Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 1 | // Copyright 2009 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 bytes implements functions for the manipulation of byte slices. |
| 6 | // It is analogous to the facilities of the strings package. |
| 7 | package bytes |
| 8 | |
| 9 | import ( |
| 10 | "unicode" |
| 11 | "unicode/utf8" |
| 12 | ) |
| 13 | |
| 14 | func equalPortable(a, b []byte) bool { |
| 15 | if len(a) != len(b) { |
| 16 | return false |
| 17 | } |
| 18 | for i, c := range a { |
| 19 | if c != b[i] { |
| 20 | return false |
| 21 | } |
| 22 | } |
| 23 | return true |
| 24 | } |
| 25 | |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 26 | // explode splits s into a slice of UTF-8 sequences, one per Unicode code point (still slices of bytes), |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 27 | // up to a maximum of n byte slices. Invalid UTF-8 sequences are chopped into individual bytes. |
| 28 | func explode(s []byte, n int) [][]byte { |
| 29 | if n <= 0 { |
| 30 | n = len(s) |
| 31 | } |
| 32 | a := make([][]byte, n) |
| 33 | var size int |
| 34 | na := 0 |
| 35 | for len(s) > 0 { |
| 36 | if na+1 >= n { |
| 37 | a[na] = s |
| 38 | na++ |
| 39 | break |
| 40 | } |
| 41 | _, size = utf8.DecodeRune(s) |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 42 | a[na] = s[0:size:size] |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 43 | s = s[size:] |
| 44 | na++ |
| 45 | } |
| 46 | return a[0:na] |
| 47 | } |
| 48 | |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 49 | // countGeneric actually implements Count |
| 50 | func countGeneric(s, sep []byte) int { |
| 51 | // special case |
| 52 | if len(sep) == 0 { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 53 | return utf8.RuneCount(s) + 1 |
| 54 | } |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 55 | n := 0 |
| 56 | for { |
| 57 | i := Index(s, sep) |
| 58 | if i == -1 { |
| 59 | return n |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 60 | } |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 61 | n++ |
| 62 | s = s[i+len(sep):] |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 63 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 64 | } |
| 65 | |
| 66 | // Contains reports whether subslice is within b. |
| 67 | func Contains(b, subslice []byte) bool { |
| 68 | return Index(b, subslice) != -1 |
| 69 | } |
| 70 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 71 | // ContainsAny reports whether any of the UTF-8-encoded code points in chars are within b. |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 72 | func ContainsAny(b []byte, chars string) bool { |
| 73 | return IndexAny(b, chars) >= 0 |
| 74 | } |
| 75 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 76 | // ContainsRune reports whether the rune is contained in the UTF-8-encoded byte slice b. |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 77 | func ContainsRune(b []byte, r rune) bool { |
| 78 | return IndexRune(b, r) >= 0 |
| 79 | } |
| 80 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 81 | func indexBytePortable(s []byte, c byte) int { |
| 82 | for i, b := range s { |
| 83 | if b == c { |
| 84 | return i |
| 85 | } |
| 86 | } |
| 87 | return -1 |
| 88 | } |
| 89 | |
| 90 | // LastIndex returns the index of the last instance of sep in s, or -1 if sep is not present in s. |
| 91 | func LastIndex(s, sep []byte) int { |
| 92 | n := len(sep) |
| 93 | if n == 0 { |
| 94 | return len(s) |
| 95 | } |
| 96 | c := sep[0] |
| 97 | for i := len(s) - n; i >= 0; i-- { |
| 98 | if s[i] == c && (n == 1 || Equal(s[i:i+n], sep)) { |
| 99 | return i |
| 100 | } |
| 101 | } |
| 102 | return -1 |
| 103 | } |
| 104 | |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 105 | // LastIndexByte returns the index of the last instance of c in s, or -1 if c is not present in s. |
| 106 | func LastIndexByte(s []byte, c byte) int { |
| 107 | for i := len(s) - 1; i >= 0; i-- { |
| 108 | if s[i] == c { |
| 109 | return i |
| 110 | } |
| 111 | } |
| 112 | return -1 |
| 113 | } |
| 114 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 115 | // IndexRune interprets s as a sequence of UTF-8-encoded code points. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 116 | // It returns the byte index of the first occurrence in s of the given rune. |
| 117 | // It returns -1 if rune is not present in s. |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 118 | // If r is utf8.RuneError, it returns the first instance of any |
