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Diffstat (limited to 'libgo/go/fmt/scan.go')
| -rw-r--r-- | libgo/go/fmt/scan.go | 985 |
1 files changed, 985 insertions, 0 deletions
diff --git a/libgo/go/fmt/scan.go b/libgo/go/fmt/scan.go new file mode 100644 index 0000000000..ebbb17155e --- /dev/null +++ b/libgo/go/fmt/scan.go @@ -0,0 +1,985 @@ +// 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 ( + "bytes" + "io" + "os" + "reflect" + "strconv" + "strings" + "unicode" + "utf8" +) + +// readRuner is the interface to something that can read runes. If +// the object provided to Scan does not satisfy this interface, the +// object will be wrapped by a readRune object. +type readRuner interface { + ReadRune() (rune int, size int, err os.Error) +} + +// unreadRuner is the interface to something that can unread runes. +// If the object provided to Scan does not satisfy this interface, +// a local buffer will be used to back up the input, but its contents +// will be lost when Scan returns. +type unreadRuner interface { + UnreadRune() os.Error +} + +// 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 { + // GetRune reads the next rune (Unicode code point) from the input. + GetRune() (rune int, err os.Error) + // UngetRune causes the next call to GetRune to return the rune. + UngetRune() + // 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) + // Token returns the next space-delimited token from the input. If + // a width has been specified, the returned token will be no longer + // than the width. + Token() (token string, err os.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 or Scanln that implements it. +type Scanner interface { + Scan(state ScanState, verb int) os.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 ...interface{}) (n int, err os.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 ...interface{}) (n int, err os.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. +func Scanf(format string, a ...interface{}) (n int, err os.Error) { + return Fscanf(os.Stdin, format, a...) +} + +// 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 ...interface{}) (n int, err os.Error) { + return Fscan(strings.NewReader(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 ...interface{}) (n int, err os.Error) { + return Fscanln(strings.NewReader(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. +func Sscanf(str string, format string, a ...interface{}) (n int, err os.Error) { + return Fscanf(strings.NewReader(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 ...interface{}) (n int, err os.Error) { + s := newScanState(r, true) + n, err = s.doScan(a) + s.free() + 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 ...interface{}) (n int, err os.Error) { + s := newScanState(r, false) + n, err = s.doScan(a) + s.free() + 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. +func Fscanf(r io.Reader, format string, a ...interface{}) (n int, err os.Error) { + s := newScanState(r, false) + n, err = s.doScanf(format, a) + s.free() + 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 os.Error +} + +const EOF = -1 + +// ss is the internal implementation of ScanState. +type ss struct { + rr readRuner // where to read input + buf bytes.Buffer // token accumulator + nlIsSpace bool // whether newline counts as white space + peekRune int // one-rune lookahead + prevRune int // last rune returned by GetRune + atEOF bool // already read EOF + maxWid int // max width of field, in runes + widPresent bool // width was specified + wid int // width consumed so far; used in accept() +} + +func (s *ss) GetRune() (rune int, err os.Error) { + if s.peekRune >= 0 { + rune = s.peekRune + s.prevRune = rune + s.peekRune = -1 + return + } + rune, _, err = s.rr.ReadRune() + if err == nil { + s.prevRune = rune + } + return +} + +func (s *ss) Width() (wid int, ok bool) { + return s.maxWid, s.widPresent +} + +// The public method returns an error; this private one panics. +// If getRune reaches EOF, the return value is EOF (-1). +func (s *ss) getRune() (rune int) { + if s.atEOF { + return EOF + } + if s.peekRune >= 0 { + rune = s.peekRune + s.prevRune = rune + s.peekRune = -1 + return + } + rune, _, err := s.rr.ReadRune() + if err == nil { + s.prevRune = rune + } else if err != nil { + if err == os.EOF { + s.atEOF = true + return EOF + } + s.error(err) + } + return +} + +// mustGetRune turns os.