// Copyright 2013 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 cldr
import (
"bufio"
"encoding/xml"
"errors"
"fmt"
"strconv"
"strings"
"unicode"
"unicode/utf8"
)
// RuleProcessor can be passed to Collator's Process method, which
// parses the rules and calls the respective method for each rule found.
type RuleProcessor interface {
Reset(anchor string, before int) error
Insert(level int, str, context, extend string) error
Index(id string)
}
const (
// cldrIndex is a Unicode-reserved sentinel value used to mark the start
// of a grouping within an index.
// We ignore any rule that starts with this rune.
// See http://unicode.org/reports/tr35/#Collation_Elements for details.
cldrIndex = "\uFDD0"
// specialAnchor is the format in which to represent logical reset positions,
// such as "first tertiary ignorable".
specialAnchor = "<%s/>"
)
// Process parses the rules for the tailorings of this collation
// and calls the respective methods of p for each rule found.
func (c Collation) Process(p RuleProcessor) (err error) {
if len(c.Cr) > 0 {
if len(c.Cr) > 1 {
return fmt.Errorf("multiple cr elements, want 0 or 1")
}
return processRules(p, c.Cr[0].Data())
}
if c.Rules.Any != nil {
return c.processXML(p)
}
return errors.New("no tailoring data")
}
// processRules parses rules in the Collation Rule Syntax defined in
// http://www.unicode.org/reports/tr35/tr35-collation.html#Collation_Tailorings.
func processRules(p RuleProcessor, s string) (err error) {
chk := func(s string, e error) string {
if err == nil {
err = e
}
return s
}
i := 0 // Save the line number for use after the loop.
scanner := bufio.NewScanner(strings.NewReader(s))
for ; scanner.Scan() && err == nil; i++ {
for s := skipSpace(scanner.Text()); s != "" && s[0] != '#'; s = skipSpace(s) {
level := 5
var ch byte
switch ch, s = s[0], s[1:]; ch {
case '&': // followed by <anchor> or '[' <key> ']'
if s = skipSpace(s); consume(&s, '[') {
s = chk(parseSpecialAnchor(p, s))
} else {
s = chk(parseAnchor(p, 0, s))
}
case '<': // sort relation '<'{1,4}, optionally followed by '*'.
for level = 1; consume(&s, '<'); level++ {
}
if level > 4 {
err = fmt.Errorf("level %d > 4", level)
}
fallthrough
case '=': // identity relation, optionally followed by *.
if consume(&s, '*') {
s = chk(parseSequence(p, level, s))
} else {
s = chk(parseOrder(p, level, s))
}
default:
chk("", fmt.Errorf("illegal operator %q", ch))
break
}
}
}
if chk("", scanner.Err()); err != nil {
return fmt.Errorf("%d: %v", i, err)
}
return nil
}
// parseSpecialAnchor parses the anchor syntax which is either of the form
// ['before' <level>] <anchor>
// or
// [<label>]
// The starting should already be consumed.
func parseSpecialAnchor(p RuleProcessor, s string) (tail string, err error) {
i := strings.IndexByte(s, ']')
if i == -1 {
return "", errors.New("unmatched bracket")
}
a := strings.TrimSpace(s[:i])
s = s[i+1:]
if strings.HasPrefix(a, "before ") {
l, err := strconv.ParseUint(skipSpace(a[len("before "):]), 10, 3)
if err != nil {
return s, err
}
return parseAnchor(p, int(l), s)
}
return s, p.Reset(fmt.Sprintf(specialAnchor, a), 0)
}
func parseAnchor(p RuleProcessor, level int, s string) (tail string, err error) {
anchor, s, err := scanString(s)
if err != nil {
return s, err
}
return s, p.Reset(anchor, level)
}
func parseOrder(p RuleProcessor, level int, s string) (tail string, err error) {
var value, context, extend string
if value, s, err = scanString(s); err != nil {
return s, err
}
if strings.HasPrefix(value, cldrIndex) {
p.Index(value[len(cldrIndex):])
return
}
if consume(&s, '|') {
if context, s, err = scanString(s); err != nil {
return s, errors.New("missing string after context")
}
}
if consume(&s, '/') {
if extend, s, err = scanString(s); err != nil {
return s, errors.New("missing string after extension")
}
}
return s, p.Insert(level, value, context, extend)
}
// scanString scans a single input string.
func scanString(s string) (str, tail string, err error) {
if s = skipSpace(s); s == "" {
return s, s, errors.New("missing string")
}
buf := [16]byte{} // small but enough to hold most cases.
value := buf[:0]
for s != "" {
if consume(&s, '\'') {
i := strings.IndexByte(s, '\'')
if i == -1 {
return "", "", errors.New(`unmatched single quote`)
}
if i == 0 {
value = append(value, '\'')
} else {
value = append(value, s[:i]...)