| 119 | // invalid UTF-8 byte sequence. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 120 | func IndexRune(s []byte, r rune) int { |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 121 | switch { |
| 122 | case 0 <= r && r < utf8.RuneSelf: |
| 123 | return IndexByte(s, byte(r)) |
| 124 | case r == utf8.RuneError: |
| 125 | for i := 0; i < len(s); { |
| 126 | r1, n := utf8.DecodeRune(s[i:]) |
| 127 | if r1 == utf8.RuneError { |
| 128 | return i |
| 129 | } |
| 130 | i += n |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 131 | } |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 132 | return -1 |
| 133 | case !utf8.ValidRune(r): |
| 134 | return -1 |
| 135 | default: |
| 136 | var b [utf8.UTFMax]byte |
| 137 | n := utf8.EncodeRune(b[:], r) |
| 138 | return Index(s, b[:n]) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 139 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 140 | } |
| 141 | |
| 142 | // IndexAny interprets s as a sequence of UTF-8-encoded Unicode code points. |
| 143 | // It returns the byte index of the first occurrence in s of any of the Unicode |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 144 | // code points in chars. It returns -1 if chars is empty or if there is no code |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 145 | // point in common. |
| 146 | func IndexAny(s []byte, chars string) int { |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 147 | if chars == "" { |
| 148 | // Avoid scanning all of s. |
| 149 | return -1 |
| 150 | } |
| 151 | if len(s) > 8 { |
| 152 | if as, isASCII := makeASCIISet(chars); isASCII { |
| 153 | for i, c := range s { |
| 154 | if as.contains(c) { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 155 | return i |
| 156 | } |
| 157 | } |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 158 | return -1 |
| 159 | } |
| 160 | } |
| 161 | var width int |
| 162 | for i := 0; i < len(s); i += width { |
| 163 | r := rune(s[i]) |
| 164 | if r < utf8.RuneSelf { |
| 165 | width = 1 |
| 166 | } else { |
| 167 | r, width = utf8.DecodeRune(s[i:]) |
| 168 | } |
| 169 | for _, ch := range chars { |
| 170 | if r == ch { |
| 171 | return i |
| 172 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 173 | } |
| 174 | } |
| 175 | return -1 |
| 176 | } |
| 177 | |
| 178 | // LastIndexAny interprets s as a sequence of UTF-8-encoded Unicode code |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 179 | // points. It returns the byte index of the last occurrence in s of any of |
| 180 | // the Unicode code points in chars. It returns -1 if chars is empty or if |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 181 | // there is no code point in common. |
| 182 | func LastIndexAny(s []byte, chars string) int { |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 183 | if chars == "" { |
| 184 | // Avoid scanning all of s. |
| 185 | return -1 |
| 186 | } |
| 187 | if len(s) > 8 { |
| 188 | if as, isASCII := makeASCIISet(chars); isASCII { |
| 189 | for i := len(s) - 1; i >= 0; i-- { |
| 190 | if as.contains(s[i]) { |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 191 | return i |
| 192 | } |
| 193 | } |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 194 | return -1 |
| 195 | } |
| 196 | } |
| 197 | for i := len(s); i > 0; { |
| 198 | r, size := utf8.DecodeLastRune(s[:i]) |
| 199 | i -= size |
| 200 | for _, c := range chars { |
| 201 | if r == c { |
| 202 | return i |
| 203 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 204 | } |
| 205 | } |
| 206 | return -1 |
| 207 | } |
| 208 | |
| 209 | // Generic split: splits after each instance of sep, |
| 210 | // including sepSave bytes of sep in the subslices. |
| 211 | func genSplit(s, sep []byte, sepSave, n int) [][]byte { |
| 212 | if n == 0 { |
| 213 | return nil |
| 214 | } |
| 215 | if len(sep) == 0 { |
| 216 | return explode(s, n) |
| 217 | } |
| 218 | if n < 0 { |
| 219 | n = Count(s, sep) + 1 |
| 220 | } |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 221 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 222 | a := make([][]byte, n) |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 223 | n-- |
| 224 | i := 0 |
| 225 | for i < n { |
| 226 | m := Index(s, sep) |
| 227 | if m < 0 { |
| 228 | break |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 229 | } |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 230 | a[i] = s[: m+sepSave : m+sepSave] |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 231 | s = s[m+len(sep):] |
