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restic/vendor/golang.org/x/text/internal/ucd/ucd.go

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