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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 } | |
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