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| 1 // Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file | |
| 2 // for details. All rights reserved. Use of this source code is governed by a | |
| 3 // BSD-style license that can be found in the LICENSE file. | |
| 4 | |
| 5 part of dart._internal; | |
| 6 | |
| 7 /** | |
| 8 * Marker interface for [Iterable] subclasses that have an efficient | |
| 9 * [length] implementation. | |
| 10 */ | |
| 11 abstract class EfficientLength { | |
| 12 /** | |
| 13 * Returns the number of elements in the iterable. | |
| 14 * | |
| 15 * This is an efficient operation that doesn't require iterating through | |
| 16 * the elements. | |
| 17 */ | |
| 18 int get length; | |
| 19 } | |
| 20 | |
| 21 /** | |
| 22 * An [Iterable] for classes that have efficient [length] and [elementAt]. | |
| 23 * | |
| 24 * All other methods are implemented in terms of [length] and [elementAt], | |
| 25 * including [iterator]. | |
| 26 */ | |
| 27 abstract class ListIterable<E> extends Iterable<E> | |
| 28 implements EfficientLength { | |
| 29 int get length; | |
| 30 E elementAt(int i); | |
| 31 | |
| 32 const ListIterable(); | |
| 33 | |
| 34 Iterator<E> get iterator => new ListIterator<E>(this); | |
| 35 | |
| 36 void forEach(void action(E element)) { | |
| 37 int length = this.length; | |
| 38 for (int i = 0; i < length; i++) { | |
| 39 action(elementAt(i)); | |
| 40 if (length != this.length) { | |
| 41 throw new ConcurrentModificationError(this); | |
| 42 } | |
| 43 } | |
| 44 } | |
| 45 | |
| 46 bool get isEmpty => length == 0; | |
| 47 | |
| 48 E get first { | |
| 49 if (length == 0) throw IterableElementError.noElement(); | |
| 50 return elementAt(0); | |
| 51 } | |
| 52 | |
| 53 E get last { | |
| 54 if (length == 0) throw IterableElementError.noElement(); | |
| 55 return elementAt(length - 1); | |
| 56 } | |
| 57 | |
| 58 E get single { | |
| 59 if (length == 0) throw IterableElementError.noElement(); | |
| 60 if (length > 1) throw IterableElementError.tooMany(); | |
| 61 return elementAt(0); | |
| 62 } | |
| 63 | |
| 64 bool contains(Object element) { | |
| 65 int length = this.length; | |
| 66 for (int i = 0; i < length; i++) { | |
| 67 if (elementAt(i) == element) return true; | |
| 68 if (length != this.length) { | |
| 69 throw new ConcurrentModificationError(this); | |
| 70 } | |
| 71 } | |
| 72 return false; | |
| 73 } | |
| 74 | |
| 75 bool every(bool test(E element)) { | |
| 76 int length = this.length; | |
| 77 for (int i = 0; i < length; i++) { | |
| 78 if (!test(elementAt(i))) return false; | |
| 79 if (length != this.length) { | |
| 80 throw new ConcurrentModificationError(this); | |
| 81 } | |
| 82 } | |
| 83 return true; | |
| 84 } | |
| 85 | |
| 86 bool any(bool test(E element)) { | |
| 87 int length = this.length; | |
| 88 for (int i = 0; i < length; i++) { | |
| 89 if (test(elementAt(i))) return true; | |
| 90 if (length != this.length) { | |
| 91 throw new ConcurrentModificationError(this); | |
| 92 } | |
| 93 } | |
| 94 return false; | |
| 95 } | |
| 96 | |
| 97 E firstWhere(bool test(E element), { E orElse() }) { | |
| 98 int length = this.length; | |
| 99 for (int i = 0; i < length; i++) { | |
| 100 E element = elementAt(i); | |
| 101 if (test(element)) return element; | |
