aboutsummaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/text/internal/language/parse.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/golang.org/x/text/internal/language/parse.go')
-rw-r--r--vendor/golang.org/x/text/internal/language/parse.go608
1 files changed, 608 insertions, 0 deletions
diff --git a/vendor/golang.org/x/text/internal/language/parse.go b/vendor/golang.org/x/text/internal/language/parse.go
new file mode 100644
index 0000000..aad1e0a
--- /dev/null
+++ b/vendor/golang.org/x/text/internal/language/parse.go
@@ -0,0 +1,608 @@
+// 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 language
+
+import (
+ "bytes"
+ "errors"
+ "fmt"
+ "sort"
+
+ "golang.org/x/text/internal/tag"
+)
+
+// isAlpha returns true if the byte is not a digit.
+// b must be an ASCII letter or digit.
+func isAlpha(b byte) bool {
+ return b > '9'
+}
+
+// isAlphaNum returns true if the string contains only ASCII letters or digits.
+func isAlphaNum(s []byte) bool {
+ for _, c := range s {
+ if !('a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9') {
+ return false
+ }
+ }
+ return true
+}
+
+// ErrSyntax is returned by any of the parsing functions when the
+// input is not well-formed, according to BCP 47.
+// TODO: return the position at which the syntax error occurred?
+var ErrSyntax = errors.New("language: tag is not well-formed")
+
+// ErrDuplicateKey is returned when a tag contains the same key twice with
+// different values in the -u section.
+var ErrDuplicateKey = errors.New("language: different values for same key in -u extension")
+
+// ValueError is returned by any of the parsing functions when the
+// input is well-formed but the respective subtag is not recognized
+// as a valid value.
+type ValueError struct {
+ v [8]byte
+}
+
+// NewValueError creates a new ValueError.
+func NewValueError(tag []byte) ValueError {
+ var e ValueError
+ copy(e.v[:], tag)
+ return e
+}
+
+func (e ValueError) tag() []byte {
+ n := bytes.IndexByte(e.v[:], 0)
+ if n == -1 {
+ n = 8
+ }
+ return e.v[:n]
+}
+
+// Error implements the error interface.
+func (e ValueError) Error() string {
+ return fmt.Sprintf("language: subtag %q is well-formed but unknown", e.tag())
+}
+
+// Subtag returns the subtag for which the error occurred.
+func (e ValueError) Subtag() string {
+ return string(e.tag())
+}
+
+// scanner is used to scan BCP 47 tokens, which are separated by _ or -.
+type scanner struct {
+ b []byte
+ bytes [max99thPercentileSize]byte
+ token []byte
+ start int // start position of the current token
+ end int // end position of the current token
+ next int // next point for scan
+ err error
+ done bool
+}
+
+func makeScannerString(s string) scanner {
+ scan := scanner{}
+ if len(s) <= len(scan.bytes) {
+ scan.b = scan.bytes[:copy(scan.bytes[:], s)]
+ } else {
+ scan.b = []byte(s)
+ }
+ scan.init()
+ return scan
+}
+
+// makeScanner returns a scanner using b as the input buffer.
+// b is not copied and may be modified by the scanner routines.
+func makeScanner(b []byte) scanner {
+ scan := scanner{b: b}
+ scan.init()
+ return scan
+}
+
+func (s *scanner) init() {
+ for i, c := range s.b {
+ if c == '_' {
+ s.b[i] = '-'
+ }
+ }
+ s.scan()
+}
+
+// restToLower converts the string between start and end to lower case.
+func (s *scanner) toLower(start, end int) {
+ for i := start; i < end; i++ {
+ c := s.b[i]
+ if 'A' <= c && c <= 'Z' {
+ s.b[i] += 'a' - 'A'
+ }
+ }
+}
+
+func (s *scanner) setError(e error) {
+ if s.err == nil || (e == ErrSyntax && s.err != ErrSyntax) {
+ s.err = e
+ }
+}
+
+// resizeRange shrinks or grows the array at position oldStart such that
+// a new string of size newSize can fit between oldStart and oldEnd.
