+ }
+ return true
+ case 'f', 'F':
+ if s.accept("aA") && (!s.accept("lL") || !s.accept("sS") || !s.accept("eE")) {
+ s.error(boolError)
+ }
+ return false
+ }
+ return false
+}
+
+// Numerical elements
+const (
+ binaryDigits = "01"
+ octalDigits = "01234567"
+ decimalDigits = "0123456789"
+ hexadecimalDigits = "0123456789aAbBcCdDeEfF"
+ sign = "+-"
+ period = "."
+ exponent = "eEpP"
+)
+
+// getBase returns the numeric base represented by the verb and its digit string.
+func (s *ss) getBase(verb rune) (base int, digits string) {
+ s.okVerb(verb, "bdoUxXv", "integer") // sets s.err
+ base = 10
+ digits = decimalDigits
+ switch verb {
+ case 'b':
+ base = 2
+ digits = binaryDigits
+ case 'o':
+ base = 8
+ digits = octalDigits
+ case 'x', 'X', 'U':
+ base = 16
+ digits = hexadecimalDigits
+ }
+ return
+}
+
+// scanNumber returns the numerical string with specified digits starting here.
+func (s *ss) scanNumber(digits string, haveDigits bool) string {
+ if !haveDigits {
+ s.notEOF()
+ if !s.accept(digits) {
+ s.errorString("expected integer")
+ }
+ }
+ for s.accept(digits) {
+ }
+ return string(s.buf)
+}
+
+// scanRune returns the next rune value in the input.
+func (s *ss) scanRune(bitSize int) int64 {
+ s.notEOF()
+ r := s.getRune()
+ n := uint(bitSize)
+ x := (int64(r) << (64 - n)) >> (64 - n)
+ if x != int64(r) {
+ s.errorString("overflow on character value " + string(r))
+ }
+ return int64(r)
+}
+
+// scanBasePrefix reports whether the integer begins with a base prefix
+// and returns the base, digit string, and whether a zero was found.
+// It is called only if the verb is %v.
+func (s *ss) scanBasePrefix() (base int, digits string, zeroFound bool) {
+ if !s.peek("0") {
+ return 0, decimalDigits + "_", false
+ }
+ s.accept("0")
+ // Special cases for 0, 0b, 0o, 0x.
+ switch {
+ case s.peek("bB"):
+ s.consume("bB", true)
+ return 0, binaryDigits + "_", true
+ case s.peek("oO"):
+ s.consume("oO", true)
+ return 0, octalDigits + "_", true
+ case s.peek("xX"):
+ s.consume("xX", true)
+ return 0, hexadecimalDigits + "_", true
+ default:
+ return 0, octalDigits + "_", true
+ }
+}
+
+// scanInt returns the value of the integer represented by the next
+// token, checking for overflow. Any error is stored in s.err.
+func (s *ss) scanInt(verb rune, bitSize int) int64 {
+ if verb == 'c' {
+ return s.scanRune(bitSize)
+ }
+ s.SkipSpace()
+ s.notEOF()
+ base, digits := s.getBase(verb)
+ haveDigits := false
+ if verb == 'U' {
+ if !s.consume("U", false) || !s.consume("+", false) {
+ s.errorString("bad unicode format ")
+ }
+ } else {
+ s.accept(sign) // If there's a sign, it will be left in the token buffer.
+ if verb == 'v' {
+ base, digits, haveDigits = s.scanBasePrefix()
+ }
+ }
+ tok := s.scanNumber(digits, haveDigits)
+ i, err := strconv.ParseInt(tok, base, 64)
+ if err != nil {
+ s.error(err)
+ }
+ n := uint(bitSize)
+ x := (i << (64 - n)) >> (64 - n)
+ if x != i {
+ s.errorString("integer overflow on token " + tok)
+ }
+ return i
+}
+
+// scanUint returns the value of the unsigned integer represented
+// by the next token, checking for overflow. Any error is stored in s.err.
+func (s *ss) scanUint(verb rune, bitSize int) uint64 {
+ if verb == 'c' {
+ return uint64(s.scanRune(bitSize))
+ }
+ s.SkipSpace()
+ s.notEOF()
+ base, digits := s.getBase(verb)
+ haveDigits := false
+ if verb == 'U' {
+ if !s.consume("U", false) || !s.consume("+", false) {
+ s.errorString("bad unicode format ")
+ }
+ } else if verb == 'v' {
+ base, digits, haveDigits = s.scanBasePrefix()
+ }
+ tok := s.scanNumber(digits, haveDigits)
+ i, err := strconv.ParseUint(tok, base, 64)
+ if err != nil {
+ s.error(err)
+ }
+ n := uint(bitSize)
+ x := (i << (64 - n)) >> (64 - n)
+ if x != i {
+ s.errorString("unsigned integer overflow on token " + tok)
+ }
+ return i
+}
+
+// floatToken returns the floating-point number starting here, no longer than swid
+// if the width is specified. It's not rigorous about syntax because it doesn't check that
+// we have at least some digits, but Atof will do that.
+func (s *ss) floatToken() string {
+ s.buf = s.buf[:0]
+ // NaN?
+ if s.accept("nN") && s.accept("aA") && s.accept("nN") {
+ return string(s.buf)
+ }
+ // leading sign?
+ s.accept(sign)
+ // Inf?
+ if s.accept("iI") && s.accept("nN") && s.accept("fF") {
+ return string(s.buf)
+ }
+ digits := decimalDigits + "_"
+ exp := exponent
+ if s.accept("0") && s.accept("xX") {
+ digits = hexadecimalDigits + "_"
+ exp = "pP"
+ }
+ // digits?
+ for s.accept(digits) {
+ }
+ // decimal point?
+ if s.accept(period) {
+ // fraction?
+ for s.accept(digits) {
+ }
+ }
+ // exponent?
+ if s.accept(exp) {
+ // leading sign?
+ s.accept(sign)
+ // digits?
+ for s.accept(decimalDigits + "_") {
+ }
+ }
+ return string(s.buf)
+}
+
+// complexTokens returns the real and imaginary parts of the complex number starting here.
+// The number might be parenthesized and has the format (N+Ni) where N is a floating-point
+// number and there are no spaces within.
+func (s *ss) complexTokens() (real, imag string) {
+ // TODO: accept N and Ni independently?
+ parens := s.accept("(")
+ real = s.floatToken()
+ s.buf = s.buf[:0]
+ // Must now have a sign.
+ if !s.accept("+-") {
+ s.error(complexError)
+ }
+ // Sign is now in buffer
+ imagSign := string(s.buf)
+ imag = s.floatToken()
+ if !s.accept("i") {
+ s.error(complexError)
+ }
+ if parens && !s.accept(")") {
+ s.error(complexError)
+ }
+ return real, imagSign + imag
+}
+
+func hasX(s string) bool {
+ for i := 0; i < len(s); i++ {
+ if s[i] == 'x' || s[i] == 'X' {
+ return true
+ }
+ }
+ return false
+}
+
+// convertFloat converts the string to a float64value.
+func (s *ss) convertFloat(str string, n int) float64 {
+ // strconv.ParseFloat will handle "+0x1.fp+2",
+ // but we have to implement our non-standard
+ // decimal+binary exponent mix (1.2p4) ourselves.
+ if p := indexRune(str, 'p'); p >= 0 && !hasX(str) {
+ // Atof doesn't handle power-of-2 exponents,
+ // but they're easy to evaluate.
+ f, err := strconv.ParseFloat(str[:p], n)
+ if err != nil {
+ // Put full string into error.
+ if e, ok := err.(*strconv.NumError); ok {
+ e.Num = str
+ }
+ s.error(err)
+ }
+ m, err := strconv.Atoi(str[p+1:])
+ if err != nil {
+ // Put full string into error.
+ if e, ok := err.(*strconv.NumError); ok {
+ e.Num = str
+ }
+ s.error(err)
+ }
+ return math.Ldexp(f, m)
+ }
+ f, err := strconv.ParseFloat(str, n)
+ if err != nil {
+ s.error(err)
+ }
+ return f
+}
+
+// convertComplex converts the next token to a complex128 value.
+// The atof argument is a type-specific reader for the underlying type.
+// If we're reading complex64, atof will parse float32s and convert them
+// to float64's to avoid reproducing this code for each complex type.
+func (s *ss) scanComplex(verb rune, n int) complex128 {
+ if !s.okVerb(verb, floatVerbs, "complex") {
+ return 0
+ }
+ s.SkipSpace()
+ s.notEOF()
+ sreal, simag := s.complexTokens()
+ real := s.convertFloat(sreal, n/2)
+ imag := s.convertFloat(simag, n/2)
+ return complex(real, imag)
+}
+
+// convertString returns the string represented by the next input characters.
+// The format of the input is determined by the verb.
+func (s *ss) convertString(verb rune) (str string) {
+ if !s.okVerb(verb, "svqxX", "string") {
+ return ""
+ }
+ s.SkipSpace()
+ s.notEOF()
+ switch verb {
+ case 'q':
+ str = s.quotedString()
+ case 'x', 'X':
+ str = s.hexString()
+ default:
+ str = string(s.token(true, notSpace)) // %s and %v just return the next word
+ }
+ return
+}
+
+// quotedString returns the double- or back-quoted string represented by the next input characters.
+func (s *ss) quotedString() string {
+ s.notEOF()
+ quote := s.getRune()
+ switch quote {
+ case '`':
+ // Back-quoted: Anything goes until EOF or back quote.
+ for {
+ r := s.mustReadRune()
+ if r == quote {
+ break
+ }
+ s.buf.writeRune(r)
+ }
+ return string(s.buf)
+ case '"':
+ // Double-quoted: Include the quotes and let strconv.Unquote do the backslash escapes.
+ s.buf.writeByte('"')
+ for {
+ r := s.mustReadRune()
+ s.buf.writeRune(r)
+ if r == '\\' {
+ // In a legal backslash escape, no matter how long, only the character
+ // immediately after the escape can itself be a backslash or quote.
+ // Thus we only need to protect the first character after the backslash.