| 102 if (length != this.length) { | |
| 103 throw new ConcurrentModificationError(this); | |
| 104 } | |
| 105 } | |
| 106 if (orElse != null) return orElse(); | |
| 107 throw IterableElementError.noElement(); | |
| 108 } | |
| 109 | |
| 110 E lastWhere(bool test(E element), { E orElse() }) { | |
| 111 int length = this.length; | |
| 112 for (int i = length - 1; i >= 0; i--) { | |
| 113 E element = elementAt(i); | |
| 114 if (test(element)) return element; | |
| 115 if (length != this.length) { | |
| 116 throw new ConcurrentModificationError(this); | |
| 117 } | |
| 118 } | |
| 119 if (orElse != null) return orElse(); | |
| 120 throw IterableElementError.noElement(); | |
| 121 } | |
| 122 | |
| 123 E singleWhere(bool test(E element)) { | |
| 124 int length = this.length; | |
| 125 E match = null; | |
| 126 bool matchFound = false; | |
| 127 for (int i = 0; i < length; i++) { | |
| 128 E element = elementAt(i); | |
| 129 if (test(element)) { | |
| 130 if (matchFound) { | |
| 131 throw IterableElementError.tooMany(); | |
| 132 } | |
| 133 matchFound = true; | |
| 134 match = element; | |
| 135 } | |
| 136 if (length != this.length) { | |
| 137 throw new ConcurrentModificationError(this); | |
| 138 } | |
| 139 } | |
| 140 if (matchFound) return match; | |
| 141 throw IterableElementError.noElement(); | |
| 142 } | |
| 143 | |
| 144 String join([String separator = ""]) { | |
| 145 int length = this.length; | |
| 146 if (!separator.isEmpty) { | |
| 147 if (length == 0) return ""; | |
| 148 String first = "${elementAt(0)}"; | |
| 149 if (length != this.length) { | |
| 150 throw new ConcurrentModificationError(this); | |
| 151 } | |
| 152 StringBuffer buffer = new StringBuffer(first); | |
| 153 for (int i = 1; i < length; i++) { | |
| 154 buffer.write(separator); | |
| 155 buffer.write(elementAt(i)); | |
| 156 if (length != this.length) { | |
| 157 throw new ConcurrentModificationError(this); | |
| 158 } | |
| 159 } | |
| 160 return buffer.toString(); | |
| 161 } else { | |
| 162 StringBuffer buffer = new StringBuffer(); | |
| 163 for (int i = 0; i < length; i++) { | |
| 164 buffer.write(elementAt(i)); | |
| 165 if (length != this.length) { | |
| 166 throw new ConcurrentModificationError(this); | |
| 167 } | |
| 168 } | |
| 169 return buffer.toString(); | |
| 170 } | |
| 171 } | |
| 172 | |
| 173 Iterable<E> where(bool test(E element)) => super.where(test); | |
| 174 | |
| 175 Iterable/*<T>*/ map/*<T>*/(/*=T*/ f(E element)) => | |
| 176 new MappedListIterable<E, dynamic/*=T*/ >(this, f); | |
| 177 | |
| 178 E reduce(E combine(var value, E element)) { | |
| 179 int length = this.length; | |
| 180 if (length == 0) throw IterableElementError.noElement(); | |
| 181 E value = elementAt(0); | |
| 182 for (int i = 1; i < length; i++) { | |
| 183 value = combine(value, elementAt(i)); | |
| 184 if (length != this.length) { | |
| 185 throw new ConcurrentModificationError(this); | |
| 186 } | |
| 187 } | |
| 188 return value; | |
| 189 } | |
| 190 | |
| 191 /*=T*/ fold/*<T>*/( | |
| 192 var/*=T*/ initialValue, /*=T*/ combine( | |
| 193 var/*=T*/ previousValue, E element)) { | |
| 194 var value = initialValue; | |
| 195 int length = this.length; | |
| 196 for (int i = 0; i < length; i++) { | |