+// Sets the scan point to after the resized range.
+func (s *scanner) resizeRange(oldStart, oldEnd, newSize int) {
+ s.start = oldStart
+ if end := oldStart + newSize; end != oldEnd {
+ diff := end - oldEnd
+ var b []byte
+ if n := len(s.b) + diff; n > cap(s.b) {
+ b = make([]byte, n)
+ copy(b, s.b[:oldStart])
+ } else {
+ b = s.b[:n]
+ }
+ copy(b[end:], s.b[oldEnd:])
+ s.b = b
+ s.next = end + (s.next - s.end)
+ s.end = end
+ }
+}
+
+// replace replaces the current token with repl.
+func (s *scanner) replace(repl string) {
+ s.resizeRange(s.start, s.end, len(repl))
+ copy(s.b[s.start:], repl)
+}
+
+// gobble removes the current token from the input.
+// Caller must call scan after calling gobble.
+func (s *scanner) gobble(e error) {
+ s.setError(e)
+ if s.start == 0 {
+ s.b = s.b[:+copy(s.b, s.b[s.next:])]
+ s.end = 0
+ } else {
+ s.b = s.b[:s.start-1+copy(s.b[s.start-1:], s.b[s.end:])]
+ s.end = s.start - 1
+ }
+ s.next = s.start
+}
+
+// deleteRange removes the given range from s.b before the current token.
+func (s *scanner) deleteRange(start, end int) {
+ s.b = s.b[:start+copy(s.b[start:], s.b[end:])]
+ diff := end - start
+ s.next -= diff
+ s.start -= diff
+ s.end -= diff
+}
+
+// scan parses the next token of a BCP 47 string. Tokens that are larger
+// than 8 characters or include non-alphanumeric characters result in an error
+// and are gobbled and removed from the output.
+// It returns the end position of the last token consumed.
+func (s *scanner) scan() (end int) {
+ end = s.end
+ s.token = nil
+ for s.start = s.next; s.next < len(s.b); {
+ i := bytes.IndexByte(s.b[s.next:], '-')
+ if i == -1 {
+ s.end = len(s.b)
+ s.next = len(s.b)
+ i = s.end - s.start
+ } else {
+ s.end = s.next + i
+ s.next = s.end + 1
+ }
+ token := s.b[s.start:s.end]
+ if i < 1 || i > 8 || !isAlphaNum(token) {
+ s.gobble(ErrSyntax)
+ continue
+ }
+ s.token = token
+ return end
+ }
+ if n := len(s.b); n > 0 && s.b[n-1] == '-' {
+ s.setError(ErrSyntax)
+ s.b = s.b[:len(s.b)-1]
+ }
+ s.done = true
+ return end
+}
+
+// acceptMinSize parses multiple tokens of the given size or greater.
+// It returns the end position of the last token consumed.
+func (s *scanner) acceptMinSize(min int) (end int) {
+ end = s.end
+ s.scan()
+ for ; len(s.token) >= min; s.scan() {
+ end = s.end
+ }
+ return end
+}
+
+// Parse parses the given BCP 47 string and returns a valid Tag. If parsing
+// failed it returns an error and any part of the tag that could be parsed.
+// If parsing succeeded but an unknown value was found, it returns
+// ValueError. The Tag returned in this case is just stripped of the unknown
+// value. All other values are preserved. It accepts tags in the BCP 47 format
+// and extensions to this standard defined in
+// https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers.
+func Parse(s string) (t Tag, err error) {
+ // TODO: consider supporting old-style locale key-value pairs.
+ if s == "" {
+ return Und, ErrSyntax
+ }
+ defer func() {
+ if recover() != nil {
+ t = Und
+ err = ErrSyntax
+ return
+ }
+ }()
+ if len(s) <= maxAltTaglen {
+ b := [maxAltTaglen]byte{}
+ for i, c := range s {
+ // Generating invalid UTF-8 is okay as it won't match.
