summaryrefslogtreecommitdiffstats
path: root/src/fmt/scan.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/fmt/scan.go')
-rw-r--r--src/fmt/scan.go1238
1 files changed, 1238 insertions, 0 deletions
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
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 13:34:47 +0000