rss-tools/vendor/golang.org/x/text/internal/language/parse.go (view raw)
| 1 | // Copyright 2013 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package language |
| 6 | |
| 7 | import ( |
| 8 | "bytes" |
| 9 | "errors" |
| 10 | "fmt" |
| 11 | "sort" |
| 12 | |
| 13 | "golang.org/x/text/internal/tag" |
| 14 | ) |
| 15 | |
| 16 | // isAlpha returns true if the byte is not a digit. |
| 17 | // b must be an ASCII letter or digit. |
| 18 | func isAlpha(b byte) bool { |
| 19 | return b > '9' |
| 20 | } |
| 21 | |
| 22 | // isAlphaNum returns true if the string contains only ASCII letters or digits. |
| 23 | func isAlphaNum(s []byte) bool { |
| 24 | for _, c := range s { |
| 25 | if !('a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9') { |
| 26 | return false |
| 27 | } |
| 28 | } |
| 29 | return true |
| 30 | } |
| 31 | |
| 32 | // ErrSyntax is returned by any of the parsing functions when the |
| 33 | // input is not well-formed, according to BCP 47. |
| 34 | // TODO: return the position at which the syntax error occurred? |
| 35 | var ErrSyntax = errors.New("language: tag is not well-formed") |
| 36 | |
| 37 | // ErrDuplicateKey is returned when a tag contains the same key twice with |
| 38 | // different values in the -u section. |
| 39 | var ErrDuplicateKey = errors.New("language: different values for same key in -u extension") |
| 40 | |
| 41 | // ValueError is returned by any of the parsing functions when the |
| 42 | // input is well-formed but the respective subtag is not recognized |
| 43 | // as a valid value. |
| 44 | type ValueError struct { |
| 45 | v [8]byte |
| 46 | } |
| 47 | |
| 48 | // NewValueError creates a new ValueError. |
| 49 | func NewValueError(tag []byte) ValueError { |
| 50 | var e ValueError |
| 51 | copy(e.v[:], tag) |
| 52 | return e |
| 53 | } |
| 54 | |
| 55 | func (e ValueError) tag() []byte { |
| 56 | n := bytes.IndexByte(e.v[:], 0) |
| 57 | if n == -1 { |
| 58 | n = 8 |
| 59 | } |
| 60 | return e.v[:n] |
| 61 | } |
| 62 | |
| 63 | // Error implements the error interface. |
| 64 | func (e ValueError) Error() string { |
| 65 | return fmt.Sprintf("language: subtag %q is well-formed but unknown", e.tag()) |
| 66 | } |
| 67 | |
| 68 | // Subtag returns the subtag for which the error occurred. |
| 69 | func (e ValueError) Subtag() string { |
| 70 | return string(e.tag()) |
| 71 | } |
| 72 | |
| 73 | // scanner is used to scan BCP 47 tokens, which are separated by _ or -. |
| 74 | type scanner struct { |
| 75 | b []byte |
| 76 | bytes [max99thPercentileSize]byte |
| 77 | token []byte |
| 78 | start int // start position of the current token |
| 79 | end int // end position of the current token |
| 80 | next int // next point for scan |
| 81 | err error |
| 82 | done bool |
| 83 | } |
| 84 | |
| 85 | func makeScannerString(s string) scanner { |
| 86 | scan := scanner{} |
| 87 | if len(s) <= len(scan.bytes) { |
| 88 | scan.b = scan.bytes[:copy(scan.bytes[:], s)] |
| 89 | } else { |
| 90 | scan.b = []byte(s) |
| 91 | } |
| 92 | scan.init() |
| 93 | return scan |
| 94 | } |
| 95 | |
| 96 | // makeScanner returns a scanner using b as the input buffer. |
| 97 | // b is not copied and may be modified by the scanner routines. |
| 98 | func makeScanner(b []byte) scanner { |
| 99 | scan := scanner{b: b} |
| 100 | scan.init() |
| 101 | return scan |
| 102 | } |
| 103 | |
