mirror of
https://github.com/octoleo/syncthing.git
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372 lines
8.8 KiB
Go
372 lines
8.8 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package ucd provides a parser for Unicode Character Database files, the
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// format of which is defined in http://www.unicode.org/reports/tr44/. See
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// http://www.unicode.org/Public/UCD/latest/ucd/ for example files.
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//
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// It currently does not support substitutions of missing fields.
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package ucd // import "golang.org/x/text/internal/ucd"
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import (
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"bufio"
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"errors"
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"fmt"
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"io"
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"log"
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"regexp"
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"strconv"
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"strings"
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)
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// UnicodeData.txt fields.
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const (
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CodePoint = iota
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Name
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GeneralCategory
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CanonicalCombiningClass
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BidiClass
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DecompMapping
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DecimalValue
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DigitValue
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NumericValue
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BidiMirrored
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Unicode1Name
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ISOComment
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SimpleUppercaseMapping
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SimpleLowercaseMapping
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SimpleTitlecaseMapping
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)
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// Parse calls f for each entry in the given reader of a UCD file. It will close
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// the reader upon return. It will call log.Fatal if any error occurred.
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//
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// This implements the most common usage pattern of using Parser.
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func Parse(r io.ReadCloser, f func(p *Parser)) {
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defer r.Close()
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p := New(r)
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for p.Next() {
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f(p)
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}
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if err := p.Err(); err != nil {
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r.Close() // os.Exit will cause defers not to be called.
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log.Fatal(err)
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}
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}
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// An Option is used to configure a Parser.
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type Option func(p *Parser)
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func keepRanges(p *Parser) {
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p.keepRanges = true
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}
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var (
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// KeepRanges prevents the expansion of ranges. The raw ranges can be
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// obtained by calling Range(0) on the parser.
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KeepRanges Option = keepRanges
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)
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// The Part option register a handler for lines starting with a '@'. The text
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// after a '@' is available as the first field. Comments are handled as usual.
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func Part(f func(p *Parser)) Option {
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return func(p *Parser) {
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p.partHandler = f
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}
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}
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// The CommentHandler option passes comments that are on a line by itself to
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// a given handler.
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func CommentHandler(f func(s string)) Option {
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return func(p *Parser) {
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p.commentHandler = f
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}
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}
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// A Parser parses Unicode Character Database (UCD) files.
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type Parser struct {
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scanner *bufio.Scanner
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keepRanges bool // Don't expand rune ranges in field 0.
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err error
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comment string
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field []string
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// parsedRange is needed in case Range(0) is called more than once for one
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// field. In some cases this requires scanning ahead.
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line int
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parsedRange bool
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rangeStart, rangeEnd rune
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partHandler func(p *Parser)
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commentHandler func(s string)
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}
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func (p *Parser) setError(err error, msg string) {
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if p.err == nil && err != nil {
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if msg == "" {
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p.err = fmt.Errorf("ucd:line:%d: %v", p.line, err)
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} else {
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p.err = fmt.Errorf("ucd:line:%d:%s: %v", p.line, msg, err)
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}
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}
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}
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func (p *Parser) getField(i int) string {
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if i >= len(p.field) {
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return ""
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}
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return p.field[i]
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}
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// Err returns a non-nil error if any error occurred during parsing.
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func (p *Parser) Err() error {
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return p.err
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}
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// New returns a Parser for the given Reader.
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func New(r io.Reader, o ...Option) *Parser {
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p := &Parser{
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scanner: bufio.NewScanner(r),
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}
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for _, f := range o {
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f(p)
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}
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return p
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}
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// Next parses the next line in the file. It returns true if a line was parsed
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// and false if it reached the end of the file.
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func (p *Parser) Next() bool {
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if !p.keepRanges && p.rangeStart < p.rangeEnd {
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p.rangeStart++
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return true
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}
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p.comment = ""
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p.field = p.field[:0]
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p.parsedRange = false
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for p.scanner.Scan() && p.err == nil {
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p.line++
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s := p.scanner.Text()
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if s == "" {
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continue
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}
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if s[0] == '#' {
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if p.commentHandler != nil {
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p.commentHandler(strings.TrimSpace(s[1:]))
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}
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continue
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}
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// Parse line
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if i := strings.IndexByte(s, '#'); i != -1 {
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p.comment = strings.TrimSpace(s[i+1:])
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s = s[:i]
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}
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if s[0] == '@' {
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if p.partHandler != nil {
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p.field = append(p.field, strings.TrimSpace(s[1:]))
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p.partHandler(p)
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p.field = p.field[:0]
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}
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p.comment = ""
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continue
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}
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for {
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i := strings.IndexByte(s, ';')
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if i == -1 {
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p.field = append(p.field, strings.TrimSpace(s))
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break
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}
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p.field = append(p.field, strings.TrimSpace(s[:i]))
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s = s[i+1:]
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}
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if !p.keepRanges {
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p.rangeStart, p.rangeEnd = p.getRange(0)
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}
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return true
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}
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p.setError(p.scanner.Err(), "scanner failed")
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return false
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}
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func parseRune(b string) (rune, error) {
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if len(b) > 2 && b[0] == 'U' && b[1] == '+' {
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b = b[2:]
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}
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x, err := strconv.ParseUint(b, 16, 32)
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return rune(x), err
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}
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func (p *Parser) parseRune(s string) rune {
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x, err := parseRune(s)
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p.setError(err, "failed to parse rune")
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return x
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}
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// Rune parses and returns field i as a rune.