| 197 value = combine(value, elementAt(i)); | |
| 198 if (length != this.length) { | |
| 199 throw new ConcurrentModificationError(this); | |
| 200 } | |
| 201 } | |
| 202 return value; | |
| 203 } | |
| 204 | |
| 205 Iterable<E> skip(int count) => new SubListIterable<E>(this, count, null); | |
| 206 | |
| 207 Iterable<E> skipWhile(bool test(E element)) => super.skipWhile(test); | |
| 208 | |
| 209 Iterable<E> take(int count) => new SubListIterable<E>(this, 0, count); | |
| 210 | |
| 211 Iterable<E> takeWhile(bool test(E element)) => super.takeWhile(test); | |
| 212 | |
| 213 List<E> toList({bool growable: true}) { | |
| 214 List<E> result; | |
| 215 if (growable) { | |
| 216 result = new List<E>()..length = length; | |
| 217 } else { | |
| 218 result = new List<E>(length); | |
| 219 } | |
| 220 for (int i = 0; i < length; i++) { | |
| 221 result[i] = elementAt(i); | |
| 222 } | |
| 223 return result; | |
| 224 } | |
| 225 | |
| 226 Set<E> toSet() { | |
| 227 Set<E> result = new Set<E>(); | |
| 228 for (int i = 0; i < length; i++) { | |
| 229 result.add(elementAt(i)); | |
| 230 } | |
| 231 return result; | |
| 232 } | |
| 233 } | |
| 234 | |
| 235 class SubListIterable<E> extends ListIterable<E> { | |
| 236 final Iterable<E> _iterable; // Has efficient length and elementAt. | |
| 237 final int _start; | |
| 238 /** If null, represents the length of the iterable. */ | |
| 239 final int _endOrLength; | |
| 240 | |
| 241 SubListIterable(this._iterable, this._start, this._endOrLength) { | |
| 242 RangeError.checkNotNegative(_start, "start"); | |
| 243 if (_endOrLength != null) { | |
| 244 RangeError.checkNotNegative(_endOrLength, "end"); | |
| 245 if (_start > _endOrLength) { | |
| 246 throw new RangeError.range(_start, 0, _endOrLength, "start"); | |
| 247 } | |
| 248 } | |
| 249 } | |
| 250 | |
| 251 int get _endIndex { | |
| 252 int length = _iterable.length; | |
| 253 if (_endOrLength == null || _endOrLength > length) return length; | |
| 254 return _endOrLength; | |
| 255 } | |
| 256 | |
| 257 int get _startIndex { | |
| 258 int length = _iterable.length; | |
| 259 if (_start > length) return length; | |
| 260 return _start; | |
| 261 } | |
| 262 | |
| 263 int get length { | |
| 264 int length = _iterable.length; | |
| 265 if (_start >= length) return 0; | |
| 266 if (_endOrLength == null || _endOrLength >= length) { | |
| 267 return length - _start; | |
| 268 } | |
| 269 return _endOrLength - _start; | |
| 270 } | |
| 271 | |
| 272 E elementAt(int index) { | |
| 273 int realIndex = _startIndex + index; | |
| 274 if (index < 0 || realIndex >= _endIndex) { | |
| 275 throw new RangeError.index(index, this, "index"); | |
| 276 } | |
| 277 return _iterable.elementAt(realIndex); | |
| 278 } | |
| 279 | |
| 280 Iterable<E> skip(int count) { | |
| 281 RangeError.checkNotNegative(count, "count"); | |
| 282 int newStart = _start + count; | |
| 283 if (_endOrLength != null && newStart >= _endOrLength) { | |
| 284 return new EmptyIterable<E>(); | |
| 285 } | |
| 286 return new SubListIterable<E>(_iterable, newStart, _endOrLength); | |
| 287 } | |
| 288 | |
| 289 Iterable<E> take(int count) { | |
| 290 RangeError.checkNotNegative(count, "count"); | |
| 291 if (_endOrLength == null) { | |
| 292 return new SubListIterable<E>(_iterable, _start, _start + count); | |
