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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.collection.dev; | |
| 6 | |
| 7 typedef T _Transformation<S, T>(S value); | |
| 8 | |
| 9 class MappedIterable<S, T> extends Iterable<T> { | |
| 10 final Iterable<S> _iterable; | |
| 11 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 12 // checked mode. http://dartbug.com/7733 | |
| 13 final /* _Transformation<S, T> */ _f; | |
| 14 | |
| 15 MappedIterable(this._iterable, T this._f(S element)); | |
| 16 | |
| 17 Iterator<T> get iterator => new MappedIterator<S, T>(_iterable.iterator, _f); | |
| 18 | |
| 19 // Length related functions are independent of the mapping. | |
| 20 int get length => _iterable.length; | |
| 21 bool get isEmpty => _iterable.isEmpty; | |
| 22 } | |
| 23 | |
| 24 | |
| 25 class MappedIterator<S, T> extends Iterator<T> { | |
| 26 T _current; | |
| 27 final Iterator<S> _iterator; | |
| 28 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 29 // checked mode. http://dartbug.com/7733 | |
| 30 final /* _Transformation<S, T> */ _f; | |
| 31 | |
| 32 MappedIterator(this._iterator, T this._f(S element)); | |
| 33 | |
| 34 bool moveNext() { | |
| 35 if (_iterator.moveNext()) { | |
| 36 _current = _f(_iterator.current); | |
| 37 return true; | |
| 38 } else { | |
| 39 _current = null; | |
| 40 return false; | |
| 41 } | |
| 42 } | |
| 43 | |
| 44 T get current => _current; | |
| 45 } | |
| 46 | |
| 47 /** Specialized alternative to [MappedIterable] for mapped [List]s. */ | |
| 48 class MappedListIterable<S, T> extends Iterable<T> { | |
| 49 final List<S> _list; | |
| 50 /** | |
| 51 * Start index of the part of the list to map. | |
| 52 * | |
| 53 * Allows mapping only a sub-list of an existing list. | |
| 54 * | |
| 55 * Used to implement lazy skip/take on a [MappedListIterable]. | |
| 56 */ | |
| 57 final int _start; | |
| 58 | |
| 59 /** | |
| 60 * End index of the part of the list to map. | |
| 61 * | |
| 62 * If null, always use the length of the list. | |
| 63 */ | |
| 64 final int _end; | |
| 65 | |
| 66 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 67 // checked mode. http://dartbug.com/7733 | |
| 68 final /* _Transformation<S, T> */ _f; | |
| 69 | |
| 70 MappedListIterable(this._list, T this._f(S element), this._start, this._end) { | |
| 71 if (_end != null && _end < _start) { | |
| 72 throw new ArgumentError("End ($_end) before start ($_start)"); | |
| 73 } | |
| 74 } | |
| 75 | |
| 76 /** The start index, limited to the current length of the list. */ | |
| 77 int get _startIndex { | |
| 78 if (_start <= _list.length) return _start; | |
| 79 return _list.length; | |
| 80 } | |
| 81 | |
| 82 /** The end index, if given, limited to the current length of the list. */ | |
| 83 int get _endIndex { | |
| 84 if (_end == null || _end > _list.length) return _list.length; | |
| 85 return _end; | |
| 86 } | |
| 87 | |
| 88 Iterator<T> get iterator => | |
| 89 new MappedListIterator<S, T>(_list, _f, _startIndex, _endIndex); | |
| 90 | |
| 91 void forEach(void action(T element)) { | |
| 92 int length = _list.length; | |
| 93 for (int i = _startIndex, n = _endIndex; i < n; i++) { | |
| 94 action(_f(_list[i])); | |
