projects / mirror_edk2.git / blame
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1 | /** @file\r |
| 2 | An OrderedCollectionLib instance that provides a red-black tree\r | |
| 3 | implementation, and allocates and releases tree nodes with\r | |
| 4 | MemoryAllocationLib.\r | |
| 5 | \r | |
| 6 | This library instance is useful when a fast associative container is needed.\r | |
| 7 | Worst case time complexity is O(log n) for Find(), Next(), Prev(), Min(),\r | |
| 8 | Max(), Insert(), and Delete(), where "n" is the number of elements in the\r | |
| 9 | tree. Complete ordered traversal takes O(n) time.\r | |
| 10 | \r | |
| 11 | The implementation is also useful as a fast priority queue.\r | |
| 12 | \r | |
| 13 | Copyright (C) 2014, Red Hat, Inc.\r | |
| 14 | \r | |
| 15 | This program and the accompanying materials are licensed and made available\r | |
| 16 | under the terms and conditions of the BSD License that accompanies this\r | |
| 17 | distribution. The full text of the license may be found at\r | |
| 18 | http://opensource.org/licenses/bsd-license.php.\r | |
| 19 | \r | |
| 20 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, WITHOUT\r | |
| 21 | WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r | |
| 22 | **/\r | |
| 23 | \r | |
| 24 | #include <Library/OrderedCollectionLib.h>\r | |
| 25 | #include <Library/DebugLib.h>\r | |
| 26 | #include <Library/MemoryAllocationLib.h>\r | |
| 27 | \r | |
| 28 | typedef enum {\r | |
| 29 | RedBlackTreeRed,\r | |
| 30 | RedBlackTreeBlack\r | |
| 31 | } RED_BLACK_TREE_COLOR;\r | |
| 32 | \r | |
| 33 | //\r | |
| 34 | // Incomplete types and convenience typedefs are present in the library class\r | |
| 35 | // header. Beside completing the types, we introduce typedefs here that reflect\r | |
| 36 | // the implementation closely.\r | |
| 37 | //\r | |
| 38 | typedef ORDERED_COLLECTION RED_BLACK_TREE;\r | |
| 39 | typedef ORDERED_COLLECTION_ENTRY RED_BLACK_TREE_NODE;\r | |
| 40 | typedef ORDERED_COLLECTION_USER_COMPARE RED_BLACK_TREE_USER_COMPARE;\r | |
| 41 | typedef ORDERED_COLLECTION_KEY_COMPARE RED_BLACK_TREE_KEY_COMPARE;\r | |
| 42 | \r | |
| 43 | struct ORDERED_COLLECTION {\r | |
| 44 | RED_BLACK_TREE_NODE *Root;\r | |
| 45 | RED_BLACK_TREE_USER_COMPARE UserStructCompare;\r | |
| 46 | RED_BLACK_TREE_KEY_COMPARE KeyCompare;\r | |
| 47 | };\r | |
| 48 | \r | |
| 49 | struct ORDERED_COLLECTION_ENTRY {\r | |
| 50 | VOID *UserStruct;\r | |
| 51 | RED_BLACK_TREE_NODE *Parent;\r | |
| 52 | RED_BLACK_TREE_NODE *Left;\r | |
| 53 | RED_BLACK_TREE_NODE *Right;\r | |
| 54 | RED_BLACK_TREE_COLOR Color;\r | |
| 55 | };\r | |
| 56 | \r | |
| 57 | \r | |
| 58 | /**\r | |
| 59 | Retrieve the user structure linked by the specified tree node.\r | |
| 60 | \r | |
| 61 | Read-only operation.\r | |
| 62 | \r | |
| 63 | @param[in] Node Pointer to the tree node whose associated user structure we\r | |
| 64 | want to retrieve. The caller is responsible for passing a\r | |
| 65 | non-NULL argument.\r | |
| 66 | \r | |
| 67 | @return Pointer to user structure linked by Node.\r | |
| 68 | **/\r | |
| 69 | VOID *\r | |
| 70 | EFIAPI\r | |
| 71 | OrderedCollectionUserStruct (\r | |
| 72 | IN CONST RED_BLACK_TREE_NODE *Node\r | |
| 73 | )\r | |
| 74 | {\r | |
| 75 | return Node->UserStruct;\r | |
| 76 | }\r | |
| 77 | \r | |
| 78 | \r | |
| 79 | //\r | |
| 80 | // Forward declaration of internal, unit test helper function. See\r | |
| 81 | // specification and function definition later.\r | |
| 82 | //\r | |
| 83 | STATIC\r | |
| 84 | VOID\r | |
| 85 | RedBlackTreeValidate (\r | |
| 86 | IN CONST RED_BLACK_TREE *Tree\r | |
| 87 | );\r | |
| 88 | \r | |
| 89 | \r | |
| 90 | /**\r | |
| 91 | Allocate and initialize the RED_BLACK_TREE structure.\r | |
| 92 | \r | |
| 93 | Allocation occurs via MemoryAllocationLib's AllocatePool() function.\r | |
| 94 | \r | |
| 95 | @param[in] UserStructCompare This caller-provided function will be used to\r | |
| 96 | order two user structures linked into the\r | |
| 97 | tree, during the insertion procedure.\r | |
| 98 | \r | |
| 99 | @param[in] KeyCompare This caller-provided function will be used to\r | |
| 100 | order the standalone search key against user\r | |
| 101 | structures linked into the tree, during the\r | |
| 102 | lookup procedure.\r | |
| 103 | \r | |
| 104 | @retval NULL If allocation failed.\r | |
| 105 | \r | |
| 106 | @return Pointer to the allocated, initialized RED_BLACK_TREE structure,\r | |
| 107 | otherwise.\r | |
| 108 | **/\r | |
| 109 | RED_BLACK_TREE *\r | |
| 110 | EFIAPI\r | |
| 111 | OrderedCollectionInit (\r | |
| 112 | IN RED_BLACK_TREE_USER_COMPARE UserStructCompare,\r | |
| 113 | IN RED_BLACK_TREE_KEY_COMPARE KeyCompare\r | |
| 114 | )\r | |
| 115 | {\r | |
| 116 | RED_BLACK_TREE *Tree;\r | |
| 117 | \r | |
| 118 | Tree = AllocatePool (sizeof *Tree);\r | |
| 119 | if (Tree == NULL) {\r | |
| 120 | return NULL;\r | |
| 121 | }\r | |
| 122 | \r | |
| 123 | Tree->Root = NULL;\r | |
| 124 | Tree->UserStructCompare = UserStructCompare;\r | |
| 125 | Tree->KeyCompare = KeyCompare;\r | |
| 126 | \r | |
| 127 | if (FeaturePcdGet (PcdValidateOrderedCollection)) {\r | |