| 293 } else { | |
| 294 int newEnd = _start + count; | |
| 295 if (_endOrLength < newEnd) return this; | |
| 296 return new SubListIterable<E>(_iterable, _start, newEnd); | |
| 297 } | |
| 298 } | |
| 299 | |
| 300 List<E> toList({bool growable: true}) { | |
| 301 int start = _start; | |
| 302 int end = _iterable.length; | |
| 303 if (_endOrLength != null && _endOrLength < end) end = _endOrLength; | |
| 304 int length = end - start; | |
| 305 if (length < 0) length = 0; | |
| 306 List<E> result = growable ? (new List<E>()..length = length) | |
| 307 : new List<E>(length); | |
| 308 for (int i = 0; i < length; i++) { | |
| 309 result[i] = _iterable.elementAt(start + i); | |
| 310 if (_iterable.length < end) throw new ConcurrentModificationError(this); | |
| 311 } | |
| 312 return result; | |
| 313 } | |
| 314 } | |
| 315 | |
| 316 /** | |
| 317 * An [Iterator] that iterates a list-like [Iterable]. | |
| 318 * | |
| 319 * All iterations is done in terms of [Iterable.length] and | |
| 320 * [Iterable.elementAt]. These operations are fast for list-like | |
| 321 * iterables. | |
| 322 */ | |
| 323 class ListIterator<E> implements Iterator<E> { | |
| 324 final Iterable<E> _iterable; | |
| 325 final int _length; | |
| 326 int _index; | |
| 327 E _current; | |
| 328 | |
| 329 ListIterator(Iterable<E> iterable) | |
| 330 : _iterable = iterable, _length = iterable.length, _index = 0; | |
| 331 | |
| 332 E get current => _current; | |
| 333 | |
| 334 bool moveNext() { | |
| 335 int length = _iterable.length; | |
| 336 if (_length != length) { | |
| 337 throw new ConcurrentModificationError(_iterable); | |
| 338 } | |
| 339 if (_index >= length) { | |
| 340 _current = null; | |
| 341 return false; | |
| 342 } | |
| 343 _current = _iterable.elementAt(_index); | |
| 344 _index++; | |
| 345 return true; | |
| 346 } | |
| 347 } | |
| 348 | |
| 349 typedef T _Transformation<S, T>(S value); | |
| 350 | |
| 351 class MappedIterable<S, T> extends Iterable<T> { | |
| 352 final Iterable<S> _iterable; | |
| 353 final _Transformation<S, T> _f; | |
| 354 | |
| 355 factory MappedIterable(Iterable<S> iterable, T function(S value)) { | |
| 356 if (iterable is EfficientLength) { | |
| 357 return new EfficientLengthMappedIterable<S, T>(iterable, function); | |
| 358 } | |
| 359 return new MappedIterable<S, T>._(iterable, function); | |
| 360 } | |
| 361 | |
| 362 MappedIterable._(this._iterable, T this._f(S element)); | |
| 363 | |
| 364 Iterator<T> get iterator => new MappedIterator<S, T>(_iterable.iterator, _f); | |
| 365 | |
| 366 // Length related functions are independent of the mapping. | |
| 367 int get length => _iterable.length; | |
| 368 bool get isEmpty => _iterable.isEmpty; | |
| 369 | |
| 370 // Index based lookup can be done before transforming. | |
| 371 T get first => _f(_iterable.first); | |
| 372 T get last => _f(_iterable.last); | |
| 373 T get single => _f(_iterable.single); | |
| 374 T elementAt(int index) => _f(_iterable.elementAt(index)); | |
| 375 } | |
| 376 | |
| 377 class EfficientLengthMappedIterable<S, T> extends MappedIterable<S, T> | |
| 378 implements EfficientLength { | |
| 379 EfficientLengthMappedIterable(Iterable<S> iterable, T function(S value)) | |