| 232 | i++ |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 233 | } |
Dan Willemsen | d279748 | 2017-07-26 13:13:13 -0700 | [diff] [blame] | 234 | a[i] = s |
| 235 | return a[:i+1] |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 236 | } |
| 237 | |
| 238 | // SplitN slices s into subslices separated by sep and returns a slice of |
| 239 | // the subslices between those separators. |
| 240 | // If sep is empty, SplitN splits after each UTF-8 sequence. |
| 241 | // The count determines the number of subslices to return: |
| 242 | // n > 0: at most n subslices; the last subslice will be the unsplit remainder. |
| 243 | // n == 0: the result is nil (zero subslices) |
| 244 | // n < 0: all subslices |
| 245 | func SplitN(s, sep []byte, n int) [][]byte { return genSplit(s, sep, 0, n) } |
| 246 | |
| 247 | // SplitAfterN slices s into subslices after each instance of sep and |
| 248 | // returns a slice of those subslices. |
| 249 | // If sep is empty, SplitAfterN splits after each UTF-8 sequence. |
| 250 | // The count determines the number of subslices to return: |
| 251 | // n > 0: at most n subslices; the last subslice will be the unsplit remainder. |
| 252 | // n == 0: the result is nil (zero subslices) |
| 253 | // n < 0: all subslices |
| 254 | func SplitAfterN(s, sep []byte, n int) [][]byte { |
| 255 | return genSplit(s, sep, len(sep), n) |
| 256 | } |
| 257 | |
| 258 | // Split slices s into all subslices separated by sep and returns a slice of |
| 259 | // the subslices between those separators. |
| 260 | // If sep is empty, Split splits after each UTF-8 sequence. |
| 261 | // It is equivalent to SplitN with a count of -1. |
| 262 | func Split(s, sep []byte) [][]byte { return genSplit(s, sep, 0, -1) } |
| 263 | |
| 264 | // SplitAfter slices s into all subslices after each instance of sep and |
| 265 | // returns a slice of those subslices. |
| 266 | // If sep is empty, SplitAfter splits after each UTF-8 sequence. |
| 267 | // It is equivalent to SplitAfterN with a count of -1. |
| 268 | func SplitAfter(s, sep []byte) [][]byte { |
| 269 | return genSplit(s, sep, len(sep), -1) |
| 270 | } |
| 271 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 272 | var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1} |
| 273 | |
| 274 | // Fields interprets s as a sequence of UTF-8-encoded code points. |
| 275 | // It splits the slice s around each instance of one or more consecutive white space |
| 276 | // characters, as defined by unicode.IsSpace, returning a slice of subslices of s or an |
| 277 | // empty slice if s contains only white space. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 278 | func Fields(s []byte) [][]byte { |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 279 | // First count the fields. |
| 280 | // This is an exact count if s is ASCII, otherwise it is an approximation. |
| 281 | n := 0 |
| 282 | wasSpace := 1 |
| 283 | // setBits is used to track which bits are set in the bytes of s. |
| 284 | setBits := uint8(0) |
| 285 | for i := 0; i < len(s); i++ { |
| 286 | r := s[i] |
| 287 | setBits |= r |
| 288 | isSpace := int(asciiSpace[r]) |
| 289 | n += wasSpace & ^isSpace |
| 290 | wasSpace = isSpace |
| 291 | } |
| 292 | |
| 293 | if setBits >= utf8.RuneSelf { |
| 294 | // Some runes in the input slice are not ASCII. |
| 295 | return FieldsFunc(s, unicode.IsSpace) |
| 296 | } |
| 297 | |
| 298 | // ASCII fast path |
| 299 | a := make([][]byte, n) |
| 300 | na := 0 |
| 301 | fieldStart := 0 |
| 302 | i := 0 |
| 303 | // Skip spaces in the front of the input. |
| 304 | for i < len(s) && asciiSpace[s[i]] != 0 { |
| 305 | i++ |
| 306 | } |
| 307 | fieldStart = i |
| 308 | for i < len(s) { |
| 309 | if asciiSpace[s[i]] == 0 { |
| 310 | i++ |
| 311 | continue |
| 312 | } |
| 313 | a[na] = s[fieldStart:i:i] |
| 314 | na++ |
| 315 | i++ |
| 316 | // Skip spaces in between fields. |
| 317 | for i < len(s) && asciiSpace[s[i]] != 0 { |
| 318 | i++ |
| 319 | } |
| 320 | fieldStart = i |
| 321 | } |
| 322 | if fieldStart < len(s) { // Last field might end at EOF. |
| 323 | a[na] = s[fieldStart:len(s):len(s)] |
| 324 | } |
| 325 | return a |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 326 | } |
| 327 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 328 | // FieldsFunc interprets s as a sequence of UTF-8-encoded code points. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 329 | // It splits the slice s at each run of code points c satisfying f(c) and |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 330 | // returns a slice of subslices of s. If all code points in s satisfy f(c), or |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 331 | // len(s) == 0, an empty slice is returned. |
