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| 1 // Copyright 2014 Google Inc. All Rights Reserved. | |
| 2 // | |
| 3 // Licensed under the Apache License, Version 2.0 (the "License"); | |
| 4 // you may not use this file except in compliance with the License. | |
| 5 // You may obtain a copy of the License at | |
| 6 // | |
| 7 // http://www.apache.org/licenses/LICENSE-2.0 | |
| 8 // | |
| 9 // Unless required by applicable law or agreed to in writing, software | |
| 10 // distributed under the License is distributed on an "AS IS" BASIS, | |
| 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| 12 // See the License for the specific language governing permissions and | |
| 13 // limitations under the License. | |
| 14 | |
| 15 part of quiver.collection; | |
| 16 | |
| 17 /** | |
| 18 * A [Set] of items stored in a binary tree according to [comparator]. | |
| 19 * Supports bidirectional iteration. | |
| 20 */ | |
| 21 abstract class TreeSet<V> extends IterableBase<V> implements Set<V> { | |
| 22 final Comparator<V> comparator; | |
| 23 | |
| 24 int get length; | |
| 25 | |
| 26 /** | |
| 27 * Create a new [TreeSet] with an ordering defined by [comparator] or the | |
| 28 * default `(a, b) => a.compareTo(b)`. | |
| 29 */ | |
| 30 factory TreeSet({Comparator<V> comparator}) { | |
| 31 if (comparator == null) { | |
| 32 comparator = (a, b) => a.compareTo(b); | |
| 33 } | |
| 34 return new AvlTreeSet(comparator: comparator); | |
| 35 } | |
| 36 | |
| 37 TreeSet._(this.comparator); | |
| 38 | |
| 39 /** | |
| 40 * Returns an [BidirectionalIterator] that iterates over this tree. | |
| 41 */ | |
| 42 BidirectionalIterator<V> get iterator; | |
| 43 | |
| 44 /** | |
| 45 * Returns an [BidirectionalIterator] that iterates over this tree, in reverse
. | |
| 46 */ | |
| 47 BidirectionalIterator<V> get reverseIterator; | |
| 48 | |
| 49 /** | |
| 50 * Returns an [BidirectionalIterator] that starts at [anchor]. | |
| 51 * By default, the iterator includes the anchor with the first movement; | |
| 52 * set [inclusive] to false if you want to exclude the anchor. Set [reversed] | |
| 53 * to true to change the direction of of moveNext and movePrevious. | |
| 54 * | |
| 55 * Note: This iterator allows you to walk the entire set. It does not present | |
| 56 * a subview. | |
| 57 */ | |
| 58 BidirectionalIterator<V> fromIterator(V anchor, | |
| 59 {bool reversed: false, bool inclusive: true}); | |
| 60 | |
| 61 /** | |
| 62 * Search the tree for the matching [object] or the [nearestOption] | |
| 63 * if missing. See [TreeSearch]. | |
| 64 */ | |
| 65 V nearest(V object, {TreeSearch nearestOption: TreeSearch.NEAREST}); | |
| 66 | |
| 67 // TODO: toString or not toString, that is the question. | |
| 68 } | |
| 69 | |
| 70 /** | |
| 71 * Controls the results for [TreeSet.searchNearest]() | |
| 72 */ | |
| 73 class TreeSearch { | |
| 74 | |
| 75 /** | |
| 76 * If result not found, always chose the smaler element | |
| 77 */ | |
| 78 static const LESS_THAN = const TreeSearch._(1); | |
| 79 | |
| 80 /** | |
| 81 * If result not found, chose the nearest based on comparison | |
| 82 */ | |
| 83 static const NEAREST = const TreeSearch._(2); | |
| 84 | |
| 85 /** | |
| 86 * If result not found, always chose the greater element | |
| 87 */ | |
| 88 static const GREATER_THAN = const TreeSearch._(3); | |
| 89 | |
| 90 final int _val; | |
| 91 const TreeSearch._(this._val); | |
| 92 } | |
| 93 | |
| 94 /** | |
| 95 * A node in the [TreeSet]. | |
| 96 */ | |
| 97 abstract class _TreeNode<V> { | |
| 98 _TreeNode<V> get left; | |
| 99 _TreeNode<V> get right; | |
| 100 | |
| 101 //TODO(codefu): Remove need for [parent]; this is just an implementation note | |
| 102 _TreeNode<V> get parent; | |
| 103 V object; | |
| 104 | |
| 105 /** | |
| 106 * TreeNodes are always allocated as leafs. | |
| 107 */ | |
| 108 _TreeNode({this.object}); | |
| 109 | |
| 110 /** | |
| 111 * Return the minimum node for the subtree | |
| 112 */ | |
| 113 _TreeNode<V> get minimumNode { | |
| 114 var node = this; | |
| 115 while (node.left != null) { | |
| 116 node = node.left; | |
| 117 } | |
| 118 return node; | |
| 119 } | |
| 120 | |
| 121 /** | |