| 380 : super._(iterable, function); | |
| 381 } | |
| 382 | |
| 383 class MappedIterator<S, T> extends Iterator<T> { | |
| 384 T _current; | |
| 385 final Iterator<S> _iterator; | |
| 386 final _Transformation<S, T> _f; | |
| 387 | |
| 388 MappedIterator(this._iterator, T this._f(S element)); | |
| 389 | |
| 390 bool moveNext() { | |
| 391 if (_iterator.moveNext()) { | |
| 392 _current = _f(_iterator.current); | |
| 393 return true; | |
| 394 } | |
| 395 _current = null; | |
| 396 return false; | |
| 397 } | |
| 398 | |
| 399 T get current => _current; | |
| 400 } | |
| 401 | |
| 402 /** | |
| 403 * Specialized alternative to [MappedIterable] for mapped [List]s. | |
| 404 * | |
| 405 * Expects efficient `length` and `elementAt` on the source iterable. | |
| 406 */ | |
| 407 class MappedListIterable<S, T> extends ListIterable<T> | |
| 408 implements EfficientLength { | |
| 409 final Iterable<S> _source; | |
| 410 final _Transformation<S, T> _f; | |
| 411 | |
| 412 MappedListIterable(this._source, T this._f(S value)); | |
| 413 | |
| 414 int get length => _source.length; | |
| 415 T elementAt(int index) => _f(_source.elementAt(index)); | |
| 416 } | |
| 417 | |
| 418 | |
| 419 typedef bool _ElementPredicate<E>(E element); | |
| 420 | |
| 421 class WhereIterable<E> extends Iterable<E> { | |
| 422 final Iterable<E> _iterable; | |
| 423 final _ElementPredicate<E> _f; | |
| 424 | |
| 425 WhereIterable(this._iterable, bool this._f(E element)); | |
| 426 | |
| 427 Iterator<E> get iterator => new WhereIterator<E>(_iterable.iterator, _f); | |
| 428 } | |
| 429 | |
| 430 class WhereIterator<E> extends Iterator<E> { | |
| 431 final Iterator<E> _iterator; | |
| 432 final _ElementPredicate<E> _f; | |
| 433 | |
| 434 WhereIterator(this._iterator, bool this._f(E element)); | |
| 435 | |
| 436 bool moveNext() { | |
| 437 while (_iterator.moveNext()) { | |
| 438 if (_f(_iterator.current)) { | |
| 439 return true; | |
| 440 } | |
| 441 } | |
| 442 return false; | |
| 443 } | |
| 444 | |
| 445 E get current => _iterator.current; | |
| 446 } | |
| 447 | |
| 448 typedef Iterable<T> _ExpandFunction<S, T>(S sourceElement); | |
| 449 | |
| 450 class ExpandIterable<S, T> extends Iterable<T> { | |
| 451 final Iterable<S> _iterable; | |
| 452 final _ExpandFunction<S, T> _f; | |
| 453 | |
| 454 ExpandIterable(this._iterable, Iterable<T> this._f(S element)); | |
| 455 | |
| 456 Iterator<T> get iterator => new ExpandIterator<S, T>(_iterable.iterator, _f); | |
| 457 } | |
| 458 | |
| 459 class ExpandIterator<S, T> implements Iterator<T> { | |
| 460 final Iterator<S> _iterator; | |
| 461 final _ExpandFunction<S, T> _f; | |
| 462 // Initialize _currentExpansion to an empty iterable. A null value | |
| 463 // marks the end of iteration, and we don't want to call _f before | |
| 464 // the first moveNext call. | |
| 465 Iterator<T> _currentExpansion = const EmptyIterator(); | |
| 466 T _current; | |
| 467 | |
| 468 ExpandIterator(this._iterator, Iterable<T> this._f(S element)); | |
| 469 | |
| 470 T get current => _current; | |
| 471 | |
| 472 bool moveNext() { | |
| 473 if (_currentExpansion == null) return false; | |
| 474 while (!_currentExpansion.moveNext()) { | |
| 475 _current = null; | |
| 476 if (_iterator.moveNext()) { | |