+ s.buf.writeRune(s.mustReadRune())
+ } else if r == '"' {
+ break
+ }
+ }
+ result, err := strconv.Unquote(string(s.buf))
+ if err != nil {
+ s.error(err)
+ }
+ return result
+ default:
+ s.errorString("expected quoted string")
+ }
+ return ""
+}
+
+// hexDigit returns the value of the hexadecimal digit.
+func hexDigit(d rune) (int, bool) {
+ digit := int(d)
+ switch digit {
+ case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
+ return digit - '0', true
+ case 'a', 'b', 'c', 'd', 'e', 'f':
+ return 10 + digit - 'a', true
+ case 'A', 'B', 'C', 'D', 'E', 'F':
+ return 10 + digit - 'A', true
+ }
+ return -1, false
+}
+
+// hexByte returns the next hex-encoded (two-character) byte from the input.
+// It returns ok==false if the next bytes in the input do not encode a hex byte.
+// If the first byte is hex and the second is not, processing stops.
+func (s *ss) hexByte() (b byte, ok bool) {
+ rune1 := s.getRune()
+ if rune1 == eof {
+ return
+ }
+ value1, ok := hexDigit(rune1)
+ if !ok {
+ s.UnreadRune()
+ return
+ }
+ value2, ok := hexDigit(s.mustReadRune())
+ if !ok {
+ s.errorString("illegal hex digit")
+ return
+ }
+ return byte(value1<<4 | value2), true
+}
+
+// hexString returns the space-delimited hexpair-encoded string.
+func (s *ss) hexString() string {
+ s.notEOF()
+ for {
+ b, ok := s.hexByte()
+ if !ok {
+ break
+ }
+ s.buf.writeByte(b)
+ }
+ if len(s.buf) == 0 {
+ s.errorString("no hex data for %x string")
+ return ""
+ }
+ return string(s.buf)
+}
+
+const (
+ floatVerbs = "beEfFgGv"
+
+ hugeWid = 1 << 30
+
+ intBits = 32 << (^uint(0) >> 63)
+ uintptrBits = 32 << (^uintptr(0) >> 63)
+)
+
+// scanPercent scans a literal percent character.
+func (s *ss) scanPercent() {
+ s.SkipSpace()
+ s.notEOF()
+ if !s.accept("%") {
+ s.errorString("missing literal %")
+ }
+}
+
+// scanOne scans a single value, deriving the scanner from the type of the argument.
+func (s *ss) scanOne(verb rune, arg any) {
+ s.buf = s.buf[:0]
+ var err error
+ // If the parameter has its own Scan method, use that.
+ if v, ok := arg.(Scanner); ok {
+ err = v.Scan(s, verb)
+ if err != nil {
+ if err == io.EOF {
+ err = io.ErrUnexpectedEOF
+ }
+ s.error(err)
+ }
+ return
+ }
+
+ switch v := arg.(type) {
+ case *bool:
+ *v = s.scanBool(verb)
+ case *complex64:
+ *v = complex64(s.scanComplex(verb, 64))
+ case *complex128:
+ *v = s.scanComplex(verb, 128)
+ case *int:
+ *v = int(s.scanInt(verb, intBits))
+ case *int8:
+ *v = int8(s.scanInt(verb, 8))
+ case *int16:
+ *v = int16(s.scanInt(verb, 16))
+ case *int32:
+ *v = int32(s.scanInt(verb, 32))
+ case *int64:
+ *v = s.scanInt(verb, 64)
+ case *uint:
+ *v = uint(s.scanUint(verb, intBits))
+ case *uint8:
+ *v = uint8(s.scanUint(verb, 8))
+ case *uint16:
+ *v = uint16(s.scanUint(verb, 16))
+ case *uint32:
+ *v = uint32(s.scanUint(verb, 32))
+ case *uint64:
+ *v = s.scanUint(verb, 64)
+ case *uintptr:
+ *v = uintptr(s.scanUint(verb, uintptrBits))
+ // Floats are tricky because you want to scan in the precision of the result, not
+ // scan in high precision and convert, in order to preserve the correct error condition.
+ case *float32:
+ if s.okVerb(verb, floatVerbs, "float32") {
+ s.SkipSpace()
+ s.notEOF()
+ *v = float32(s.convertFloat(s.floatToken(), 32))
+ }
+ case *float64:
+ if s.okVerb(verb, floatVerbs, "float64") {
+ s.SkipSpace()
+ s.notEOF()
+ *v = s.convertFloat(s.floatToken(), 64)
+ }
+ case *string:
+ *v = s.convertString(verb)
+ case *[]byte:
+ // We scan to string and convert so we get a copy of the data.
+ // If we scanned to bytes, the slice would point at the buffer.
+ *v = []byte(s.convertString(verb))
+ default:
+ val := reflect.ValueOf(v)
+ ptr := val
+ if ptr.Kind() != reflect.Pointer {
+ s.errorString("type not a pointer: " + val.Type().String())
+ return
+ }
+ switch v := ptr.Elem(); v.Kind() {
+ case reflect.Bool:
+ v.SetBool(s.scanBool(verb))
+ case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+ v.SetInt(s.scanInt(verb, v.Type().Bits()))
+ case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+ v.SetUint(s.scanUint(verb, v.Type().Bits()))
+ case reflect.String:
+ v.SetString(s.convertString(verb))
+ case reflect.Slice:
+ // For now, can only handle (renamed) []byte.
+ typ := v.Type()
+ if typ.Elem().Kind() != reflect.Uint8 {
+ s.errorString("can't scan type: " + val.Type().String())
+ }
+ str := s.convertString(verb)
+ v.Set(reflect.MakeSlice(typ, len(str), len(str)))
+ for i := 0; i < len(str); i++ {
+ v.Index(i).SetUint(uint64(str[i]))
+ }
+ case reflect.Float32, reflect.Float64:
+ s.SkipSpace()
+ s.notEOF()
+ v.SetFloat(s.convertFloat(s.floatToken(), v.Type().Bits()))
+ case reflect.Complex64, reflect.Complex128:
+ v.SetComplex(s.scanComplex(verb, v.Type().Bits()))
+ default:
+ s.errorString("can't scan type: " + val.Type().String())
+ }
+ }
+}
+
+// errorHandler turns local panics into error returns.
+func errorHandler(errp *error) {
+ if e := recover(); e != nil {
+ if se, ok := e.(scanError); ok { // catch local error
+ *errp = se.err
+ } else if eof, ok := e.(error); ok && eof == io.EOF { // out of input
+ *errp = eof
+ } else {
+ panic(e)
+ }
+ }
+}
+
+// doScan does the real work for scanning without a format string.
+func (s *ss) doScan(a []any) (numProcessed int, err error) {
+ defer errorHandler(&err)
+ for _, arg := range a {
+ s.scanOne('v', arg)
+ numProcessed++
+ }
+ // Check for newline (or EOF) if required (Scanln etc.).
+ if s.nlIsEnd {
+ for {
+ r := s.getRune()
+ if r == '\n' || r == eof {
+ break
+ }
+ if !isSpace(r) {
+ s.errorString("expected newline")
+ break
+ }
+ }
+ }
+ return
+}
+
+// advance determines whether the next characters in the input match
+// those of the format. It returns the number of bytes (sic) consumed
+// in the format. All runs of space characters in either input or
+// format behave as a single space. Newlines are special, though:
+// newlines in the format must match those in the input and vice versa.
+// This routine also handles the %% case. If the return value is zero,
+// either format starts with a % (with no following %) or the input
+// is empty. If it is negative, the input did not match the string.
+func (s *ss) advance(format string) (i int) {
+ for i < len(format) {
+ fmtc, w := utf8.DecodeRuneInString(format[i:])
+
+ // Space processing.
+ // In the rest of this comment "space" means spaces other than newline.
+ // Newline in the format matches input of zero or more spaces and then newline or end-of-input.
+ // Spaces in the format before the newline are collapsed into the newline.
+ // Spaces in the format after the newline match zero or more spaces after the corresponding input newline.
+ // Other spaces in the format match input of one or more spaces or end-of-input.
+ if isSpace(fmtc) {
+ newlines := 0
+ trailingSpace := false
+ for isSpace(fmtc) && i < len(format) {
+ if fmtc == '\n' {
+ newlines++
+ trailingSpace = false
+ } else {
+ trailingSpace = true
+ }
+ i += w
+ fmtc, w = utf8.DecodeRuneInString(format[i:])
+ }
+ for j := 0; j < newlines; j++ {
+ inputc := s.getRune()
+ for isSpace(inputc) && inputc != '\n' {
+ inputc = s.getRune()
+ }
+ if inputc != '\n' && inputc != eof {
+ s.errorString("newline in format does not match input")
+ }
+ }
+ if trailingSpace {
+ inputc := s.getRune()
+ if newlines == 0 {
+ // If the trailing space stood alone (did not follow a newline),
+ // it must find at least one space to consume.
+ if !isSpace(inputc) && inputc != eof {
+ s.errorString("expected space in input to match format")
+ }
+ if inputc == '\n' {
+ s.errorString("newline in input does not match format")
+ }
+ }
+ for isSpace(inputc) && inputc != '\n' {
+ inputc = s.getRune()
+ }
+ if inputc != eof {
+ s.UnreadRune()
+ }
+ }
+ continue
+ }
+
+ // Verbs.
+ if fmtc == '%' {
+ // % at end of string is an error.
+ if i+w == len(format) {
+ s.errorString("missing verb: % at end of format string")
+ }
+ // %% acts like a real percent
+ nextc, _ := utf8.DecodeRuneInString(format[i+w:]) // will not match % if string is empty
+ if nextc != '%' {
+ return
+ }
+ i += w // skip the first %
+ }
+
+ // Literals.
+ inputc := s.mustReadRune()
+ if fmtc != inputc {
+ s.UnreadRune()
+ return -1
+ }
+ i += w
+ }
+ return
+}
+
+// doScanf does the real work when scanning with a format string.
+// At the moment, it handles only pointers to basic types.
+func (s *ss) doScanf(format string, a []any) (numProcessed int, err error) {
+ defer errorHandler(&err)
+ end := len(format) - 1
+ // We process one item per non-trivial format
+ for i := 0; i <= end; {
+ w := s.advance(format[i:])
+ if w > 0 {
+ i += w
+ continue
+ }
+ // Either we failed to advance, we have a percent character, or we ran out of input.