| 122 * Return the maximum node for the subtree | |
| 123 */ | |
| 124 _TreeNode<V> get maximumNode { | |
| 125 var node = this; | |
| 126 while (node.right != null) { | |
| 127 node = node.right; | |
| 128 } | |
| 129 return node; | |
| 130 } | |
| 131 | |
| 132 /** | |
| 133 * Return the next greatest element (or null) | |
| 134 */ | |
| 135 _TreeNode<V> get successor { | |
| 136 var node = this; | |
| 137 if (node.right != null) { | |
| 138 return node.right.minimumNode; | |
| 139 } | |
| 140 while (node.parent != null && node == node.parent.right) { | |
| 141 node = node.parent; | |
| 142 } | |
| 143 return node.parent; | |
| 144 } | |
| 145 | |
| 146 /** | |
| 147 * Return the next smaller element (or null) | |
| 148 */ | |
| 149 _TreeNode<V> get predecessor { | |
| 150 var node = this; | |
| 151 if (node.left != null) { | |
| 152 return node.left.maximumNode; | |
| 153 } | |
| 154 while (node.parent != null && node.parent._left == node) { | |
| 155 node = node.parent; | |
| 156 } | |
| 157 return node.parent; | |
| 158 } | |
| 159 } | |
| 160 | |
| 161 /** | |
| 162 * AVL implementation of a self-balancing binary tree. Optimized for lookup | |
| 163 * operations. | |
| 164 * | |
| 165 * Notes: Adapted from "Introduction to Algorithms", second edition, | |
| 166 * by Thomas H. Cormen, Charles E. Leiserson, | |
| 167 * Ronald L. Rivest, Clifford Stein. | |
| 168 * chapter 13.2 | |
| 169 */ | |
| 170 class AvlTreeSet<V> extends TreeSet<V> { | |
| 171 int _length = 0; | |
| 172 AvlNode<V> _root; | |
| 173 // Modification count to the tree, monotonically increasing | |
| 174 int _modCount = 0; | |
| 175 | |
| 176 int get length => _length; | |
| 177 | |
| 178 AvlTreeSet({Comparator<V> comparator}) : super._(comparator); | |
| 179 | |
| 180 /** | |
| 181 * Add the element to the tree. | |
| 182 */ | |
| 183 bool add(V element) { | |
| 184 if (_root == null) { | |
| 185 AvlNode<V> node = new AvlNode<V>(object: element); | |
| 186 _root = node; | |
| 187 ++_length; | |
| 188 ++_modCount; | |
| 189 return true; | |
| 190 } | |
| 191 | |
| 192 AvlNode<V> x = _root; | |
| 193 while (true) { | |
| 194 int compare = comparator(element, x.object); | |
| 195 if (compare == 0) { | |
| 196 return false; | |
| 197 } else if (compare < 0) { | |
| 198 if (x._left == null) { | |
| 199 AvlNode<V> node = new AvlNode<V>(object: element).._parent = x; | |
| 200 x | |
| 201 .._left = node | |
| 202 .._balanceFactor -= 1; | |
| 203 break; | |
| 204 } | |
| 205 x = x.left; | |
| 206 } else { | |
| 207 if (x._right == null) { | |
| 208 AvlNode<V> node = new AvlNode<V>(object: element).._parent = x; | |
| 209 x | |
| 210 .._right = node | |
| 211 .._balanceFactor += 1; | |
| 212 break; | |
| 213 } | |
| 214 x = x.right; | |
| 215 } | |
| 216 } | |
| 217 | |
| 218 ++_modCount; | |
| 219 | |
| 220 // AVL balancing act (for height balanced trees) | |
| 221 // Now that we've inserted, we've unbalanced some trees, we need | |
| 222 // to follow the tree back up to the _root double checking that the tree | |
| 223 // is still balanced and _maybe_ perform a single or double rotation. | |
| 224 // Note: Left additions == -1, Right additions == +1 | |
| 225 // Balanced Node = { -1, 0, 1 }, out of balance = { -2, 2 } | |
| 226 // Single rotation when Parent & Child share signed balance, | |
| 227 // Double rotation when sign differs! | |
| 228 AvlNode<V> node = x; | |
| 229 while (node._balanceFactor != 0 && node.parent != null) { | |
| 230 // Find out which side of the parent we're on | |
| 231 if (node.parent._left == node) { | |
| 232 node.parent._balanceFactor -= 1; | |
| 233 } else { | |
| 234 node.parent._balanceFactor += 1; | |
| 235 } | |
| 236 | |
| 237 node = node.parent; | |
| 238 if (node._balanceFactor == 2) { | |
| 239 // Heavy on the right side - Test for which rotation to perform | |
| 240 if (node.right._balanceFactor == 1) { | |
| 241 // Single (left) rotation; this will balance everything to zero | |
| 242 _rotateLeft(node); | |
| 243 node._balanceFactor = node.parent._balanceFactor = 0; | |
| 244 node = node.parent; | |
| 245 } else { | |
| 246 // Double (Right/Left) rotation | |
| 247 // node will now be old node.right.left | |