| 95 if (_list.length != length) { | |
| 96 throw new ConcurrentModificationError(_list); | |
| 97 } | |
| 98 } | |
| 99 } | |
| 100 | |
| 101 bool get isEmpty => _startIndex == _endIndex; | |
| 102 | |
| 103 int get length => _endIndex - _startIndex; | |
| 104 | |
| 105 T get first { | |
| 106 int start = _startIndex; | |
| 107 if (start == _endIndex) { | |
| 108 throw new StateError("No elements"); | |
| 109 } | |
| 110 return _f(_list.elementAt(start)); | |
| 111 } | |
| 112 | |
| 113 T get last { | |
| 114 int end = _endIndex; | |
| 115 if (end == _startIndex) { | |
| 116 throw new StateError("No elements"); | |
| 117 } | |
| 118 return _f(_list.elementAt(end - 1)); | |
| 119 } | |
| 120 | |
| 121 T get single { | |
| 122 int start = _startIndex; | |
| 123 int end = _endIndex; | |
| 124 if (start != end - 1) { | |
| 125 if (start == end) { | |
| 126 throw new StateError("No elements"); | |
| 127 } | |
| 128 throw new StateError("Too many elements"); | |
| 129 } | |
| 130 return _f(_list[start]); | |
| 131 } | |
| 132 | |
| 133 T elementAt(int index) { | |
| 134 index += _startIndex; | |
| 135 if (index >= _endIndex) { | |
| 136 throw new StateError("No matching element"); | |
| 137 } | |
| 138 return _f(_list.elementAt(index)); | |
| 139 } | |
| 140 | |
| 141 bool contains(T element) { | |
| 142 int length = _list.length; | |
| 143 for (int i = _startIndex, n = _endIndex; i < n; i++) { | |
| 144 if (_f(_list[i]) == element) { | |
| 145 return true; | |
| 146 } | |
| 147 if (_list.length != length) { | |
| 148 throw new ConcurrentModificationError(_list); | |
| 149 } | |
| 150 } | |
| 151 return false; | |
| 152 } | |
| 153 | |
| 154 bool every(bool test(T element)) { | |
| 155 int length = _list.length; | |
| 156 for (int i = _startIndex, n = _endIndex; i < n; i++) { | |
| 157 if (!test(_f(_list[i]))) return false; | |
| 158 if (_list.length != length) { | |
| 159 throw new ConcurrentModificationError(_list); | |
| 160 } | |
| 161 } | |
| 162 return true; | |
| 163 } | |
| 164 | |
| 165 bool any(bool test(T element)) { | |
| 166 int length = _list.length; | |
| 167 for (int i = _startIndex, n = _endIndex; i < n; i++) { | |
| 168 if (test(_f(_list[i]))) return true; | |
| 169 if (_list.length != length) { | |
| 170 throw new ConcurrentModificationError(_list); | |
| 171 } | |
| 172 } | |
| 173 return false; | |
| 174 } | |
| 175 | |
| 176 T firstMatching(bool test(T element), { T orElse() }) { | |
| 177 int length = _list.length; | |
| 178 for (int i = _startIndex, n = _endIndex; i < n; i++) { | |
| 179 T value = _f(_list[i]); | |
| 180 if (test(value)) return value; | |
| 181 if (_list.length != length) { | |
| 182 throw new ConcurrentModificationError(_list); | |
| 183 } | |
| 184 } | |
| 185 if (orElse != null) return orElse(); | |
| 186 throw new StateError("No matching element"); | |
| 187 } | |
| 188 | |
| 189 T lastMatching(bool test(T element), { T orElse() }) { | |
| 190 int length = _list.length; | |
| 191 for (int i = _endIndex - 1, start = _startIndex; i >= start; i++) { | |
| 192 T value = _f(_list[i]); | |
| 193 if (test(value)) return value; | |
| 194 if (_list.length != length) { | |
| 195 throw new ConcurrentModificationError(_list); | |
| 196 } | |
| 197 } | |