+ if format[i] != '%' {
+ // Can't advance format. Why not?
+ if w < 0 {
+ s.errorString("input does not match format")
+ }
+ // Otherwise at EOF; "too many operands" error handled below
+ break
+ }
+ i++ // % is one byte
+
+ // do we have 20 (width)?
+ var widPresent bool
+ s.maxWid, widPresent, i = parsenum(format, i, end)
+ if !widPresent {
+ s.maxWid = hugeWid
+ }
+
+ c, w := utf8.DecodeRuneInString(format[i:])
+ i += w
+
+ if c != 'c' {
+ s.SkipSpace()
+ }
+ if c == '%' {
+ s.scanPercent()
+ continue // Do not consume an argument.
+ }
+ s.argLimit = s.limit
+ if f := s.count + s.maxWid; f < s.argLimit {
+ s.argLimit = f
+ }
+
+ if numProcessed >= len(a) { // out of operands
+ s.errorString("too few operands for format '%" + format[i-w:] + "'")
+ break
+ }
+ arg := a[numProcessed]
+
+ s.scanOne(c, arg)
+ numProcessed++
+ s.argLimit = s.limit
+ }
+ if numProcessed < len(a) {
+ s.errorString("too many operands")
+ }
+ return
+}
diff --git a/src/fmt/scan_test.go b/src/fmt/scan_test.go
new file mode 100644
index 0000000..da0dfd1
--- /dev/null
+++ b/src/fmt/scan_test.go
@@ -0,0 +1,1331 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt_test
+
+import (
+ "bufio"
+ "bytes"
+ "errors"
+ . "fmt"
+ "io"
+ "math"
+ "reflect"
+ "regexp"
+ "strings"
+ "testing"
+ "testing/iotest"
+ "unicode/utf8"
+)
+
+type ScanTest struct {
+ text string
+ in any
+ out any
+}
+
+type ScanfTest struct {
+ format string
+ text string
+ in any
+ out any
+}
+
+type ScanfMultiTest struct {
+ format string
+ text string
+ in []any
+ out []any
+ err string
+}
+
+var (
+ boolVal bool
+ intVal int
+ int8Val int8
+ int16Val int16
+ int32Val int32
+ int64Val int64
+ uintVal uint
+ uint8Val uint8
+ uint16Val uint16
+ uint32Val uint32
+ uint64Val uint64
+ float32Val float32
+ float64Val float64
+ stringVal string
+ bytesVal []byte
+ runeVal rune
+ complex64Val complex64
+ complex128Val complex128
+ renamedBoolVal renamedBool
+ renamedIntVal renamedInt
+ renamedInt8Val renamedInt8
+ renamedInt16Val renamedInt16
+ renamedInt32Val renamedInt32
+ renamedInt64Val renamedInt64
+ renamedUintVal renamedUint
+ renamedUint8Val renamedUint8
+ renamedUint16Val renamedUint16
+ renamedUint32Val renamedUint32
+ renamedUint64Val renamedUint64
+ renamedUintptrVal renamedUintptr
+ renamedStringVal renamedString
+ renamedBytesVal renamedBytes
+ renamedFloat32Val renamedFloat32
+ renamedFloat64Val renamedFloat64
+ renamedComplex64Val renamedComplex64
+ renamedComplex128Val renamedComplex128
+)
+
+// Xs accepts any non-empty run of the verb character
+type Xs string
+
+func (x *Xs) Scan(state ScanState, verb rune) error {
+ tok, err := state.Token(true, func(r rune) bool { return r == verb })
+ if err != nil {
+ return err
+ }
+ s := string(tok)
+ if !regexp.MustCompile("^" + string(verb) + "+$").MatchString(s) {
+ return errors.New("syntax error for xs")
+ }
+ *x = Xs(s)
+ return nil
+}
+
+var xVal Xs
+
+// IntString accepts an integer followed immediately by a string.
+// It tests the embedding of a scan within a scan.
+type IntString struct {
+ i int
+ s string
+}
+
+func (s *IntString) Scan(state ScanState, verb rune) error {
+ if _, err := Fscan(state, &s.i); err != nil {
+ return err
+ }
+
+ tok, err := state.Token(true, nil)
+ if err != nil {
+ return err
+ }
+ s.s = string(tok)
+ return nil
+}
+
+var intStringVal IntString
+
+var scanTests = []ScanTest{
+ // Basic types
+ {"T\n", &boolVal, true}, // boolean test vals toggle to be sure they are written
+ {"F\n", &boolVal, false}, // restored to zero value
+ {"21\n", &intVal, 21},
+ {"2_1\n", &intVal, 21},
+ {"0\n", &intVal, 0},
+ {"000\n", &intVal, 0},
+ {"0x10\n", &intVal, 0x10},
+ {"0x_1_0\n", &intVal, 0x10},
+ {"-0x10\n", &intVal, -0x10},
+ {"0377\n", &intVal, 0377},
+ {"0_3_7_7\n", &intVal, 0377},
+ {"0o377\n", &intVal, 0377},
+ {"0o_3_7_7\n", &intVal, 0377},
+ {"-0377\n", &intVal, -0377},
+ {"-0o377\n", &intVal, -0377},
+ {"0\n", &uintVal, uint(0)},
+ {"000\n", &uintVal, uint(0)},
+ {"0x10\n", &uintVal, uint(0x10)},
+ {"0377\n", &uintVal, uint(0377)},
+ {"22\n", &int8Val, int8(22)},
+ {"23\n", &int16Val, int16(23)},
+ {"24\n", &int32Val, int32(24)},
+ {"25\n", &int64Val, int64(25)},
+ {"127\n", &int8Val, int8(127)},
+ {"-21\n", &intVal, -21},
+ {"-22\n", &int8Val, int8(-22)},
+ {"-23\n", &int16Val, int16(-23)},
+ {"-24\n", &int32Val, int32(-24)},
+ {"-25\n", &int64Val, int64(-25)},
+ {"-128\n", &int8Val, int8(-128)},
+ {"+21\n", &intVal, +21},
+ {"+22\n", &int8Val, int8(+22)},
+ {"+23\n", &int16Val, int16(+23)},
+ {"+24\n", &int32Val, int32(+24)},
+ {"+25\n", &int64Val, int64(+25)},
+ {"+127\n", &int8Val, int8(+127)},
+ {"26\n", &uintVal, uint(26)},
+ {"27\n", &uint8Val, uint8(27)},
+ {"28\n", &uint16Val, uint16(28)},
+ {"29\n", &uint32Val, uint32(29)},
+ {"30\n", &uint64Val, uint64(30)},
+ {"255\n", &uint8Val, uint8(255)},
+ {"32767\n", &int16Val, int16(32767)},
+ {"2.3\n", &float64Val, 2.3},
+ {"2.3e1\n", &float32Val, float32(2.3e1)},
+ {"2.3e2\n", &float64Val, 2.3e2},
+ {"2.3p2\n", &float64Val, 2.3 * 4},
+ {"2.3p+2\n", &float64Val, 2.3 * 4},
+ {"2.3p+66\n", &float64Val, 2.3 * (1 << 66)},
+ {"2.3p-66\n", &float64Val, 2.3 / (1 << 66)},
+ {"0x2.3p-66\n", &float64Val, float64(0x23) / (1 << 70)},
+ {"2_3.4_5\n", &float64Val, 23.45},
+ {"2.35\n", &stringVal, "2.35"},
+ {"2345678\n", &bytesVal, []byte("2345678")},
+ {"(3.4e1-2i)\n", &complex128Val, 3.4e1 - 2i},
+ {"-3.45e1-3i\n", &complex64Val, complex64(-3.45e1 - 3i)},
+ {"-.45e1-1e2i\n", &complex128Val, complex128(-.45e1 - 100i)},
+ {"-.4_5e1-1E2i\n", &complex128Val, complex128(-.45e1 - 100i)},
+ {"0x1.0p1+0x1.0P2i\n", &complex128Val, complex128(2 + 4i)},
+ {"-0x1p1-0x1p2i\n", &complex128Val, complex128(-2 - 4i)},
+ {"-0x1ep-1-0x1p2i\n", &complex128Val, complex128(-15 - 4i)},
+ {"-0x1_Ep-1-0x1p0_2i\n", &complex128Val, complex128(-15 - 4i)},
+ {"hello\n", &stringVal, "hello"},
+
+ // Carriage-return followed by newline. (We treat \r\n as \n always.)
+ {"hello\r\n", &stringVal, "hello"},
+ {"27\r\n", &uint8Val, uint8(27)},
+
+ // Renamed types
+ {"true\n", &renamedBoolVal, renamedBool(true)},
+ {"F\n", &renamedBoolVal, renamedBool(false)},
+ {"101\n", &renamedIntVal, renamedInt(101)},
+ {"102\n", &renamedIntVal, renamedInt(102)},
+ {"103\n", &renamedUintVal, renamedUint(103)},
+ {"104\n", &renamedUintVal, renamedUint(104)},
+ {"105\n", &renamedInt8Val, renamedInt8(105)},
+ {"106\n", &renamedInt16Val, renamedInt16(106)},
+ {"107\n", &renamedInt32Val, renamedInt32(107)},
+ {"108\n", &renamedInt64Val, renamedInt64(108)},
+ {"109\n", &renamedUint8Val, renamedUint8(109)},
+ {"110\n", &renamedUint16Val, renamedUint16(110)},
+ {"111\n", &renamedUint32Val, renamedUint32(111)},
+ {"112\n", &renamedUint64Val, renamedUint64(112)},
+ {"113\n", &renamedUintptrVal, renamedUintptr(113)},
+ {"114\n", &renamedStringVal, renamedString("114")},
+ {"115\n", &renamedBytesVal, renamedBytes([]byte("115"))},
+
+ // Custom scanners.