| 248 _rotateRightLeft(node); | |
| 249 node = node.parent; // Update to new parent (old grandchild) | |
| 250 if (node._balanceFactor == 1) { | |
| 251 node.right._balanceFactor = 0; | |
| 252 node.left._balanceFactor = -1; | |
| 253 } else if (node._balanceFactor == 0) { | |
| 254 node.right._balanceFactor = 0; | |
| 255 node.left._balanceFactor = 0; | |
| 256 } else { | |
| 257 node.right._balanceFactor = 1; | |
| 258 node.left._balanceFactor = 0; | |
| 259 } | |
| 260 node._balanceFactor = 0; | |
| 261 } | |
| 262 break; // out of loop, we're balanced | |
| 263 } else if (node._balanceFactor == -2) { | |
| 264 // Heavy on the left side - Test for which rotation to perform | |
| 265 if (node.left._balanceFactor == -1) { | |
| 266 _rotateRight(node); | |
| 267 node._balanceFactor = node.parent._balanceFactor = 0; | |
| 268 node = node.parent; | |
| 269 } else { | |
| 270 // Double (Left/Right) rotation | |
| 271 // node will now be old node.left.right | |
| 272 _rotateLeftRight(node); | |
| 273 node = node.parent; | |
| 274 if (node._balanceFactor == -1) { | |
| 275 node.right._balanceFactor = 1; | |
| 276 node.left._balanceFactor = 0; | |
| 277 } else if (node._balanceFactor == 0) { | |
| 278 node.right._balanceFactor = 0; | |
| 279 node.left._balanceFactor = 0; | |
| 280 } else { | |
| 281 node.right._balanceFactor = 0; | |
| 282 node.left._balanceFactor = -1; | |
| 283 } | |
| 284 node._balanceFactor = 0; | |
| 285 } | |
| 286 break; // out of loop, we're balanced | |
| 287 } | |
| 288 } // end of while (balancing) | |
| 289 _length++; | |
| 290 return true; | |
| 291 } | |
| 292 | |
| 293 /** | |
| 294 * Test to see if an element is stored in the tree | |
| 295 */ | |
| 296 AvlNode<V> _getNode(V element) { | |
| 297 if (element == null) return null; | |
| 298 AvlNode<V> x = _root; | |
| 299 while (x != null) { | |
| 300 int compare = comparator(element, x.object); | |
| 301 if (compare == 0) { | |
| 302 // This only means our node matches; we need to search for the exact | |
| 303 // element. We could have been glutons and used a hashmap to back. | |
| 304 return x; | |
| 305 } else if (compare < 0) { | |
| 306 x = x.left; | |
| 307 } else { | |
| 308 x = x.right; | |
| 309 } | |
| 310 } | |
| 311 return null; | |
| 312 } | |
| 313 | |
| 314 /** | |
| 315 * This function will right rotate/pivot N with its left child, placing | |
| 316 * it on the right of its left child. | |
| 317 * | |
| 318 * N Y | |
| 319 * / \ / \ | |
| 320 * Y A Z N | |
| 321 * / \ ==> / \ / \ | |
| 322 * Z B D CB A | |
| 323 * / \ | |
| 324 *D C | |
| 325 * | |
| 326 * Assertion: must have a left element | |
| 327 */ | |
| 328 void _rotateRight(AvlNode<V> node) { | |
| 329 AvlNode<V> y = node.left; | |
| 330 if (y == null) throw new AssertionError(); | |
| 331 | |
| 332 // turn Y's right subtree(B) into N's left subtree. | |
| 333 node._left = y.right; | |
| 334 if (node.left != null) { | |
| 335 node.left._parent = node; | |
| 336 } | |
| 337 y._parent = node.parent; | |
| 338 if (y._parent == null) { | |
| 339 _root = y; | |
| 340 } else { | |
| 341 if (node.parent._left == node) { | |
| 342 node.parent._left = y; | |
| 343 } else { | |
| 344 node.parent._right = y; | |
| 345 } | |
| 346 } | |
| 347 y._right = node; | |
| 348 node._parent = y; | |
| 349 } | |
| 350 | |
| 351 /** | |
| 352 * This function will left rotate/pivot N with its right child, placing | |
| 353 * it on the left of its right child. | |
| 354 * | |
| 355 * N Y | |
| 356 * / \ / \ | |
| 357 * A Y N Z | |
| 358 * / \ ==> / \ / \ | |
| 359 * B Z A BC D | |
| 360 * / \ | |
| 361 * C D | |
| 362 * | |
| 363 * Assertion: must have a right element | |
| 364 */ | |
| 365 void _rotateLeft(AvlNode<V> node) { | |
| 366 AvlNode<V> y = node.right; | |
| 367 if (y == null) throw new AssertionError(); | |
| 368 | |
| 369 // turn Y's left subtree(B) into N's right subtree. | |
| 370 node._right = y.left; | |
| 371 if (node.right != null) { | |
| 372 node.right._parent = node; | |
| 373 } | |
| 374 y._parent = node.parent; | |
| 375 if (y._parent == null) { | |
| 376 _root = y; | |
| 377 } else { | |
| 378 if (node.parent._left == node) { | |
| 379 y.parent._left = y; | |
| 380 } else { | |