| 477 // If _f throws, this ends iteration. Otherwise _currentExpansion and | |
| 478 // _current will be set again below. | |
| 479 _currentExpansion = null; | |
| 480 _currentExpansion = _f(_iterator.current).iterator; | |
| 481 } else { | |
| 482 return false; | |
| 483 } | |
| 484 } | |
| 485 _current = _currentExpansion.current; | |
| 486 return true; | |
| 487 } | |
| 488 } | |
| 489 | |
| 490 class TakeIterable<E> extends Iterable<E> { | |
| 491 final Iterable<E> _iterable; | |
| 492 final int _takeCount; | |
| 493 | |
| 494 factory TakeIterable(Iterable<E> iterable, int takeCount) { | |
| 495 if (takeCount is! int || takeCount < 0) { | |
| 496 throw new ArgumentError(takeCount); | |
| 497 } | |
| 498 if (iterable is EfficientLength) { | |
| 499 return new EfficientLengthTakeIterable<E>(iterable, takeCount); | |
| 500 } | |
| 501 return new TakeIterable<E>._(iterable, takeCount); | |
| 502 } | |
| 503 | |
| 504 TakeIterable._(this._iterable, this._takeCount); | |
| 505 | |
| 506 Iterator<E> get iterator { | |
| 507 return new TakeIterator<E>(_iterable.iterator, _takeCount); | |
| 508 } | |
| 509 } | |
| 510 | |
| 511 class EfficientLengthTakeIterable<E> extends TakeIterable<E> | |
| 512 implements EfficientLength { | |
| 513 EfficientLengthTakeIterable(Iterable<E> iterable, int takeCount) | |
| 514 : super._(iterable, takeCount); | |
| 515 | |
| 516 int get length { | |
| 517 int iterableLength = _iterable.length; | |
| 518 if (iterableLength > _takeCount) return _takeCount; | |
| 519 return iterableLength; | |
| 520 } | |
| 521 } | |
| 522 | |
| 523 | |
| 524 class TakeIterator<E> extends Iterator<E> { | |
| 525 final Iterator<E> _iterator; | |
| 526 int _remaining; | |
| 527 | |
| 528 TakeIterator(this._iterator, this._remaining) { | |
| 529 assert(_remaining is int && _remaining >= 0); | |
| 530 } | |
| 531 | |
| 532 bool moveNext() { | |
| 533 _remaining--; | |
| 534 if (_remaining >= 0) { | |
| 535 return _iterator.moveNext(); | |
| 536 } | |
| 537 _remaining = -1; | |
| 538 return false; | |
| 539 } | |
| 540 | |
| 541 E get current { | |
| 542 if (_remaining < 0) return null; | |
| 543 return _iterator.current; | |
| 544 } | |
| 545 } | |
| 546 | |
| 547 class TakeWhileIterable<E> extends Iterable<E> { | |
| 548 final Iterable<E> _iterable; | |
| 549 final _ElementPredicate<E> _f; | |
| 550 | |
| 551 TakeWhileIterable(this._iterable, bool this._f(E element)); | |
| 552 | |
| 553 Iterator<E> get iterator { | |
| 554 return new TakeWhileIterator<E>(_iterable.iterator, _f); | |
| 555 } | |
| 556 } | |
| 557 | |
| 558 class TakeWhileIterator<E> extends Iterator<E> { | |
| 559 final Iterator<E> _iterator; | |
| 560 final _ElementPredicate<E> _f; | |
| 561 bool _isFinished = false; | |
| 562 | |
| 563 TakeWhileIterator(this._iterator, bool this._f(E element)); | |
| 564 | |
| 565 bool moveNext() { | |
| 566 if (_isFinished) return false; | |
| 567 if (!_iterator.moveNext() || !_f(_iterator.current)) { | |
| 568 _isFinished = true; | |
| 569 return false; | |
| 570 } | |
| 571 return true; | |
| 572 } | |
| 573 | |
| 574 E get current { | |
| 575 if (_isFinished) return null; | |
| 576 return _iterator.current; | |
| 577 } | |
| 578 } | |
| 579 | |
| 580 class SkipIterable<E> extends Iterable<E> { | |
| 581 final Iterable<E> _iterable; | |