| 332 | // FieldsFunc makes no guarantees about the order in which it calls f(c). |
| 333 | // If f does not return consistent results for a given c, FieldsFunc may crash. |
| 334 | func FieldsFunc(s []byte, f func(rune) bool) [][]byte { |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 335 | // A span is used to record a slice of s of the form s[start:end]. |
| 336 | // The start index is inclusive and the end index is exclusive. |
| 337 | type span struct { |
| 338 | start int |
| 339 | end int |
| 340 | } |
| 341 | spans := make([]span, 0, 32) |
| 342 | |
| 343 | // Find the field start and end indices. |
| 344 | wasField := false |
| 345 | fromIndex := 0 |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 346 | for i := 0; i < len(s); { |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 347 | size := 1 |
| 348 | r := rune(s[i]) |
| 349 | if r >= utf8.RuneSelf { |
| 350 | r, size = utf8.DecodeRune(s[i:]) |
| 351 | } |
| 352 | if f(r) { |
| 353 | if wasField { |
| 354 | spans = append(spans, span{start: fromIndex, end: i}) |
| 355 | wasField = false |
| 356 | } |
| 357 | } else { |
| 358 | if !wasField { |
| 359 | fromIndex = i |
| 360 | wasField = true |
| 361 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 362 | } |
| 363 | i += size |
| 364 | } |
| 365 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 366 | // Last field might end at EOF. |
| 367 | if wasField { |
| 368 | spans = append(spans, span{fromIndex, len(s)}) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 369 | } |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 370 | |
| 371 | // Create subslices from recorded field indices. |
| 372 | a := make([][]byte, len(spans)) |
| 373 | for i, span := range spans { |
| 374 | a[i] = s[span.start:span.end:span.end] |
| 375 | } |
| 376 | |
| 377 | return a |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 378 | } |
| 379 | |
| 380 | // Join concatenates the elements of s to create a new byte slice. The separator |
| 381 | // sep is placed between elements in the resulting slice. |
| 382 | func Join(s [][]byte, sep []byte) []byte { |
| 383 | if len(s) == 0 { |
| 384 | return []byte{} |
| 385 | } |
| 386 | if len(s) == 1 { |
| 387 | // Just return a copy. |
| 388 | return append([]byte(nil), s[0]...) |
| 389 | } |
| 390 | n := len(sep) * (len(s) - 1) |
| 391 | for _, v := range s { |
| 392 | n += len(v) |
| 393 | } |
| 394 | |
| 395 | b := make([]byte, n) |
| 396 | bp := copy(b, s[0]) |
| 397 | for _, v := range s[1:] { |
| 398 | bp += copy(b[bp:], sep) |
| 399 | bp += copy(b[bp:], v) |
| 400 | } |
| 401 | return b |
| 402 | } |
| 403 | |
| 404 | // HasPrefix tests whether the byte slice s begins with prefix. |
| 405 | func HasPrefix(s, prefix []byte) bool { |
| 406 | return len(s) >= len(prefix) && Equal(s[0:len(prefix)], prefix) |
| 407 | } |
| 408 | |
| 409 | // HasSuffix tests whether the byte slice s ends with suffix. |
| 410 | func HasSuffix(s, suffix []byte) bool { |
| 411 | return len(s) >= len(suffix) && Equal(s[len(s)-len(suffix):], suffix) |
| 412 | } |
| 413 | |
| 414 | // Map returns a copy of the byte slice s with all its characters modified |
| 415 | // according to the mapping function. If mapping returns a negative value, the character is |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 416 | // dropped from the byte slice with no replacement. The characters in s and the |
| 417 | // output are interpreted as UTF-8-encoded code points. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 418 | func Map(mapping func(r rune) rune, s []byte) []byte { |
| 419 | // In the worst case, the slice can grow when mapped, making |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 420 | // things unpleasant. But it's so rare we barge in assuming it's |
| 421 | // fine. It could also shrink but that falls out naturally. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 422 | maxbytes := len(s) // length of b |
| 423 | nbytes := 0 // number of bytes encoded in b |
| 424 | b := make([]byte, maxbytes) |
| 425 | for i := 0; i < len(s); { |
| 426 | wid := 1 |
| 427 | r := rune(s[i]) |
| 428 | if r >= utf8.RuneSelf { |
| 429 | r, wid = utf8.DecodeRune(s[i:]) |
| 430 | } |
| 431 | r = mapping(r) |
| 432 | if r >= 0 { |
| 433 | rl := utf8.RuneLen(r) |
| 434 | if rl < 0 { |
| 435 | rl = len(string(utf8.RuneError)) |