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func (p *Parser) Rune(i int) rune {
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if i > 0 || p.keepRanges {
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return p.parseRune(p.getField(i))
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}
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return p.rangeStart
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}
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// Runes interprets and returns field i as a sequence of runes.
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func (p *Parser) Runes(i int) (runes []rune) {
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add := func(s string) {
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if s = strings.TrimSpace(s); len(s) > 0 {
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runes = append(runes, p.parseRune(s))
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}
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}
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for b := p.getField(i); ; {
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i := strings.IndexByte(b, ' ')
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if i == -1 {
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add(b)
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break
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}
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add(b[:i])
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b = b[i+1:]
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}
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return
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}
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var (
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errIncorrectLegacyRange = errors.New("ucd: unmatched <* First>")
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// reRange matches one line of a legacy rune range.
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reRange = regexp.MustCompile("^([0-9A-F]*);<([^,]*), ([^>]*)>(.*)$")
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)
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// Range parses and returns field i as a rune range. A range is inclusive at
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// both ends. If the field only has one rune, first and last will be identical.
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// It supports the legacy format for ranges used in UnicodeData.txt.
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func (p *Parser) Range(i int) (first, last rune) {
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if !p.keepRanges {
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return p.rangeStart, p.rangeStart
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}
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return p.getRange(i)
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}
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func (p *Parser) getRange(i int) (first, last rune) {
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b := p.getField(i)
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if k := strings.Index(b, ".."); k != -1 {
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return p.parseRune(b[:k]), p.parseRune(b[k+2:])
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}
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// The first field may not be a rune, in which case we may ignore any error
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// and set the range as 0..0.
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x, err := parseRune(b)
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if err != nil {
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// Disable range parsing henceforth. This ensures that an error will be
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// returned if the user subsequently will try to parse this field as
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// a Rune.
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p.keepRanges = true
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}
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// Special case for UnicodeData that was retained for backwards compatibility.
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if i == 0 && len(p.field) > 1 && strings.HasSuffix(p.field[1], "First>") {
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if p.parsedRange {
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return p.rangeStart, p.rangeEnd
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}
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mf := reRange.FindStringSubmatch(p.scanner.Text())
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p.line++
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if mf == nil || !p.scanner.Scan() {
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p.setError(errIncorrectLegacyRange, "")
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return x, x
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}
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// Using Bytes would be more efficient here, but Text is a lot easier
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// and this is not a frequent case.
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ml := reRange.FindStringSubmatch(p.scanner.Text())
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if ml == nil || mf[2] != ml[2] || ml[3] != "Last" || mf[4] != ml[4] {
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p.setError(errIncorrectLegacyRange, "")
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return x, x
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}
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p.rangeStart, p.rangeEnd = x, p.parseRune(p.scanner.Text()[:len(ml[1])])
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p.parsedRange = true
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return p.rangeStart, p.rangeEnd
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}
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return x, x
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}
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// bools recognizes all valid UCD boolean values.
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var bools = map[string]bool{
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"": false,
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"N": false,
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"No": false,
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"F": false,
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"False": false,
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"Y": true,
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"Yes": true,
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"T": true,
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"True": true,
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}
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// Bool parses and returns field i as a boolean value.
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func (p *Parser) Bool(i int) bool {
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f := p.getField(i)
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for s, v := range bools {
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if f == s {
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return v
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}
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}
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p.setError(strconv.ErrSyntax, "error parsing bool")
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return false
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}
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// Int parses and returns field i as an integer value.
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func (p *Parser) Int(i int) int {
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x, err := strconv.ParseInt(string(p.getField(i)), 10, 64)
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p.setError(err, "error parsing int")
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return int(x)
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}
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// Uint parses and returns field i as an unsigned integer value.
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func (p *Parser) Uint(i int) uint {
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x, err := strconv.ParseUint(string(p.getField(i)), 10, 64)
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p.setError(err, "error parsing uint")
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return uint(x)
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}
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// Float parses and returns field i as a decimal value.
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func (p *Parser) Float(i int) float64 {
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x, err := strconv.ParseFloat(string(p.getField(i)), 64)
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p.setError(err, "error parsing float")
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return x
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}
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// String parses and returns field i as a string value.
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func (p *Parser) String(i int) string {
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return string(p.getField(i))
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}
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// Strings parses and returns field i as a space-separated list of strings.
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func (p *Parser) Strings(i int) []string {
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ss := strings.Split(string(p.getField(i)), " ")
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for i, s := range ss {
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ss[i] = strings.TrimSpace(s)
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}
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return ss
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}
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// Comment returns the comments for the current line.
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func (p *Parser) Comment() string {
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return string(p.comment)
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}
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var errUndefinedEnum = errors.New("ucd: undefined enum value")
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// Enum interprets and returns field i as a value that must be one of the values
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// in enum.
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func (p *Parser) Enum(i int, enum ...string) string {
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f := p.getField(i)
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for _, s := range enum {
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if f == s {
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return s
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}
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}
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p.setError(errUndefinedEnum, "error parsing enum")
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return ""
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}
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