| 128 | RedBlackTreeValidate (Tree);\r | |
| 129 | }\r | |
| 130 | return Tree;\r | |
| 131 | }\r | |
| 132 | \r | |
| 133 | \r | |
| 134 | /**\r | |
| 135 | Check whether the tree is empty (has no nodes).\r | |
| 136 | \r | |
| 137 | Read-only operation.\r | |
| 138 | \r | |
| 139 | @param[in] Tree The tree to check for emptiness.\r | |
| 140 | \r | |
| 141 | @retval TRUE The tree is empty.\r | |
| 142 | \r | |
| 143 | @retval FALSE The tree is not empty.\r | |
| 144 | **/\r | |
| 145 | BOOLEAN\r | |
| 146 | EFIAPI\r | |
| 147 | OrderedCollectionIsEmpty (\r | |
| 148 | IN CONST RED_BLACK_TREE *Tree\r | |
| 149 | )\r | |
| 150 | {\r | |
| 151 | return Tree->Root == NULL;\r | |
| 152 | }\r | |
| 153 | \r | |
| 154 | \r | |
| 155 | /**\r | |
| 156 | Uninitialize and release an empty RED_BLACK_TREE structure.\r | |
| 157 | \r | |
| 158 | Read-write operation.\r | |
| 159 | \r | |
| 160 | Release occurs via MemoryAllocationLib's FreePool() function.\r | |
| 161 | \r | |
| 162 | It is the caller's responsibility to delete all nodes from the tree before\r | |
| 163 | calling this function.\r | |
| 164 | \r | |
| 165 | @param[in] Tree The empty tree to uninitialize and release.\r | |
| 166 | **/\r | |
| 167 | VOID\r | |
| 168 | EFIAPI\r | |
| 169 | OrderedCollectionUninit (\r | |
| 170 | IN RED_BLACK_TREE *Tree\r | |
| 171 | )\r | |
| 172 | {\r | |
| 173 | ASSERT (OrderedCollectionIsEmpty (Tree));\r | |
| 174 | FreePool (Tree);\r | |
| 175 | }\r | |
| 176 | \r | |
| 177 | \r | |
| 178 | /**\r | |
| 179 | Look up the tree node that links the user structure that matches the\r | |
| 180 | specified standalone key.\r | |
| 181 | \r | |
| 182 | Read-only operation.\r | |
| 183 | \r | |
| 184 | @param[in] Tree The tree to search for StandaloneKey.\r | |
| 185 | \r | |
| 186 | @param[in] StandaloneKey The key to locate among the user structures linked\r | |
| 187 | into Tree. StandaloneKey will be passed to\r | |
| 188 | Tree->KeyCompare().\r | |
| 189 | \r | |
| 190 | @retval NULL StandaloneKey could not be found.\r | |
| 191 | \r | |
| 192 | @return The tree node that links to the user structure matching\r | |
| 193 | StandaloneKey, otherwise.\r | |
| 194 | **/\r | |
| 195 | RED_BLACK_TREE_NODE *\r | |
| 196 | EFIAPI\r | |
| 197 | OrderedCollectionFind (\r | |
| 198 | IN CONST RED_BLACK_TREE *Tree,\r | |
| 199 | IN CONST VOID *StandaloneKey\r | |
| 200 | )\r | |
| 201 | {\r | |
| 202 | RED_BLACK_TREE_NODE *Node;\r | |
| 203 | \r | |
| 204 | Node = Tree->Root;\r | |
| 205 | while (Node != NULL) {\r | |
| 206 | INTN Result;\r | |
| 207 | \r | |
| 208 | Result = Tree->KeyCompare (StandaloneKey, Node->UserStruct);\r | |
| 209 | if (Result == 0) {\r | |
| 210 | break;\r | |
| 211 | }\r | |
| 212 | Node = (Result < 0) ? Node->Left : Node->Right;\r | |
| 213 | }\r | |
| 214 | return Node;\r | |
| 215 | }\r | |
| 216 | \r | |
| 217 | \r | |
| 218 | /**\r | |
| 219 | Find the tree node of the minimum user structure stored in the tree.\r | |
| 220 | \r | |
| 221 | Read-only operation.\r | |
| 222 | \r | |
| 223 | @param[in] Tree The tree to return the minimum node of. The user structure\r | |
| 224 | linked by the minimum node compares less than all other user\r | |
| 225 | structures in the tree.\r | |
| 226 | \r | |
| 227 | @retval NULL If Tree is empty.\r | |
| 228 | \r | |
| 229 | @return The tree node that links the minimum user structure, otherwise.\r | |
| 230 | **/\r | |
| 231 | RED_BLACK_TREE_NODE *\r | |
| 232 | EFIAPI\r | |
| 233 | OrderedCollectionMin (\r | |
| 234 | IN CONST RED_BLACK_TREE *Tree\r | |
| 235 | )\r | |
| 236 | {\r | |
| 237 | RED_BLACK_TREE_NODE *Node;\r | |
| 238 | \r | |
| 239 | Node = Tree->Root;\r | |
| 240 | if (Node == NULL) {\r | |
| 241 | return NULL;\r | |
| 242 | }\r | |
| 243 | while (Node->Left != NULL) {\r | |
| 244 | Node = Node->Left;\r | |
| 245 | }\r | |
| 246 | return Node;\r | |
| 247 | }\r | |
| 248 | \r | |
| 249 | \r | |
| 250 | /**\r | |
| 251 | Find the tree node of the maximum user structure stored in the tree.\r | |
| 252 | \r | |
| 253 | Read-only operation.\r | |
| 254 | \r | |
| 255 | @param[in] Tree The tree to return the maximum node of. The user structure\r | |
| 256 | linked by the maximum node compares greater than all other\r | |
| 257 | user structures in the tree.\r | |
| 258 | \r | |
| 259 | @retval NULL If Tree is empty.\r | |
| 260 | \r | |
| 261 | @return The tree node that links the maximum user structure, otherwise.\r | |
| 262 | **/\r | |
| 263 | RED_BLACK_TREE_NODE *\r | |
| 264 | EFIAPI\r | |
| 265 | OrderedCollectionMax (\r | |
| 266 | IN CONST RED_BLACK_TREE *Tree\r | |
| 267 | )\r | |
| 268 | {\r | |
| 269 | RED_BLACK_TREE_NODE *Node;\r | |
| 270 | \r | |
| 271 | Node = Tree->Root;\r | |
| 272 | if (Node == NULL) {\r | |
| 273 | return NULL;\r | |
| 274 | }\r | |
| 275 | while (Node->Right != NULL) {\r | |
| 276 | Node = Node->Right;\r | |
| 277 | }\r | |
| 278 | return Node;\r | |
| 279 | }\r | |
| 280 | \r | |
| 281 | \r | |
| 282 | /**\r | |
| 283 | Get the tree node of the least user structure that is greater than the one\r | |
| 284 | linked by Node.\r | |
| 285 | \r | |
| 286 | Read-only operation.\r | |
| 287 | \r | |