| 198 if (orElse != null) return orElse(); | |
| 199 throw new StateError("No matching element"); | |
| 200 } | |
| 201 | |
| 202 T singleMatching(bool test(T element)) { | |
| 203 int length = _list.length; | |
| 204 T match; | |
| 205 bool matchFound = false; | |
| 206 for (int i = _startIndex, n = _endIndex; i < n; i++) { | |
| 207 T value = _f(_list[i]); | |
| 208 if (test(value)) { | |
| 209 if (matchFound) { | |
| 210 throw new StateError("More than one matching element"); | |
| 211 } | |
| 212 matchFound = true; | |
| 213 match = value; | |
| 214 } | |
| 215 if (_list.length != length) { | |
| 216 throw new ConcurrentModificationError(_list); | |
| 217 } | |
| 218 } | |
| 219 if (matchFound) return match; | |
| 220 throw new StateError("No matching element"); | |
| 221 } | |
| 222 | |
| 223 T min([int compare(T a, T b)]) { | |
| 224 if (compare == null) { | |
| 225 var defaultCompare = Comparable.compare; | |
| 226 compare = defaultCompare; | |
| 227 } | |
| 228 int length = _list.length; | |
| 229 int start = _startIndex; | |
| 230 int end = _endIndex; | |
| 231 if (start == end) return null; | |
| 232 T value = _f(_list[start]); | |
| 233 if (_list.length != length) { | |
| 234 throw new ConcurrentModificationError(_list); | |
| 235 } | |
| 236 for (int i = start + 1; i < end; i++) { | |
| 237 T nextValue = _f(_list[i]); | |
| 238 if (compare(value, nextValue) > 0) { | |
| 239 value = nextValue; | |
| 240 } | |
| 241 if (_list.length != length) { | |
| 242 throw new ConcurrentModificationError(_list); | |
| 243 } | |
| 244 } | |
| 245 return value; | |
| 246 } | |
| 247 | |
| 248 T max([int compare(T a, T b)]) { | |
| 249 if (compare == null) { | |
| 250 var defaultCompare = Comparable.compare; | |
| 251 compare = defaultCompare; | |
| 252 } | |
| 253 int length = _list.length; | |
| 254 int start = _startIndex; | |
| 255 int end = _endIndex; | |
| 256 if (start == end) return null; | |
| 257 T value = _f(_list[start]); | |
| 258 if (_list.length != length) { | |
| 259 throw new ConcurrentModificationError(_list); | |
| 260 } | |
| 261 for (int i = start + 1; i < end; i++) { | |
| 262 T nextValue = _f(_list[i]); | |
| 263 if (compare(value, nextValue) < 0) { | |
| 264 value = nextValue; | |
| 265 } | |
| 266 if (_list.length != length) { | |
| 267 throw new ConcurrentModificationError(_list); | |
| 268 } | |
| 269 } | |
| 270 return value; | |
| 271 } | |
| 272 | |
| 273 String join([String separator]) { | |
| 274 int start = _startIndex; | |
| 275 int end = _endIndex; | |
| 276 if (start == end) return ""; | |
| 277 StringBuffer buffer = new StringBuffer("${_f(_list[start])}"); | |
| 278 if (_list.length != length) { | |
| 279 throw new ConcurrentModificationError(_list); | |
| 280 } | |
| 281 for (int i = start + 1; i < end; i++) { | |
| 282 buffer.add(separator); | |
| 283 buffer.add("${_f(_list[i])}"); | |
| 284 if (_list.length != length) { | |
| 285 throw new ConcurrentModificationError(_list); | |
| 286 } | |
| 287 } | |
| 288 return buffer.toString(); | |
| 289 } | |
| 290 | |
| 291 Iterable<T> where(bool test(T element)) => super.where(test); | |
| 292 | |
| 293 Iterable map(f(T element)) { | |
| 294 return new MappedListIterable(_list, (S v) => f(_f(v)), _start, _end); | |