+ {" vvv ", &xVal, Xs("vvv")},
+ {" 1234hello", &intStringVal, IntString{1234, "hello"}},
+
+ // Fixed bugs
+ {"2147483648\n", &int64Val, int64(2147483648)}, // was: integer overflow
+}
+
+var scanfTests = []ScanfTest{
+ {"%v", "TRUE\n", &boolVal, true},
+ {"%t", "false\n", &boolVal, false},
+ {"%v", "-71\n", &intVal, -71},
+ {"%v", "-7_1\n", &intVal, -71},
+ {"%v", "0b111\n", &intVal, 7},
+ {"%v", "0b_1_1_1\n", &intVal, 7},
+ {"%v", "0377\n", &intVal, 0377},
+ {"%v", "0_3_7_7\n", &intVal, 0377},
+ {"%v", "0o377\n", &intVal, 0377},
+ {"%v", "0o_3_7_7\n", &intVal, 0377},
+ {"%v", "0x44\n", &intVal, 0x44},
+ {"%v", "0x_4_4\n", &intVal, 0x44},
+ {"%d", "72\n", &intVal, 72},
+ {"%c", "a\n", &runeVal, 'a'},
+ {"%c", "\u5072\n", &runeVal, '\u5072'},
+ {"%c", "\u1234\n", &runeVal, '\u1234'},
+ {"%d", "73\n", &int8Val, int8(73)},
+ {"%d", "+74\n", &int16Val, int16(74)},
+ {"%d", "75\n", &int32Val, int32(75)},
+ {"%d", "76\n", &int64Val, int64(76)},
+ {"%b", "1001001\n", &intVal, 73},
+ {"%o", "075\n", &intVal, 075},
+ {"%x", "a75\n", &intVal, 0xa75},
+ {"%v", "71\n", &uintVal, uint(71)},
+ {"%d", "72\n", &uintVal, uint(72)},
+ {"%d", "7_2\n", &uintVal, uint(7)}, // only %v takes underscores
+ {"%d", "73\n", &uint8Val, uint8(73)},
+ {"%d", "74\n", &uint16Val, uint16(74)},
+ {"%d", "75\n", &uint32Val, uint32(75)},
+ {"%d", "76\n", &uint64Val, uint64(76)},
+ {"%b", "1001001\n", &uintVal, uint(73)},
+ {"%b", "100_1001\n", &uintVal, uint(4)},
+ {"%o", "075\n", &uintVal, uint(075)},
+ {"%o", "07_5\n", &uintVal, uint(07)}, // only %v takes underscores
+ {"%x", "a75\n", &uintVal, uint(0xa75)},
+ {"%x", "A75\n", &uintVal, uint(0xa75)},
+ {"%x", "A7_5\n", &uintVal, uint(0xa7)}, // only %v takes underscores
+ {"%U", "U+1234\n", &intVal, int(0x1234)},
+ {"%U", "U+4567\n", &uintVal, uint(0x4567)},
+
+ {"%e", "2.3\n", &float64Val, 2.3},
+ {"%E", "2.3e1\n", &float32Val, float32(2.3e1)},
+ {"%f", "2.3e2\n", &float64Val, 2.3e2},
+ {"%g", "2.3p2\n", &float64Val, 2.3 * 4},
+ {"%G", "2.3p+2\n", &float64Val, 2.3 * 4},
+ {"%v", "2.3p+66\n", &float64Val, 2.3 * (1 << 66)},
+ {"%f", "2.3p-66\n", &float64Val, 2.3 / (1 << 66)},
+ {"%G", "0x2.3p-66\n", &float64Val, float64(0x23) / (1 << 70)},
+ {"%E", "2_3.4_5\n", &float64Val, 23.45},
+
+ // Strings
+ {"%s", "using-%s\n", &stringVal, "using-%s"},
+ {"%x", "7573696e672d2578\n", &stringVal, "using-%x"},
+ {"%X", "7573696E672D2558\n", &stringVal, "using-%X"},
+ {"%q", `"quoted\twith\\do\u0075bl\x65s"` + "\n", &stringVal, "quoted\twith\\doubles"},
+ {"%q", "`quoted with backs`\n", &stringVal, "quoted with backs"},
+
+ // Byte slices
+ {"%s", "bytes-%s\n", &bytesVal, []byte("bytes-%s")},
+ {"%x", "62797465732d2578\n", &bytesVal, []byte("bytes-%x")},
+ {"%X", "62797465732D2558\n", &bytesVal, []byte("bytes-%X")},
+ {"%q", `"bytes\rwith\vdo\u0075bl\x65s"` + "\n", &bytesVal, []byte("bytes\rwith\vdoubles")},
+ {"%q", "`bytes with backs`\n", &bytesVal, []byte("bytes with backs")},
+
+ // Renamed types
+ {"%v\n", "true\n", &renamedBoolVal, renamedBool(true)},
+ {"%t\n", "F\n", &renamedBoolVal, renamedBool(false)},
+ {"%v", "101\n", &renamedIntVal, renamedInt(101)},
+ {"%c", "\u0101\n", &renamedIntVal, renamedInt('\u0101')},
+ {"%o", "0146\n", &renamedIntVal, renamedInt(102)},
+ {"%v", "103\n", &renamedUintVal, renamedUint(103)},
+ {"%d", "104\n", &renamedUintVal, renamedUint(104)},
+ {"%d", "105\n", &renamedInt8Val, renamedInt8(105)},
+ {"%d", "106\n", &renamedInt16Val, renamedInt16(106)},
+ {"%d", "107\n", &renamedInt32Val, renamedInt32(107)},
+ {"%d", "108\n", &renamedInt64Val, renamedInt64(108)},
+ {"%x", "6D\n", &renamedUint8Val, renamedUint8(109)},
+ {"%o", "0156\n", &renamedUint16Val, renamedUint16(110)},
+ {"%d", "111\n", &renamedUint32Val, renamedUint32(111)},
+ {"%d", "112\n", &renamedUint64Val, renamedUint64(112)},
+ {"%d", "113\n", &renamedUintptrVal, renamedUintptr(113)},
+ {"%s", "114\n", &renamedStringVal, renamedString("114")},
+ {"%q", "\"1155\"\n", &renamedBytesVal, renamedBytes([]byte("1155"))},
+ {"%g", "116e1\n", &renamedFloat32Val, renamedFloat32(116e1)},
+ {"%g", "-11.7e+1", &renamedFloat64Val, renamedFloat64(-11.7e+1)},
+ {"%g", "11+6e1i\n", &renamedComplex64Val, renamedComplex64(11 + 6e1i)},
+ {"%g", "-11.+7e+1i", &renamedComplex128Val, renamedComplex128(-11. + 7e+1i)},
+
+ // Interesting formats
+ {"here is\tthe value:%d", "here is the\tvalue:118\n", &intVal, 118},
+ {"%% %%:%d", "% %:119\n", &intVal, 119},
+ {"%d%%", "42%", &intVal, 42}, // %% at end of string.
+
+ // Corner cases
+ {"%x", "FFFFFFFF\n", &uint32Val, uint32(0xFFFFFFFF)},
+
+ // Custom scanner.
+ {"%s", " sss ", &xVal, Xs("sss")},
+ {"%2s", "sssss", &xVal, Xs("ss")},
+
+ // Fixed bugs
+ {"%d\n", "27\n", &intVal, 27}, // ok
+ {"%d\n", "28 \n", &intVal, 28}, // was: "unexpected newline"
+ {"%v", "0", &intVal, 0}, // was: "EOF"; 0 was taken as base prefix and not counted.
+ {"%v", "0", &uintVal, uint(0)}, // was: "EOF"; 0 was taken as base prefix and not counted.
+ {"%c", " ", &uintVal, uint(' ')}, // %c must accept a blank.
+ {"%c", "\t", &uintVal, uint('\t')}, // %c must accept any space.
+ {"%c", "\n", &uintVal, uint('\n')}, // %c must accept any space.
+ {"%d%%", "23%\n", &uintVal, uint(23)}, // %% matches literal %.
+ {"%%%d", "%23\n", &uintVal, uint(23)}, // %% matches literal %.