+ if 'A' <= c && c <= 'Z' {
+ c += 'a' - 'A'
+ } else if c == '_' {
+ c = '-'
+ }
+ b[i] = byte(c)
+ }
+ if t, ok := grandfathered(b); ok {
+ return t, nil
+ }
+ }
+ scan := makeScannerString(s)
+ return parse(&scan, s)
+}
+
+func parse(scan *scanner, s string) (t Tag, err error) {
+ t = Und
+ var end int
+ if n := len(scan.token); n <= 1 {
+ scan.toLower(0, len(scan.b))
+ if n == 0 || scan.token[0] != 'x' {
+ return t, ErrSyntax
+ }
+ end = parseExtensions(scan)
+ } else if n >= 4 {
+ return Und, ErrSyntax
+ } else { // the usual case
+ t, end = parseTag(scan, true)
+ if n := len(scan.token); n == 1 {
+ t.pExt = uint16(end)
+ end = parseExtensions(scan)
+ } else if end < len(scan.b) {
+ scan.setError(ErrSyntax)
+ scan.b = scan.b[:end]
+ }
+ }
+ if int(t.pVariant) < len(scan.b) {
+ if end < len(s) {
+ s = s[:end]
+ }
+ if len(s) > 0 && tag.Compare(s, scan.b) == 0 {
+ t.str = s
+ } else {
+ t.str = string(scan.b)
+ }
+ } else {
+ t.pVariant, t.pExt = 0, 0
+ }
+ return t, scan.err
+}
+
+// parseTag parses language, script, region and variants.
+// It returns a Tag and the end position in the input that was parsed.
+// If doNorm is true, then <lang>-<extlang> will be normalized to <extlang>.
+func parseTag(scan *scanner, doNorm bool) (t Tag, end int) {
+ var e error
+ // TODO: set an error if an unknown lang, script or region is encountered.
+ t.LangID, e = getLangID(scan.token)
+ scan.setError(e)
+ scan.replace(t.LangID.String())
+ langStart := scan.start
+ end = scan.scan()
+ for len(scan.token) == 3 && isAlpha(scan.token[0]) {
+ // From http://tools.ietf.org/html/bcp47, <lang>-<extlang> tags are equivalent
+ // to a tag of the form <extlang>.
+ if doNorm {
+ lang, e := getLangID(scan.token)
+ if lang != 0 {
+ t.LangID = lang
+ langStr := lang.String()
+ copy(scan.b[langStart:], langStr)
+ scan.b[langStart+len(langStr)] = '-'
+ scan.start = langStart + len(langStr) + 1
+ }
+ scan.gobble(e)
+ }
+ end = scan.scan()
+ }
+ if len(scan.token) == 4 && isAlpha(scan.token[0]) {
+ t.ScriptID, e = getScriptID(script, scan.token)
+ if t.ScriptID == 0 {
+ scan.gobble(e)
+ }
+ end = scan.scan()
+ }
+ if n := len(scan.token); n >= 2 && n <= 3 {
+ t.RegionID, e = getRegionID(scan.token)
+ if t.RegionID == 0 {
+ scan.gobble(e)
+ } else {
+ scan.replace(t.RegionID.String())
+ }
+ end = scan.scan()
+ }
+ scan.toLower(scan.start, len(scan.b))
+ t.pVariant = byte(end)
+ end = parseVariants(scan, end, t)
+ t.pExt = uint16(end)
+ return t, end
+}
+
+var separator = []byte{'-'}
+
+// parseVariants scans tokens as long as each token is a valid variant string.
+// Duplicate variants are removed.
+func parseVariants(scan *scanner, end int, t Tag) int {
+ start := scan.start
+ varIDBuf := [4]uint8{}
+ variantBuf := [4][]byte{}
+ varID := varIDBuf[:0]
+ variant := variantBuf[:0]
+ last := -1
+ needSort := false
+ for ; len(scan.token) >= 4; scan.scan() {
+ // TODO: measure the impact of needing this conversion and redesign
+ // the data structure if there is an issue.