| 104 | func (s *scanner) init() { |
| 105 | for i, c := range s.b { |
| 106 | if c == '_' { |
| 107 | s.b[i] = '-' |
| 108 | } |
| 109 | } |
| 110 | s.scan() |
| 111 | } |
| 112 | |
| 113 | // restToLower converts the string between start and end to lower case. |
| 114 | func (s *scanner) toLower(start, end int) { |
| 115 | for i := start; i < end; i++ { |
| 116 | c := s.b[i] |
| 117 | if 'A' <= c && c <= 'Z' { |
| 118 | s.b[i] += 'a' - 'A' |
| 119 | } |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | func (s *scanner) setError(e error) { |
| 124 | if s.err == nil || (e == ErrSyntax && s.err != ErrSyntax) { |
| 125 | s.err = e |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | // resizeRange shrinks or grows the array at position oldStart such that |
| 130 | // a new string of size newSize can fit between oldStart and oldEnd. |
| 131 | // Sets the scan point to after the resized range. |
| 132 | func (s *scanner) resizeRange(oldStart, oldEnd, newSize int) { |
| 133 | s.start = oldStart |
| 134 | if end := oldStart + newSize; end != oldEnd { |
| 135 | diff := end - oldEnd |
| 136 | var b []byte |
| 137 | if n := len(s.b) + diff; n > cap(s.b) { |
| 138 | b = make([]byte, n) |
| 139 | copy(b, s.b[:oldStart]) |
| 140 | } else { |
| 141 | b = s.b[:n] |
| 142 | } |
| 143 | copy(b[end:], s.b[oldEnd:]) |
| 144 | s.b = b |
| 145 | s.next = end + (s.next - s.end) |
| 146 | s.end = end |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | // replace replaces the current token with repl. |
| 151 | func (s *scanner) replace(repl string) { |
| 152 | s.resizeRange(s.start, s.end, len(repl)) |
| 153 | copy(s.b[s.start:], repl) |
| 154 | } |
| 155 | |
| 156 | // gobble removes the current token from the input. |
| 157 | // Caller must call scan after calling gobble. |
| 158 | func (s *scanner) gobble(e error) { |
| 159 | s.setError(e) |
| 160 | if s.start == 0 { |
| 161 | s.b = s.b[:+copy(s.b, s.b[s.next:])] |
| 162 | s.end = 0 |
| 163 | } else { |
| 164 | s.b = s.b[:s.start-1+copy(s.b[s.start-1:], s.b[s.end:])] |
| 165 | s.end = s.start - 1 |
| 166 | } |
| 167 | s.next = s.start |
| 168 | } |
| 169 | |
| 170 | // deleteRange removes the given range from s.b before the current token. |
| 171 | func (s *scanner) deleteRange(start, end int) { |
| 172 | s.b = s.b[:start+copy(s.b[start:], s.b[end:])] |
| 173 | diff := end - start |
| 174 | s.next -= diff |
| 175 | s.start -= diff |
| 176 | s.end -= diff |
| 177 | } |
| 178 | |
| 179 | // scan parses the next token of a BCP 47 string. Tokens that are larger |
| 180 | // than 8 characters or include non-alphanumeric characters result in an error |
| 181 | // and are gobbled and removed from the output. |
| 182 | // It returns the end position of the last token consumed. |
| 183 | func (s *scanner) scan() (end int) { |
| 184 | end = s.end |
| 185 | s.token = nil |
| 186 | for s.start = s.next; s.next < len(s.b); { |
| 187 | i := bytes.IndexByte(s.b[s.next:], '-') |
| 188 | if i == -1 { |
| 189 | s.end = len(s.b) |
| 190 | s.next = len(s.b) |
| 191 | i = s.end - s.start |
| 192 | } else { |
| 193 | s.end = s.next + i |
| 194 | s.next = s.end + 1 |
| 195 | } |
| 196 | token := s.b[s.start:s.end] |
| 197 | if i < 1 || i > 8 || !isAlphaNum(token) { |
| 198 | s.gobble(ErrSyntax) |
| 199 | continue |
| 200 | } |
| 201 | s.token = token |
| 202 | return end |
| 203 | } |