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) mustGetRune() (rune int) { + if s.atEOF { + s.error(io.ErrUnexpectedEOF) + } + if s.peekRune >= 0 { + rune = s.peekRune + s.peekRune = -1 + return + } + rune, _, err := s.rr.ReadRune() + if err != nil { + if err == os.EOF { + err = io.ErrUnexpectedEOF + } + s.error(err) + } + return +} + + +func (s *ss) UngetRune() { + if u, ok := s.rr.(unreadRuner); ok { + u.UnreadRune() + } else { + s.peekRune = s.prevRune + } +} + +func (s *ss) error(err os.Error) { + panic(scanError{err}) +} + +func (s *ss) errorString(err string) { + panic(scanError{os.ErrorString(err)}) +} + +func (s *ss) Token() (tok string, err os.Error) { + defer func() { + if e := recover(); e != nil { + if se, ok := e.(scanError); ok { + err = se.err + } else { + panic(e) + } + } + }() + tok = s.token() + return +} + +// 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 ReadRuner. +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 +} + +// 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 os.Error) { + if r.pending > 0 { + b = r.pendBuf[0] + copy(r.pendBuf[0:], r.pendBuf[1:]) + r.pending-- + return + } + _, err = r.reader.Read(r.pendBuf[0:1]) + return r.pendBuf[0], err +} + +// unread saves the bytes for the next read. +func (r *readRune) unread(buf []byte) { + copy(r.pendBuf[r.pending:], buf) + r.pending += len(buf) +} + +// ReadRune returns the next UTF-8 encoded code point from the +// io.Reader inside r. +func (r *readRune) ReadRune() (rune int, size int, err os.Error) { + r.buf[0], err = r.readByte() + if err != nil { + return 0, 0, err + } + if r.buf[0] < utf8.RuneSelf { // fast check for common ASCII case + rune = int(r.buf[0]) + return + } + var n int + for n = 1; !utf8.FullRune(r.buf[0:n]); n++ { + r.buf[n], err = r.readByte() + if err != nil { + if err == os.EOF { + err = nil + break + } + return + } + } + rune, size = utf8.DecodeRune(r.buf[0:n]) + if size < n { // an error + r.unread(r.buf[size:n]) + } + return +} + + +// A leaky bucket of reusable ss structures. +var ssFree = make(chan *ss, 100) + +// Allocate a new ss struct. Probably can grab the previous one from ssFree. +func newScanState(r io.Reader, nlIsSpace bool) *ss { + s, ok := <-ssFree + if !ok { + s = new(ss) + } + if rr, ok := r.(readRuner); ok { + s.rr = rr + } else { + s.rr = &readRune{reader: r} + } + s.nlIsSpace = nlIsSpace + s.peekRune = -1 + s.atEOF = false + s.maxWid = 0 + s.widPresent = false + return s +} + +// Save used ss structs in ssFree; avoid an allocation per invocation. +func (s *ss) free() { + // Don't hold on to ss structs with large buffers. + if cap(s.buf.Bytes()) > 1024 { + return + } + s.buf.Reset() + s.rr = nil + _ = ssFree <- s +} + +// skipSpace skips spaces and maybe newlines. +func (s *ss) skipSpace(stopAtNewline bool) { + for { + rune := s.getRune() + if rune == EOF { + return + } + if rune == '\n' { + if stopAtNewline { + break + } + if s.nlIsSpace { + continue + } + s.errorString("unexpected newline") + return + } + if !unicode.IsSpace(rune) { + s.UngetRune() + 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() string { + s.skipSpace(false) + // read until white space or newline + for nrunes := 0; !s.widPresent || nrunes < s.maxWid; nrunes++ { + rune := s.getRune() + if rune == EOF { + break + } + if unicode.IsSpace(rune) { + s.UngetRune() + break + } + s.buf.WriteRune(rune) + } + return s.buf.String() +} + +// typeError indicates that the type of the operand did not match the format +func (s *ss) typeError(field interface{}, expected string) { + s.errorString("expected field of type pointer to " + expected + "; found " + reflect.Typeof(field).String()) +} + +var complexError = os.ErrorString("syntax error scanning complex number") +var boolError = os.ErrorString("syntax error scanning boolean") + +// 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 { + if s.wid >= s.maxWid { + return false + } + rune := s.getRune() + if rune == EOF { + return false + } + for i := 0; i < len(ok); i++ { + if int(ok[i]) == rune { + if accept { + s.buf.WriteRune(rune) + s.wid++ + } + return true + } + } + if rune != EOF && accept { + s.UngetRune() + } + return false +} + +// 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 int, 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 int) bool { + if !s.okVerb(verb, "tv", "boolean") { + return false + } + // Syntax-checking a boolean is annoying. We're not fastidious about case. + switch s.mustGetRune() { + 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("aL") && (!