diff options
Diffstat (limited to 'vendor/github.com/go-git/gcfg/scanner/scanner.go')
-rw-r--r-- | vendor/github.com/go-git/gcfg/scanner/scanner.go | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/vendor/github.com/go-git/gcfg/scanner/scanner.go b/vendor/github.com/go-git/gcfg/scanner/scanner.go new file mode 100644 index 000000000..41aafec75 --- /dev/null +++ b/vendor/github.com/go-git/gcfg/scanner/scanner.go @@ -0,0 +1,342 @@ +// 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 scanner implements a scanner for gcfg configuration text. +// It takes a []byte as source which can then be tokenized +// through repeated calls to the Scan method. +// +// Note that the API for the scanner package may change to accommodate new +// features or implementation changes in gcfg. +// +package scanner + +import ( + "fmt" + "path/filepath" + "unicode" + "unicode/utf8" +) + +import ( + "github.com/go-git/gcfg/token" +) + +// An ErrorHandler may be provided to Scanner.Init. If a syntax error is +// encountered and a handler was installed, the handler is called with a +// position and an error message. The position points to the beginning of +// the offending token. +// +type ErrorHandler func(pos token.Position, msg string) + +// A Scanner holds the scanner's internal state while processing +// a given text. It can be allocated as part of another data +// structure but must be initialized via Init before use. +// +type Scanner struct { + // immutable state + file *token.File // source file handle + dir string // directory portion of file.Name() + src []byte // source + err ErrorHandler // error reporting; or nil + mode Mode // scanning mode + + // scanning state + ch rune // current character + offset int // character offset + rdOffset int // reading offset (position after current character) + lineOffset int // current line offset + nextVal bool // next token is expected to be a value + + // public state - ok to modify + ErrorCount int // number of errors encountered +} + +// Read the next Unicode char into s.ch. +// s.ch < 0 means end-of-file. +// +func (s *Scanner) next() { + if s.rdOffset < len(s.src) { + s.offset = s.rdOffset + if s.ch == '\n' { + s.lineOffset = s.offset + s.file.AddLine(s.offset) + } + r, w := rune(s.src[s.rdOffset]), 1 + switch { + case r == 0: + s.error(s.offset, "illegal character NUL") + case r >= 0x80: + // not ASCII + r, w = utf8.DecodeRune(s.src[s.rdOffset:]) + if r == utf8.RuneError && w == 1 { + s.error(s.offset, "illegal UTF-8 encoding") + } + } + s.rdOffset += w + s.ch = r + } else { + s.offset = len(s.src) + if s.ch == '\n' { + s.lineOffset = s.offset + s.file.AddLine(s.offset) + } + s.ch = -1 // eof + } +} + +// A mode value is a set of flags (or 0). +// They control scanner behavior. +// +type Mode uint + +const ( + ScanComments Mode = 1 << iota // return comments as COMMENT tokens +) + +// Init prepares the scanner s to tokenize the text src by setting the +// scanner at the beginning of src. The scanner uses the file set file +// for position information and it adds line information for each line. +// It is ok to re-use the same file when re-scanning the same file as +// line information which is already present is ignored. Init causes a +// panic if the file size does not match the src size. +// +// Calls to Scan will invoke the error handler err if they encounter a +// syntax error and err is not nil. Also, for each error encountered, +// the Scanner field ErrorCount is incremented by one. The mode parameter +// determines how comments are handled. +// +// Note that Init may call err if there is an error in the first character +// of the file. +// +func (s *Scanner) Init(file *token.File, src []byte, err ErrorHandler, mode Mode) { + // Explicitly initialize all fields since a scanner may be reused. + if file.Size() != len(src) { + panic(fmt.Sprintf("file size (%d) does not match src len (%d)", file.Size(), len(src))) + } + s.file = file + s.dir, _ = filepath.Split(file.Name()) + s.src = src + s.err = err + s.mode = mode + + s.ch = ' ' + s.offset = 0 + s.rdOffset = 0 + s.lineOffset = 0 + s.ErrorCount = 0 + s.nextVal = false + + s.next() +} + +func (s *Scanner) error(offs int, msg string) { + if s.err != nil { + s.err(s.file.Position(s.file.Pos(offs)), msg) + } + s.ErrorCount++ +} + +func (s *Scanner) scanComment() string { + // initial [;#] already consumed + offs := s.offset - 1 // position of initial [;#] + + for s.ch != '\n' && s.ch >= 0 { + s.next() + } + return string(s.src[offs:s.offset]) +} + +func isLetter(ch rune) bool { + return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch >= 0x80 && unicode.IsLetter(ch) +} + +func isDigit(ch rune) bool { + return '0' <= ch && ch <= '9' || ch >= 0x80 && unicode.IsDigit(ch) +} + +func (s *Scanner) scanIdentifier() string { + offs := s.offset + for isLetter(s.ch) || isDigit(s.ch) || s.ch == '-' { + s.next() + } + return string(s.src[offs:s.offset]) +} + +func (s *Scanner) scanEscape(val bool) { + offs := s.offset + ch := s.ch + s.next() // always make progress + switch ch { + case '\\', '"': + // ok + case 'n', 't', 'b': + if val { + break // ok + } + fallthrough + default: + s.error(offs, "unknown escape sequence") + } +} + +func (s *Scanner) scanString() string { + // '"' opening already consumed + offs := s.offset - 1 + + for s.ch != '"' { + ch := s.ch + s.next() + if ch == '\n' || ch < 0 { + s.error(offs, "string not terminated") + break + } + if ch == '\\' { + s.scanEscape(false) + } + } + + s.next() + + return string(s.src[offs:s.offset]) +} + +func stripCR(b []byte) []byte { + c := make([]byte, len(b)) + i := 0 + for _, ch := range b { + if ch != '\r' { + c[i] = ch + i++ + } + } + return c[:i] +} + +func (s *Scanner) scanValString() string { + offs := s.offset + + hasCR := false + end := offs + inQuote := false +loop: + for inQuote || s.ch >= 0 && s.ch != '\n' && s.ch != ';' && s.ch != '#' { + ch := s.ch + s.next() + switch { + case inQuote && ch == '\\': + s.scanEscape(true) + case !inQuote && ch == '\\': + if s.ch == '\r' { + hasCR = true + s.next() + } + if s.ch != '\n' { + s.scanEscape(true) + } else { + s.next() + } + case ch == '"': + inQuote = !inQuote + case ch == '\r': + hasCR = true + case ch < 0 || inQuote && ch == '\n': + s.error(offs, "string not terminated") + break loop + } + if inQuote || !isWhiteSpace(ch) { + end = s.offset + } + } + + lit := s.src[offs:end] + if hasCR { + lit = stripCR(lit) + } + + return string(lit) +} + +func isWhiteSpace(ch rune) bool { + return ch == ' ' || ch == '\t' || ch == '\r' +} + +func (s *Scanner) skipWhitespace() { + for isWhiteSpace(s.ch) { + s.next() + } +} + +// Scan scans the next token and returns the token position, the token, +// and its literal string if applicable. The source end is indicated by +// token.EOF. +// +// If the returned token is a literal (token.IDENT, token.STRING) or +// token.COMMENT, the literal string has the corresponding value. +// +// If the returned token is token.ILLEGAL, the literal string is the +// offending character. +// +// In all other cases, Scan returns an empty literal string. +// +// For more tolerant parsing, Scan will return a valid token if +// possible even if a syntax error was encountered. Thus, even +// if the resulting token sequence contains no illegal tokens, +// a client may not assume that no error occurred. Instead it +// must check the scanner's ErrorCount or the number of calls +// of the error handler, if there was one installed. +// +// Scan adds line information to the file added to the file +// set with Init. Token positions are relative to that file +// and thus relative to the file set. +// +func (s *Scanner) Scan() (pos token.Pos, tok token.Token, lit string) { +scanAgain: + s.skipWhitespace() + + // current token start + pos = s.file.Pos(s.offset) + + // determine token value + switch ch := s.ch; { + case s.nextVal: + lit = s.scanValString() + tok = token.STRING + s.nextVal = false + case isLetter(ch): + lit = s.scanIdentifier() + tok = token.IDENT + default: + s.next() // always make progress + switch ch { + case -1: + tok = token.EOF + case '\n': + tok = token.EOL + case '"': + tok = token.STRING + lit = s.scanString() + case '[': + tok = token.LBRACK + case ']': + tok = token.RBRACK + case ';', '#': + // comment + lit = s.scanComment() + if s.mode&ScanComments == 0 { + // skip comment + goto scanAgain + } + tok = token.COMMENT + case '=': + tok = token.ASSIGN + s.nextVal = true + default: + s.error(s.file.Offset(pos), fmt.Sprintf("illegal character %#U", ch)) + tok = token.ILLEGAL + lit = string(ch) + } + } + + return +} |