| 288 | @param[in] Node The node to get the successor node of.\r | |
| 289 | \r | |
| 290 | @retval NULL If Node is NULL, or Node is the maximum node of its containing\r | |
| 291 | tree (ie. Node has no successor node).\r | |
| 292 | \r | |
| 293 | @return The tree node linking the least user structure that is greater\r | |
| 294 | than the one linked by Node, otherwise.\r | |
| 295 | **/\r | |
| 296 | RED_BLACK_TREE_NODE *\r | |
| 297 | EFIAPI\r | |
| 298 | OrderedCollectionNext (\r | |
| 299 | IN CONST RED_BLACK_TREE_NODE *Node\r | |
| 300 | )\r | |
| 301 | {\r | |
| 302 | RED_BLACK_TREE_NODE *Walk;\r | |
| 303 | CONST RED_BLACK_TREE_NODE *Child;\r | |
| 304 | \r | |
| 305 | if (Node == NULL) {\r | |
| 306 | return NULL;\r | |
| 307 | }\r | |
| 308 | \r | |
| 309 | //\r | |
| 310 | // If Node has a right subtree, then the successor is the minimum node of\r | |
| 311 | // that subtree.\r | |
| 312 | //\r | |
| 313 | Walk = Node->Right;\r | |
| 314 | if (Walk != NULL) {\r | |
| 315 | while (Walk->Left != NULL) {\r | |
| 316 | Walk = Walk->Left;\r | |
| 317 | }\r | |
| 318 | return Walk;\r | |
| 319 | }\r | |
| 320 | \r | |
| 321 | //\r | |
| 322 | // Otherwise we have to ascend as long as we're our parent's right child (ie.\r | |
| 323 | // ascending to the left).\r | |
| 324 | //\r | |
| 325 | Child = Node;\r | |
| 326 | Walk = Child->Parent;\r | |
| 327 | while (Walk != NULL && Child == Walk->Right) {\r | |
| 328 | Child = Walk;\r | |
| 329 | Walk = Child->Parent;\r | |
| 330 | }\r | |
| 331 | return Walk;\r | |
| 332 | }\r | |
| 333 | \r | |
| 334 | \r | |
| 335 | /**\r | |
| 336 | Get the tree node of the greatest user structure that is less than the one\r | |
| 337 | linked by Node.\r | |
| 338 | \r | |
| 339 | Read-only operation.\r | |
| 340 | \r | |
| 341 | @param[in] Node The node to get the predecessor node of.\r | |
| 342 | \r | |
| 343 | @retval NULL If Node is NULL, or Node is the minimum node of its containing\r | |
| 344 | tree (ie. Node has no predecessor node).\r | |
| 345 | \r | |
| 346 | @return The tree node linking the greatest user structure that is less\r | |
| 347 | than the one linked by Node, otherwise.\r | |
| 348 | **/\r | |
| 349 | RED_BLACK_TREE_NODE *\r | |
| 350 | EFIAPI\r | |
| 351 | OrderedCollectionPrev (\r | |
| 352 | IN CONST RED_BLACK_TREE_NODE *Node\r | |
| 353 | )\r | |
| 354 | {\r | |
| 355 | RED_BLACK_TREE_NODE *Walk;\r | |
| 356 | CONST RED_BLACK_TREE_NODE *Child;\r | |
| 357 | \r | |
| 358 | if (Node == NULL) {\r | |
| 359 | return NULL;\r | |
| 360 | }\r | |
| 361 | \r | |
| 362 | //\r | |
| 363 | // If Node has a left subtree, then the predecessor is the maximum node of\r | |
| 364 | // that subtree.\r | |
| 365 | //\r | |
| 366 | Walk = Node->Left;\r | |
| 367 | if (Walk != NULL) {\r | |
| 368 | while (Walk->Right != NULL) {\r | |
| 369 | Walk = Walk->Right;\r | |
| 370 | }\r | |
| 371 | return Walk;\r | |
| 372 | }\r | |
| 373 | \r | |
| 374 | //\r | |
| 375 | // Otherwise we have to ascend as long as we're our parent's left child (ie.\r | |
| 376 | // ascending to the right).\r | |
| 377 | //\r | |
| 378 | Child = Node;\r | |
| 379 | Walk = Child->Parent;\r | |
| 380 | while (Walk != NULL && Child == Walk->Left) {\r | |
| 381 | Child = Walk;\r | |
| 382 | Walk = Child->Parent;\r | |
| 383 | }\r | |
| 384 | return Walk;\r | |
| 385 | }\r | |
| 386 | \r | |
| 387 | \r | |
| 388 | /**\r | |
| 389 | Rotate tree nodes around Pivot to the right.\r | |
| 390 | \r | |
| 391 | Parent Parent\r | |
| 392 | | |\r | |
| 393 | Pivot LeftChild\r | |
| 394 | / . . \_\r | |
| 395 | LeftChild Node1 ---> Node2 Pivot\r | |
| 396 | . \ / .\r | |
| 397 | Node2 LeftRightChild LeftRightChild Node1\r | |
| 398 | \r | |
| 399 | The ordering Node2 < LeftChild < LeftRightChild < Pivot < Node1 is kept\r | |
| 400 | intact. Parent (if any) is either at the left extreme or the right extreme of\r | |
| 401 | this ordering, and that relation is also kept intact.\r | |
| 402 | \r | |
| 403 | Edges marked with a dot (".") don't change during rotation.\r | |
| 404 | \r | |
| 405 | Internal read-write operation.\r | |
| 406 | \r | |
| 407 | @param[in,out] Pivot The tree node to rotate other nodes right around. It\r | |
| 408 | is the caller's responsibility to ensure that\r | |
| 409 | Pivot->Left is not NULL.\r | |
| 410 | \r | |
| 411 | @param[out] NewRoot If Pivot has a parent node on input, then the\r | |
| 412 | function updates Pivot's original parent on output\r | |
| 413 | according to the rotation, and NewRoot is not\r | |
| 414 | accessed.\r | |
| 415 | \r | |
| 416 | If Pivot has no parent node on input (ie. Pivot is\r | |
| 417 | the root of the tree), then the function stores the\r | |
| 418 | new root node of the tree in NewRoot.\r | |
| 419 | **/\r | |
| 420 | STATIC\r | |
| 421 | VOID\r | |
| 422 | RedBlackTreeRotateRight (\r | |
| 423 | IN OUT RED_BLACK_TREE_NODE *Pivot,\r | |
| 424 | OUT RED_BLACK_TREE_NODE **NewRoot\r | |
| 425 | )\r | |
| 426 | {\r | |
| 427 | RED_BLACK_TREE_NODE *Parent, *LeftChild, *LeftRightChild;\r | |
| 428 | \r | |
| 429 | Parent = Pivot->Parent;\r | |
| 430 | LeftChild = Pivot->Left;\r | |