+
+ // space handling
+ {"%d", "27", &intVal, 27},
+ {"%d", "27 ", &intVal, 27},
+ {"%d", " 27", &intVal, 27},
+ {"%d", " 27 ", &intVal, 27},
+
+ {"X%d", "X27", &intVal, 27},
+ {"X%d", "X27 ", &intVal, 27},
+ {"X%d", "X 27", &intVal, 27},
+ {"X%d", "X 27 ", &intVal, 27},
+
+ {"X %d", "X27", &intVal, nil}, // expected space in input to match format
+ {"X %d", "X27 ", &intVal, nil}, // expected space in input to match format
+ {"X %d", "X 27", &intVal, 27},
+ {"X %d", "X 27 ", &intVal, 27},
+
+ {"%dX", "27X", &intVal, 27},
+ {"%dX", "27 X", &intVal, nil}, // input does not match format
+ {"%dX", " 27X", &intVal, 27},
+ {"%dX", " 27 X", &intVal, nil}, // input does not match format
+
+ {"%d X", "27X", &intVal, nil}, // expected space in input to match format
+ {"%d X", "27 X", &intVal, 27},
+ {"%d X", " 27X", &intVal, nil}, // expected space in input to match format
+ {"%d X", " 27 X", &intVal, 27},
+
+ {"X %d X", "X27X", &intVal, nil}, // expected space in input to match format
+ {"X %d X", "X27 X", &intVal, nil}, // expected space in input to match format
+ {"X %d X", "X 27X", &intVal, nil}, // expected space in input to match format
+ {"X %d X", "X 27 X", &intVal, 27},
+
+ {"X %s X", "X27X", &stringVal, nil}, // expected space in input to match format
+ {"X %s X", "X27 X", &stringVal, nil}, // expected space in input to match format
+ {"X %s X", "X 27X", &stringVal, nil}, // unexpected EOF
+ {"X %s X", "X 27 X", &stringVal, "27"},
+
+ {"X%sX", "X27X", &stringVal, nil}, // unexpected EOF
+ {"X%sX", "X27 X", &stringVal, nil}, // input does not match format
+ {"X%sX", "X 27X", &stringVal, nil}, // unexpected EOF
+ {"X%sX", "X 27 X", &stringVal, nil}, // input does not match format
+
+ {"X%s", "X27", &stringVal, "27"},
+ {"X%s", "X27 ", &stringVal, "27"},
+ {"X%s", "X 27", &stringVal, "27"},
+ {"X%s", "X 27 ", &stringVal, "27"},
+
+ {"X%dX", "X27X", &intVal, 27},
+ {"X%dX", "X27 X", &intVal, nil}, // input does not match format
+ {"X%dX", "X 27X", &intVal, 27},
+ {"X%dX", "X 27 X", &intVal, nil}, // input does not match format
+
+ {"X%dX", "X27X", &intVal, 27},
+ {"X%dX", "X27X ", &intVal, 27},
+ {"X%dX", " X27X", &intVal, nil}, // input does not match format
+ {"X%dX", " X27X ", &intVal, nil}, // input does not match format
+
+ {"X%dX\n", "X27X", &intVal, 27},
+ {"X%dX \n", "X27X ", &intVal, 27},
+ {"X%dX\n", "X27X\n", &intVal, 27},
+ {"X%dX\n", "X27X \n", &intVal, 27},
+
+ {"X%dX \n", "X27X", &intVal, 27},
+ {"X%dX \n", "X27X ", &intVal, 27},
+ {"X%dX \n", "X27X\n", &intVal, 27},
+ {"X%dX \n", "X27X \n", &intVal, 27},
+
+ {"X%c", "X\n", &runeVal, '\n'},
+ {"X%c", "X \n", &runeVal, ' '},
+ {"X %c", "X!", &runeVal, nil}, // expected space in input to match format
+ {"X %c", "X\n", &runeVal, nil}, // newline in input does not match format
+ {"X %c", "X !", &runeVal, '!'},
+ {"X %c", "X \n", &runeVal, '\n'},
+
+ {" X%dX", "X27X", &intVal, nil}, // expected space in input to match format
+ {" X%dX", "X27X ", &intVal, nil}, // expected space in input to match format
+ {" X%dX", " X27X", &intVal, 27},
+ {" X%dX", " X27X ", &intVal, 27},
+
+ {"X%dX ", "X27X", &intVal, 27},
+ {"X%dX ", "X27X ", &intVal, 27},
+ {"X%dX ", " X27X", &intVal, nil}, // input does not match format
+ {"X%dX ", " X27X ", &intVal, nil}, // input does not match format
+
+ {" X%dX ", "X27X", &intVal, nil}, // expected space in input to match format
+ {" X%dX ", "X27X ", &intVal, nil}, // expected space in input to match format
+ {" X%dX ", " X27X", &intVal, 27},
+ {" X%dX ", " X27X ", &intVal, 27},
+
+ {"%d\nX", "27\nX", &intVal, 27},
+ {"%dX\n X", "27X\n X", &intVal, 27},
+}
+
+var overflowTests = []ScanTest{
+ {"128", &int8Val, 0},
+ {"32768", &int16Val, 0},
+ {"-129", &int8Val, 0},
+ {"-32769", &int16Val, 0},
+ {"256", &uint8Val, 0},
+ {"65536", &uint16Val, 0},
+ {"1e100", &float32Val, 0},
+ {"1e500", &float64Val, 0},
+ {"(1e100+0i)", &complex64Val, 0},
+ {"(1+1e100i)", &complex64Val, 0},
+ {"(1-1e500i)", &complex128Val, 0},
+}
+
+var truth bool
+var i, j, k int
+var f float64
+var s, t string
+var c complex128
+var x, y Xs
+var z IntString
+var r1, r2, r3 rune
+
+var multiTests = []ScanfMultiTest{
+ {"", "", []any{}, []any{}, ""},
+ {"%d", "23", args(&i), args(23), ""},
+ {"%2s%3s", "22333", args(&s, &t), args("22", "333"), ""},
+ {"%2d%3d", "44555", args(&i, &j), args(44, 555), ""},
+ {"%2d.%3d", "66.777", args(&i, &j), args(66, 777), ""},
+ {"%d, %d", "23, 18", args(&i, &j), args(23, 18), ""},
+ {"%3d22%3d", "33322333", args(&i, &j), args(333, 333), ""},
+ {"%6vX=%3fY", "3+2iX=2.5Y", args(&c, &f), args((3 + 2i), 2.5), ""},
+ {"%d%s", "123abc", args(&i, &s), args(123, "abc"), ""},
+ {"%c%c%c", "2\u50c2X", args(&r1, &r2, &r3), args('2', '\u50c2', 'X'), ""},
+ {"%5s%d", " 1234567 ", args(&s, &i), args("12345", 67), ""},
+ {"%5s%d", " 12 34 567 ", args(&s, &i), args("12", 34), ""},
+
+ // Custom scanners.
+ {"%e%f", "eefffff", args(&x, &y), args(Xs("ee"), Xs("fffff")), ""},
+ {"%4v%s", "12abcd", args(&z, &s), args(IntString{12, "ab"}, "cd"), ""},
+
+ // Errors
+ {"%t", "23 18", args(&i), nil, "bad verb"},
+ {"%d %d %d", "23 18", args(&i, &j), args(23, 18), "too few operands"},
+ {"%d %d", "23 18 27", args(&i, &j, &k), args(23, 18), "too many operands"},
+ {"%c", "\u0100", args(&int8Val), nil, "overflow"},
+ {"X%d", "10X", args(&intVal), nil, "input does not match format"},
+ {"%d%", "42%", args(&intVal), args(42), "missing verb: % at end of format string"},
+ {"%d% ", "42%", args(&intVal), args(42), "too few operands for format '% '"}, // Slightly odd error, but correct.
+ {"%%%d", "xxx 42", args(&intVal), args(42), "missing literal %"},
+ {"%%%d", "x42", args(&intVal), args(42), "missing literal %"},
+ {"%%%d", "42", args(&intVal), args(42), "missing literal %"},
+
+ // Bad UTF-8: should see every byte.
+ {"%c%c%c", "\xc2X\xc2", args(&r1, &r2, &r3), args(utf8.RuneError, 'X', utf8.RuneError), ""},
+
+ // Fixed bugs
+ {"%v%v", "FALSE23", args(&truth, &i), args(false, 23), ""},
+}
+
+var readers = []struct {
+ name string
+ f func(string) io.Reader
+}{
+ {"StringReader", func(s string) io.Reader {
+ return strings.NewReader(s)
+ }},
+ {"ReaderOnly", func(s string) io.Reader {
+ return struct{ io.Reader }{strings.NewReader(s)}
+ }},
+ {"OneByteReader", func(s string) io.Reader {
+ return iotest.OneByteReader(strings.NewReader(s))
+ }},
+ {"DataErrReader", func(s string) io.Reader {
+ return iotest.DataErrReader(strings.NewReader(s))
+ }},
+}
+
+func testScan(t *testing.T, f func(string) io.Reader, scan func(r io.Reader, a ...any) (int, error)) {
+ for _, test := range scanTests {
+ r := f(test.text)
+ n, err := scan(r, test.in)
+ if err != nil {
+ m := ""
+ if n > 0 {
+ m = Sprintf(" (%d fields ok)", n)
+ }
+ t.Errorf("got error scanning %q: %s%s", test.text, err, m)
+ continue
+ }
+ if n != 1 {
+ t.Errorf("count error on entry %q: got %d", test.text, n)
+ continue
+ }
+ // The incoming value may be a pointer
+ v := reflect.ValueOf(test.in)
+ if p := v; p.Kind() == reflect.Pointer {
+ v = p.Elem()
+ }
+ val := v.Interface()
+ if !reflect.DeepEqual(val, test.out) {
+ t.Errorf("scanning %q: expected %#v got %#v, type %T", test.text, test.out, val, val)
+ }
+ }
+}
+
+func TestScan(t *testing.T) {
+ for _, r := range readers {
+ t.Run(r.name, func(t *testing.T) {
+ testScan(t, r.f, Fscan)
+ })
+ }
+}
+
+func TestScanln(t *testing.T) {
+ for _, r := range readers {
+ t.Run(r.name, func(t *testing.T) {
+ testScan(t, r.f, Fscanln)
+ })
+ }
+}
+
+func TestScanf(t *testing.T) {
+ for _, test := range scanfTests {
+ n, err := Sscanf(test.text, test.format, test.in)
+ if err != nil {
+ if test.out != nil {
+ t.Errorf("Sscanf(%q, %q): unexpected error: %v", test.text, test.format, err)
+ }
+ continue
+ }
+ if test.out == nil {
+ t.Errorf("Sscanf(%q, %q): unexpected success", test.text, test.format)
+ continue
+ }
+ if n != 1 {
+ t.Errorf("Sscanf(%q, %q): parsed %d field, want 1", test.text, test.format, n)
+ continue
+ }
+ // The incoming value may be a pointer
+ v := reflect.ValueOf(test.in)
+ if p := v; p.Kind() == reflect.Pointer {
+ v = p.Elem()
+ }
+ val := v.Interface()
+ if !reflect.DeepEqual(val, test.out) {
+ t.Errorf("Sscanf(%q, %q): parsed value %T(%#v), want %T(%#v)", test.text, test.format, val, val, test.out, test.out)
+ }
+ }
+}
+
+func TestScanOverflow(t *testing.T) {
+ // different machines and different types report errors with different strings.