| 204 | if n := len(s.b); n > 0 && s.b[n-1] == '-' { |
| 205 | s.setError(ErrSyntax) |
| 206 | s.b = s.b[:len(s.b)-1] |
| 207 | } |
| 208 | s.done = true |
| 209 | return end |
| 210 | } |
| 211 | |
| 212 | // acceptMinSize parses multiple tokens of the given size or greater. |
| 213 | // It returns the end position of the last token consumed. |
| 214 | func (s *scanner) acceptMinSize(min int) (end int) { |
| 215 | end = s.end |
| 216 | s.scan() |
| 217 | for ; len(s.token) >= min; s.scan() { |
| 218 | end = s.end |
| 219 | } |
| 220 | return end |
| 221 | } |
| 222 | |
| 223 | // Parse parses the given BCP 47 string and returns a valid Tag. If parsing |
| 224 | // failed it returns an error and any part of the tag that could be parsed. |
| 225 | // If parsing succeeded but an unknown value was found, it returns |
| 226 | // ValueError. The Tag returned in this case is just stripped of the unknown |
| 227 | // value. All other values are preserved. It accepts tags in the BCP 47 format |
| 228 | // and extensions to this standard defined in |
| 229 | // https://www.unicode.org/reports/tr35/#Unicode_Language_and_Locale_Identifiers. |
| 230 | func Parse(s string) (t Tag, err error) { |
| 231 | // TODO: consider supporting old-style locale key-value pairs. |
| 232 | if s == "" { |
| 233 | return Und, ErrSyntax |
| 234 | } |
| 235 | defer func() { |
| 236 | if recover() != nil { |
| 237 | t = Und |
| 238 | err = ErrSyntax |
| 239 | return |
| 240 | } |
| 241 | }() |
| 242 | if len(s) <= maxAltTaglen { |
| 243 | b := [maxAltTaglen]byte{} |
| 244 | for i, c := range s { |
| 245 | // Generating invalid UTF-8 is okay as it won't match. |
| 246 | if 'A' <= c && c <= 'Z' { |
| 247 | c += 'a' - 'A' |
| 248 | } else if c == '_' { |
| 249 | c = '-' |
| 250 | } |
| 251 | b[i] = byte(c) |
| 252 | } |
| 253 | if t, ok := grandfathered(b); ok { |
| 254 | return t, nil |
| 255 | } |
| 256 | } |
| 257 | scan := makeScannerString(s) |
| 258 | return parse(&scan, s) |
| 259 | } |
| 260 | |
| 261 | func parse(scan *scanner, s string) (t Tag, err error) { |
| 262 | t = Und |
| 263 | var end int |
| 264 | if n := len(scan.token); n <= 1 { |
| 265 | scan.toLower(0, len(scan.b)) |
| 266 | if n == 0 || scan.token[0] != 'x' { |
| 267 | return t, ErrSyntax |
| 268 | } |
| 269 | end = parseExtensions(scan) |
| 270 | } else if n >= 4 { |
| 271 | return Und, ErrSyntax |
| 272 | } else { // the usual case |
| 273 | t, end = parseTag(scan, true) |
| 274 | if n := len(scan.token); n == 1 { |
| 275 | t.pExt = uint16(end) |
| 276 | end = parseExtensions(scan) |
| 277 | } else if end < len(scan.b) { |
| 278 | scan.setError(ErrSyntax) |
| 279 | scan.b = scan.b[:end] |
| 280 | } |
| 281 | } |
| 282 | if int(t.pVariant) < len(scan.b) { |
| 283 | if end < len(s) { |
| 284 | s = s[:end] |
| 285 | } |
| 286 | if len(s) > 0 && tag.Compare(s, scan.b) == 0 { |
| 287 | t.str = s |
| 288 | } else { |
| 289 | t.str = string(scan.b) |
| 290 | } |
| 291 | } else { |
| 292 | t.pVariant, t.pExt = 0, 0 |
| 293 | } |
| 294 | return t, scan.err |
| 295 | } |
| 296 | |
| 297 | // parseTag parses language, script, region and variants. |
| 298 | // It returns a Tag and the end position in the input that was parsed. |
| 299 | // If doNorm is true, then <lang>-<extlang> will be normalized to <extlang>. |
| 300 | func parseTag(scan *scanner, doNorm bool) (t Tag, end int) { |