| 431 | LeftRightChild = LeftChild->Right;\r | |
| 432 | \r | |
| 433 | Pivot->Left = LeftRightChild;\r | |
| 434 | if (LeftRightChild != NULL) {\r | |
| 435 | LeftRightChild->Parent = Pivot;\r | |
| 436 | }\r | |
| 437 | LeftChild->Parent = Parent;\r | |
| 438 | if (Parent == NULL) {\r | |
| 439 | *NewRoot = LeftChild;\r | |
| 440 | } else {\r | |
| 441 | if (Pivot == Parent->Left) {\r | |
| 442 | Parent->Left = LeftChild;\r | |
| 443 | } else {\r | |
| 444 | Parent->Right = LeftChild;\r | |
| 445 | }\r | |
| 446 | }\r | |
| 447 | LeftChild->Right = Pivot;\r | |
| 448 | Pivot->Parent = LeftChild;\r | |
| 449 | }\r | |
| 450 | \r | |
| 451 | \r | |
| 452 | /**\r | |
| 453 | Rotate tree nodes around Pivot to the left.\r | |
| 454 | \r | |
| 455 | Parent Parent\r | |
| 456 | | |\r | |
| 457 | Pivot RightChild\r | |
| 458 | . \ / .\r | |
| 459 | Node1 RightChild ---> Pivot Node2\r | |
| 460 | /. . \_\r | |
| 461 | RightLeftChild Node2 Node1 RightLeftChild\r | |
| 462 | \r | |
| 463 | The ordering Node1 < Pivot < RightLeftChild < RightChild < Node2 is kept\r | |
| 464 | intact. Parent (if any) is either at the left extreme or the right extreme of\r | |
| 465 | this ordering, and that relation is also kept intact.\r | |
| 466 | \r | |
| 467 | Edges marked with a dot (".") don't change during rotation.\r | |
| 468 | \r | |
| 469 | Internal read-write operation.\r | |
| 470 | \r | |
| 471 | @param[in,out] Pivot The tree node to rotate other nodes left around. It\r | |
| 472 | is the caller's responsibility to ensure that\r | |
| 473 | Pivot->Right is not NULL.\r | |
| 474 | \r | |
| 475 | @param[out] NewRoot If Pivot has a parent node on input, then the\r | |
| 476 | function updates Pivot's original parent on output\r | |
| 477 | according to the rotation, and NewRoot is not\r | |
| 478 | accessed.\r | |
| 479 | \r | |
| 480 | If Pivot has no parent node on input (ie. Pivot is\r | |
| 481 | the root of the tree), then the function stores the\r | |
| 482 | new root node of the tree in NewRoot.\r | |
| 483 | **/\r | |
| 484 | STATIC\r | |
| 485 | VOID\r | |
| 486 | RedBlackTreeRotateLeft (\r | |
| 487 | IN OUT RED_BLACK_TREE_NODE *Pivot,\r | |
| 488 | OUT RED_BLACK_TREE_NODE **NewRoot\r | |
| 489 | )\r | |
| 490 | {\r | |
| 491 | RED_BLACK_TREE_NODE *Parent, *RightChild, *RightLeftChild;\r | |
| 492 | \r | |
| 493 | Parent = Pivot->Parent;\r | |
| 494 | RightChild = Pivot->Right;\r | |
| 495 | RightLeftChild = RightChild->Left;\r | |
| 496 | \r | |
| 497 | Pivot->Right = RightLeftChild;\r | |
| 498 | if (RightLeftChild != NULL) {\r | |
| 499 | RightLeftChild->Parent = Pivot;\r | |
| 500 | }\r | |
| 501 | RightChild->Parent = Parent;\r | |
| 502 | if (Parent == NULL) {\r | |
| 503 | *NewRoot = RightChild;\r | |
| 504 | } else {\r | |
| 505 | if (Pivot == Parent->Left) {\r | |
| 506 | Parent->Left = RightChild;\r | |
| 507 | } else {\r | |
| 508 | Parent->Right = RightChild;\r | |
| 509 | }\r | |
| 510 | }\r | |
| 511 | RightChild->Left = Pivot;\r | |
| 512 | Pivot->Parent = RightChild;\r | |
| 513 | }\r | |
| 514 | \r | |
| 515 | \r | |
| 516 | /**\r | |
| 517 | Insert (link) a user structure into the tree.\r | |
| 518 | \r | |
| 519 | Read-write operation.\r | |
| 520 | \r | |
| 521 | This function allocates the new tree node with MemoryAllocationLib's\r | |
| 522 | AllocatePool() function.\r | |
| 523 | \r | |
| 524 | @param[in,out] Tree The tree to insert UserStruct into.\r | |
| 525 | \r | |
| 526 | @param[out] Node The meaning of this optional, output-only\r | |
| 527 | parameter depends on the return value of the\r | |
| 528 | function.\r | |
| 529 | \r | |
| 530 | When insertion is successful (RETURN_SUCCESS),\r | |
| 531 | Node is set on output to the new tree node that\r | |
| 532 | now links UserStruct.\r | |
| 533 | \r | |
| 534 | When insertion fails due to lack of memory\r | |
| 535 | (RETURN_OUT_OF_RESOURCES), Node is not changed.\r | |
| 536 | \r | |
| 537 | When insertion fails due to key collision (ie.\r | |
| 538 | another user structure is already in the tree that\r | |
| 539 | compares equal to UserStruct), with return value\r | |
| 540 | RETURN_ALREADY_STARTED, then Node is set on output\r | |
| 541 | to the node that links the colliding user\r | |
| 542 | structure. This enables "find-or-insert" in one\r | |
| 543 | function call, or helps with later removal of the\r | |
| 544 | colliding element.\r | |
| 545 | \r | |
| 546 | @param[in] UserStruct The user structure to link into the tree.\r | |
| 547 | UserStruct is ordered against in-tree user\r | |
| 548 | structures with the Tree->UserStructCompare()\r | |
| 549 | function.\r | |
| 550 | \r | |
| 551 | @retval RETURN_SUCCESS Insertion successful. A new tree node has\r | |
| 552 | been allocated, linking UserStruct. The new\r | |
| 553 | tree node is reported back in Node (if the\r | |
| 554 | caller requested it).\r | |
| 555 | \r | |
| 556 | Existing RED_BLACK_TREE_NODE pointers into\r | |
| 557 | Tree remain valid. For example, on-going\r | |
| 558 | iterations in the caller can continue with\r | |
| 559 | OrderedCollectionNext() /\r | |
| 560 | OrderedCollectionPrev(), and they will\r | |
| 561 | return the new node at some point if user\r | |
