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diff --git a/libgo/go/scanner/scanner.go b/libgo/go/scanner/scanner.go
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+// 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.
+
+// A scanner and tokenizer for UTF-8-encoded text. Takes an io.Reader
+// providing the source, which then can be tokenized through repeated calls
+// to the Scan function. For compatibility with existing tools, the NUL
+// character is not allowed (implementation restriction).
+//
+// By default, a Scanner skips white space and Go comments and recognizes all
+// literals as defined by the Go language specification. It may be
+// customized to recognize only a subset of those literals and to recognize
+// different white space characters.
+//
+// Basic usage pattern:
+//
+// var s scanner.Scanner
+// s.Init(src)
+// tok := s.Scan()
+// for tok != scanner.EOF {
+// // do something with tok
+// tok = s.Scan()
+// }
+//
+package scanner
+
+import (
+ "bytes"
+ "fmt"
+ "io"
+ "os"
+ "unicode"
+ "utf8"
+)
+
+
+// A source position is represented by a Position value.
+// A position is valid if Line > 0.
+type Position struct {
+ Filename string // filename, if any
+ Offset int // byte offset, starting at 0
+ Line int // line number, starting at 1
+ Column int // column number, starting at 0 (character count per line)
+}
+
+
+// IsValid returns true if the position is valid.
+func (pos *Position) IsValid() bool { return pos.Line > 0 }
+
+
+func (pos Position) String() string {
+ s := pos.Filename
+ if pos.IsValid() {
+ if s != "" {
+ s += ":"
+ }
+ s += fmt.Sprintf("%d:%d", pos.Line, pos.Column)
+ }
+ if s == "" {
+ s = "???"
+ }
+ return s
+}
+
+
+// Predefined mode bits to control recognition of tokens. For instance,
+// to configure a Scanner such that it only recognizes (Go) identifiers,
+// integers, and skips comments, set the Scanner's Mode field to:
+//
+// ScanIdents | ScanInts | SkipComments
+//
+const (
+ ScanIdents = 1 << -Ident
+ ScanInts = 1 << -Int
+ ScanFloats = 1 << -Float // includes Ints
+ ScanChars = 1 << -Char
+ ScanStrings = 1 << -String
+ ScanRawStrings = 1 << -RawString
+ ScanComments = 1 << -Comment
+ SkipComments = 1 << -skipComment // if set with ScanComments, comments become white space
+ GoTokens = ScanIdents | ScanFloats | ScanChars | ScanStrings | ScanRawStrings | ScanComments | SkipComments
+)
+
+
+// The result of Scan is one of the following tokens or a Unicode character.
+const (
+ EOF = -(iota + 1)
+ Ident
+ Int
+ Float
+ Char
+ String
+ RawString
+ Comment
+ skipComment
+)
+
+
+var tokenString = map[int]string{
+ EOF: "EOF",
+ Ident: "Ident",
+ Int: "Int",
+ Float: "Float",
+ Char: "Char",
+ String: "String",
+ RawString: "RawString",
+ Comment: "Comment",
+}
+
+
+// TokenString returns a (visible) string for a token or Unicode character.
+func TokenString(tok int) string {
+ if s, found := tokenString[tok]; found {
+ return s
+ }
+ return fmt.Sprintf("U+%04X", tok)
+}
+
+
+// GoWhitespace is the default value for the Scanner's Whitespace field.
+// Its value selects Go's white space characters.
+const GoWhitespace = 1<<'\t' | 1<<'\n' | 1<<'\r' | 1<<' '
+
+
+const bufLen = 1024 // at least utf8.UTFMax
+
+// A Scanner implements reading of Unicode characters and tokens from an io.Reader.
+type Scanner struct {
+ // Input
+ src io.Reader
+
+ // Source buffer
+ srcBuf [bufLen + 1]byte // +1 for sentinel for common case of s.next()
+ srcPos int // reading position (srcBuf index)
+ srcEnd int // source end (srcBuf index)
+
+ // Source position
+ srcBufOffset int // byte offset of srcBuf[0] in source
+ line int // newline count + 1
+ column int // character count on line
+
+ // Token text buffer
+ // Typically, token text is stored completely in srcBuf, but in general
+ // the token text's head may be buffered in tokBuf while the token text's
+ // tail is stored in srcBuf.
+ tokBuf bytes.Buffer // token text head that is not in srcBuf anymore
+ tokPos int // token text tail position (srcBuf index)
+ tokEnd int // token text tail end (srcBuf index)
+
+ // One character look-ahead
+ ch int // character before current srcPos
+
+ // Error is called for each error encountered. If no Error
+ // function is set, the error is reported to os.Stderr.
+ Error func(s *Scanner, msg string)
+
+ // ErrorCount is incremented by one for each error encountered.