| 301 | var e error |
| 302 | // TODO: set an error if an unknown lang, script or region is encountered. |
| 303 | t.LangID, e = getLangID(scan.token) |
| 304 | scan.setError(e) |
| 305 | scan.replace(t.LangID.String()) |
| 306 | langStart := scan.start |
| 307 | end = scan.scan() |
| 308 | for len(scan.token) == 3 && isAlpha(scan.token[0]) { |
| 309 | // From http://tools.ietf.org/html/bcp47, <lang>-<extlang> tags are equivalent |
| 310 | // to a tag of the form <extlang>. |
| 311 | if doNorm { |
| 312 | lang, e := getLangID(scan.token) |
| 313 | if lang != 0 { |
| 314 | t.LangID = lang |
| 315 | langStr := lang.String() |
| 316 | copy(scan.b[langStart:], langStr) |
| 317 | scan.b[langStart+len(langStr)] = '-' |
| 318 | scan.start = langStart + len(langStr) + 1 |
| 319 | } |
| 320 | scan.gobble(e) |
| 321 | } |
| 322 | end = scan.scan() |
| 323 | } |
| 324 | if len(scan.token) == 4 && isAlpha(scan.token[0]) { |
| 325 | t.ScriptID, e = getScriptID(script, scan.token) |
| 326 | if t.ScriptID == 0 { |
| 327 | scan.gobble(e) |
| 328 | } |
| 329 | end = scan.scan() |
| 330 | } |
| 331 | if n := len(scan.token); n >= 2 && n <= 3 { |
| 332 | t.RegionID, e = getRegionID(scan.token) |
| 333 | if t.RegionID == 0 { |
| 334 | scan.gobble(e) |
| 335 | } else { |
| 336 | scan.replace(t.RegionID.String()) |
| 337 | } |
| 338 | end = scan.scan() |
| 339 | } |
| 340 | scan.toLower(scan.start, len(scan.b)) |
| 341 | t.pVariant = byte(end) |
| 342 | end = parseVariants(scan, end, t) |
| 343 | t.pExt = uint16(end) |
| 344 | return t, end |
| 345 | } |
| 346 | |
| 347 | var separator = []byte{'-'} |
| 348 | |
| 349 | // parseVariants scans tokens as long as each token is a valid variant string. |
| 350 | // Duplicate variants are removed. |
| 351 | func parseVariants(scan *scanner, end int, t Tag) int { |
| 352 | start := scan.start |
| 353 | varIDBuf := [4]uint8{} |
| 354 | variantBuf := [4][]byte{} |
| 355 | varID := varIDBuf[:0] |
| 356 | variant := variantBuf[:0] |
| 357 | last := -1 |
| 358 | needSort := false |
| 359 | for ; len(scan.token) >= 4; scan.scan() { |
| 360 | // TODO: measure the impact of needing this conversion and redesign |
| 361 | // the data structure if there is an issue. |
| 362 | v, ok := variantIndex[string(scan.token)] |
| 363 | if !ok { |
| 364 | // unknown variant |
| 365 | // TODO: allow user-defined variants? |
| 366 | scan.gobble(NewValueError(scan.token)) |
| 367 | continue |
| 368 | } |
| 369 | varID = append(varID, v) |
| 370 | variant = append(variant, scan.token) |
| 371 | if !needSort { |
| 372 | if last < int(v) { |
| 373 | last = int(v) |
| 374 | } else { |
| 375 | needSort = true |
| 376 | // There is no legal combinations of more than 7 variants |
| 377 | // (and this is by no means a useful sequence). |
| 378 | const maxVariants = 8 |
| 379 | if len(varID) > maxVariants { |
| 380 | break |
| 381 | } |
| 382 | } |
| 383 | } |
| 384 | end = scan.end |
| 385 | } |
| 386 | if needSort { |
| 387 | sort.Sort(variantsSort{varID, variant}) |
| 388 | k, l := 0, -1 |
| 389 | for i, v := range varID { |
| 390 | w := int(v) |
| 391 | if l == w { |
| 392 | // Remove duplicates. |
| 393 | continue |
| 394 | } |
| 395 | varID[k] = varID[i] |
| 396 | variant[k] = variant[i] |
| 397 | k++ |
| 398 | l = w |
| 399 | } |
| 400 | if str := bytes.Join(variant[:k], separator); len(str) == 0 { |