| 562 | structure order dictates it.\r | |
| 563 | \r | |
| 564 | @retval RETURN_OUT_OF_RESOURCES AllocatePool() failed to allocate memory for\r | |
| 565 | the new tree node. The tree has not been\r | |
| 566 | changed. Existing RED_BLACK_TREE_NODE\r | |
| 567 | pointers into Tree remain valid.\r | |
| 568 | \r | |
| 569 | @retval RETURN_ALREADY_STARTED A user structure has been found in the tree\r | |
| 570 | that compares equal to UserStruct. The node\r | |
| 571 | linking the colliding user structure is\r | |
| 572 | reported back in Node (if the caller\r | |
| 573 | requested it). The tree has not been\r | |
| 574 | changed. Existing RED_BLACK_TREE_NODE\r | |
| 575 | pointers into Tree remain valid.\r | |
| 576 | **/\r | |
| 577 | RETURN_STATUS\r | |
| 578 | EFIAPI\r | |
| 579 | OrderedCollectionInsert (\r | |
| 580 | IN OUT RED_BLACK_TREE *Tree,\r | |
| 581 | OUT RED_BLACK_TREE_NODE **Node OPTIONAL,\r | |
| 582 | IN VOID *UserStruct\r | |
| 583 | )\r | |
| 584 | {\r | |
| 585 | RED_BLACK_TREE_NODE *Tmp, *Parent;\r | |
| 586 | INTN Result;\r | |
| 587 | RETURN_STATUS Status;\r | |
| 588 | RED_BLACK_TREE_NODE *NewRoot;\r | |
| 589 | \r | |
| 590 | Tmp = Tree->Root;\r | |
| 591 | Parent = NULL;\r | |
| 75955444 | 592 | Result = 0;\r |
| cf556c6a LE |
593 | \r |
| 594 | //\r | |
| 595 | // First look for a collision, saving the last examined node for the case\r | |
| 596 | // when there's no collision.\r | |
| 597 | //\r | |
| 598 | while (Tmp != NULL) {\r | |
| 599 | Result = Tree->UserStructCompare (UserStruct, Tmp->UserStruct);\r | |
| 600 | if (Result == 0) {\r | |
| 601 | break;\r | |
| 602 | }\r | |
| 603 | Parent = Tmp;\r | |
| 604 | Tmp = (Result < 0) ? Tmp->Left : Tmp->Right;\r | |
| 605 | }\r | |
| 606 | \r | |
| 607 | if (Tmp != NULL) {\r | |
| 608 | if (Node != NULL) {\r | |
| 609 | *Node = Tmp;\r | |
| 610 | }\r | |
| 611 | Status = RETURN_ALREADY_STARTED;\r | |
| 612 | goto Done;\r | |
| 613 | }\r | |
| 614 | \r | |
| 615 | //\r | |
| 616 | // no collision, allocate a new node\r | |
| 617 | //\r | |
| 618 | Tmp = AllocatePool (sizeof *Tmp);\r | |
| 619 | if (Tmp == NULL) {\r | |
| 620 | Status = RETURN_OUT_OF_RESOURCES;\r | |
| 621 | goto Done;\r | |
| 622 | }\r | |
| 623 | if (Node != NULL) {\r | |
| 624 | *Node = Tmp;\r | |
| 625 | }\r | |
| 626 | \r | |
| 627 | //\r | |
| 628 | // reference the user structure from the node\r | |
| 629 | //\r | |
| 630 | Tmp->UserStruct = UserStruct;\r | |
| 631 | \r | |
| 632 | //\r | |
| 633 | // Link the node as a child to the correct side of the parent.\r | |
| 634 | // If there's no parent, the new node is the root node in the tree.\r | |
| 635 | //\r | |
| 636 | Tmp->Parent = Parent;\r | |
| 637 | Tmp->Left = NULL;\r | |
| 638 | Tmp->Right = NULL;\r | |
| 639 | if (Parent == NULL) {\r | |
| 640 | Tree->Root = Tmp;\r | |
| 641 | Tmp->Color = RedBlackTreeBlack;\r | |
| 642 | Status = RETURN_SUCCESS;\r | |
| 643 | goto Done;\r | |
| 644 | }\r | |
| 645 | if (Result < 0) {\r | |
| 646 | Parent->Left = Tmp;\r | |
| 647 | } else {\r | |
| 648 | Parent->Right = Tmp;\r | |
| 649 | }\r | |
| 650 | Tmp->Color = RedBlackTreeRed;\r | |
| 651 | \r | |
| 652 | //\r | |
| 653 | // Red-black tree properties:\r | |
| 654 | //\r | |
| 655 | // #1 Each node is either red or black (RED_BLACK_TREE_NODE.Color).\r | |
| 656 | //\r | |
| 657 | // #2 Each leaf (ie. a pseudo-node pointed-to by a NULL valued\r | |
| 658 | // RED_BLACK_TREE_NODE.Left or RED_BLACK_TREE_NODE.Right field) is black.\r | |
| 659 | //\r | |
| 660 | // #3 Each red node has two black children.\r | |
| 661 | //\r | |
| 662 | // #4 For any node N, and for any leaves L1 and L2 reachable from N, the\r | |
| 663 | // paths N..L1 and N..L2 contain the same number of black nodes.\r | |
| 664 | //\r | |
| 665 | // #5 The root node is black.\r | |
| 666 | //\r | |
| 667 | // By replacing a leaf with a red node above, only property #3 may have been\r | |
| 668 | // broken. (Note that this is the only edge across which property #3 might\r | |
| 669 | // not hold in the entire tree.) Restore property #3.\r | |
| 670 | //\r | |
| 671 | \r | |
| 672 | NewRoot = Tree->Root;\r | |
| 673 | while (Tmp != NewRoot && Parent->Color == RedBlackTreeRed) {\r | |
| 674 | RED_BLACK_TREE_NODE *GrandParent, *Uncle;\r | |
| 675 | \r | |
| 676 | //\r | |
| 677 | // Tmp is not the root node. Tmp is red. Tmp's parent is red. (Breaking\r | |
| 678 | // property #3.)\r | |
| 679 | //\r | |
| 680 | // Due to property #5, Tmp's parent cannot be the root node, hence Tmp's\r | |
| 681 | // grandparent exists.\r | |
| 682 | //\r | |
| 683 | // Tmp's grandparent is black, because property #3 is only broken between\r | |
| 684 | // Tmp and Tmp's parent.\r | |
| 685 | //\r | |
| 686 | GrandParent = Parent->Parent;\r | |
| 687 | \r | |
| 688 | if (Parent == GrandParent->Left) {\r | |
| 689 | Uncle = GrandParent->Right;\r | |
| 690 | if (Uncle != NULL && Uncle->Color == RedBlackTreeRed) {\r | |
| 691 | //\r | |
| 692 | // GrandParent (black)\r | |
| 693 | // / \_\r | |
| 694 | // Parent (red) Uncle (red)\r | |
| 695 | // |\r | |
| 696 | // Tmp (red)\r | |
| 697 | //\r | |
| 698 | \r | |