| 381 y.parent._right = y; | |
| 382 } | |
| 383 } | |
| 384 y._left = node; | |
| 385 node._parent = y; | |
| 386 } | |
| 387 | |
| 388 /** | |
| 389 * This function will double rotate node with right/left operations. | |
| 390 * node is S. | |
| 391 * | |
| 392 * S G | |
| 393 * / \ / \ | |
| 394 * A C S C | |
| 395 * / \ ==> / \ / \ | |
| 396 * G B A DC B | |
| 397 * / \ | |
| 398 * D C | |
| 399 */ | |
| 400 void _rotateRightLeft(AvlNode<V> node) { | |
| 401 _rotateRight(node.right); | |
| 402 _rotateLeft(node); | |
| 403 } | |
| 404 | |
| 405 /** | |
| 406 * This function will double rotate node with left/right operations. | |
| 407 * node is S. | |
| 408 * | |
| 409 * S G | |
| 410 * / \ / \ | |
| 411 * C A C S | |
| 412 * / \ ==> / \ / \ | |
| 413 *B G B CD A | |
| 414 * / \ | |
| 415 * C D | |
| 416 */ | |
| 417 void _rotateLeftRight(AvlNode<V> node) { | |
| 418 _rotateLeft(node.left); | |
| 419 _rotateRight(node); | |
| 420 } | |
| 421 | |
| 422 bool addAll(Iterable<V> items) { | |
| 423 bool modified = false; | |
| 424 for (V ele in items) { | |
| 425 modified = add(ele) ? true : modified; | |
| 426 } | |
| 427 return modified; | |
| 428 } | |
| 429 | |
| 430 void clear() { | |
| 431 _length = 0; | |
| 432 _root = null; | |
| 433 ++_modCount; | |
| 434 } | |
| 435 | |
| 436 bool containsAll(Iterable<Object> items) { | |
| 437 for (var ele in items) { | |
| 438 if (!contains(ele)) return false; | |
| 439 } | |
| 440 return true; | |
| 441 } | |
| 442 | |
| 443 bool remove(Object item) { | |
| 444 AvlNode<V> x = _getNode(item); | |
| 445 if (x != null) { | |
| 446 _removeNode(x); | |
| 447 return true; | |
| 448 } | |
| 449 return false; | |
| 450 } | |
| 451 | |
| 452 void _removeNode(AvlNode<V> node) { | |
| 453 AvlNode<V> y, w; | |
| 454 | |
| 455 ++_modCount; | |
| 456 --_length; | |
| 457 | |
| 458 // note: if you read wikipedia, it states remove the node if its a leaf, | |
| 459 // otherwise, replace it with its predecessor or successor. We're not. | |
| 460 if (node._right == null || node.right._left == null) { | |
| 461 // simple solutions | |
| 462 if (node.right != null) { | |
| 463 y = node.right; | |
| 464 y._parent = node.parent; | |
| 465 y._balanceFactor = node._balanceFactor - 1; | |
| 466 y._left = node.left; | |
| 467 if (y.left != null) { | |
| 468 y.left._parent = y; | |
| 469 } | |
| 470 } else if (node.left != null) { | |
| 471 y = node.left; | |
| 472 y._parent = node.parent; | |
| 473 y._balanceFactor = node._balanceFactor + 1; | |
| 474 } else { | |
| 475 y = null; | |
| 476 } | |
| 477 if (_root == node) { | |
| 478 _root = y; | |
| 479 } else if (node.parent._left == node) { | |
| 480 node.parent._left = y; | |
| 481 if (y == null) { | |
| 482 // account for leaf deletions changing the balance | |
| 483 node.parent._balanceFactor += 1; | |
| 484 y = node.parent; // start searching from here; | |
| 485 } | |
| 486 } else { | |
| 487 node.parent._right = y; | |
| 488 if (y == null) { | |
| 489 node.parent._balanceFactor -= 1; | |
| 490 y = node.parent; | |
| 491 } | |
| 492 } | |
| 493 w = y; | |
| 494 } else { | |
| 495 // This node is not a leaf; we should find the successor node, swap | |
| 496 //it with this* and then update the balance factors. | |
| 497 y = node.successor; | |
| 498 y._left = node.left; | |
| 499 if (y.left != null) { | |
| 500 y.left._parent = y; | |
| 501 } | |
| 502 | |
| 503 w = y.parent; | |
| 504 w._left = y.right; | |
| 505 if (w.left != null) { | |
| 506 w.left._parent = w; | |
| 507 } | |
| 508 // known: we're removing from the left | |
| 509 w._balanceFactor += 1; | |
| 510 | |
| 511 // known due to test for n->r->l above | |
| 512 y._right = node.right; | |
| 513 y.right._parent = y; | |
| 514 y._balanceFactor = node._balanceFactor; | |
| 515 | |
| 516 y._parent = node.parent; | |
| 517 if (_root == node) { | |
| 518 _root = y; | |
| 519 } else if (node.parent._left == node) { | |
| 520 node.parent._left = y; | |
| 521 } else { | |
| 522 node.parent._right = y; | |
| 523 } | |
| 524 } | |
| 525 | |
| 526 // Safe to kill node now; its free to go. | |
| 527 node._balanceFactor = 0; | |
| 528 node._left = node._right = node._parent = null; | |
