diff options
author | Gibheer <gibheer+git@zero-knowledge.org> | 2024-09-05 19:38:25 +0200 |
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committer | Gibheer <gibheer+git@zero-knowledge.org> | 2024-09-05 19:38:25 +0200 |
commit | 6ea4d2c82de80efc87708e5e182034b7c6c2019e (patch) | |
tree | 35c0856a929040216c82153ca62d43b27530a887 /vendor/golang.org/x/text/internal/language/parse.go | |
parent | 6f64eeace1b66639b9380b44e88a8d54850a4306 (diff) |
lib/pq is out of maintenance for some time now, so switch to the newer
more active library. Looks like it finally stabilized after a long time.
Diffstat (limited to 'vendor/golang.org/x/text/internal/language/parse.go')
-rw-r--r-- | vendor/golang.org/x/text/internal/language/parse.go | 608 |
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) +} |