+ ErrorCount int
+
+ // The Mode field controls which tokens are recognized. For instance,
+ // to recognize Ints, set the ScanInts bit in Mode. The field may be
+ // changed at any time.
+ Mode uint
+
+ // The Whitespace field controls which characters are recognized
+ // as white space. To recognize a character ch <= ' ' as white space,
+ // set the ch'th bit in Whitespace (the Scanner's behavior is undefined
+ // for values ch > ' '). The field may be changed at any time.
+ Whitespace uint64
+
+ // Current token position. The Offset, Line, and Column fields
+ // are set by Scan(); the Filename field is left untouched by the
+ // Scanner.
+ Position
+}
+
+
+// Init initializes a Scanner with a new source and returns itself.
+// Error is set to nil, ErrorCount is set to 0, Mode is set to GoTokens,
+// and Whitespace is set to GoWhitespace.
+func (s *Scanner) Init(src io.Reader) *Scanner {
+ s.src = src
+
+ // initialize source buffer
+ s.srcBuf[0] = utf8.RuneSelf // sentinel
+ s.srcPos = 0
+ s.srcEnd = 0
+
+ // initialize source position
+ s.srcBufOffset = 0
+ s.line = 1
+ s.column = 0
+
+ // initialize token text buffer
+ s.tokPos = -1
+
+ // initialize one character look-ahead
+ s.ch = s.next()
+
+ // initialize public fields
+ s.Error = nil
+ s.ErrorCount = 0
+ s.Mode = GoTokens
+ s.Whitespace = GoWhitespace
+
+ return s
+}
+
+
+// next reads and returns the next Unicode character. It is designed such
+// that only a minimal amount of work needs to be done in the common ASCII
+// case (one test to check for both ASCII and end-of-buffer, and one test
+// to check for newlines).
+func (s *Scanner) next() int {
+ ch := int(s.srcBuf[s.srcPos])
+
+ if ch >= utf8.RuneSelf {
+ // uncommon case: not ASCII or not enough bytes
+ for s.srcPos+utf8.UTFMax > s.srcEnd && !utf8.FullRune(s.srcBuf[s.srcPos:s.srcEnd]) {
+ // not enough bytes: read some more, but first
+ // save away token text if any
+ if s.tokPos >= 0 {
+ s.tokBuf.Write(s.srcBuf[s.tokPos:s.srcPos])
+ s.tokPos = 0
+ }
+ // move unread bytes to beginning of buffer
+ copy(s.srcBuf[0:], s.srcBuf[s.srcPos:s.srcEnd])
+ s.srcBufOffset += s.srcPos
+ // read more bytes
+ i := s.srcEnd - s.srcPos
+ n, err := s.src.Read(s.srcBuf[i:bufLen])
+ s.srcEnd = i + n
+ s.srcPos = 0
+ s.srcBuf[s.srcEnd] = utf8.RuneSelf // sentinel
+ if err != nil {
+ if s.srcEnd == 0 {
+ return EOF
+ }
+ if err != os.EOF {
+ s.error(err.String())
+ break
+ }
+ }
+ }
+ // at least one byte
+ ch = int(s.srcBuf[s.srcPos])
+ if ch >= utf8.RuneSelf {
+ // uncommon case: not ASCII
+ var width int
+ ch, width = utf8.DecodeRune(s.srcBuf[s.srcPos:s.srcEnd])
+ if ch == utf8.RuneError && width == 1 {
+ s.error("illegal UTF-8 encoding")
+ }
+ s.srcPos += width - 1
+ }
+ }
+
+ s.srcPos++
+ s.column++
+ switch ch {
+ case 0:
+ // implementation restriction for compatibility with other tools
+ s.error("illegal character NUL")
+ case '\n':
+ s.line++
+ s.column = 0
+ }
+
+ return ch
+}
+
+
+// Next reads and returns the next Unicode character.
+// It returns EOF at the end of the source. It reports
+// a read error by calling s.Error, if set, or else
+// prints an error message to os.Stderr. Next does not
+// update the Scanner's Position field; use Pos() to
+// get the current position.
+func (s *Scanner) Next() int {
+ s.tokPos = -1 // don't collect token text
+ ch := s.ch
+ s.ch = s.next()
+ return ch
+}
+
+
+// Peek returns the next Unicode character in the source without advancing
+// the scanner. It returns EOF if the scanner's position is at the last
+// character of the source.