| 699 | Parent->Color = RedBlackTreeBlack;\r | |
| 700 | Uncle->Color = RedBlackTreeBlack;\r | |
| 701 | GrandParent->Color = RedBlackTreeRed;\r | |
| 702 | \r | |
| 703 | //\r | |
| 704 | // GrandParent (red)\r | |
| 705 | // / \_\r | |
| 706 | // Parent (black) Uncle (black)\r | |
| 707 | // |\r | |
| 708 | // Tmp (red)\r | |
| 709 | //\r | |
| 710 | // We restored property #3 between Tmp and Tmp's parent, without\r | |
| 711 | // breaking property #4. However, we may have broken property #3\r | |
| 712 | // between Tmp's grandparent and Tmp's great-grandparent (if any), so\r | |
| 713 | // repeat the loop for Tmp's grandparent.\r | |
| 714 | //\r | |
| 715 | // If Tmp's grandparent has no parent, then the loop will terminate,\r | |
| 716 | // and we will have broken property #5, by coloring the root red. We'll\r | |
| 717 | // restore property #5 after the loop, without breaking any others.\r | |
| 718 | //\r | |
| 719 | Tmp = GrandParent;\r | |
| 720 | Parent = Tmp->Parent;\r | |
| 721 | } else {\r | |
| 722 | //\r | |
| 723 | // Tmp's uncle is black (satisfied by the case too when Tmp's uncle is\r | |
| 724 | // NULL, see property #2).\r | |
| 725 | //\r | |
| 726 | \r | |
| 727 | if (Tmp == Parent->Right) {\r | |
| 728 | //\r | |
| 729 | // GrandParent (black): D\r | |
| 730 | // / \_\r | |
| 731 | // Parent (red): A Uncle (black): E\r | |
| 732 | // \_\r | |
| 733 | // Tmp (red): B\r | |
| 734 | // \_\r | |
| 735 | // black: C\r | |
| 736 | //\r | |
| 737 | // Rotate left, pivoting on node A. This keeps the breakage of\r | |
| 738 | // property #3 in the same spot, and keeps other properties intact\r | |
| 739 | // (because both Tmp and its parent are red).\r | |
| 740 | //\r | |
| 741 | Tmp = Parent;\r | |
| 742 | RedBlackTreeRotateLeft (Tmp, &NewRoot);\r | |
| 743 | Parent = Tmp->Parent;\r | |
| 744 | \r | |
| 745 | //\r | |
| 746 | // With the rotation we reached the same configuration as if Tmp had\r | |
| 747 | // been a left child to begin with.\r | |
| 748 | //\r | |
| 749 | // GrandParent (black): D\r | |
| 750 | // / \_\r | |
| 751 | // Parent (red): B Uncle (black): E\r | |
| 752 | // / \_\r | |
| 753 | // Tmp (red): A black: C\r | |
| 754 | //\r | |
| 755 | ASSERT (GrandParent == Parent->Parent);\r | |
| 756 | }\r | |
| 757 | \r | |
| 758 | Parent->Color = RedBlackTreeBlack;\r | |
| 759 | GrandParent->Color = RedBlackTreeRed;\r | |
| 760 | \r | |
| 761 | //\r | |
| 762 | // Property #3 is now restored, but we've broken property #4. Namely,\r | |
| 763 | // paths going through node E now see a decrease in black count, while\r | |
| 764 | // paths going through node B don't.\r | |
| 765 | //\r | |
| 766 | // GrandParent (red): D\r | |
| 767 | // / \_\r | |
| 768 | // Parent (black): B Uncle (black): E\r | |
| 769 | // / \_\r | |
| 770 | // Tmp (red): A black: C\r | |
| 771 | //\r | |
| 772 | \r | |
| 773 | RedBlackTreeRotateRight (GrandParent, &NewRoot);\r | |
| 774 | \r | |
| 775 | //\r | |
| 776 | // Property #4 has been restored for node E, and preserved for others.\r | |
| 777 | //\r | |
| 778 | // Parent (black): B\r | |
| 779 | // / \_\r | |
| 780 | // Tmp (red): A [GrandParent] (red): D\r | |
| 781 | // / \_\r | |
| 782 | // black: C [Uncle] (black): E\r | |
| 783 | //\r | |
| 784 | // This configuration terminates the loop because Tmp's parent is now\r | |
| 785 | // black.\r | |
| 786 | //\r | |
| 787 | }\r | |
| 788 | } else {\r | |
| 789 | //\r | |
| 790 | // Symmetrical to the other branch.\r | |
| 791 | //\r | |
| 792 | Uncle = GrandParent->Left;\r | |
| 793 | if (Uncle != NULL && Uncle->Color == RedBlackTreeRed) {\r | |
| 794 | Parent->Color = RedBlackTreeBlack;\r | |
| 795 | Uncle->Color = RedBlackTreeBlack;\r | |
| 796 | GrandParent->Color = RedBlackTreeRed;\r | |
| 797 | Tmp = GrandParent;\r | |
| 798 | Parent = Tmp->Parent;\r | |
| 799 | } else {\r | |
| 800 | if (Tmp == Parent->Left) {\r | |
| 801 | Tmp = Parent;\r | |
| 802 | RedBlackTreeRotateRight (Tmp, &NewRoot);\r | |
| 803 | Parent = Tmp->Parent;\r | |
| 804 | ASSERT (GrandParent == Parent->Parent);\r | |
| 805 | }\r | |
| 806 | Parent->Color = RedBlackTreeBlack;\r | |
| 807 | GrandParent->Color = RedBlackTreeRed;\r | |
| 808 | RedBlackTreeRotateLeft (GrandParent, &NewRoot);\r | |
| 809 | }\r | |
| 810 | }\r | |
| 811 | }\r | |
| 812 | \r | |
| 813 | NewRoot->Color = RedBlackTreeBlack;\r | |
| 814 | Tree->Root = NewRoot;\r | |
| 815 | Status = RETURN_SUCCESS;\r | |
| 816 | \r | |
| 817 | Done:\r | |
| 818 | if (FeaturePcdGet (PcdValidateOrderedCollection)) {\r | |
| 819 | RedBlackTreeValidate (Tree);\r | |
| 820 | }\r | |
| 821 | return Status;\r | |
| 822 | }\r | |
| 823 | \r | |
| 824 | \r | |
| 825 | /**\r | |
| 826 | Check if a node is black, allowing for leaf nodes (see property #2).\r | |
| 827 | \r | |
| 828 | This is a convenience shorthand.\r | |
| 829 | \r | |
| 830 | param[in] Node The node to check. Node may be NULL, corresponding to a leaf.\r | |
| 831 | \r | |
| 832 | @return If Node is NULL or colored black.\r | |
| 833 | **/\r | |
| 834 | \r | |
| 835 | STATIC\r | |
| 836 | BOOLEAN\r | |
| 837 | NodeIsNullOrBlack (\r | |
| 838 | IN CONST RED_BLACK_TREE_NODE *Node\r | |