| 295 } | |
| 296 | |
| 297 Iterable mappedBy(f(T element)) => map(f); | |
| 298 | |
| 299 reduce(var initialValue, combine(var previousValue, T element)) { | |
| 300 return _list.reduce(initialValue, (v, S e) => combine(v, _f(e))); | |
| 301 } | |
| 302 | |
| 303 Iterable<T> skip(int count) { | |
| 304 int start = _startIndex + count; | |
| 305 if (_end != null && start >= _end) { | |
| 306 return new EmptyIterable<T>(); | |
| 307 } | |
| 308 return new MappedListIterable(_list, _f, start, _end); | |
| 309 } | |
| 310 | |
| 311 Iterable<T> skipWhile(bool test(T element)) => super.skipWhile(test); | |
| 312 | |
| 313 Iterable<T> take(int count) { | |
| 314 int newEnd = _start + count; | |
| 315 if (_end == null || newEnd < _end) { | |
| 316 return new MappedListIterable(_list, _f, _start, newEnd); | |
| 317 } | |
| 318 // Equivalent to "this". | |
| 319 return new MappedListIterable(_list, _f, _start, _end); | |
| 320 } | |
| 321 | |
| 322 Iterable<T> takeWhile(bool test(T element)) => super.takeWhile(test); | |
| 323 | |
| 324 List<T> toList() { | |
| 325 List<T> result = new List<T>(); | |
| 326 forEach(result.add); | |
| 327 return result; | |
| 328 } | |
| 329 | |
| 330 Set<T> toSet() { | |
| 331 Set<T> result = new Set<T>(); | |
| 332 forEach(result.add); | |
| 333 return result; | |
| 334 } | |
| 335 } | |
| 336 | |
| 337 /** | |
| 338 * Iterator for [MappedListIterable]. | |
| 339 * | |
| 340 * A list iterator that iterates over (a sublist of) a list and | |
| 341 * returns the values transformed by a function. | |
| 342 * | |
| 343 * As a list iterator, it throws if the length of the list has | |
| 344 * changed during iteration. | |
| 345 */ | |
| 346 class MappedListIterator<S, T> implements Iterator<T> { | |
| 347 List<S> _list; | |
| 348 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 349 // checked mode. http://dartbug.com/7733 | |
| 350 final /* _Transformation<S, T> */ _f; | |
| 351 final int _endIndex; | |
| 352 final int _length; | |
| 353 int _index; | |
| 354 T _current; | |
| 355 | |
| 356 MappedListIterator(List<S> list, this._f, int start, this._endIndex) | |
| 357 : _list = list, _length = list.length, _index = start; | |
| 358 | |
| 359 T get current => _current; | |
| 360 | |
| 361 bool moveNext() { | |
| 362 if (_list.length != _length) { | |
| 363 throw new ConcurrentModificationError(_list); | |
| 364 } | |
| 365 if (_index >= _endIndex) { | |
| 366 _current = null; | |
| 367 return false; | |
| 368 } | |
| 369 _current = _f(_list[_index]); | |
| 370 _index++; | |
| 371 return true; | |
| 372 } | |
| 373 } | |
| 374 | |
| 375 typedef bool _ElementPredicate<E>(E element); | |
| 376 | |
| 377 class WhereIterable<E> extends Iterable<E> { | |
| 378 final Iterable<E> _iterable; | |
| 379 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 380 // checked mode. http://dartbug.com/7733 | |
| 381 final /* _ElementPredicate */ _f; | |
| 382 | |
| 383 WhereIterable(this._iterable, bool this._f(E element)); | |
| 384 | |
| 385 Iterator<E> get iterator => new WhereIterator<E>(_iterable.iterator, _f); | |
| 386 } | |
| 387 | |
| 388 class WhereIterator<E> extends Iterator<E> { | |
| 389 final Iterator<E> _iterator; | |