+ re := regexp.MustCompile("overflow|too large|out of range|not representable")
+ for _, test := range overflowTests {
+ _, err := Sscan(test.text, test.in)
+ if err == nil {
+ t.Errorf("expected overflow scanning %q", test.text)
+ continue
+ }
+ if !re.MatchString(err.Error()) {
+ t.Errorf("expected overflow error scanning %q: %s", test.text, err)
+ }
+ }
+}
+
+func verifyNaN(str string, t *testing.T) {
+ var f float64
+ var f32 float32
+ var f64 float64
+ text := str + " " + str + " " + str
+ n, err := Fscan(strings.NewReader(text), &f, &f32, &f64)
+ if err != nil {
+ t.Errorf("got error scanning %q: %s", text, err)
+ }
+ if n != 3 {
+ t.Errorf("count error scanning %q: got %d", text, n)
+ }
+ if !math.IsNaN(float64(f)) || !math.IsNaN(float64(f32)) || !math.IsNaN(f64) {
+ t.Errorf("didn't get NaNs scanning %q: got %g %g %g", text, f, f32, f64)
+ }
+}
+
+func TestNaN(t *testing.T) {
+ for _, s := range []string{"nan", "NAN", "NaN"} {
+ verifyNaN(s, t)
+ }
+}
+
+func verifyInf(str string, t *testing.T) {
+ var f float64
+ var f32 float32
+ var f64 float64
+ text := str + " " + str + " " + str
+ n, err := Fscan(strings.NewReader(text), &f, &f32, &f64)
+ if err != nil {
+ t.Errorf("got error scanning %q: %s", text, err)
+ }
+ if n != 3 {
+ t.Errorf("count error scanning %q: got %d", text, n)
+ }
+ sign := 1
+ if str[0] == '-' {
+ sign = -1
+ }
+ if !math.IsInf(float64(f), sign) || !math.IsInf(float64(f32), sign) || !math.IsInf(f64, sign) {
+ t.Errorf("didn't get right Infs scanning %q: got %g %g %g", text, f, f32, f64)
+ }
+}
+
+func TestInf(t *testing.T) {
+ for _, s := range []string{"inf", "+inf", "-inf", "INF", "-INF", "+INF", "Inf", "-Inf", "+Inf"} {
+ verifyInf(s, t)
+ }
+}
+
+func testScanfMulti(t *testing.T, f func(string) io.Reader) {
+ sliceType := reflect.TypeOf(make([]any, 1))
+ for _, test := range multiTests {
+ r := f(test.text)
+ n, err := Fscanf(r, test.format, test.in...)
+ if err != nil {
+ if test.err == "" {
+ t.Errorf("got error scanning (%q, %q): %q", test.format, test.text, err)
+ } else if !strings.Contains(err.Error(), test.err) {
+ t.Errorf("got wrong error scanning (%q, %q): %q; expected %q", test.format, test.text, err, test.err)
+ }
+ continue
+ }
+ if test.err != "" {
+ t.Errorf("expected error %q error scanning (%q, %q)", test.err, test.format, test.text)
+ }
+ if n != len(test.out) {
+ t.Errorf("count error on entry (%q, %q): expected %d got %d", test.format, test.text, len(test.out), n)
+ continue
+ }
+ // Convert the slice of pointers into a slice of values
+ resultVal := reflect.MakeSlice(sliceType, n, n)
+ for i := 0; i < n; i++ {
+ v := reflect.ValueOf(test.in[i]).Elem()
+ resultVal.Index(i).Set(v)
+ }
+ result := resultVal.Interface()
+ if !reflect.DeepEqual(result, test.out) {
+ t.Errorf("scanning (%q, %q): expected %#v got %#v", test.format, test.text, test.out, result)
+ }
+ }
+}
+
+func TestScanfMulti(t *testing.T) {
+ for _, r := range readers {
+ t.Run(r.name, func(t *testing.T) {
+ testScanfMulti(t, r.f)
+ })
+ }
+}
+
+func TestScanMultiple(t *testing.T) {
+ var a int
+ var s string
+ n, err := Sscan("123abc", &a, &s)
+ if n != 2 {
+ t.Errorf("Sscan count error: expected 2: got %d", n)
+ }
+ if err != nil {
+ t.Errorf("Sscan expected no error; got %s", err)
+ }
+ if a != 123 || s != "abc" {
+ t.Errorf("Sscan wrong values: got (%d %q) expected (123 \"abc\")", a, s)
+ }
+ n, err = Sscan("asdf", &s, &a)
+ if n != 1 {
+ t.Errorf("Sscan count error: expected 1: got %d", n)
+ }
+ if err == nil {
+ t.Errorf("Sscan expected error; got none: %s", err)
+ }
+ if s != "asdf" {
+ t.Errorf("Sscan wrong values: got %q expected \"asdf\"", s)
+ }
+}
+
+// Empty strings are not valid input when scanning a string.
+func TestScanEmpty(t *testing.T) {
+ var s1, s2 string
+ n, err := Sscan("abc", &s1, &s2)
+ if n != 1 {
+ t.Errorf("Sscan count error: expected 1: got %d", n)
+ }
+ if err == nil {
+ t.Error("Sscan <one item> expected error; got none")
+ }
+ if s1 != "abc" {
+ t.Errorf("Sscan wrong values: got %q expected \"abc\"", s1)
+ }
+ n, err = Sscan("", &s1, &s2)
+ if n != 0 {
+ t.Errorf("Sscan count error: expected 0: got %d", n)
+ }
+ if err == nil {
+ t.Error("Sscan <empty> expected error; got none")
+ }
+ // Quoted empty string is OK.
+ n, err = Sscanf(`""`, "%q", &s1)
+ if n != 1 {
+ t.Errorf("Sscanf count error: expected 1: got %d", n)
+ }
+ if err != nil {
+ t.Errorf("Sscanf <empty> expected no error with quoted string; got %s", err)
+ }
+}
+
+func TestScanNotPointer(t *testing.T) {
+ r := strings.NewReader("1")
+ var a int
+ _, err := Fscan(r, a)
+ if err == nil {
+ t.Error("expected error scanning non-pointer")
+ } else if !strings.Contains(err.Error(), "pointer") {
+ t.Errorf("expected pointer error scanning non-pointer, got: %s", err)
+ }
+}
+
+func TestScanlnNoNewline(t *testing.T) {
+ var a int
+ _, err := Sscanln("1 x\n", &a)
+ if err == nil {
+ t.Error("expected error scanning string missing newline")
+ } else if !strings.Contains(err.Error(), "newline") {
+ t.Errorf("expected newline error scanning string missing newline, got: %s", err)
+ }
+}
+
+func TestScanlnWithMiddleNewline(t *testing.T) {
+ r := strings.NewReader("123\n456\n")
+ var a, b int
+ _, err := Fscanln(r, &a, &b)
+ if err == nil {
+ t.Error("expected error scanning string with extra newline")
+ } else if !strings.Contains(err.Error(), "newline") {
+ t.Errorf("expected newline error scanning string with extra newline, got: %s", err)
+ }
+}
+
+// eofCounter is a special Reader that counts reads at end of file.
+type eofCounter struct {
+ reader *strings.Reader
+ eofCount int
+}
+
+func (ec *eofCounter) Read(b []byte) (n int, err error) {
+ n, err = ec.reader.Read(b)
+ if n == 0 {
+ ec.eofCount++
+ }
+ return
+}
+
+// TestEOF verifies that when we scan, we see at most EOF once per call to a
+// Scan function, and then only when it's really an EOF.
+func TestEOF(t *testing.T) {
+ ec := &eofCounter{strings.NewReader("123\n"), 0}
+ var a int
+ n, err := Fscanln(ec, &a)
+ if err != nil {
+ t.Error("unexpected error", err)
+ }
+ if n != 1 {
+ t.Error("expected to scan one item, got", n)
+ }
+ if ec.eofCount != 0 {
+ t.Error("expected zero EOFs", ec.eofCount)
+ ec.eofCount = 0 // reset for next test
+ }
+ n, err = Fscanln(ec, &a)
+ if err == nil {
+ t.Error("expected error scanning empty string")
+ }
+ if n != 0 {
+ t.Error("expected to scan zero items, got", n)
+ }
+ if ec.eofCount != 1 {
+ t.Error("expected one EOF, got", ec.eofCount)
+ }
+}
+
+// TestEOFAtEndOfInput verifies that we see an EOF error if we run out of input.
+// This was a buglet: we used to get "expected integer".
+func TestEOFAtEndOfInput(t *testing.T) {
+ var i, j int
+ n, err := Sscanf("23", "%d %d", &i, &j)
+ if n != 1 || i != 23 {
+ t.Errorf("Sscanf expected one value of 23; got %d %d", n, i)
+ }
+ if err != io.EOF {
+ t.Errorf("Sscanf expected EOF; got %q", err)
+ }
+ n, err = Sscan("234", &i, &j)
+ if n != 1 || i != 234 {
+ t.Errorf("Sscan expected one value of 234; got %d %d", n, i)
+ }
+ if err != io.EOF {
+ t.Errorf("Sscan expected EOF; got %q", err)
+ }
+ // Trailing space is tougher.
+ n, err = Sscan("234 ", &i, &j)
+ if n != 1 || i != 234 {
+ t.Errorf("Sscan expected one value of 234; got %d %d", n, i)
+ }
+ if err != io.EOF {
+ t.Errorf("Sscan expected EOF; got %q", err)
+ }
+}
+
+var eofTests = []struct {
+ format string
+ v any
+}{
+ {"%s", &stringVal},
+ {"%q", &stringVal},
+ {"%x", &stringVal},
+ {"%v", &stringVal},
+ {"%v", &bytesVal},
+ {"%v", &intVal},
+ {"%v", &uintVal},
+ {"%v", &boolVal},
+ {"%v", &float32Val},
+ {"%v", &complex64Val},
+ {"%v", &renamedStringVal},
+ {"%v", &renamedBytesVal},
+ {"%v", &renamedIntVal},
+ {"%v", &renamedUintVal},
+ {"%v", &renamedBoolVal},
+ {"%v", &renamedFloat32Val},
+ {"%v", &renamedComplex64Val},
+}
+
+func TestEOFAllTypes(t *testing.T) {
+ for i, test := range eofTests {
+ if _, err := Sscanf("", test.format, test.v); err != io.EOF {
+ t.Errorf("#%d: %s %T not eof on empty string: %s", i, test.format, test.v, err)
+ }
+ if _, err := Sscanf(" ", test.format, test.v); err != io.EOF {
+ t.Errorf("#%d: %s %T not eof on trailing blanks: %s", i, test.format, test.v, err)
+ }
+ }
+}
+
+// TestUnreadRuneWithBufio verifies that, at least when using bufio, successive
+// calls to Fscan do not lose runes.
+func TestUnreadRuneWithBufio(t *testing.T) {
+ r := bufio.NewReader(strings.NewReader("123αb"))
+ var i int
+ var a string
+ n, err := Fscanf(r, "%d", &i)
+ if n != 1 || err != nil {
+ t.Errorf("reading int expected one item, no errors; got %d %q", n, err)
+ }
+ if i != 123 {
+ t.Errorf("expected 123; got %d", i)
+ }
+ n, err = Fscanf(r, "%s", &a)
+ if n != 1 || err != nil {
+ t.Errorf("reading string expected one item, no errors; got %d %q", n, err)
+ }
+ if a != "αb" {
+ t.Errorf("expected αb; got %q", a)
+ }
+}
+
+type TwoLines string
+
+// Scan attempts to read two lines into the object. Scanln should prevent this
+// because it stops at newline; Scan and Scanf should be fine.