| 529 node.object = null; | |
| 530 | |
| 531 // Recalculate max values all the way to the top. | |
| 532 node = w; | |
| 533 while (node != null) { | |
| 534 node = node.parent; | |
| 535 } | |
| 536 | |
| 537 // Re-balance to the top, ending early if OK | |
| 538 node = w; | |
| 539 while (node != null) { | |
| 540 if (node._balanceFactor == -1 || node._balanceFactor == 1) { | |
| 541 // The height of node hasn't changed; done! | |
| 542 break; | |
| 543 } | |
| 544 if (node._balanceFactor == 2) { | |
| 545 // Heavy on the right side; figure out which rotation to perform | |
| 546 if (node.right._balanceFactor == -1) { | |
| 547 _rotateRightLeft(node); | |
| 548 node = node.parent; // old grand-child! | |
| 549 if (node._balanceFactor == 1) { | |
| 550 node.right._balanceFactor = 0; | |
| 551 node.left._balanceFactor = -1; | |
| 552 } else if (node._balanceFactor == 0) { | |
| 553 node.right._balanceFactor = 0; | |
| 554 node.left._balanceFactor = 0; | |
| 555 } else { | |
| 556 node.right._balanceFactor = 1; | |
| 557 node.left._balanceFactor = 0; | |
| 558 } | |
| 559 node._balanceFactor = 0; | |
| 560 } else { | |
| 561 // single left-rotation | |
| 562 _rotateLeft(node); | |
| 563 if (node.parent._balanceFactor == 0) { | |
| 564 node.parent._balanceFactor = -1; | |
| 565 node._balanceFactor = 1; | |
| 566 break; | |
| 567 } else { | |
| 568 node.parent._balanceFactor = 0; | |
| 569 node._balanceFactor = 0; | |
| 570 node = node.parent; | |
| 571 continue; | |
| 572 } | |
| 573 } | |
| 574 } else if (node._balanceFactor == -2) { | |
| 575 // Heavy on the left | |
| 576 if (node.left._balanceFactor == 1) { | |
| 577 _rotateLeftRight(node); | |
| 578 node = node.parent; // old grand-child! | |
| 579 if (node._balanceFactor == -1) { | |
| 580 node.right._balanceFactor = 1; | |
| 581 node.left._balanceFactor = 0; | |
| 582 } else if (node._balanceFactor == 0) { | |
| 583 node.right._balanceFactor = 0; | |
| 584 node.left._balanceFactor = 0; | |
| 585 } else { | |
| 586 node.right._balanceFactor = 0; | |
| 587 node.left._balanceFactor = -1; | |
| 588 } | |
| 589 node._balanceFactor = 0; | |
| 590 } else { | |
| 591 _rotateRight(node); | |
| 592 if (node.parent._balanceFactor == 0) { | |
| 593 node.parent._balanceFactor = 1; | |
| 594 node._balanceFactor = -1; | |
| 595 break; | |
| 596 } else { | |
| 597 node.parent._balanceFactor = 0; | |
| 598 node._balanceFactor = 0; | |
| 599 node = node.parent; | |
| 600 continue; | |
| 601 } | |
| 602 } | |
| 603 } | |
| 604 | |
| 605 // continue up the tree for testing | |
| 606 if (node.parent != null) { | |
| 607 // The concept of balance here is reverse from addition; since | |
| 608 // we are taking away weight from one side or the other (thus | |
| 609 // the balance changes in favor of the other side) | |
| 610 if (node.parent.left == node) { | |
| 611 node.parent._balanceFactor += 1; | |
| 612 } else { | |
| 613 node.parent._balanceFactor -= 1; | |
| 614 } | |
| 615 } | |
| 616 node = node.parent; | |
| 617 } | |
| 618 } | |
| 619 | |
| 620 /** | |
| 621 * See [Set.removeAll] | |
| 622 */ | |
| 623 void removeAll(Iterable items) { | |
| 624 for (var ele in items) { | |
| 625 remove(ele); | |
| 626 } | |
| 627 } | |
| 628 | |
| 629 /** | |
| 630 * See [Set.retainAll] | |
| 631 */ | |
| 632 void retainAll(Iterable<Object> elements) { | |
| 633 List<V> chosen = []; | |
| 634 for (var target in elements) { | |
| 635 if (contains(target)) { | |
| 636 chosen.add(target); | |
| 637 } | |
| 638 } | |
| 639 clear(); | |
| 640 addAll(chosen); | |
| 641 } | |
| 642 | |
| 643 /** | |
| 644 * See [Set.retainWhere] | |
| 645 */ | |
| 646 void retainWhere(bool test(V element)) { | |
| 647 List<V> chosen = []; | |
| 648 for (var target in this) { | |
| 649 if (test(target)) { | |
| 650 chosen.add(target); | |
| 651 } | |
| 652 } | |
| 653 clear(); | |
| 654 addAll(chosen); | |
| 655 } | |
| 656 | |
| 657 /** | |
| 658 * See [Set.removeWhere] | |
| 659 */ | |
| 660 void removeWhere(bool test(V element)) { | |
| 661 List<V> damned = []; | |
| 662 for (var target in this) { | |
| 663 if (test(target)) { | |
| 664 damned.add(target); | |
| 665 } | |
| 666 } | |
| 667 removeAll(damned); | |