| 390 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 391 // checked mode. http://dartbug.com/7733 | |
| 392 final /* _ElementPredicate */ _f; | |
| 393 | |
| 394 WhereIterator(this._iterator, bool this._f(E element)); | |
| 395 | |
| 396 bool moveNext() { | |
| 397 while (_iterator.moveNext()) { | |
| 398 if (_f(_iterator.current)) { | |
| 399 return true; | |
| 400 } | |
| 401 } | |
| 402 return false; | |
| 403 } | |
| 404 | |
| 405 E get current => _iterator.current; | |
| 406 } | |
| 407 | |
| 408 typedef Iterable<T> _ExpandFunction<S, T>(S sourceElement); | |
| 409 | |
| 410 class ExpandIterable<S, T> extends Iterable<T> { | |
| 411 final Iterable<S> _iterable; | |
| 412 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 413 // checked mode. http://dartbug.com/7733 | |
| 414 final /* _ExpandFunction */ _f; | |
| 415 | |
| 416 ExpandIterable(this._iterable, Iterable<T> this._f(S element)); | |
| 417 | |
| 418 Iterator<T> get iterator => new ExpandIterator<S, T>(_iterable.iterator, _f); | |
| 419 } | |
| 420 | |
| 421 class ExpandIterator<S, T> implements Iterator<T> { | |
| 422 final Iterator<S> _iterator; | |
| 423 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 424 // checked mode. http://dartbug.com/7733 | |
| 425 final /* _ExpandFunction */ _f; | |
| 426 // Initialize _currentExpansion to an empty iterable. A null value | |
| 427 // marks the end of iteration, and we don't want to call _f before | |
| 428 // the first moveNext call. | |
| 429 Iterator<T> _currentExpansion = const EmptyIterator(); | |
| 430 T _current; | |
| 431 | |
| 432 ExpandIterator(this._iterator, Iterable<T> this._f(S element)); | |
| 433 | |
| 434 void _nextExpansion() { | |
| 435 } | |
| 436 | |
| 437 T get current => _current; | |
| 438 | |
| 439 bool moveNext() { | |
| 440 if (_currentExpansion == null) return false; | |
| 441 while (!_currentExpansion.moveNext()) { | |
| 442 _current = null; | |
| 443 if (_iterator.moveNext()) { | |
| 444 // If _f throws, this ends iteration. Otherwise _currentExpansion and | |
| 445 // _current will be set again below. | |
| 446 _currentExpansion = null; | |
| 447 _currentExpansion = _f(_iterator.current).iterator; | |
| 448 } else { | |
| 449 return false; | |
| 450 } | |
| 451 } | |
| 452 _current = _currentExpansion.current; | |
| 453 return true; | |
| 454 } | |
| 455 } | |
| 456 | |
| 457 class TakeIterable<E> extends Iterable<E> { | |
| 458 final Iterable<E> _iterable; | |
| 459 final int _takeCount; | |
| 460 | |
| 461 TakeIterable(this._iterable, this._takeCount) { | |
| 462 if (_takeCount is! int || _takeCount < 0) { | |
| 463 throw new ArgumentError(_takeCount); | |
| 464 } | |
| 465 } | |
| 466 | |
| 467 Iterator<E> get iterator { | |
| 468 return new TakeIterator<E>(_iterable.iterator, _takeCount); | |
| 469 } | |
| 470 } | |
| 471 | |
| 472 class TakeIterator<E> extends Iterator<E> { | |
| 473 final Iterator<E> _iterator; | |
| 474 int _remaining; | |
| 475 | |
| 476 TakeIterator(this._iterator, this._remaining) { | |
| 477 assert(_remaining is int && _remaining >= 0); | |
| 478 } | |
| 479 | |
| 480 bool moveNext() { | |
| 481 _remaining--; | |
| 482 if (_remaining >= 0) { | |
| 483 return _iterator.moveNext(); | |