+func (t *TwoLines) Scan(state ScanState, verb rune) error {
+ chars := make([]rune, 0, 100)
+ for nlCount := 0; nlCount < 2; {
+ c, _, err := state.ReadRune()
+ if err != nil {
+ return err
+ }
+ chars = append(chars, c)
+ if c == '\n' {
+ nlCount++
+ }
+ }
+ *t = TwoLines(string(chars))
+ return nil
+}
+
+func TestMultiLine(t *testing.T) {
+ input := "abc\ndef\n"
+ // Sscan should work
+ var tscan TwoLines
+ n, err := Sscan(input, &tscan)
+ if n != 1 {
+ t.Errorf("Sscan: expected 1 item; got %d", n)
+ }
+ if err != nil {
+ t.Errorf("Sscan: expected no error; got %s", err)
+ }
+ if string(tscan) != input {
+ t.Errorf("Sscan: expected %q; got %q", input, tscan)
+ }
+ // Sscanf should work
+ var tscanf TwoLines
+ n, err = Sscanf(input, "%s", &tscanf)
+ if n != 1 {
+ t.Errorf("Sscanf: expected 1 item; got %d", n)
+ }
+ if err != nil {
+ t.Errorf("Sscanf: expected no error; got %s", err)
+ }
+ if string(tscanf) != input {
+ t.Errorf("Sscanf: expected %q; got %q", input, tscanf)
+ }
+ // Sscanln should not work
+ var tscanln TwoLines
+ n, err = Sscanln(input, &tscanln)
+ if n != 0 {
+ t.Errorf("Sscanln: expected 0 items; got %d: %q", n, tscanln)
+ }
+ if err == nil {
+ t.Error("Sscanln: expected error; got none")
+ } else if err != io.ErrUnexpectedEOF {
+ t.Errorf("Sscanln: expected io.ErrUnexpectedEOF (ha!); got %s", err)
+ }
+}
+
+// TestLineByLineFscanf tests that Fscanf does not read past newline. Issue
+// 3481.
+func TestLineByLineFscanf(t *testing.T) {
+ r := struct{ io.Reader }{strings.NewReader("1\n2\n")}
+ var i, j int
+ n, err := Fscanf(r, "%v\n", &i)
+ if n != 1 || err != nil {
+ t.Fatalf("first read: %d %q", n, err)
+ }
+ n, err = Fscanf(r, "%v\n", &j)
+ if n != 1 || err != nil {
+ t.Fatalf("second read: %d %q", n, err)
+ }
+ if i != 1 || j != 2 {
+ t.Errorf("wrong values; wanted 1 2 got %d %d", i, j)
+ }
+}
+
+// TestScanStateCount verifies the correct byte count is returned. Issue 8512.
+
+// runeScanner implements the Scanner interface for TestScanStateCount.
+type runeScanner struct {
+ rune rune
+ size int
+}
+
+func (rs *runeScanner) Scan(state ScanState, verb rune) error {
+ r, size, err := state.ReadRune()
+ rs.rune = r
+ rs.size = size
+ return err
+}
+
+func TestScanStateCount(t *testing.T) {
+ var a, b, c runeScanner
+ n, err := Sscanf("12➂", "%c%c%c", &a, &b, &c)
+ if err != nil {
+ t.Fatal(err)
+ }
+ if n != 3 {
+ t.Fatalf("expected 3 items consumed, got %d", n)
+ }
+ if a.rune != '1' || b.rune != '2' || c.rune != '➂' {
+ t.Errorf("bad scan rune: %q %q %q should be '1' '2' '➂'", a.rune, b.rune, c.rune)
+ }
+ if a.size != 1 || b.size != 1 || c.size != 3 {
+ t.Errorf("bad scan size: %q %q %q should be 1 1 3", a.size, b.size, c.size)
+ }
+}
+
+// RecursiveInt accepts a string matching %d.%d.%d....
+// and parses it into a linked list.
+// It allows us to benchmark recursive descent style scanners.
+type RecursiveInt struct {
+ i int
+ next *RecursiveInt
+}
+
+func (r *RecursiveInt) Scan(state ScanState, verb rune) (err error) {
+ _, err = Fscan(state, &r.i)
+ if err != nil {
+ return
+ }
+ next := new(RecursiveInt)
+ _, err = Fscanf(state, ".%v", next)
+ if err != nil {
+ if err == io.ErrUnexpectedEOF {
+ err = nil
+ }
+ return
+ }
+ r.next = next
+ return
+}
+
+// scanInts performs the same scanning task as RecursiveInt.Scan
+// but without recurring through scanner, so we can compare
+// performance more directly.
+func scanInts(r *RecursiveInt, b *bytes.Buffer) (err error) {
+ r.next = nil
+ _, err = Fscan(b, &r.i)
+ if err != nil {
+ return
+ }
+ c, _, err := b.ReadRune()
+ if err != nil {
+ if err == io.EOF {
+ err = nil
+ }
+ return
+ }
+ if c != '.' {
+ return
+ }
+ next := new(RecursiveInt)
+ err = scanInts(next, b)
+ if err == nil {
+ r.next = next
+ }
+ return
+}
+
+func makeInts(n int) []byte {
+ var buf bytes.Buffer
+ Fprintf(&buf, "1")
+ for i := 1; i < n; i++ {
+ Fprintf(&buf, ".%d", i+1)
+ }
+ return buf.Bytes()
+}
+
+func TestScanInts(t *testing.T) {
+ testScanInts(t, scanInts)
+ testScanInts(t, func(r *RecursiveInt, b *bytes.Buffer) (err error) {
+ _, err = Fscan(b, r)
+ return
+ })
+}
+
+// 800 is small enough to not overflow the stack when using gccgo on a
+// platform that does not support split stack.
+const intCount = 800
+
+func testScanInts(t *testing.T, scan func(*RecursiveInt, *bytes.Buffer) error) {
+ r := new(RecursiveInt)
+ ints := makeInts(intCount)
+ buf := bytes.NewBuffer(ints)
+ err := scan(r, buf)
+ if err != nil {
+ t.Error("unexpected error", err)
+ }
+ i := 1
+ for ; r != nil; r = r.next {
+ if r.i != i {
+ t.Fatalf("bad scan: expected %d got %d", i, r.i)
+ }
+ i++
+ }
+ if i-1 != intCount {
+ t.Fatalf("bad scan count: expected %d got %d", intCount, i-1)
+ }
+}
+
+func BenchmarkScanInts(b *testing.B) {
+ b.ResetTimer()
+ ints := makeInts(intCount)
+ var r RecursiveInt
+ for i := b.N - 1; i >= 0; i-- {
+ buf := bytes.NewBuffer(ints)
+ b.StartTimer()
+ scanInts(&r, buf)
+ b.StopTimer()
+ }
+}
+
+func BenchmarkScanRecursiveInt(b *testing.B) {
+ b.ResetTimer()
+ ints := makeInts(intCount)
+ var r RecursiveInt
+ for i := b.N - 1; i >= 0; i-- {
+ buf := bytes.NewBuffer(ints)
+ b.StartTimer()
+ Fscan(buf, &r)
+ b.StopTimer()
+ }
+}
+
+func BenchmarkScanRecursiveIntReaderWrapper(b *testing.B) {
+ b.ResetTimer()
+ ints := makeInts(intCount)
+ var r RecursiveInt
+ for i := b.N - 1; i >= 0; i-- {
+ buf := struct{ io.Reader }{strings.NewReader(string(ints))}
+ b.StartTimer()
+ Fscan(buf, &r)
+ b.StopTimer()
+ }
+}
+
+// Issue 9124.
+// %x on bytes couldn't handle non-space bytes terminating the scan.
+func TestHexBytes(t *testing.T) {
+ var a, b []byte
+ n, err := Sscanf("00010203", "%x", &a)
+ if n != 1 || err != nil {
+ t.Errorf("simple: got count, err = %d, %v; expected 1, nil", n, err)
+ }
+ check := func(msg string, x []byte) {
+ if len(x) != 4 {
+ t.Errorf("%s: bad length %d", msg, len(x))
+ }
+ for i, b := range x {
+ if int(b) != i {
+ t.Errorf("%s: bad x[%d] = %x", msg, i, x[i])
+ }
+ }
+ }
+ check("simple", a)
+ a = nil
+
+ n, err = Sscanf("00010203 00010203", "%x %x", &a, &b)
+ if n != 2 || err != nil {
+ t.Errorf("simple pair: got count, err = %d, %v; expected 2, nil", n, err)
+ }
+ check("simple pair a", a)
+ check("simple pair b", b)
+ a = nil
+ b = nil
+
+ n, err = Sscanf("00010203:", "%x", &a)
+ if n != 1 || err != nil {
+ t.Errorf("colon: got count, err = %d, %v; expected 1, nil", n, err)
+ }
+ check("colon", a)
+ a = nil
+
+ n, err = Sscanf("00010203:00010203", "%x:%x", &a, &b)
+ if n != 2 || err != nil {
+ t.Errorf("colon pair: got count, err = %d, %v; expected 2, nil", n, err)
+ }
+ check("colon pair a", a)
+ check("colon pair b", b)
+ a = nil
+ b = nil
+
+ // This one fails because there is a hex byte after the data,
+ // that is, an odd number of hex input bytes.