| 436 | } |
| 437 | if nbytes+rl > maxbytes { |
| 438 | // Grow the buffer. |
| 439 | maxbytes = maxbytes*2 + utf8.UTFMax |
| 440 | nb := make([]byte, maxbytes) |
| 441 | copy(nb, b[0:nbytes]) |
| 442 | b = nb |
| 443 | } |
| 444 | nbytes += utf8.EncodeRune(b[nbytes:maxbytes], r) |
| 445 | } |
| 446 | i += wid |
| 447 | } |
| 448 | return b[0:nbytes] |
| 449 | } |
| 450 | |
| 451 | // Repeat returns a new byte slice consisting of count copies of b. |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 452 | // |
| 453 | // It panics if count is negative or if |
| 454 | // the result of (len(b) * count) overflows. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 455 | func Repeat(b []byte, count int) []byte { |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 456 | // Since we cannot return an error on overflow, |
| 457 | // we should panic if the repeat will generate |
| 458 | // an overflow. |
| 459 | // See Issue golang.org/issue/16237. |
| 460 | if count < 0 { |
| 461 | panic("bytes: negative Repeat count") |
| 462 | } else if count > 0 && len(b)*count/count != len(b) { |
| 463 | panic("bytes: Repeat count causes overflow") |
| 464 | } |
| 465 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 466 | nb := make([]byte, len(b)*count) |
| 467 | bp := copy(nb, b) |
| 468 | for bp < len(nb) { |
| 469 | copy(nb[bp:], nb[:bp]) |
| 470 | bp *= 2 |
| 471 | } |
| 472 | return nb |
| 473 | } |
| 474 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 475 | // ToUpper treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters within it mapped to their upper case. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 476 | func ToUpper(s []byte) []byte { return Map(unicode.ToUpper, s) } |
| 477 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 478 | // ToLower treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their lower case. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 479 | func ToLower(s []byte) []byte { return Map(unicode.ToLower, s) } |
| 480 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 481 | // ToTitle treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their title case. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 482 | func ToTitle(s []byte) []byte { return Map(unicode.ToTitle, s) } |
| 483 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 484 | // ToUpperSpecial treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 485 | // upper case, giving priority to the special casing rules. |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 486 | func ToUpperSpecial(c unicode.SpecialCase, s []byte) []byte { |
| 487 | return Map(func(r rune) rune { return c.ToUpper(r) }, s) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 488 | } |
| 489 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 490 | // ToLowerSpecial treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 491 | // lower case, giving priority to the special casing rules. |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 492 | func ToLowerSpecial(c unicode.SpecialCase, s []byte) []byte { |
| 493 | return Map(func(r rune) rune { return c.ToLower(r) }, s) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 494 | } |
| 495 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 496 | // ToTitleSpecial treats s as UTF-8-encoded bytes and returns a copy with all the Unicode letters mapped to their |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 497 | // title case, giving priority to the special casing rules. |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 498 | func ToTitleSpecial(c unicode.SpecialCase, s []byte) []byte { |
| 499 | return Map(func(r rune) rune { return c.ToTitle(r) }, s) |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 500 | } |
| 501 | |
| 502 | // isSeparator reports whether the rune could mark a word boundary. |
| 503 | // TODO: update when package unicode captures more of the properties. |
| 504 | func isSeparator(r rune) bool { |
| 505 | // ASCII alphanumerics and underscore are not separators |
| 506 | if r <= 0x7F { |
| 507 | switch { |
| 508 | case '0' <= r && r <= '9': |
| 509 | return false |
| 510 | case 'a' <= r && r <= 'z': |
| 511 | return false |
| 512 | case 'A' <= r && r <= 'Z': |
| 513 | return false |
| 514 | case r == '_': |
| 515 | return false |
| 516 | } |
| 517 | return true |
| 518 | } |
| 519 | // Letters and digits are not separators |
| 520 | if unicode.IsLetter(r) || unicode.IsDigit(r) { |
| 521 | return false |
| 522 | } |