}
s = s[i+1:]
continue
}
r, sz := utf8.DecodeRuneInString(s)
if unicode.IsSpace(r) || strings.ContainsRune("&<=#", r) {
break
}
value = append(value, s[:sz]...)
s = s[sz:]
}
return string(value), skipSpace(s), nil
}
func parseSequence(p RuleProcessor, level int, s string) (tail string, err error) {
if s = skipSpace(s); s == "" {
return s, errors.New("empty sequence")
}
last := rune(0)
for s != "" {
r, sz := utf8.DecodeRuneInString(s)
s = s[sz:]
if r == '-' {
// We have a range. The first element was already written.
if last == 0 {
return s, errors.New("range without starter value")
}
r, sz = utf8.DecodeRuneInString(s)
s = s[sz:]
if r == utf8.RuneError || r < last {
return s, fmt.Errorf("invalid range %q-%q", last, r)
}
for i := last + 1; i <= r; i++ {
if err := p.Insert(level, string(i), "", ""); err != nil {
return s, err
}
}
last = 0
continue
}
if unicode.IsSpace(r) || unicode.IsPunct(r) {
break
}
// normal case
if err := p.Insert(level, string(r), "", ""); err != nil {
return s, err
}
last = r
}
return s, nil
}
func skipSpace(s string) string {
return strings.TrimLeftFunc(s, unicode.IsSpace)
}
// consumes returns whether the next byte is ch. If so, it gobbles it by
// updating s.
func consume(s *string, ch byte) (ok bool) {
if *s == "" || (*s)[0] != ch {
return false
}
*s = (*s)[1:]
return true
}
// The following code parses Collation rules of CLDR version 24 and before.
var lmap = map[byte]int{
'p': 1,
's': 2,
't': 3,
'i': 5,
}
type rulesElem struct {
Rules struct {
Common
Any []*struct {
XMLName xml.Name
rule
} `xml:",any"`
} `xml:"rules"`
}
type rule struct {
Value string `xml:",chardata"`
Before string `xml:"before,attr"`
Any []*struct {
XMLName xml.Name
rule
} `xml:",any"`
}
var emptyValueError = errors.New("cldr: empty rule value")
func (r *rule) value() (string, error) {
// Convert hexadecimal Unicode codepoint notation to a string.
s := charRe.ReplaceAllStringFunc(r.Value, replaceUnicode)
r.Value = s
if s == "" {
if len(r.Any) != 1 {
return "", emptyValueError
}
r.Value = fmt.Sprintf(specialAnchor, r.Any[0].XMLName.Local)
r.Any = nil
} else if len(r.Any) != 0 {
return "", fmt.Errorf("cldr: XML elements found in collation rule: %v", r.Any)
}
return r.Value, nil
}
func (r rule) process(p RuleProcessor, name, context, extend string) error {
v, err := r.value()
if err != nil {
return err
}
switch name {
case "p", "s", "t", "i":
if strings.HasPrefix(v, cldrIndex) {
p.Index(v[len(cldrIndex):])
return nil
}
if err := p.Insert(lmap[name[0]], v, context, extend); err != nil {
return err
}
case "pc", "sc", "tc", "ic":
level := lmap[name[0]]
for _, s := range v {
if err := p.Insert(level, string(s), context, extend); err != nil {
return err
}
}
default:
return fmt.Errorf("cldr: unsupported tag: %q", name)
}
return nil
}
// processXML parses the format of CLDR versions 24 and older.
func (c Collation) processXML(p RuleProcessor) (err error) {
// Collation is generated and defined in xml.go.
var v string
for _, r := range c.Rules.Any {
switch r.XMLName.Local {
case "reset":
level := 0
switch r.Before {
case "primary", "1":
level = 1
case "secondary", "2":
level = 2
case "tertiary", "3":
level = 3
case "":
default:
return fmt.Errorf("cldr: unknown level %q", r.Before)
}
v, err = r.value()
if err == nil {
err = p.Reset(v, level)
}
case "x":
var context, extend string
for _, r1 := range r.Any {
v, err = r1.value()
switch r1.XMLName.Local {
case "context":
context = v
case "extend":
extend = v
}
}
for _, r1 := range r.Any {
if t := r1.XMLName.Local; t == "context" || t == "extend" {
continue
}
r1.rule.process(p, r1.XMLName.Local, context, extend)
}
default:
err = r.rule.process(p, r.XMLName.Local, "", "")
}
if err != nil {
return err
}
}
return nil
}