| 668 } | |
| 669 | |
| 670 /** | |
| 671 * See [IterableBase.first] | |
| 672 */ | |
| 673 V get first { | |
| 674 if (_root == null) return null; | |
| 675 AvlNode<V> min = _root.minimumNode; | |
| 676 return min != null ? min.object : null; | |
| 677 } | |
| 678 | |
| 679 /** | |
| 680 * See [IterableBase.last] | |
| 681 */ | |
| 682 V get last { | |
| 683 if (_root == null) return null; | |
| 684 AvlNode<V> max = _root.maximumNode; | |
| 685 return max != null ? max.object : null; | |
| 686 } | |
| 687 | |
| 688 /** | |
| 689 * See [Set.lookup] | |
| 690 */ | |
| 691 V lookup(Object element) { | |
| 692 if (element == null || _root == null) return null; | |
| 693 AvlNode<V> x = _root; | |
| 694 int compare = 0; | |
| 695 while (x != null) { | |
| 696 compare = comparator(element, x.object); | |
| 697 if (compare == 0) { | |
| 698 return x.object; | |
| 699 } else if (compare < 0) { | |
| 700 x = x.left; | |
| 701 } else { | |
| 702 x = x.right; | |
| 703 } | |
| 704 } | |
| 705 return null; | |
| 706 } | |
| 707 | |
| 708 V nearest(V object, {TreeSearch nearestOption: TreeSearch.NEAREST}) { | |
| 709 AvlNode<V> found = _searchNearest(object, option: nearestOption); | |
| 710 return (found != null) ? found.object : null; | |
| 711 } | |
| 712 | |
| 713 /** | |
| 714 * Search the tree for the matching element, or the 'nearest' node. | |
| 715 * NOTE: [BinaryTree.comparator] needs to have finer granulatity than -1,0,1 | |
| 716 * in order for this to return something that's meaningful. | |
| 717 */ | |
| 718 AvlNode<V> _searchNearest(V element, | |
| 719 {TreeSearch option: TreeSearch.NEAREST}) { | |
| 720 if (element == null || _root == null) { | |
| 721 return null; | |
| 722 } | |
| 723 AvlNode<V> x = _root; | |
| 724 AvlNode<V> previous; | |
| 725 int compare = 0; | |
| 726 while (x != null) { | |
| 727 previous = x; | |
| 728 compare = comparator(element, x.object); | |
| 729 if (compare == 0) { | |
| 730 return x; | |
| 731 } else if (compare < 0) { | |
| 732 x = x.left; | |
| 733 } else { | |
| 734 x = x.right; | |
| 735 } | |
| 736 } | |
| 737 | |
| 738 if (option == TreeSearch.GREATER_THAN) { | |
| 739 return (compare < 0) ? previous : previous.successor; | |
| 740 } else if (option == TreeSearch.LESS_THAN) { | |
| 741 return (compare < 0) ? previous.predecessor : previous; | |
| 742 } | |
| 743 // Default: nearest absolute value | |
| 744 // Fell off the tree looking for the exact match; now we need | |
| 745 // to find the nearest element. | |
| 746 x = (compare < 0) ? previous.predecessor : previous.successor; | |
| 747 if (x == null) { | |
| 748 return previous; | |
| 749 } | |
| 750 int otherCompare = comparator(element, x.object); | |
| 751 if (compare < 0) { | |
| 752 return compare.abs() < otherCompare ? previous : x; | |
| 753 } | |
| 754 return otherCompare.abs() < compare ? x : previous; | |
| 755 } | |
| 756 | |
| 757 // | |
| 758 // [IterableBase]<V> Methods | |
| 759 // | |
| 760 | |
| 761 /** | |
| 762 * See [IterableBase.iterator] | |
| 763 */ | |
| 764 BidirectionalIterator<V> get iterator => new _AvlTreeIterator._(this); | |
| 765 | |
| 766 /** | |
| 767 * See [TreeSet.reverseIterator] | |
| 768 */ | |
| 769 BidirectionalIterator<V> get reverseIterator => | |
| 770 new _AvlTreeIterator._(this, reversed: true); | |
| 771 | |
| 772 /** | |
| 773 * See [TreeSet.fromIterator] | |
| 774 */ | |
| 775 BidirectionalIterator<V> fromIterator(V anchor, | |
| 776 {bool reversed: false, bool inclusive: true}) => | |
| 777 new _AvlTreeIterator<V>._(this, | |
| 778 anchorObject: anchor, reversed: reversed, inclusive: inclusive); | |
| 779 | |
| 780 /** | |
| 781 * See [IterableBase.contains] | |
| 782 */ | |
| 783 bool contains(Object object) { | |
| 784 AvlNode<V> x = _getNode(object as V); | |
| 785 return x != null; | |
| 786 } | |
| 787 | |
| 788 // | |
| 789 // [Set] methods | |
| 790 // | |
| 791 | |
| 792 /** | |
| 793 * See [Set.intersection] | |
| 794 */ | |
| 795 Set<V> intersection(Set<Object> other) { | |
| 796 TreeSet<V> set = new TreeSet(comparator: comparator); | |
| 797 | |
| 798 // Opitimized for sorted sets | |
| 799 if (other is TreeSet) { | |
| 800 var i1 = iterator; | |