| 523 | // Otherwise, all we can do for now is treat spaces as separators. |
| 524 | return unicode.IsSpace(r) |
| 525 | } |
| 526 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 527 | // Title treats s as UTF-8-encoded bytes and returns a copy with all Unicode letters that begin |
| 528 | // words mapped to their title case. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 529 | // |
Dan Willemsen | 09eb3b1 | 2015-09-16 14:34:17 -0700 | [diff] [blame] | 530 | // BUG(rsc): The rule Title uses for word boundaries does not handle Unicode punctuation properly. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 531 | func Title(s []byte) []byte { |
| 532 | // Use a closure here to remember state. |
| 533 | // Hackish but effective. Depends on Map scanning in order and calling |
| 534 | // the closure once per rune. |
| 535 | prev := ' ' |
| 536 | return Map( |
| 537 | func(r rune) rune { |
| 538 | if isSeparator(prev) { |
| 539 | prev = r |
| 540 | return unicode.ToTitle(r) |
| 541 | } |
| 542 | prev = r |
| 543 | return r |
| 544 | }, |
| 545 | s) |
| 546 | } |
| 547 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 548 | // TrimLeftFunc treats s as UTF-8-encoded bytes and returns a subslice of s by slicing off |
| 549 | // all leading UTF-8-encoded code points c that satisfy f(c). |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 550 | func TrimLeftFunc(s []byte, f func(r rune) bool) []byte { |
| 551 | i := indexFunc(s, f, false) |
| 552 | if i == -1 { |
| 553 | return nil |
| 554 | } |
| 555 | return s[i:] |
| 556 | } |
| 557 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 558 | // TrimRightFunc returns a subslice of s by slicing off all trailing |
| 559 | // UTF-8-encoded code points c that satisfy f(c). |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 560 | func TrimRightFunc(s []byte, f func(r rune) bool) []byte { |
| 561 | i := lastIndexFunc(s, f, false) |
| 562 | if i >= 0 && s[i] >= utf8.RuneSelf { |
| 563 | _, wid := utf8.DecodeRune(s[i:]) |
| 564 | i += wid |
| 565 | } else { |
| 566 | i++ |
| 567 | } |
| 568 | return s[0:i] |
| 569 | } |
| 570 | |
| 571 | // TrimFunc returns a subslice of s by slicing off all leading and trailing |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 572 | // UTF-8-encoded code points c that satisfy f(c). |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 573 | func TrimFunc(s []byte, f func(r rune) bool) []byte { |
| 574 | return TrimRightFunc(TrimLeftFunc(s, f), f) |
| 575 | } |
| 576 | |
| 577 | // TrimPrefix returns s without the provided leading prefix string. |
| 578 | // If s doesn't start with prefix, s is returned unchanged. |
| 579 | func TrimPrefix(s, prefix []byte) []byte { |
| 580 | if HasPrefix(s, prefix) { |
| 581 | return s[len(prefix):] |
| 582 | } |
| 583 | return s |
| 584 | } |
| 585 | |
| 586 | // TrimSuffix returns s without the provided trailing suffix string. |
| 587 | // If s doesn't end with suffix, s is returned unchanged. |
| 588 | func TrimSuffix(s, suffix []byte) []byte { |
| 589 | if HasSuffix(s, suffix) { |
| 590 | return s[:len(s)-len(suffix)] |
| 591 | } |
| 592 | return s |
| 593 | } |
| 594 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 595 | // IndexFunc interprets s as a sequence of UTF-8-encoded code points. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 596 | // It returns the byte index in s of the first Unicode |
| 597 | // code point satisfying f(c), or -1 if none do. |
| 598 | func IndexFunc(s []byte, f func(r rune) bool) int { |
| 599 | return indexFunc(s, f, true) |
| 600 | } |
| 601 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 602 | // LastIndexFunc interprets s as a sequence of UTF-8-encoded code points. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 603 | // It returns the byte index in s of the last Unicode |
| 604 | // code point satisfying f(c), or -1 if none do. |
| 605 | func LastIndexFunc(s []byte, f func(r rune) bool) int { |
| 606 | return lastIndexFunc(s, f, true) |
| 607 | } |
| 608 | |
| 609 | // indexFunc is the same as IndexFunc except that if |
| 610 | // truth==false, the sense of the predicate function is |
| 611 | // inverted. |
| 612 | func indexFunc(s []byte, f func(r rune) bool, truth bool) int { |
| 613 | start := 0 |
| 614 | for start < len(s) { |
| 615 | wid := 1 |
| 616 | r := rune(s[start]) |
| 617 | if r >= utf8.RuneSelf { |
| 618 | r, wid = utf8.DecodeRune(s[start:]) |
| 619 | } |
| 620 | if f(r) == truth { |
| 621 | return start |
| 622 | } |