+ n, err = Sscanf("000102034:", "%x", &a)
+ if n != 0 || err == nil {
+ t.Errorf("odd count: got count, err = %d, %v; expected 0, error", n, err)
+ }
+}
+
+func TestScanNewlinesAreSpaces(t *testing.T) {
+ var a, b int
+ var tests = []struct {
+ name string
+ text string
+ count int
+ }{
+ {"newlines", "1\n2\n", 2},
+ {"no final newline", "1\n2", 2},
+ {"newlines with spaces ", "1 \n 2 \n", 2},
+ {"no final newline with spaces", "1 \n 2", 2},
+ }
+ for _, test := range tests {
+ n, err := Sscan(test.text, &a, &b)
+ if n != test.count {
+ t.Errorf("%s: expected to scan %d item(s), scanned %d", test.name, test.count, n)
+ }
+ if err != nil {
+ t.Errorf("%s: unexpected error: %s", test.name, err)
+ }
+ }
+}
+
+func TestScanlnNewlinesTerminate(t *testing.T) {
+ var a, b int
+ var tests = []struct {
+ name string
+ text string
+ count int
+ ok bool
+ }{
+ {"one line one item", "1\n", 1, false},
+ {"one line two items with spaces ", " 1 2 \n", 2, true},
+ {"one line two items no newline", " 1 2", 2, true},
+ {"two lines two items", "1\n2\n", 1, false},
+ }
+ for _, test := range tests {
+ n, err := Sscanln(test.text, &a, &b)
+ if n != test.count {
+ t.Errorf("%s: expected to scan %d item(s), scanned %d", test.name, test.count, n)
+ }
+ if test.ok && err != nil {
+ t.Errorf("%s: unexpected error: %s", test.name, err)
+ }
+ if !test.ok && err == nil {
+ t.Errorf("%s: expected error; got none", test.name)
+ }
+ }
+}
+
+func TestScanfNewlineMatchFormat(t *testing.T) {
+ var a, b int
+ var tests = []struct {
+ name string
+ text string
+ format string
+ count int
+ ok bool
+ }{
+ {"newline in both", "1\n2", "%d\n%d\n", 2, true},
+ {"newline in input", "1\n2", "%d %d", 1, false},
+ {"space-newline in input", "1 \n2", "%d %d", 1, false},
+ {"newline in format", "1 2", "%d\n%d", 1, false},
+ {"space-newline in format", "1 2", "%d \n%d", 1, false},
+ {"space-newline in both", "1 \n2", "%d \n%d", 2, true},
+ {"extra space in format", "1\n2", "%d\n %d", 2, true},
+ {"two extra spaces in format", "1\n2", "%d \n %d", 2, true},
+ {"space vs newline 0000", "1\n2", "%d\n%d", 2, true},
+ {"space vs newline 0001", "1\n2", "%d\n %d", 2, true},
+ {"space vs newline 0010", "1\n2", "%d \n%d", 2, true},
+ {"space vs newline 0011", "1\n2", "%d \n %d", 2, true},
+ {"space vs newline 0100", "1\n 2", "%d\n%d", 2, true},
+ {"space vs newline 0101", "1\n 2", "%d\n%d ", 2, true},
+ {"space vs newline 0110", "1\n 2", "%d \n%d", 2, true},
+ {"space vs newline 0111", "1\n 2", "%d \n %d", 2, true},
+ {"space vs newline 1000", "1 \n2", "%d\n%d", 2, true},
+ {"space vs newline 1001", "1 \n2", "%d\n %d", 2, true},
+ {"space vs newline 1010", "1 \n2", "%d \n%d", 2, true},
+ {"space vs newline 1011", "1 \n2", "%d \n %d", 2, true},
+ {"space vs newline 1100", "1 \n 2", "%d\n%d", 2, true},
+ {"space vs newline 1101", "1 \n 2", "%d\n %d", 2, true},
+ {"space vs newline 1110", "1 \n 2", "%d \n%d", 2, true},
+ {"space vs newline 1111", "1 \n 2", "%d \n %d", 2, true},
+ {"space vs newline no-percent 0000", "1\n2", "1\n2", 0, true},
+ {"space vs newline no-percent 0001", "1\n2", "1\n 2", 0, true},
+ {"space vs newline no-percent 0010", "1\n2", "1 \n2", 0, true},
+ {"space vs newline no-percent 0011", "1\n2", "1 \n 2", 0, true},
+ {"space vs newline no-percent 0100", "1\n 2", "1\n2", 0, false}, // fails: space after nl in input but not pattern
+ {"space vs newline no-percent 0101", "1\n 2", "1\n2 ", 0, false}, // fails: space after nl in input but not pattern
+ {"space vs newline no-percent 0110", "1\n 2", "1 \n2", 0, false}, // fails: space after nl in input but not pattern
+ {"space vs newline no-percent 0111", "1\n 2", "1 \n 2", 0, true},
+ {"space vs newline no-percent 1000", "1 \n2", "1\n2", 0, true},
+ {"space vs newline no-percent 1001", "1 \n2", "1\n 2", 0, true},
+ {"space vs newline no-percent 1010", "1 \n2", "1 \n2", 0, true},
+ {"space vs newline no-percent 1011", "1 \n2", "1 \n 2", 0, true},
+ {"space vs newline no-percent 1100", "1 \n 2", "1\n2", 0, false}, // fails: space after nl in input but not pattern
+ {"space vs newline no-percent 1101", "1 \n 2", "1\n 2", 0, true},
+ {"space vs newline no-percent 1110", "1 \n 2", "1 \n2", 0, false}, // fails: space after nl in input but not pattern
+ {"space vs newline no-percent 1111", "1 \n 2", "1 \n 2", 0, true},
+ }
+ for _, test := range tests {
+ var n int
+ var err error
+ if strings.Contains(test.format, "%") {
+ n, err = Sscanf(test.text, test.format, &a, &b)
+ } else {
+ n, err = Sscanf(test.text, test.format)
+ }
+ if n != test.count {
+ t.Errorf("%s: expected to scan %d item(s), scanned %d", test.name, test.count, n)
+ }
+ if test.ok && err != nil {
+ t.Errorf("%s: unexpected error: %s", test.name, err)
+ }
+ if !test.ok && err == nil {
+ t.Errorf("%s: expected error; got none", test.name)
+ }
+ }
+}
+
+// Test for issue 12090: Was unreading at EOF, double-scanning a byte.
+
+type hexBytes [2]byte
+
+func (h *hexBytes) Scan(ss ScanState, verb rune) error {
+ var b []byte
+ _, err := Fscanf(ss, "%4x", &b)
+ if err != nil {
+ panic(err) // Really shouldn't happen.
+ }
+ copy((*h)[:], b)
+ return err
+}
+
+func TestHexByte(t *testing.T) {
+ var h hexBytes
+ n, err := Sscanln("0123\n", &h)
+ if err != nil {
+ t.Fatal(err)
+ }
+ if n != 1 {
+ t.Fatalf("expected 1 item; scanned %d", n)
+ }
+ if h[0] != 0x01 || h[1] != 0x23 {
+ t.Fatalf("expected 0123 got %x", h)
+ }
+}
diff --git a/src/fmt/stringer_example_test.go b/src/fmt/stringer_example_test.go
new file mode 100644
index 0000000..c77e788
--- /dev/null
+++ b/src/fmt/stringer_example_test.go
@@ -0,0 +1,29 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt_test
+
+import (
+ "fmt"
+)
+
+// Animal has a Name and an Age to represent an animal.
+type Animal struct {
+ Name string
+ Age uint
+}
+
+// String makes Animal satisfy the Stringer interface.
+func (a Animal) String() string {
+ return fmt.Sprintf("%v (%d)", a.Name, a.Age)
+}
+
+func ExampleStringer() {
+ a := Animal{
+ Name: "Gopher",
+ Age: 2,
+ }
+ fmt.Println(a)
+ // Output: Gopher (2)
+}
diff --git a/src/fmt/stringer_test.go b/src/fmt/stringer_test.go
new file mode 100644
index 0000000..0ca3f52
--- /dev/null
+++ b/src/fmt/stringer_test.go
@@ -0,0 +1,61 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package fmt_test
+
+import (
+ . "fmt"
+ "testing"
+)
+
+type TI int
+type TI8 int8
+type TI16 int16
+type TI32 int32
+type TI64 int64
+type TU uint
+type TU8 uint8
+type TU16 uint16
+type TU32 uint32
+type TU64 uint64
+type TUI uintptr
+type TF float64
+type TF32 float32
+type TF64 float64
+type TB bool
+type TS string
+
+func (v TI) String() string { return Sprintf("I: %d", int(v)) }
+func (v TI8) String() string { return Sprintf("I8: %d", int8(v)) }
+func (v TI16) String() string { return Sprintf("I16: %d", int16(v)) }
+func (v TI32) String() string { return Sprintf("I32: %d", int32(v)) }
+func (v TI64) String() string { return Sprintf("I64: %d", int64(v)) }
+func (v TU) String() string { return Sprintf("U: %d", uint(v)) }
+func (v TU8) String() string { return Sprintf("U8: %d", uint8(v)) }
+func (v TU16) String() string { return Sprintf("U16: %d", uint16(v)) }
+func (v TU32) String() string { return Sprintf("U32: %d", uint32(v)) }
+func (v TU64) String() string { return Sprintf("U64: %d", uint64(v)) }
+func (v TUI) String() string { return Sprintf("UI: %d", uintptr(v)) }
+func (v TF) String() string { return Sprintf("F: %f", float64(v)) }
+func (v TF32) String() string { return Sprintf("F32: %f", float32(v)) }
+func (v TF64) String() string { return Sprintf("F64: %f", float64(v)) }
+func (v TB) String() string { return Sprintf("B: %t", bool(v)) }
+func (v TS) String() string { return Sprintf("S: %q", string(v)) }
+
+func check(t *testing.T, got, want string) {
+ if got != want {
+ t.Error(got, "!=", want)
+ }
+}
+
+func TestStringer(t *testing.T) {
+ s := Sprintf("%v %v %v %v %v", TI(0), TI8(1), TI16(2), TI32(3), TI64(4))
+ check(t, s, "I: 0 I8: 1 I16: 2 I32: 3 I64: 4")
+ s = Sprintf("%v %v %v %v %v %v", TU(5), TU8(6), TU16(7), TU32(8), TU64(9), TUI(10))
+ check(t, s, "U: 5 U8: 6 U16: 7 U32: 8 U64: 9 UI: 10")
+ s = Sprintf("%v %v %v", TF(1.0), TF32(2.0), TF64(3.0))
+ check(t, s, "F: 1.000000 F32: 2.000000 F64: 3.000000")
+ s = Sprintf("%v %v", TB(true), TS("x"))
+ check(t, s, "B: true S: \"x\"")
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-04 10:55:48 +0000