+ v, ok := variantIndex[string(scan.token)]
+ if !ok {
+ // unknown variant
+ // TODO: allow user-defined variants?
+ scan.gobble(NewValueError(scan.token))
+ continue
+ }
+ varID = append(varID, v)
+ variant = append(variant, scan.token)
+ if !needSort {
+ if last < int(v) {
+ last = int(v)
+ } else {
+ needSort = true
+ // There is no legal combinations of more than 7 variants
+ // (and this is by no means a useful sequence).
+ const maxVariants = 8
+ if len(varID) > maxVariants {
+ break
+ }
+ }
+ }
+ end = scan.end
+ }
+ if needSort {
+ sort.Sort(variantsSort{varID, variant})
+ k, l := 0, -1
+ for i, v := range varID {
+ w := int(v)
+ if l == w {
+ // Remove duplicates.
+ continue
+ }
+ varID[k] = varID[i]
+ variant[k] = variant[i]
+ k++
+ l = w
+ }
+ if str := bytes.Join(variant[:k], separator); len(str) == 0 {
+ end = start - 1
+ } else {
+ scan.resizeRange(start, end, len(str))
+ copy(scan.b[scan.start:], str)
+ end = scan.end
+ }
+ }
+ return end
+}
+
+type variantsSort struct {
+ i []uint8
+ v [][]byte
+}
+
+func (s variantsSort) Len() int {
+ return len(s.i)
+}
+
+func (s variantsSort) Swap(i, j int) {
+ s.i[i], s.i[j] = s.i[j], s.i[i]
+ s.v[i], s.v[j] = s.v[j], s.v[i]
+}
+
+func (s variantsSort) Less(i, j int) bool {
+ return s.i[i] < s.i[j]
+}
+
+type bytesSort struct {
+ b [][]byte
+ n int // first n bytes to compare
+}
+
+func (b bytesSort) Len() int {
+ return len(b.b)
+}
+
+func (b bytesSort) Swap(i, j int) {
+ b.b[i], b.b[j] = b.b[j], b.b[i]
+}
+
+func (b bytesSort) Less(i, j int) bool {
+ for k := 0; k < b.n; k++ {
+ if b.b[i][k] == b.b[j][k] {
+ continue
+ }
+ return b.b[i][k] < b.b[j][k]
+ }
+ return false
+}
+
+// parseExtensions parses and normalizes the extensions in the buffer.
+// It returns the last position of scan.b that is part of any extension.
+// It also trims scan.b to remove excess parts accordingly.
+func parseExtensions(scan *scanner) int {
+ start := scan.start
+ exts := [][]byte{}
+ private := []byte{}
+ end := scan.end
+ for len(scan.token) == 1 {
+ extStart := scan.start
+ ext := scan.token[0]
+ end = parseExtension(scan)
+ extension := scan.b[extStart:end]
+ if len(extension) < 3 || (ext != 'x' && len(extension) < 4) {
+ scan.setError(ErrSyntax)
+ end = extStart
+ continue
+ } else if start == extStart && (ext == 'x' || scan.start == len(scan.b)) {
+ scan.b = scan.b[:end]
+ return end
+ } else if ext == 'x' {
+ private = extension
+ break
+ }
+ exts = append(exts, extension)
+ }
+ sort.Sort(bytesSort{exts, 1})
+ if len(private) > 0 {
+ exts = append(exts, private)
+ }
+ scan.b = scan.b[:start]
+ if len(exts) > 0 {
+ scan.b = append(scan.b, bytes.Join(exts, separator)...)
+ } else if start > 0 {
+ // Strip trailing '-'.
+ scan.b = scan.b[:start-1]
+ }
+ return end
+}
+
+// parseExtension parses a single extension and returns the position of
+// the extension end.