| 484 } | |
| 485 _remaining = -1; | |
| 486 return false; | |
| 487 } | |
| 488 | |
| 489 E get current { | |
| 490 if (_remaining < 0) return null; | |
| 491 return _iterator.current; | |
| 492 } | |
| 493 } | |
| 494 | |
| 495 class TakeWhileIterable<E> extends Iterable<E> { | |
| 496 final Iterable<E> _iterable; | |
| 497 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 498 // checked mode. http://dartbug.com/7733 | |
| 499 final /* _ElementPredicate */ _f; | |
| 500 | |
| 501 TakeWhileIterable(this._iterable, bool this._f(E element)); | |
| 502 | |
| 503 Iterator<E> get iterator { | |
| 504 return new TakeWhileIterator<E>(_iterable.iterator, _f); | |
| 505 } | |
| 506 } | |
| 507 | |
| 508 class TakeWhileIterator<E> extends Iterator<E> { | |
| 509 final Iterator<E> _iterator; | |
| 510 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 511 // checked mode. http://dartbug.com/7733 | |
| 512 final /* _ElementPredicate */ _f; | |
| 513 bool _isFinished = false; | |
| 514 | |
| 515 TakeWhileIterator(this._iterator, bool this._f(E element)); | |
| 516 | |
| 517 bool moveNext() { | |
| 518 if (_isFinished) return false; | |
| 519 if (!_iterator.moveNext() || !_f(_iterator.current)) { | |
| 520 _isFinished = true; | |
| 521 return false; | |
| 522 } | |
| 523 return true; | |
| 524 } | |
| 525 | |
| 526 E get current { | |
| 527 if (_isFinished) return null; | |
| 528 return _iterator.current; | |
| 529 } | |
| 530 } | |
| 531 | |
| 532 class SkipIterable<E> extends Iterable<E> { | |
| 533 final Iterable<E> _iterable; | |
| 534 final int _skipCount; | |
| 535 | |
| 536 SkipIterable(this._iterable, this._skipCount) { | |
| 537 if (_skipCount is! int || _skipCount < 0) { | |
| 538 throw new ArgumentError(_skipCount); | |
| 539 } | |
| 540 } | |
| 541 | |
| 542 Iterable<E> skip(int n) { | |
| 543 if (n is! int || n < 0) { | |
| 544 throw new ArgumentError(n); | |
| 545 } | |
| 546 return new SkipIterable<E>(_iterable, _skipCount + n); | |
| 547 } | |
| 548 | |
| 549 Iterator<E> get iterator { | |
| 550 return new SkipIterator<E>(_iterable.iterator, _skipCount); | |
| 551 } | |
| 552 } | |
| 553 | |
| 554 class SkipIterator<E> extends Iterator<E> { | |
| 555 final Iterator<E> _iterator; | |
| 556 int _skipCount; | |
| 557 | |
| 558 SkipIterator(this._iterator, this._skipCount) { | |
| 559 assert(_skipCount is int && _skipCount >= 0); | |
| 560 } | |
| 561 | |
| 562 bool moveNext() { | |
| 563 for (int i = 0; i < _skipCount; i++) _iterator.moveNext(); | |
| 564 _skipCount = 0; | |
| 565 return _iterator.moveNext(); | |
| 566 } | |
| 567 | |
| 568 E get current => _iterator.current; | |
| 569 } | |
| 570 | |
| 571 class SkipWhileIterable<E> extends Iterable<E> { | |
| 572 final Iterable<E> _iterable; | |
| 573 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 574 // checked mode. http://dartbug.com/7733 | |
| 575 final /* _ElementPredicate */ _f; | |
| 576 | |
| 577 SkipWhileIterable(this._iterable, bool this._f(E element)); | |
| 578 | |
| 579 Iterator<E> get iterator { | |
| 580 return new SkipWhileIterator<E>(_iterable.iterator, _f); | |
| 581 } | |
| 582 } | |
| 583 | |
| 584 class SkipWhileIterator<E> extends Iterator<E> { | |
