diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-16 19:23:18 +0000 |
commit | 43a123c1ae6613b3efeed291fa552ecd909d3acf (patch) | |
tree | fd92518b7024bc74031f78a1cf9e454b65e73665 /src/fmt/print.go | |
parent | Initial commit. (diff) | |
download | golang-1.20-upstream.tar.xz golang-1.20-upstream.zip |
Adding upstream version 1.20.14.upstream/1.20.14upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/fmt/print.go')
-rw-r--r-- | src/fmt/print.go | 1226 |
1 files changed, 1226 insertions, 0 deletions
diff --git a/src/fmt/print.go b/src/fmt/print.go new file mode 100644 index 0000000..b3dd43c --- /dev/null +++ b/src/fmt/print.go @@ -0,0 +1,1226 @@ +// 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" + "strconv" + "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 +} + +// FormatString returns a string representing the fully qualified formatting +// directive captured by the State, followed by the argument verb. (State does not +// itself contain the verb.) The result has a leading percent sign followed by any +// flags, the width, and the precision. Missing flags, width, and precision are +// omitted. This function allows a Formatter to reconstruct the original +// directive triggering the call to Format. +func FormatString(state State, verb rune) string { + var tmp [16]byte // Use a local buffer. + b := append(tmp[:0], '%') + for _, c := range " +-#0" { // All known flags + if state.Flag(int(c)) { // The argument is an int for historical reasons. + b = append(b, byte(c)) + } + } + if w, ok := state.Width(); ok { + b = strconv.AppendInt(b, int64(w), 10) + } + if p, ok := state.Precision(); ok { + b = append(b, '.') + b = strconv.AppendInt(b, int64(p), 10) + } + b = utf8.AppendRune(b, verb) + return string(b) +} + +// 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) { + *bp = utf8.AppendRune(*bp, r) +} + +// 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 + // wrappedErrs records the targets of the %w verb. + wrappedErrs []int +} + +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. If the buffer is larger than the + // limit, we drop the buffer and recycle just the printer. + // + // See https://golang.org/issue/23199. + if cap(p.buf) > 64*1024 { + p.buf = nil + } else { + p.buf = p.buf[:0] + } + if cap(p.wrappedErrs) > 8 { + p.wrappedErrs = nil + } + + p.arg = nil + p.value = reflect.Value{} + p.wrappedErrs = p.wrappedErrs[:0] + 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 +} + +// Appendf formats according to a format specifier, appends the result to the byte +// slice, and returns the updated slice. +func Appendf(b []byte, format string, a ...any) []byte { + p := newPrinter() + p.doPrintf(format, a) + b = append(b, p.buf...) + p.free() + return b +} + +// 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 +} + +// Append formats using the default formats for its operands, appends the result to +// the byte slice, and returns the updated slice. +func Append(b []byte, a ...any) []byte { + p := newPrinter() + p.doPrint(a) + b = append(b, p.buf...) + p.free() + return b +} + +// 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 +} + +// Appendln formats using the default formats for its operands, appends the result +// to the byte slice, and returns the updated slice. Spaces are always added +// between operands and a newline is appended. +func Appendln(b []byte, a ...any) []byte { + p := newPrinter() + p.doPrintln(a) + b = append(b, p.buf...) + p.free() + return b +} + +// 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 or with a non-error arg. + _, ok := p.arg.(error) + if !ok || !p.wrapErrs { + p.badVerb(verb) + return true + } + // 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) { + switch c { + case 'w': + p.wrappedErrs = append(p.wrappedErrs, argNum) + fallthrough + case '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 == 'w': + p.wrappedErrs = append(p.wrappedErrs, argNum) + fallthrough + 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') +} |