| 582 final int _skipCount; | |
| 583 | |
| 584 factory SkipIterable(Iterable<E> iterable, int count) { | |
| 585 if (iterable is EfficientLength) { | |
| 586 return new EfficientLengthSkipIterable<E>(iterable, count); | |
| 587 } | |
| 588 return new SkipIterable<E>._(iterable, count); | |
| 589 } | |
| 590 | |
| 591 SkipIterable._(this._iterable, this._skipCount) { | |
| 592 if (_skipCount is! int) { | |
| 593 throw new ArgumentError.value(_skipCount, "count is not an integer"); | |
| 594 } | |
| 595 RangeError.checkNotNegative(_skipCount, "count"); | |
| 596 } | |
| 597 | |
| 598 Iterable<E> skip(int count) { | |
| 599 if (_skipCount is! int) { | |
| 600 throw new ArgumentError.value(_skipCount, "count is not an integer"); | |
| 601 } | |
| 602 RangeError.checkNotNegative(_skipCount, "count"); | |
| 603 return new SkipIterable<E>._(_iterable, _skipCount + count); | |
| 604 } | |
| 605 | |
| 606 Iterator<E> get iterator { | |
| 607 return new SkipIterator<E>(_iterable.iterator, _skipCount); | |
| 608 } | |
| 609 } | |
| 610 | |
| 611 class EfficientLengthSkipIterable<E> extends SkipIterable<E> | |
| 612 implements EfficientLength { | |
| 613 EfficientLengthSkipIterable(Iterable<E> iterable, int skipCount) | |
| 614 : super._(iterable, skipCount); | |
| 615 | |
| 616 int get length { | |
| 617 int length = _iterable.length - _skipCount; | |
| 618 if (length >= 0) return length; | |
| 619 return 0; | |
| 620 } | |
| 621 } | |
| 622 | |
| 623 class SkipIterator<E> extends Iterator<E> { | |
| 624 final Iterator<E> _iterator; | |
| 625 int _skipCount; | |
| 626 | |
| 627 SkipIterator(this._iterator, this._skipCount) { | |
| 628 assert(_skipCount is int && _skipCount >= 0); | |
| 629 } | |
| 630 | |
| 631 bool moveNext() { | |
| 632 for (int i = 0; i < _skipCount; i++) _iterator.moveNext(); | |
| 633 _skipCount = 0; | |
| 634 return _iterator.moveNext(); | |
| 635 } | |
| 636 | |
| 637 E get current => _iterator.current; | |
| 638 } | |
| 639 | |
| 640 class SkipWhileIterable<E> extends Iterable<E> { | |
| 641 final Iterable<E> _iterable; | |
| 642 final _ElementPredicate<E> _f; | |
| 643 | |
| 644 SkipWhileIterable(this._iterable, bool this._f(E element)); | |
| 645 | |
| 646 Iterator<E> get iterator { | |
| 647 return new SkipWhileIterator<E>(_iterable.iterator, _f); | |
| 648 } | |
| 649 } | |
| 650 | |
| 651 class SkipWhileIterator<E> extends Iterator<E> { | |
| 652 final Iterator<E> _iterator; | |
| 653 final _ElementPredicate<E> _f; | |
| 654 bool _hasSkipped = false; | |
| 655 | |
| 656 SkipWhileIterator(this._iterator, bool this._f(E element)); | |
| 657 | |
| 658 bool moveNext() { | |
| 659 if (!_hasSkipped) { | |
| 660 _hasSkipped = true; | |
| 661 while (_iterator.moveNext()) { | |
| 662 if (!_f(_iterator.current)) return true; | |
| 663 } | |
| 664 } | |
| 665 return _iterator.moveNext(); | |
| 666 } | |
| 667 | |
| 668 E get current => _iterator.current; | |
| 669 } | |
| 670 | |
| 671 /** | |
| 672 * The always empty [Iterable]. | |
| 673 */ | |
| 674 class EmptyIterable<E> extends Iterable<E> implements EfficientLength { | |
| 675 const EmptyIterable(); | |
| 676 | |
| 677 Iterator<E> get iterator => const EmptyIterator(); | |
| 678 | |
| 679 void forEach(void action(E element)) {} | |