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 = "eE" +) + +// getBase returns the numeric base represented by the verb and its digit string. +func (s *ss) getBase(verb int) (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) string { + if !s.accept(digits) { + s.errorString("expected integer") + } + for s.accept(digits) { + } + return s.buf.String() +} + +// scanRune returns the next rune value in the input. +func (s *ss) scanRune(bitSize int) int64 { + rune := int64(s.mustGetRune()) + n := uint(bitSize) + x := (rune << (64 - n)) >> (64 - n) + if x != rune { + s.errorString("overflow on character value " + string(rune)) + } + return rune +} + +// 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 int, bitSize int) int64 { + if verb == 'c' { + return s.scanRune(bitSize) + } + base, digits := s.getBase(verb) + s.skipSpace(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. + } + tok := s.scanNumber(digits) + i, err := strconv.Btoi64(tok, base) + 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 int, bitSize int) uint64 { + if verb == 'c' { + return uint64(s.scanRune(bitSize)) + } + base, digits := s.getBase(verb) + s.skipSpace(false) + if verb == 'U' { + if !s.consume("U", false) || !s.consume("+", false) { + s.errorString("bad unicode format ") + } + } + tok := s.scanNumber(digits) + i, err := strconv.Btoui64(tok, base) + 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.Reset() + // NaN? + if s.accept("nN") && s.accept("aA") && s.accept("nN") { + return s.buf.String() + } + // leading sign? + s.accept(sign) + // Inf? + if s.accept("iI") && s.accept("nN") && s.accept("fF") { + return s.buf.String() + } + // digits? + for s.accept(decimalDigits) { + } + // decimal point? + if s.accept(period) { + // fraction? + for s.accept(decimalDigits) { + } + } + // exponent? + if s.accept(exponent) { + // leading sign? + s.accept(sign) + // digits? + for s.accept(decimalDigits) { + } + } + return s.buf.String() +} + +// 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.Reset() + // Must now have a sign. + if !s.accept("+-") { + s.error(complexError) + } + // Sign is now in buffer + imagSign := s.buf.String() + imag = s.floatToken() + if !s.accept("i") { + s.error(complexError) + } + if parens && !s.accept(")") { + s.error(complexError) + } + return real, imagSign + imag +} + +// convertFloat converts the string to a float64value. +func (s *ss) convertFloat(str string, n int) float64 { + f, err := strconv.AtofN(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 int, n int) complex128 { + if !s.okVerb(verb, floatVerbs, "complex") { + return 0 + } + s.skipSpace(false) + 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 int) (str string) { + if !s.okVerb(verb, "svqx", "string") { + return "" + } + s.skipSpace(false) + switch verb { + case 'q': + str = s.quotedString() + case 'x': + str = s.hexString() + default: + str = s.token() // %s and %v just return the next word + } + // Empty strings other than with %q are not OK. + if len(str) == 0 && verb != 'q' && s.maxWid > 0 { + s.errorString("Scan: no data for string") + } + return +} + +// quotedString returns the double- or back-quoted string represented by the next input characters. +func (s *ss) quotedString() string { + quote := s.mustGetRune() + switch quote { + case '`': + // Back-quoted: Anything goes until EOF or back quote. + for { + rune := s.mustGetRune() + if rune == quote { + break + } + s.buf.WriteRune(rune) + } + return s.buf.String() + case '"': + // Double-quoted: Include the quotes and let strconv.Unquote do the backslash escapes. + s.buf.WriteRune(quote) + for { + rune := s.mustGetRune() + s.buf.WriteRune(rune) + if rune == '\\' { + // 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. + rune := s.mustGetRune() + s.buf.WriteRune(rune) + } else if rune == '"' { + break + } + } + result, err := strconv.Unquote(s.buf.String()) + if err != nil { + s.error(err) + } + return result + default: + s.errorString("expected quoted string") + } + return "" +} + +// hexDigit returns the value of the hexadecimal digit +func (s *ss) hexDigit(digit int) int { + switch digit { + case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9': + return digit - '0' + case 'a', 'b', 'c', 'd', 'e', 'f': + return 10 + digit - 'a' + case 'A', 'B', 'C', 'D', 'E', 'F': + return 10 + digit - 'A' + } + s.errorString("Scan: illegal hex digit") + return 0 +} + +// hexByte returns the next hex-encoded (two-character) byte from the input. +// There must be either two hexadecimal digits or a space character in the input. +func (s *ss) hexByte() (b byte, ok bool) { + rune1 := s.getRune() + if rune1 == EOF { + return + } + if unicode.IsSpace(rune1) { + s.UngetRune() + return + } + rune2 := s.mustGetRune() + return byte(s.hexDigit(rune1)<<4 | s.hexDigit(rune2)), true +} + +// hexString returns the space-delimited hexpair-encoded string. +func (s *ss) hexString() string { + for { + b, ok := s.hexByte() + if !ok { + break + } + s.buf.WriteByte(b) + } + if s.buf.Len() == 0 { + s.errorString("Scan: no hex data for %x string") + return "" + } + return s.buf.String() +} + +const floatVerbs = "eEfFgGv" + +// scanOne scans a single value, deriving the scanner from the type of the argument. +func (s *ss) scanOne(verb int, field interface{}) { + s.buf.Reset() + var err os.Error + // If the parameter has its own Scan method, use that. + if v, ok := field.(Scanner); ok { + err = v.Scan(s, verb) + if err != nil { + s.error(err) + } + return + } + if !s.widPresent { + s.maxWid = 1 << 30 // Huge + } + s.wid = 0 + switch v := field.(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(false) + *v = float32(s.convertFloat(s.floatToken(), 32)) + } + case *float64: + if s.okVerb(verb, floatVerbs, "float64") { + s.skipSpace(false) + *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.NewValue(v) + ptr, ok := val.(*reflect.PtrValue) + if !ok { + s.errorString("Scan: type not a pointer: " + val.Type().String()) + return + } + switch v := ptr.Elem().(type) { + case *reflect.BoolValue: + v.Set(s.scanBool(verb)) + case *reflect.IntValue: + v.Set(s.scanInt(verb, v.Type().Bits())) + case *reflect.UintValue: + v.Set(s.scanUint(verb, v.Type().Bits())) + case *reflect.StringValue: + v.Set(s.convertString(verb)) + case *reflect.SliceValue: + // For now, can only handle (renamed) []byte. + typ := v.Type().(*reflect.SliceType) + if typ.Elem().Kind() != reflect.Uint8 { + goto CantHandle + } + str := s.convertString(verb) + v.Set(reflect.MakeSlice(typ, len(str), len(str))) + for i := 0; i < len(str); i++ { + v.Elem(i).(*reflect.UintValue).Set(uint64(str[i])) + } + case *reflect.FloatValue: + s.skipSpace(false) + v.Set(s.convertFloat(s.floatToken(), v.Type().Bits())) + case *reflect.ComplexValue: + v.Set(s.scanComplex(verb, v.Type().Bits())) + default: + CantHandle: + s.errorString("Scan: can't handle type: " + val.Type().String()) + } + } +} + +// errorHandler turns local panics into error returns. EOFs are benign. +func errorHandler(errp *os.Error) { + if e := recover(); e != nil { + if se, ok := e.(scanError); ok { // catch local error + if se.err != os.EOF { + *errp = se.err + } + } else { + panic(e) + } + } +} + +// doScan does the real work for scanning without a format string. +// At the moment, it handles only pointers to basic types. +func (s *ss) doScan(a []interface{}) (numProcessed int, err os.Error) { + defer errorHandler(&err) + for _, field := range a { + s.scanOne('v', field) + numProcessed++ + } + // Check for newline if required. + if !s.nlIsSpace { + for { + rune := s.getRune() + if rune == '\n' || rune == EOF { + break + } + if !unicode.IsSpace(rune) { + s.errorString("Scan: 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. Newlines included, all runs of space characters in +// either input or format behave as a single space. 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:]) + if fmtc == '%' { + // %% 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 % + } + sawSpace := false + for unicode.IsSpace(fmtc) && i < len(format) { + sawSpace = true + i += w + fmtc, w = utf8.DecodeRuneInString(format[i:]) + } + if sawSpace { + // There was space in the format, so there should be space (EOF) + // in the input. + inputc := s.getRune() + if inputc == EOF { + return + } + if !unicode.IsSpace(inputc) { + // Space in format but not in input: error + s.errorString("expected space in input to match format") + } + s.skipSpace(true) + continue + } + inputc := s.mustGetRune() + if fmtc != inputc { + s.UngetRune() + 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 []interface{}) (numProcessed int, err os.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)? + s.maxWid, s.widPresent, i = parsenum(format, i, end) + + c, w := utf8.DecodeRuneInString(format[i:]) + i += w + + if numProcessed >= len(a) { // out of operands + s.errorString("too few operands for format %" + format[i-w:]) + break + } + field := a[numProcessed] + + s.scanOne(c, field) + numProcessed++ + } + if numProcessed < len(a) { + s.errorString("too many operands") + } + return +} |