| 585 final Iterator<E> _iterator; | |
| 586 // TODO(ahe): Restore type when feature is implemented in dart2js | |
| 587 // checked mode. http://dartbug.com/7733 | |
| 588 final /* _ElementPredicate */ _f; | |
| 589 bool _hasSkipped = false; | |
| 590 | |
| 591 SkipWhileIterator(this._iterator, bool this._f(E element)); | |
| 592 | |
| 593 bool moveNext() { | |
| 594 if (!_hasSkipped) { | |
| 595 _hasSkipped = true; | |
| 596 while (_iterator.moveNext()) { | |
| 597 if (!_f(_iterator.current)) return true; | |
| 598 } | |
| 599 } | |
| 600 return _iterator.moveNext(); | |
| 601 } | |
| 602 | |
| 603 E get current => _iterator.current; | |
| 604 } | |
| 605 | |
| 606 /** | |
| 607 * The always empty [Iterable]. | |
| 608 */ | |
| 609 class EmptyIterable<E> extends Iterable<E> { | |
| 610 const EmptyIterable(); | |
| 611 | |
| 612 Iterator<E> get iterator => const EmptyIterator(); | |
| 613 | |
| 614 void forEach(void action(E element)) {} | |
| 615 | |
| 616 bool get isEmpty => true; | |
| 617 | |
| 618 int get length => 0; | |
| 619 | |
| 620 E get first { throw new StateError("No elements"); } | |
| 621 | |
| 622 E get last { throw new StateError("No elements"); } | |
| 623 | |
| 624 E get single { throw new StateError("No elements"); } | |
| 625 | |
| 626 E elementAt(int index) { throw new RangeError.value(index); } | |
| 627 | |
| 628 bool contains(E element) => false; | |
| 629 | |
| 630 bool every(bool test(E element)) => true; | |
| 631 | |
| 632 bool any(bool test(E element)) => false; | |
| 633 | |
| 634 E firstMatching(bool test(E element), { E orElse() }) { | |
| 635 if (orElse != null) return orElse(); | |
| 636 throw new StateError("No matching element"); | |
| 637 } | |
| 638 | |
| 639 E lastMatching(bool test(E element), { E orElse() }) { | |
| 640 if (orElse != null) return orElse(); | |
| 641 throw new StateError("No matching element"); | |
| 642 } | |
| 643 | |
| 644 E singleMatching(bool test(E element), { E orElse() }) { | |
| 645 if (orElse != null) return orElse(); | |
| 646 throw new StateError("No matching element"); | |
| 647 } | |
| 648 | |
| 649 E min([int compare(E a, E b)]) => null; | |
| 650 | |
| 651 E max([int compare(E a, E b)]) => null; | |
| 652 | |
| 653 String join([String separator]) => ""; | |
| 654 | |
| 655 Iterable<E> where(bool test(E element)) => this; | |
| 656 | |
| 657 Iterable map(f(E element)) => const EmptyIterable(); | |
| 658 | |
| 659 Iterable mappedBy(f(E element)) => const EmptyIterable(); | |
| 660 | |
| 661 reduce(var initialValue, combine(var previousValue, E element)) { | |
| 662 return initialValue; | |
| 663 } | |
| 664 | |
| 665 Iterable<E> skip(int count) => this; | |
| 666 | |
| 667 Iterable<E> skipWhile(bool test(E element)) => this; | |
| 668 | |
| 669 Iterable<E> take(int count) => this; | |
| 670 | |
| 671 Iterable<E> takeWhile(bool test(E element)) => this; | |
| 672 | |
| 673 List toList() => <E>[]; | |
| 674 | |
| 675 Set toSet() => new Set<E>(); | |
| 676 } | |
| 677 | |
| 678 /** The always empty iterator. */ | |
| 679 class EmptyIterator<E> implements Iterator<E> { | |
| 680 const EmptyIterator(); | |
| 681 bool moveNext() => false; | |
| 682 E get current => null; | |
| 683 } | |
| OLD | NEW |