| 623 | start += wid |
| 624 | } |
| 625 | return -1 |
| 626 | } |
| 627 | |
| 628 | // lastIndexFunc is the same as LastIndexFunc except that if |
| 629 | // truth==false, the sense of the predicate function is |
| 630 | // inverted. |
| 631 | func lastIndexFunc(s []byte, f func(r rune) bool, truth bool) int { |
| 632 | for i := len(s); i > 0; { |
| 633 | r, size := rune(s[i-1]), 1 |
| 634 | if r >= utf8.RuneSelf { |
| 635 | r, size = utf8.DecodeLastRune(s[0:i]) |
| 636 | } |
| 637 | i -= size |
| 638 | if f(r) == truth { |
| 639 | return i |
| 640 | } |
| 641 | } |
| 642 | return -1 |
| 643 | } |
| 644 | |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 645 | // asciiSet is a 32-byte value, where each bit represents the presence of a |
| 646 | // given ASCII character in the set. The 128-bits of the lower 16 bytes, |
| 647 | // starting with the least-significant bit of the lowest word to the |
| 648 | // most-significant bit of the highest word, map to the full range of all |
| 649 | // 128 ASCII characters. The 128-bits of the upper 16 bytes will be zeroed, |
| 650 | // ensuring that any non-ASCII character will be reported as not in the set. |
| 651 | type asciiSet [8]uint32 |
| 652 | |
| 653 | // makeASCIISet creates a set of ASCII characters and reports whether all |
| 654 | // characters in chars are ASCII. |
| 655 | func makeASCIISet(chars string) (as asciiSet, ok bool) { |
| 656 | for i := 0; i < len(chars); i++ { |
| 657 | c := chars[i] |
| 658 | if c >= utf8.RuneSelf { |
| 659 | return as, false |
| 660 | } |
| 661 | as[c>>5] |= 1 << uint(c&31) |
| 662 | } |
| 663 | return as, true |
| 664 | } |
| 665 | |
| 666 | // contains reports whether c is inside the set. |
| 667 | func (as *asciiSet) contains(c byte) bool { |
| 668 | return (as[c>>5] & (1 << uint(c&31))) != 0 |
| 669 | } |
| 670 | |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 671 | func makeCutsetFunc(cutset string) func(r rune) bool { |
Dan Willemsen | ebae302 | 2017-01-13 23:01:08 -0800 | [diff] [blame] | 672 | if len(cutset) == 1 && cutset[0] < utf8.RuneSelf { |
| 673 | return func(r rune) bool { |
| 674 | return r == rune(cutset[0]) |
| 675 | } |
| 676 | } |
| 677 | if as, isASCII := makeASCIISet(cutset); isASCII { |
| 678 | return func(r rune) bool { |
| 679 | return r < utf8.RuneSelf && as.contains(byte(r)) |
| 680 | } |
| 681 | } |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 682 | return func(r rune) bool { |
| 683 | for _, c := range cutset { |
| 684 | if c == r { |
| 685 | return true |
| 686 | } |
| 687 | } |
| 688 | return false |
| 689 | } |
| 690 | } |
| 691 | |
| 692 | // Trim returns a subslice of s by slicing off all leading and |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 693 | // trailing UTF-8-encoded code points contained in cutset. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 694 | func Trim(s []byte, cutset string) []byte { |
| 695 | return TrimFunc(s, makeCutsetFunc(cutset)) |
| 696 | } |
| 697 | |
| 698 | // TrimLeft returns a subslice of s by slicing off all leading |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 699 | // UTF-8-encoded code points contained in cutset. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 700 | func TrimLeft(s []byte, cutset string) []byte { |
| 701 | return TrimLeftFunc(s, makeCutsetFunc(cutset)) |
| 702 | } |
| 703 | |
| 704 | // TrimRight returns a subslice of s by slicing off all trailing |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 705 | // UTF-8-encoded code points that are contained in cutset. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 706 | func TrimRight(s []byte, cutset string) []byte { |
| 707 | return TrimRightFunc(s, makeCutsetFunc(cutset)) |
| 708 | } |
| 709 | |
| 710 | // TrimSpace returns a subslice of s by slicing off all leading and |
| 711 | // trailing white space, as defined by Unicode. |
| 712 | func TrimSpace(s []byte) []byte { |
| 713 | return TrimFunc(s, unicode.IsSpace) |
| 714 | } |
| 715 | |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 716 | // Runes interprets s as a sequence of UTF-8-encoded code points. |
| 717 | // It returns a slice of runes (Unicode code points) equivalent to s. |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 718 | func Runes(s []byte) []rune { |
| 719 | t := make([]rune, utf8.RuneCount(s)) |
| 720 | i := 0 |
| 721 | for len(s) > 0 { |
| 722 | r, l := utf8.DecodeRune(s) |
| 723 | t[i] = r |
| 724 | i++ |
| 725 | s = s[l:] |
| 726 | } |
| 727 | return t |
| 728 | } |
| 729 | |