| 401 | end = start - 1 |
| 402 | } else { |
| 403 | scan.resizeRange(start, end, len(str)) |
| 404 | copy(scan.b[scan.start:], str) |
| 405 | end = scan.end |
| 406 | } |
| 407 | } |
| 408 | return end |
| 409 | } |
| 410 | |
| 411 | type variantsSort struct { |
| 412 | i []uint8 |
| 413 | v [][]byte |
| 414 | } |
| 415 | |
| 416 | func (s variantsSort) Len() int { |
| 417 | return len(s.i) |
| 418 | } |
| 419 | |
| 420 | func (s variantsSort) Swap(i, j int) { |
| 421 | s.i[i], s.i[j] = s.i[j], s.i[i] |
| 422 | s.v[i], s.v[j] = s.v[j], s.v[i] |
| 423 | } |
| 424 | |
| 425 | func (s variantsSort) Less(i, j int) bool { |
| 426 | return s.i[i] < s.i[j] |
| 427 | } |
| 428 | |
| 429 | type bytesSort struct { |
| 430 | b [][]byte |
| 431 | n int // first n bytes to compare |
| 432 | } |
| 433 | |
| 434 | func (b bytesSort) Len() int { |
| 435 | return len(b.b) |
| 436 | } |
| 437 | |
| 438 | func (b bytesSort) Swap(i, j int) { |
| 439 | b.b[i], b.b[j] = b.b[j], b.b[i] |
| 440 | } |
| 441 | |
| 442 | func (b bytesSort) Less(i, j int) bool { |
| 443 | for k := 0; k < b.n; k++ { |
| 444 | if b.b[i][k] == b.b[j][k] { |
| 445 | continue |
| 446 | } |
| 447 | return b.b[i][k] < b.b[j][k] |
| 448 | } |
| 449 | return false |
| 450 | } |
| 451 | |
| 452 | // parseExtensions parses and normalizes the extensions in the buffer. |
| 453 | // It returns the last position of scan.b that is part of any extension. |
| 454 | // It also trims scan.b to remove excess parts accordingly. |
| 455 | func parseExtensions(scan *scanner) int { |
| 456 | start := scan.start |
| 457 | exts := [][]byte{} |
| 458 | private := []byte{} |
| 459 | end := scan.end |
| 460 | for len(scan.token) == 1 { |
| 461 | extStart := scan.start |
| 462 | ext := scan.token[0] |
| 463 | end = parseExtension(scan) |
| 464 | extension := scan.b[extStart:end] |
| 465 | if len(extension) < 3 || (ext != 'x' && len(extension) < 4) { |
| 466 | scan.setError(ErrSyntax) |
| 467 | end = extStart |
| 468 | continue |
| 469 | } else if start == extStart && (ext == 'x' || scan.start == len(scan.b)) { |
| 470 | scan.b = scan.b[:end] |
| 471 | return end |
| 472 | } else if ext == 'x' { |
| 473 | private = extension |
| 474 | break |
| 475 | } |
| 476 | exts = append(exts, extension) |
| 477 | } |
| 478 | sort.Sort(bytesSort{exts, 1}) |
| 479 | if len(private) > 0 { |
| 480 | exts = append(exts, private) |
| 481 | } |
| 482 | scan.b = scan.b[:start] |
| 483 | if len(exts) > 0 { |
| 484 | scan.b = append(scan.b, bytes.Join(exts, separator)...) |
| 485 | } else if start > 0 { |
| 486 | // Strip trailing '-'. |
| 487 | scan.b = scan.b[:start-1] |
| 488 | } |
| 489 | return end |
| 490 | } |
| 491 | |
| 492 | // parseExtension parses a single extension and returns the position of |
| 493 | // the extension end. |
| 494 | func parseExtension(scan *scanner) int { |
| 495 | start, end := scan.start, scan.end |
| 496 | switch scan.token[0] { |
| 497 | case 'u': // https://www.ietf.org/rfc/rfc6067.txt |
| 498 | attrStart := end |
| 499 | scan.scan() |
| 500 | for last := []byte{}; len(scan.token) > 2; scan.scan() { |
| 501 | if bytes.Compare(scan.token, last) != -1 { |
| 502 | // Attributes are unsorted. Start over from scratch. |
| 503 | p := attrStart + 1 |
| 504 | scan.next = p |
| 505 | attrs := [][]byte{} |
| 506 | for scan.scan(); len(scan.token) > 2; scan.scan() { |