+func (s *Scanner) Peek() int {
+ return s.ch
+}
+
+
+func (s *Scanner) error(msg string) {
+ s.ErrorCount++
+ if s.Error != nil {
+ s.Error(s, msg)
+ return
+ }
+ fmt.Fprintf(os.Stderr, "%s: %s", s.Position, msg)
+}
+
+
+func (s *Scanner) scanIdentifier() int {
+ ch := s.next() // read character after first '_' or letter
+ for ch == '_' || unicode.IsLetter(ch) || unicode.IsDigit(ch) {
+ ch = s.next()
+ }
+ return ch
+}
+
+
+func digitVal(ch int) int {
+ switch {
+ case '0' <= ch && ch <= '9':
+ return ch - '0'
+ case 'a' <= ch && ch <= 'f':
+ return ch - 'a' + 10
+ case 'A' <= ch && ch <= 'F':
+ return ch - 'A' + 10
+ }
+ return 16 // larger than any legal digit val
+}
+
+
+func isDecimal(ch int) bool { return '0' <= ch && ch <= '9' }
+
+
+func (s *Scanner) scanMantissa(ch int) int {
+ for isDecimal(ch) {
+ ch = s.next()
+ }
+ return ch
+}
+
+
+func (s *Scanner) scanFraction(ch int) int {
+ if ch == '.' {
+ ch = s.scanMantissa(s.next())
+ }
+ return ch
+}
+
+
+func (s *Scanner) scanExponent(ch int) int {
+ if ch == 'e' || ch == 'E' {
+ ch = s.next()
+ if ch == '-' || ch == '+' {
+ ch = s.next()
+ }
+ ch = s.scanMantissa(ch)
+ }
+ return ch
+}
+
+
+func (s *Scanner) scanNumber(ch int) (int, int) {
+ // isDecimal(ch)
+ if ch == '0' {
+ // int or float
+ ch = s.next()
+ if ch == 'x' || ch == 'X' {
+ // hexadecimal int
+ ch = s.next()
+ for digitVal(ch) < 16 {
+ ch = s.next()
+ }
+ } else {
+ // octal int or float
+ seenDecimalDigit := false
+ for isDecimal(ch) {
+ if ch > '7' {
+ seenDecimalDigit = true
+ }
+ ch = s.next()
+ }
+ if s.Mode&ScanFloats != 0 && (ch == '.' || ch == 'e' || ch == 'E') {
+ // float
+ ch = s.scanFraction(ch)
+ ch = s.scanExponent(ch)
+ return Float, ch
+ }
+ // octal int
+ if seenDecimalDigit {
+ s.error("illegal octal number")
+ }
+ }
+ return Int, ch
+ }
+ // decimal int or float
+ ch = s.scanMantissa(ch)
+ if s.Mode&ScanFloats != 0 && (ch == '.' || ch == 'e' || ch == 'E') {
+ // float
+ ch = s.scanFraction(ch)
+ ch = s.scanExponent(ch)
+ return Float, ch
+ }
+ return Int, ch
+}
+
+
+func (s *Scanner) scanDigits(ch, base, n int) int {
+ for n > 0 && digitVal(ch) < base {
+ ch = s.next()
+ n--
+ }
+ if n > 0 {
+ s.error("illegal char escape")
+ }
+ return ch
+}
+
+
+func (s *Scanner) scanEscape(quote int) int {
+ ch := s.next() // read character after '/'
+ switch ch {
+ case 'a', 'b', 'f', 'n', 'r', 't', 'v', '\\', quote:
+ // nothing to do
+ ch = s.next()
+ case '0', '1', '2', '3', '4', '5', '6', '7':
+ ch = s.scanDigits(ch, 8, 3)
+ case 'x':
+ ch = s.scanDigits(s.next(), 16, 2)
+ case 'u':
+ ch = s.scanDigits(s.next(), 16, 4)
+ case 'U':
+ ch = s.scanDigits(s.next(), 16, 8)
+ default:
+ s.error("illegal char escape")
+ }
+ return ch
+}
+
+
+func (s *Scanner) scanString(quote int) (n int) {
+ ch := s.next() // read character after quote
+ for ch != quote {
+ if ch == '\n' || ch < 0 {
+ s.error("literal not terminated")
+ return
+ }
+ if ch == '\\' {
+ ch = s.scanEscape(quote)
+ } else {
+ ch = s.next()
+ }
+ n++
+ }
+ return
+}
+
+
+func (s *Scanner) scanRawString() {
+ ch := s.next() // read character after '`'
+ for ch != '`' {
+ if ch < 0 {
+ s.error("literal not terminated")
+ return
+ }
+ ch = s.next()
+ }
+}
+
+
+func (s *Scanner) scanChar() {
+ if s.scanString('\'') != 1 {
+ s.error("illegal char literal")
+ }
+}
+
+
+func (s *Scanner) scanLineComment() {
+ ch := s.next() // read character after "//"
+ for ch != '\n' {
+ if ch < 0 {
+ s.error("comment not terminated")
+ return
+ }
+ ch = s.next()
+ }
+}
+
+
+func (s *Scanner) scanGeneralComment() {
+ ch := s.next() // read character after "/*"
+ for {
+ if ch < 0 {
+ s.error("comment not terminated")
+ return
+ }
+ ch0 := ch
+ ch = s.next()
+ if ch0 == '*' && ch == '/' {
+ break
+ }
+ }
+}
+
+
+func (s *Scanner) scanComment(ch int) {
+ // ch == '/' || ch == '*'
+ if ch == '/' {
+ s.scanLineComment()
+ return
+ }
+ s.scanGeneralComment()
+}
+
+
+// Scan reads the next token or Unicode character from source and returns it.