| 730 | // Replace returns a copy of the slice s with the first n |
| 731 | // non-overlapping instances of old replaced by new. |
| 732 | // If old is empty, it matches at the beginning of the slice |
| 733 | // and after each UTF-8 sequence, yielding up to k+1 replacements |
| 734 | // for a k-rune slice. |
| 735 | // If n < 0, there is no limit on the number of replacements. |
| 736 | func Replace(s, old, new []byte, n int) []byte { |
| 737 | m := 0 |
| 738 | if n != 0 { |
| 739 | // Compute number of replacements. |
| 740 | m = Count(s, old) |
| 741 | } |
| 742 | if m == 0 { |
| 743 | // Just return a copy. |
| 744 | return append([]byte(nil), s...) |
| 745 | } |
| 746 | if n < 0 || m < n { |
| 747 | n = m |
| 748 | } |
| 749 | |
| 750 | // Apply replacements to buffer. |
| 751 | t := make([]byte, len(s)+n*(len(new)-len(old))) |
| 752 | w := 0 |
| 753 | start := 0 |
| 754 | for i := 0; i < n; i++ { |
| 755 | j := start |
| 756 | if len(old) == 0 { |
| 757 | if i > 0 { |
| 758 | _, wid := utf8.DecodeRune(s[start:]) |
| 759 | j += wid |
| 760 | } |
| 761 | } else { |
| 762 | j += Index(s[start:], old) |
| 763 | } |
| 764 | w += copy(t[w:], s[start:j]) |
| 765 | w += copy(t[w:], new) |
| 766 | start = j + len(old) |
| 767 | } |
| 768 | w += copy(t[w:], s[start:]) |
| 769 | return t[0:w] |
| 770 | } |
| 771 | |
| 772 | // EqualFold reports whether s and t, interpreted as UTF-8 strings, |
| 773 | // are equal under Unicode case-folding. |
| 774 | func EqualFold(s, t []byte) bool { |
| 775 | for len(s) != 0 && len(t) != 0 { |
| 776 | // Extract first rune from each. |
| 777 | var sr, tr rune |
| 778 | if s[0] < utf8.RuneSelf { |
| 779 | sr, s = rune(s[0]), s[1:] |
| 780 | } else { |
| 781 | r, size := utf8.DecodeRune(s) |
| 782 | sr, s = r, s[size:] |
| 783 | } |
| 784 | if t[0] < utf8.RuneSelf { |
| 785 | tr, t = rune(t[0]), t[1:] |
| 786 | } else { |
| 787 | r, size := utf8.DecodeRune(t) |
| 788 | tr, t = r, t[size:] |
| 789 | } |
| 790 | |
| 791 | // If they match, keep going; if not, return false. |
| 792 | |
| 793 | // Easy case. |
| 794 | if tr == sr { |
| 795 | continue |
| 796 | } |
| 797 | |
| 798 | // Make sr < tr to simplify what follows. |
| 799 | if tr < sr { |
| 800 | tr, sr = sr, tr |
| 801 | } |
| 802 | // Fast check for ASCII. |
| 803 | if tr < utf8.RuneSelf && 'A' <= sr && sr <= 'Z' { |
| 804 | // ASCII, and sr is upper case. tr must be lower case. |
| 805 | if tr == sr+'a'-'A' { |
| 806 | continue |
| 807 | } |
| 808 | return false |
| 809 | } |
| 810 | |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 811 | // General case. SimpleFold(x) returns the next equivalent rune > x |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 812 | // or wraps around to smaller values. |
| 813 | r := unicode.SimpleFold(sr) |
| 814 | for r != sr && r < tr { |
| 815 | r = unicode.SimpleFold(r) |
| 816 | } |
| 817 | if r == tr { |
| 818 | continue |
| 819 | } |
| 820 | return false |
| 821 | } |
| 822 | |
Dan Willemsen | 38f2dba | 2016-07-08 14:54:35 -0700 | [diff] [blame] | 823 | // One string is empty. Are both? |
Brent Austin | ba3052e | 2015-04-21 16:08:23 -0700 | [diff] [blame] | 824 | return len(s) == len(t) |
| 825 | } |
Dan Willemsen | a322328 | 2018-02-27 19:41:43 -0800 | [diff] [blame^] | 826 | |
| 827 | func indexRabinKarp(s, sep []byte) int { |
| 828 | // Rabin-Karp search |
| 829 | hashsep, pow := hashStr(sep) |
| 830 | n := len(sep) |
| 831 | var h uint32 |
| 832 | for i := 0; i < n; i++ { |
| 833 | h = h*primeRK + uint32(s[i]) |
| 834 | } |
| 835 | if h == hashsep && Equal(s[:n], sep) { |
| 836 | return 0 |
| 837 | } |
| 838 | for i := n; i < len(s); { |
| 839 | h *= primeRK |
| 840 | h += uint32(s[i]) |
| 841 | h -= pow * uint32(s[i-n]) |
| 842 | i++ |
| 843 | if h == hashsep && Equal(s[i-n:i], sep) { |
| 844 | return i - n |
| 845 | } |
| 846 | } |
| 847 | return -1 |
| 848 | } |
| 849 | |
| 850 | // primeRK is the prime base used in Rabin-Karp algorithm. |
| 851 | const primeRK = 16777619 |
| 852 | |
| 853 | // hashStr returns the hash and the appropriate multiplicative |
| 854 | // factor for use in Rabin-Karp algorithm. |
| 855 | func hashStr(sep []byte) (uint32, uint32) { |
| 856 | hash := uint32(0) |
| 857 | for i := 0; i < len(sep); i++ { |
| 858 | hash = hash*primeRK + uint32(sep[i]) |
| 859 | } |
| 860 | var pow, sq uint32 = 1, primeRK |
| 861 | for i := len(sep); i > 0; i >>= 1 { |
| 862 | if i&1 != 0 { |
| 863 | pow *= sq |
| 864 | } |
| 865 | sq *= sq |
| 866 | } |
| 867 | return hash, pow |
| 868 | } |