| 801 var i2 = other.iterator; | |
| 802 var hasMore1 = i1.moveNext(); | |
| 803 var hasMore2 = i2.moveNext(); | |
| 804 while (hasMore1 && hasMore2) { | |
| 805 var c = comparator(i1.current, i2.current); | |
| 806 if (c == 0) { | |
| 807 set.add(i1.current); | |
| 808 hasMore1 = i1.moveNext(); | |
| 809 hasMore2 = i2.moveNext(); | |
| 810 } else if (c < 0) { | |
| 811 hasMore1 = i1.moveNext(); | |
| 812 } else { | |
| 813 hasMore2 = i2.moveNext(); | |
| 814 } | |
| 815 } | |
| 816 return set; | |
| 817 } | |
| 818 | |
| 819 // Non-optimized version. | |
| 820 for (var target in this) { | |
| 821 if (other.contains(target)) { | |
| 822 set.add(target); | |
| 823 } | |
| 824 } | |
| 825 return set; | |
| 826 } | |
| 827 | |
| 828 /** | |
| 829 * See [Set.union] | |
| 830 */ | |
| 831 Set<V> union(Set<V> other) { | |
| 832 TreeSet<V> set = new TreeSet(comparator: comparator); | |
| 833 | |
| 834 if (other is TreeSet) { | |
| 835 var i1 = iterator; | |
| 836 var i2 = other.iterator; | |
| 837 var hasMore1 = i1.moveNext(); | |
| 838 var hasMore2 = i2.moveNext(); | |
| 839 while (hasMore1 && hasMore2) { | |
| 840 var c = comparator(i1.current, i2.current); | |
| 841 if (c == 0) { | |
| 842 set.add(i1.current); | |
| 843 hasMore1 = i1.moveNext(); | |
| 844 hasMore2 = i2.moveNext(); | |
| 845 } else if (c < 0) { | |
| 846 set.add(i1.current); | |
| 847 hasMore1 = i1.moveNext(); | |
| 848 } else { | |
| 849 set.add(i2.current); | |
| 850 hasMore2 = i2.moveNext(); | |
| 851 } | |
| 852 } | |
| 853 if (hasMore1 || hasMore2) { | |
| 854 i1 = hasMore1 ? i1 : i2; | |
| 855 do { | |
| 856 set.add(i1.current); | |
| 857 } while (i1.moveNext()); | |
| 858 } | |
| 859 return set; | |
| 860 } | |
| 861 | |
| 862 // Non-optimized version. | |
| 863 return set | |
| 864 ..addAll(this) | |
| 865 ..addAll(other); | |
| 866 } | |
| 867 | |
| 868 /** | |
| 869 * See [Set.difference] | |
| 870 */ | |
| 871 Set<V> difference(Set<V> other) { | |
| 872 TreeSet<V> set = new TreeSet(comparator: comparator); | |
| 873 | |
| 874 if (other is TreeSet) { | |
| 875 var i1 = iterator; | |
| 876 var i2 = other.iterator; | |
| 877 var hasMore1 = i1.moveNext(); | |
| 878 var hasMore2 = i2.moveNext(); | |
| 879 while (hasMore1 && hasMore2) { | |
| 880 var c = comparator(i1.current, i2.current); | |
| 881 if (c == 0) { | |
| 882 hasMore1 = i1.moveNext(); | |
| 883 hasMore2 = i2.moveNext(); | |
| 884 } else if (c < 0) { | |
| 885 set.add(i1.current); | |
| 886 hasMore1 = i1.moveNext(); | |
| 887 } else { | |
| 888 hasMore2 = i2.moveNext(); | |
| 889 } | |
| 890 } | |
| 891 if (hasMore1) { | |
| 892 do { | |
| 893 set.add(i1.current); | |
| 894 } while (i1.moveNext()); | |
| 895 } | |
| 896 return set; | |
| 897 } | |
| 898 | |
| 899 // Non-optimized version. | |
| 900 for (var target in this) { | |
| 901 if (!other.contains(target)) { | |
| 902 set.add(target); | |
| 903 } | |
| 904 } | |
| 905 return set; | |
| 906 } | |
| 907 | |
| 908 /** | |
| 909 * Visible for testing only. | |
| 910 */ | |
| 911 AvlNode<V> getNode(V object) => _getNode(object); | |
| 912 } | |
| 913 | |
| 914 typedef bool _IteratorMove(); | |
| 915 | |
| 916 /** | |
| 917 * This iterator either starts at the beginning or end (see [TreeSet.iterator] | |
| 918 * and [TreeSet.reverseIterator]) or from an anchor point in the set (see | |
| 919 * [TreeSet.fromIterator]). When using fromIterator, the inital | |
| 920 * anchor point is included in the first movement (either [moveNext] or | |
| 921 * [movePrevious]) but can optionally be excluded in the constructor. | |
| 922 */ | |
| 923 class _AvlTreeIterator<V> implements BidirectionalIterator<V> { | |
| 924 static const LEFT = -1; | |
| 925 static const WALK = 0; | |
| 926 static const RIGHT = 1; | |
| 927 | |
| 928 final bool reversed; | |
| 929 final AvlTreeSet<V> tree; | |
| 930 final int _modCountGuard; | |
| 931 final Object anchorObject; | |
| 932 final bool inclusive; | |
| 933 | |
| 934 _IteratorMove _moveNext; | |
| 935 _IteratorMove _movePrevious; | |
| 936 | |
| 937 int state; | |
| 938 _TreeNode<V> _current; | |
| 939 | |
| 940 _AvlTreeIterator._(AvlTreeSet<V> tree, | |
| 941 {reversed: false, this.inclusive: true, this.anchorObject: null}) | |