| 507 | attrs = append(attrs, scan.token) |
| 508 | end = scan.end |
| 509 | } |
| 510 | sort.Sort(bytesSort{attrs, 3}) |
| 511 | copy(scan.b[p:], bytes.Join(attrs, separator)) |
| 512 | break |
| 513 | } |
| 514 | last = scan.token |
| 515 | end = scan.end |
| 516 | } |
| 517 | // Scan key-type sequences. A key is of length 2 and may be followed |
| 518 | // by 0 or more "type" subtags from 3 to the maximum of 8 letters. |
| 519 | var last, key []byte |
| 520 | for attrEnd := end; len(scan.token) == 2; last = key { |
| 521 | key = scan.token |
| 522 | end = scan.end |
| 523 | for scan.scan(); end < scan.end && len(scan.token) > 2; scan.scan() { |
| 524 | end = scan.end |
| 525 | } |
| 526 | // TODO: check key value validity |
| 527 | if bytes.Compare(key, last) != 1 || scan.err != nil { |
| 528 | // We have an invalid key or the keys are not sorted. |
| 529 | // Start scanning keys from scratch and reorder. |
| 530 | p := attrEnd + 1 |
| 531 | scan.next = p |
| 532 | keys := [][]byte{} |
| 533 | for scan.scan(); len(scan.token) == 2; { |
| 534 | keyStart := scan.start |
| 535 | end = scan.end |
| 536 | for scan.scan(); end < scan.end && len(scan.token) > 2; scan.scan() { |
| 537 | end = scan.end |
| 538 | } |
| 539 | keys = append(keys, scan.b[keyStart:end]) |
| 540 | } |
| 541 | sort.Stable(bytesSort{keys, 2}) |
| 542 | if n := len(keys); n > 0 { |
| 543 | k := 0 |
| 544 | for i := 1; i < n; i++ { |
| 545 | if !bytes.Equal(keys[k][:2], keys[i][:2]) { |
| 546 | k++ |
| 547 | keys[k] = keys[i] |
| 548 | } else if !bytes.Equal(keys[k], keys[i]) { |
| 549 | scan.setError(ErrDuplicateKey) |
| 550 | } |
| 551 | } |
| 552 | keys = keys[:k+1] |
| 553 | } |
| 554 | reordered := bytes.Join(keys, separator) |
| 555 | if e := p + len(reordered); e < end { |
| 556 | scan.deleteRange(e, end) |
| 557 | end = e |
| 558 | } |
| 559 | copy(scan.b[p:], reordered) |
| 560 | break |
| 561 | } |
| 562 | } |
| 563 | case 't': // https://www.ietf.org/rfc/rfc6497.txt |
| 564 | scan.scan() |
| 565 | if n := len(scan.token); n >= 2 && n <= 3 && isAlpha(scan.token[1]) { |
| 566 | _, end = parseTag(scan, false) |
| 567 | scan.toLower(start, end) |
| 568 | } |
| 569 | for len(scan.token) == 2 && !isAlpha(scan.token[1]) { |
| 570 | end = scan.acceptMinSize(3) |
| 571 | } |
| 572 | case 'x': |
| 573 | end = scan.acceptMinSize(1) |
| 574 | default: |
| 575 | end = scan.acceptMinSize(2) |
| 576 | } |
| 577 | return end |
| 578 | } |
| 579 | |
| 580 | // getExtension returns the name, body and end position of the extension. |
| 581 | func getExtension(s string, p int) (end int, ext string) { |
| 582 | if s[p] == '-' { |
| 583 | p++ |
| 584 | } |
| 585 | if s[p] == 'x' { |
| 586 | return len(s), s[p:] |
| 587 | } |
| 588 | end = nextExtension(s, p) |
| 589 | return end, s[p:end] |
| 590 | } |
| 591 | |
| 592 | // nextExtension finds the next extension within the string, searching |
| 593 | // for the -<char>- pattern from position p. |
| 594 | // In the fast majority of cases, language tags will have at most |
| 595 | // one extension and extensions tend to be small. |
| 596 | func nextExtension(s string, p int) int { |
| 597 | for n := len(s) - 3; p < n; { |
| 598 | if s[p] == '-' { |
| 599 | if s[p+2] == '-' { |
| 600 | return p |
| 601 | } |
| 602 | p += 3 |
| 603 | } else { |
| 604 | p++ |
| 605 | } |
| 606 | } |
| 607 | return len(s) |
| 608 | } |