| 680 | |
| 681 bool get isEmpty => true; | |
| 682 | |
| 683 int get length => 0; | |
| 684 | |
| 685 E get first { throw IterableElementError.noElement(); } | |
| 686 | |
| 687 E get last { throw IterableElementError.noElement(); } | |
| 688 | |
| 689 E get single { throw IterableElementError.noElement(); } | |
| 690 | |
| 691 E elementAt(int index) { throw new RangeError.range(index, 0, 0, "index"); } | |
| 692 | |
| 693 bool contains(Object element) => false; | |
| 694 | |
| 695 bool every(bool test(E element)) => true; | |
| 696 | |
| 697 bool any(bool test(E element)) => false; | |
| 698 | |
| 699 E firstWhere(bool test(E element), {E orElse()}) { | |
| 700 if (orElse != null) return orElse(); | |
| 701 throw IterableElementError.noElement(); | |
| 702 } | |
| 703 | |
| 704 E lastWhere(bool test(E element), {E orElse()}) { | |
| 705 if (orElse != null) return orElse(); | |
| 706 throw IterableElementError.noElement(); | |
| 707 } | |
| 708 | |
| 709 E singleWhere(bool test(E element), {E orElse()}) { | |
| 710 if (orElse != null) return orElse(); | |
| 711 throw IterableElementError.noElement(); | |
| 712 } | |
| 713 | |
| 714 String join([String separator = ""]) => ""; | |
| 715 | |
| 716 Iterable<E> where(bool test(E element)) => this; | |
| 717 | |
| 718 Iterable/*<T>*/ map/*<T>*/(/*=T*/ f(E element)) => const EmptyIterable(); | |
| 719 | |
| 720 E reduce(E combine(E value, E element)) { | |
| 721 throw IterableElementError.noElement(); | |
| 722 } | |
| 723 | |
| 724 /*=T*/ fold/*<T>*/( | |
| 725 var/*=T*/ initialValue, /*=T*/ combine( | |
| 726 var/*=T*/ previousValue, E element)) { | |
| 727 return initialValue; | |
| 728 } | |
| 729 | |
| 730 Iterable<E> skip(int count) { | |
| 731 RangeError.checkNotNegative(count, "count"); | |
| 732 return this; | |
| 733 } | |
| 734 | |
| 735 Iterable<E> skipWhile(bool test(E element)) => this; | |
| 736 | |
| 737 Iterable<E> take(int count) { | |
| 738 RangeError.checkNotNegative(count, "count"); | |
| 739 return this; | |
| 740 } | |
| 741 | |
| 742 Iterable<E> takeWhile(bool test(E element)) => this; | |
| 743 | |
| 744 List<E> toList({bool growable: true}) => growable ? <E>[] : new List<E>(0); | |
| 745 | |
| 746 Set<E> toSet() => new Set<E>(); | |
| 747 } | |
| 748 | |
| 749 /** The always empty iterator. */ | |
| 750 class EmptyIterator<E> implements Iterator<E> { | |
| 751 const EmptyIterator(); | |
| 752 bool moveNext() => false; | |
| 753 E get current => null; | |
| 754 } | |
| 755 | |
| 756 /** | |
| 757 * Creates errors throw by [Iterable] when the element count is wrong. | |
| 758 */ | |
| 759 abstract class IterableElementError { | |
| 760 /** Error thrown thrown by, e.g., [Iterable.first] when there is no result. */ | |
| 761 static StateError noElement() => new StateError("No element"); | |
| 762 /** Error thrown by, e.g., [Iterable.single] if there are too many results. */ | |
| 763 static StateError tooMany() => new StateError("Too many elements"); | |
| 764 /** Error thrown by, e.g., [List.setRange] if there are too few elements. */ | |
| 765 static StateError tooFew() => new StateError("Too few elements"); | |
| 766 } | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2698353003:
unfork DDC's copy of most SDK libraries (Closed)