| 839 | )\r | |
| 840 | {\r | |
| 841 | return Node == NULL || Node->Color == RedBlackTreeBlack;\r | |
| 842 | }\r | |
| 843 | \r | |
| 844 | \r | |
| 845 | /**\r | |
| 846 | Delete a node from the tree, unlinking the associated user structure.\r | |
| 847 | \r | |
| 848 | Read-write operation.\r | |
| 849 | \r | |
| 850 | @param[in,out] Tree The tree to delete Node from.\r | |
| 851 | \r | |
| 852 | @param[in] Node The tree node to delete from Tree. The caller is\r | |
| 853 | responsible for ensuring that Node belongs to\r | |
| 854 | Tree, and that Node is non-NULL and valid. Node is\r | |
| 855 | typically an earlier return value, or output\r | |
| 856 | parameter, of:\r | |
| 857 | \r | |
| 858 | - OrderedCollectionFind(), for deleting a node by\r | |
| 859 | user structure key,\r | |
| 860 | \r | |
| 861 | - OrderedCollectionMin() / OrderedCollectionMax(),\r | |
| 862 | for deleting the minimum / maximum node,\r | |
| 863 | \r | |
| 864 | - OrderedCollectionNext() /\r | |
| 865 | OrderedCollectionPrev(), for deleting a node\r | |
| 866 | found during an iteration,\r | |
| 867 | \r | |
| 868 | - OrderedCollectionInsert() with return value\r | |
| 869 | RETURN_ALREADY_STARTED, for deleting a node\r | |
| 870 | whose linked user structure caused collision\r | |
| 871 | during insertion.\r | |
| 872 | \r | |
| 873 | Given a non-empty Tree, Tree->Root is also a valid\r | |
| 874 | Node argument (typically used for simplicity in\r | |
| 875 | loops that empty the tree completely).\r | |
| 876 | \r | |
| 877 | Node is released with MemoryAllocationLib's\r | |
| 878 | FreePool() function.\r | |
| 879 | \r | |
| 880 | Existing RED_BLACK_TREE_NODE pointers (ie.\r | |
| 881 | iterators) *different* from Node remain valid. For\r | |
| 882 | example:\r | |
| 883 | \r | |
| 884 | - OrderedCollectionNext() /\r | |
| 885 | OrderedCollectionPrev() iterations in the caller\r | |
| 886 | can be continued from Node, if\r | |
| 887 | OrderedCollectionNext() or\r | |
| 888 | OrderedCollectionPrev() is called on Node\r | |
| 889 | *before* OrderedCollectionDelete() is. That is,\r | |
| 890 | fetch the successor / predecessor node first,\r | |
| 891 | then delete Node.\r | |
| 892 | \r | |
| 893 | - On-going iterations in the caller that would\r | |
| 894 | have otherwise returned Node at some point, as\r | |
| 895 | dictated by user structure order, will correctly\r | |
| 896 | reflect the absence of Node after\r | |
| 897 | OrderedCollectionDelete() is called\r | |
| 898 | mid-iteration.\r | |
| 899 | \r | |
| 900 | @param[out] UserStruct If the caller provides this optional output-only\r | |
| 901 | parameter, then on output it is set to the user\r | |
| 902 | structure originally linked by Node (which is now\r | |
| 903 | freed).\r | |
| 904 | \r | |
| 905 | This is a convenience that may save the caller a\r | |
| 906 | OrderedCollectionUserStruct() invocation before\r | |
| 907 | calling OrderedCollectionDelete(), in order to\r | |
| 908 | retrieve the user structure being unlinked.\r | |
| 909 | **/\r | |
| 910 | VOID\r | |
| 911 | EFIAPI\r | |
| 912 | OrderedCollectionDelete (\r | |
| 913 | IN OUT RED_BLACK_TREE *Tree,\r | |
| 914 | IN RED_BLACK_TREE_NODE *Node,\r | |
| 915 | OUT VOID **UserStruct OPTIONAL\r | |
| 916 | )\r | |
| 917 | {\r | |
| 918 | RED_BLACK_TREE_NODE *NewRoot;\r | |
| 919 | RED_BLACK_TREE_NODE *OrigLeftChild, *OrigRightChild, *OrigParent;\r | |
| 920 | RED_BLACK_TREE_NODE *Child, *Parent;\r | |
| 921 | RED_BLACK_TREE_COLOR ColorOfUnlinked;\r | |
| 922 | \r | |
| 923 | NewRoot = Tree->Root;\r | |
| 924 | OrigLeftChild = Node->Left,\r | |
| 925 | OrigRightChild = Node->Right,\r | |
| 926 | OrigParent = Node->Parent;\r | |
| 927 | \r | |
| 928 | if (UserStruct != NULL) {\r | |
| 929 | *UserStruct = Node->UserStruct;\r | |
| 930 | }\r | |
| 931 | \r | |
| 932 | //\r | |
| 933 | // After this block, no matter which branch we take:\r | |
| 934 | // - Child will point to the unique (or NULL) original child of the node that\r | |
| 935 | // we will have unlinked,\r | |
| 936 | // - Parent will point to the *position* of the original parent of the node\r | |
| 937 | // that we will have unlinked.\r | |
| 938 | //\r | |
| 939 | if (OrigLeftChild == NULL || OrigRightChild == NULL) {\r | |
| 940 | //\r | |
| 941 | // Node has at most one child. We can connect that child (if any) with\r | |
| 942 | // Node's parent (if any), unlinking Node. This will preserve ordering\r | |
| 943 | // because the subtree rooted in Node's child (if any) remains on the same\r | |
| 944 | // side of Node's parent (if any) that Node was before.\r | |
| 945 | //\r | |
| 946 | Parent = OrigParent;\r | |
| 947 | Child = (OrigLeftChild != NULL) ? OrigLeftChild : OrigRightChild;\r | |
| 948 | ColorOfUnlinked = Node->Color;\r | |
| 949 | \r | |
| 950 | if (Child != NULL) {\r | |
| 951 | Child->Parent = Parent;\r | |
| 952 | }\r | |
| 953 | if (OrigParent == NULL) {\r | |
| 954 | NewRoot = Child;\r | |
| 955 | } else {\r | |
| 956 | if (Node == OrigParent->Left) {\r | |
| 957 | OrigParent->Left = Child;\r | |
| 958 | } else {\r | |
| 959 | OrigParent->Right = Child;\r | |
| 960 | }\r | |
| 961 | }\r | |