+// It only recognizes tokens t for which the respective Mode bit (1<<-t) is set.
+// It returns EOF at the end of the source. It reports scanner errors (read and
+// token errors) by calling s.Error, if set; otherwise it prints an error message
+// to os.Stderr.
+func (s *Scanner) Scan() int {
+ ch := s.ch
+
+ // reset token text position
+ s.tokPos = -1
+
+redo:
+ // skip white space
+ for s.Whitespace&(1<<uint(ch)) != 0 {
+ ch = s.next()
+ }
+
+ // start collecting token text
+ s.tokBuf.Reset()
+ s.tokPos = s.srcPos - 1
+
+ // set token position
+ s.Offset = s.srcBufOffset + s.tokPos
+ s.Line = s.line
+ s.Column = s.column
+
+ // determine token value
+ tok := ch
+ switch {
+ case unicode.IsLetter(ch) || ch == '_':
+ if s.Mode&ScanIdents != 0 {
+ tok = Ident
+ ch = s.scanIdentifier()
+ } else {
+ ch = s.next()
+ }
+ case isDecimal(ch):
+ if s.Mode&(ScanInts|ScanFloats) != 0 {
+ tok, ch = s.scanNumber(ch)
+ } else {
+ ch = s.next()
+ }
+ default:
+ switch ch {
+ case '"':
+ if s.Mode&ScanStrings != 0 {
+ s.scanString('"')
+ tok = String
+ }
+ ch = s.next()
+ case '\'':
+ if s.Mode&ScanChars != 0 {
+ s.scanChar()
+ tok = Char
+ }
+ ch = s.next()
+ case '.':
+ ch = s.next()
+ if isDecimal(ch) && s.Mode&ScanFloats != 0 {
+ tok = Float
+ ch = s.scanMantissa(ch)
+ ch = s.scanExponent(ch)
+ }
+ case '/':
+ ch = s.next()
+ if (ch == '/' || ch == '*') && s.Mode&ScanComments != 0 {
+ if s.Mode&SkipComments != 0 {
+ s.tokPos = -1 // don't collect token text
+ s.scanComment(ch)
+ ch = s.next()
+ goto redo
+ }
+ s.scanComment(ch)
+ tok = Comment
+ ch = s.next()
+ }
+ case '`':
+ if s.Mode&ScanRawStrings != 0 {
+ s.scanRawString()
+ tok = String
+ }
+ ch = s.next()
+ default:
+ ch = s.next()
+ }
+ }
+
+ // end of token text
+ s.tokEnd = s.srcPos - 1
+
+ s.ch = ch
+ return tok
+}
+
+
+// Position returns the current source position. If called before Next()
+// or Scan(), it returns the position of the next Unicode character or token
+// returned by these functions. If called afterwards, it returns the position
+// immediately after the last character of the most recent token or character
+// scanned.
+func (s *Scanner) Pos() Position {
+ return Position{
+ s.Filename,
+ s.srcBufOffset + s.srcPos - 1,
+ s.line,
+ s.column,
+ }
+}
+
+
+// TokenText returns the string corresponding to the most recently scanned token.
+// Valid after calling Scan().
+func (s *Scanner) TokenText() string {
+ if s.tokPos < 0 {
+ // no token text
+ return ""
+ }
+
+ if s.tokEnd < 0 {
+ // if EOF was reached, s.tokEnd is set to -1 (s.srcPos == 0)
+ s.tokEnd = s.tokPos
+ }
+
+ if s.tokBuf.Len() == 0 {
+ // common case: the entire token text is still in srcBuf
+ return string(s.srcBuf[s.tokPos:s.tokEnd])
+ }
+
+ // part of the token text was saved in tokBuf: save the rest in
+ // tokBuf as well and return its content
+ s.tokBuf.Write(s.srcBuf[s.tokPos:s.tokEnd])
+ s.tokPos = s.tokEnd // ensure idempotency of TokenText() call
+ return s.tokBuf.String()
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-09 21:54:43 +0000