+func parseExtension(scan *scanner) int {
+ start, end := scan.start, scan.end
+ switch scan.token[0] {
+ case 'u': // https://www.ietf.org/rfc/rfc6067.txt
+ attrStart := end
+ scan.scan()
+ for last := []byte{}; len(scan.token) > 2; scan.scan() {
+ if bytes.Compare(scan.token, last) != -1 {
+ // Attributes are unsorted. Start over from scratch.
+ p := attrStart + 1
+ scan.next = p
+ attrs := [][]byte{}
+ for scan.scan(); len(scan.token) > 2; scan.scan() {
+ attrs = append(attrs, scan.token)
+ end = scan.end
+ }
+ sort.Sort(bytesSort{attrs, 3})
+ copy(scan.b[p:], bytes.Join(attrs, separator))
+ break
+ }
+ last = scan.token
+ end = scan.end
+ }
+ // Scan key-type sequences. A key is of length 2 and may be followed
+ // by 0 or more "type" subtags from 3 to the maximum of 8 letters.
+ var last, key []byte
+ for attrEnd := end; len(scan.token) == 2; last = key {
+ key = scan.token
+ end = scan.end
+ for scan.scan(); end < scan.end && len(scan.token) > 2; scan.scan() {
+ end = scan.end
+ }
+ // TODO: check key value validity
+ if bytes.Compare(key, last) != 1 || scan.err != nil {
+ // We have an invalid key or the keys are not sorted.
+ // Start scanning keys from scratch and reorder.
+ p := attrEnd + 1
+ scan.next = p
+ keys := [][]byte{}
+ for scan.scan(); len(scan.token) == 2; {
+ keyStart := scan.start
+ end = scan.end
+ for scan.scan(); end < scan.end && len(scan.token) > 2; scan.scan() {
+ end = scan.end
+ }
+ keys = append(keys, scan.b[keyStart:end])
+ }
+ sort.Stable(bytesSort{keys, 2})
+ if n := len(keys); n > 0 {
+ k := 0
+ for i := 1; i < n; i++ {
+ if !bytes.Equal(keys[k][:2], keys[i][:2]) {
+ k++
+ keys[k] = keys[i]
+ } else if !bytes.Equal(keys[k], keys[i]) {
+ scan.setError(ErrDuplicateKey)
+ }
+ }
+ keys = keys[:k+1]
+ }
+ reordered := bytes.Join(keys, separator)
+ if e := p + len(reordered); e < end {
+ scan.deleteRange(e, end)
+ end = e
+ }
+ copy(scan.b[p:], reordered)
+ break
+ }
+ }
+ case 't': // https://www.ietf.org/rfc/rfc6497.txt
+ scan.scan()
+ if n := len(scan.token); n >= 2 && n <= 3 && isAlpha(scan.token[1]) {
+ _, end = parseTag(scan, false)
+ scan.toLower(start, end)
+ }
+ for len(scan.token) == 2 && !isAlpha(scan.token[1]) {
+ end = scan.acceptMinSize(3)
+ }
+ case 'x':
+ end = scan.acceptMinSize(1)
+ default:
+ end = scan.acceptMinSize(2)
+ }
+ return end
+}
+
+// getExtension returns the name, body and end position of the extension.
+func getExtension(s string, p int) (end int, ext string) {
+ if s[p] == '-' {
+ p++
+ }
+ if s[p] == 'x' {
+ return len(s), s[p:]
+ }
+ end = nextExtension(s, p)
+ return end, s[p:end]
+}
+
+// nextExtension finds the next extension within the string, searching
+// for the -<char>- pattern from position p.
+// In the fast majority of cases, language tags will have at most
+// one extension and extensions tend to be small.
+func nextExtension(s string, p int) int {
+ for n := len(s) - 3; p < n; {
+ if s[p] == '-' {
+ if s[p+2] == '-' {
+ return p
+ }
+ p += 3
+ } else {
+ p++
+ }
+ }
+ return len(s)
+}
generated by cgit v1.2.3-70-g09d2 (git 2.47.0) at 2024-11-01 06:37:12 +0000