File size: 3,022 Bytes
da86720 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 | // Copyright 2015 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 lex
import (
"go/build/constraint"
"io"
"os"
"strings"
"text/scanner"
"unicode"
"cmd/asm/internal/flags"
"cmd/internal/objabi"
"cmd/internal/src"
)
// A Tokenizer is a simple wrapping of text/scanner.Scanner, configured
// for our purposes and made a TokenReader. It forms the lowest level,
// turning text from readers into tokens.
type Tokenizer struct {
tok ScanToken
s *scanner.Scanner
base *src.PosBase
line int
file *os.File // If non-nil, file descriptor to close.
}
func NewTokenizer(name string, r io.Reader, file *os.File) *Tokenizer {
var s scanner.Scanner
s.Init(r)
// Newline is like a semicolon; other space characters are fine.
s.Whitespace = 1<<'\t' | 1<<'\r' | 1<<' '
// Don't skip comments: we need to count newlines.
s.Mode = scanner.ScanChars |
scanner.ScanFloats |
scanner.ScanIdents |
scanner.ScanInts |
scanner.ScanStrings |
scanner.ScanComments
s.Position.Filename = name
s.IsIdentRune = isIdentRune
return &Tokenizer{
s: &s,
base: src.NewFileBase(name, objabi.AbsFile(objabi.WorkingDir(), name, *flags.TrimPath)),
line: 1,
file: file,
}
}
// We want center dot (·) and division slash (∕) to work as identifier characters.
func isIdentRune(ch rune, i int) bool {
if unicode.IsLetter(ch) {
return true
}
switch ch {
case '_': // Underscore; traditional.
return true
case '\u00B7': // Represents the period in runtime.exit. U+00B7 '·' middle dot
return true
case '\u2215': // Represents the slash in runtime/debug.setGCPercent. U+2215 '∕' division slash
return true
}
// Digits are OK only after the first character.
return i > 0 && unicode.IsDigit(ch)
}
func (t *Tokenizer) Text() string {
switch t.tok {
case LSH:
return "<<"
case RSH:
return ">>"
case ARR:
return "->"
case ROT:
return "@>"
}
return t.s.TokenText()
}
func (t *Tokenizer) File() string {
return t.base.Filename()
}
func (t *Tokenizer) Base() *src.PosBase {
return t.base
}
func (t *Tokenizer) SetBase(base *src.PosBase) {
t.base = base
}
func (t *Tokenizer) Line() int {
return t.line
}
func (t *Tokenizer) Col() int {
return t.s.Pos().Column
}
func (t *Tokenizer) Next() ScanToken {
s := t.s
for {
t.tok = ScanToken(s.Scan())
if t.tok != scanner.Comment {
break
}
text := s.TokenText()
t.line += strings.Count(text, "\n")
if constraint.IsGoBuild(text) {
t.tok = BuildComment
break
}
}
switch t.tok {
case '\n':
t.line++
case '-':
if s.Peek() == '>' {
s.Next()
t.tok = ARR
return ARR
}
case '@':
if s.Peek() == '>' {
s.Next()
t.tok = ROT
return ROT
}
case '<':
if s.Peek() == '<' {
s.Next()
t.tok = LSH
return LSH
}
case '>':
if s.Peek() == '>' {
s.Next()
t.tok = RSH
return RSH
}
}
return t.tok
}
func (t *Tokenizer) Close() {
if t.file != nil {
t.file.Close()
}
}
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