| 942 : this.tree = tree, | |
| 943 this._modCountGuard = tree._modCount, | |
| 944 this.reversed = reversed { | |
| 945 if (anchorObject == null || tree.length == 0) { | |
| 946 // If the anchor is far left or right, we're just a normal iterator. | |
| 947 state = reversed ? RIGHT : LEFT; | |
| 948 _moveNext = reversed ? _movePreviousNormal : _moveNextNormal; | |
| 949 _movePrevious = reversed ? _moveNextNormal : _movePreviousNormal; | |
| 950 return; | |
| 951 } | |
| 952 | |
| 953 state = WALK; | |
| 954 // Else we've got an anchor we have to worry about initalizing from. | |
| 955 // This isn't known till the caller actually performs a previous/next. | |
| 956 _moveNext = () { | |
| 957 _current = tree._searchNearest(anchorObject, | |
| 958 option: reversed ? TreeSearch.LESS_THAN : TreeSearch.GREATER_THAN); | |
| 959 _moveNext = reversed ? _movePreviousNormal : _moveNextNormal; | |
| 960 _movePrevious = reversed ? _moveNextNormal : _movePreviousNormal; | |
| 961 if (_current == null) { | |
| 962 state = reversed ? LEFT : RIGHT; | |
| 963 } else if (tree.comparator(_current.object, anchorObject) == 0 && | |
| 964 !inclusive) { | |
| 965 _moveNext(); | |
| 966 } | |
| 967 return state == WALK; | |
| 968 }; | |
| 969 | |
| 970 _movePrevious = () { | |
| 971 _current = tree._searchNearest(anchorObject, | |
| 972 option: reversed ? TreeSearch.GREATER_THAN : TreeSearch.LESS_THAN); | |
| 973 _moveNext = reversed ? _movePreviousNormal : _moveNextNormal; | |
| 974 _movePrevious = reversed ? _moveNextNormal : _movePreviousNormal; | |
| 975 if (_current == null) { | |
| 976 state = reversed ? RIGHT : LEFT; | |
| 977 } else if (tree.comparator(_current.object, anchorObject) == 0 && | |
| 978 !inclusive) { | |
| 979 _movePrevious(); | |
| 980 } | |
| 981 return state == WALK; | |
| 982 }; | |
| 983 } | |
| 984 | |
| 985 V get current => (state != WALK || _current == null) ? null : _current.object; | |
| 986 | |
| 987 bool moveNext() => _moveNext(); | |
| 988 bool movePrevious() => _movePrevious(); | |
| 989 | |
| 990 bool _moveNextNormal() { | |
| 991 if (_modCountGuard != tree._modCount) { | |
| 992 throw new ConcurrentModificationError(tree); | |
| 993 } | |
| 994 if (state == RIGHT || tree.length == 0) return false; | |
| 995 switch (state) { | |
| 996 case LEFT: | |
| 997 _current = tree._root.minimumNode; | |
| 998 state = WALK; | |
| 999 return true; | |
| 1000 case WALK: | |
| 1001 default: | |
| 1002 _current = _current.successor; | |
| 1003 if (_current == null) { | |
| 1004 state = RIGHT; | |
| 1005 } | |
| 1006 return state == WALK; | |
| 1007 } | |
| 1008 } | |
| 1009 | |
| 1010 bool _movePreviousNormal() { | |
| 1011 if (_modCountGuard != tree._modCount) { | |
| 1012 throw new ConcurrentModificationError(tree); | |
| 1013 } | |
| 1014 if (state == LEFT || tree.length == 0) return false; | |
| 1015 switch (state) { | |
| 1016 case RIGHT: | |
| 1017 _current = tree._root.maximumNode; | |
| 1018 state = WALK; | |
| 1019 return true; | |
| 1020 case WALK: | |
| 1021 default: | |
| 1022 _current = _current.predecessor; | |
| 1023 if (_current == null) { | |
| 1024 state = LEFT; | |
| 1025 } | |
| 1026 return state == WALK; | |
| 1027 } | |
| 1028 } | |
| 1029 } | |
| 1030 | |
| 1031 /** | |
| 1032 * Private class used to track element insertions in the [TreeSet]. | |
| 1033 */ | |
| 1034 class AvlNode<V> extends _TreeNode<V> { | |
| 1035 AvlNode<V> _left; | |
| 1036 AvlNode<V> _right; | |
| 1037 //TODO(codefu): Remove need for [parent]; this is just an implementation note | |
| 1038 AvlNode<V> _parent; | |
| 1039 int _balanceFactor = 0; | |
| 1040 | |
| 1041 AvlNode<V> get left => _left; | |
| 1042 AvlNode<V> get right => _right; | |
| 1043 AvlNode<V> get parent => _parent; | |
| 1044 int get balance => _balanceFactor; | |
| 1045 | |
| 1046 AvlNode({V object}) : super(object: object); | |
| 1047 | |
| 1048 String toString() => | |
| 1049 "(b:$balance o: $object l:${left != null} r:${right != null})"; | |
| 1050 } | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1400473008:
Roll Observatory packages and add a roll script (Closed)
Base URL: git@github.com:dart-lang/observatory_pub_packages.git@master