| 962 | } else {\r | |
| 963 | //\r | |
| 964 | // Node has two children. We unlink Node's successor, and then link it into\r | |
| 965 | // Node's place, keeping Node's original color. This preserves ordering\r | |
| 966 | // because:\r | |
| 967 | // - Node's left subtree is less than Node, hence less than Node's\r | |
| 968 | // successor.\r | |
| 969 | // - Node's right subtree is greater than Node. Node's successor is the\r | |
| 970 | // minimum of that subtree, hence Node's successor is less than Node's\r | |
| 971 | // right subtree with its minimum removed.\r | |
| 972 | // - Node's successor is in Node's subtree, hence it falls on the same side\r | |
| 973 | // of Node's parent as Node itself. The relinking doesn't change this\r | |
| 974 | // relation.\r | |
| 975 | //\r | |
| 976 | RED_BLACK_TREE_NODE *ToRelink;\r | |
| 977 | \r | |
| 978 | ToRelink = OrigRightChild;\r | |
| 979 | if (ToRelink->Left == NULL) {\r | |
| 980 | //\r | |
| 981 | // OrigRightChild itself is Node's successor, it has no left child:\r | |
| 982 | //\r | |
| 983 | // OrigParent\r | |
| 984 | // |\r | |
| 985 | // Node: B\r | |
| 986 | // / \_\r | |
| 987 | // OrigLeftChild: A OrigRightChild: E <--- Parent, ToRelink\r | |
| 988 | // \_\r | |
| 989 | // F <--- Child\r | |
| 990 | //\r | |
| 991 | Parent = OrigRightChild;\r | |
| 992 | Child = OrigRightChild->Right;\r | |
| 993 | } else {\r | |
| 994 | do {\r | |
| 995 | ToRelink = ToRelink->Left;\r | |
| 996 | } while (ToRelink->Left != NULL);\r | |
| 997 | \r | |
| 998 | //\r | |
| 999 | // Node's successor is the minimum of OrigRightChild's proper subtree:\r | |
| 1000 | //\r | |
| 1001 | // OrigParent\r | |
| 1002 | // |\r | |
| 1003 | // Node: B\r | |
| 1004 | // / \_\r | |
| 1005 | // OrigLeftChild: A OrigRightChild: E <--- Parent\r | |
| 1006 | // /\r | |
| 1007 | // C <--- ToRelink\r | |
| 1008 | // \_\r | |
| 1009 | // D <--- Child\r | |
| 1010 | Parent = ToRelink->Parent;\r | |
| 1011 | Child = ToRelink->Right;\r | |
| 1012 | \r | |
| 1013 | //\r | |
| 1014 | // Unlink Node's successor (ie. ToRelink):\r | |
| 1015 | //\r | |
| 1016 | // OrigParent\r | |
| 1017 | // |\r | |
| 1018 | // Node: B\r | |
| 1019 | // / \_\r | |
| 1020 | // OrigLeftChild: A OrigRightChild: E <--- Parent\r | |
| 1021 | // /\r | |
| 1022 | // D <--- Child\r | |
| 1023 | //\r | |
| 1024 | // C <--- ToRelink\r | |
| 1025 | //\r | |
| 1026 | Parent->Left = Child;\r | |
| 1027 | if (Child) {\r | |
| 1028 | Child->Parent = Parent;\r | |
| 1029 | }\r | |
| 1030 | \r | |
| 1031 | //\r | |
| 1032 | // We start to link Node's unlinked successor into Node's place:\r | |
| 1033 | //\r | |
| 1034 | // OrigParent\r | |
| 1035 | // |\r | |
| 1036 | // Node: B C <--- ToRelink\r | |
| 1037 | // / \_\r | |
| 1038 | // OrigLeftChild: A OrigRightChild: E <--- Parent\r | |
| 1039 | // /\r | |
| 1040 | // D <--- Child\r | |
| 1041 | //\r | |
| 1042 | //\r | |
| 1043 | //\r | |
| 1044 | ToRelink->Right = OrigRightChild;\r | |
| 1045 | OrigRightChild->Parent = ToRelink;\r | |
| 1046 | }\r | |
| 1047 | \r | |
| 1048 | //\r | |
| 1049 | // The rest handles both cases, attaching ToRelink (Node's original\r | |
| 1050 | // successor) to OrigLeftChild and OrigParent.\r | |
| 1051 | //\r | |
| 1052 | // Parent,\r | |
| 1053 | // OrigParent ToRelink OrigParent\r | |
| 1054 | // | | |\r | |
| 1055 | // Node: B | Node: B Parent\r | |
| 1056 | // v |\r | |
| 1057 | // OrigRightChild: E C <--- ToRelink |\r | |
| 1058 | // / \ / \ v\r | |
| 1059 | // OrigLeftChild: A F OrigLeftChild: A OrigRightChild: E\r | |
| 1060 | // ^ /\r | |
| 1061 | // | D <--- Child\r | |
| 1062 | // Child\r | |
| 1063 | //\r | |
| 1064 | ToRelink->Left = OrigLeftChild;\r | |
| 1065 | OrigLeftChild->Parent = ToRelink;\r | |
| 1066 | \r | |
| 1067 | //\r | |
| 1068 | // Node's color must be preserved in Node's original place.\r | |
| 1069 | //\r | |
| 1070 | ColorOfUnlinked = ToRelink->Color;\r | |
| 1071 | ToRelink->Color = Node->Color;\r | |
| 1072 | \r | |
| 1073 | //\r | |
| 1074 | // Finish linking Node's unlinked successor into Node's place.\r | |
| 1075 | //\r | |
| 1076 | // Parent,\r | |
| 1077 | // Node: B ToRelink Node: B\r | |
| 1078 | // |\r | |
| 1079 | // OrigParent | OrigParent Parent\r | |
| 1080 | // | v | |\r | |
| 1081 | // OrigRightChild: E C <--- ToRelink |\r | |
| 1082 | // / \ / \ v\r | |
| 1083 | // OrigLeftChild: A F OrigLeftChild: A OrigRightChild: E\r | |
| 1084 | // ^ /\r | |
| 1085 | // | D <--- Child\r | |
| 1086 | // Child\r | |
| 1087 | //\r | |
| 1088 | ToRelink->Parent = OrigParent;\r | |
| 1089 | if (OrigParent == NULL) {\r | |
| 1090 | NewRoot = ToRelink;\r | |
| 1091 | } else {\r | |
| 1092 | if (Node == OrigParent->Left) {\r | |
| 1093 | OrigParent->Left = ToRelink;\r | |
| 1094 | } else {\r | |
| 1095 | OrigParent->Right = ToRelink;\r | |
| 1096 | }\r | |
| 1097 | }\r | |
| 1098 | }\r | |
| 1099 | \r | |
| 1100 | FreePool (Node);\r | |
| 1101 | \r | |
| 1102 | //\r | |
| 1103 | // If the node that we unlinked from its original spot (ie. Node itself, or\r | |
| 1104 | // Node's successor), was red, then we broke neither property #3 nor property\r | |
| 1105 | // #4: we didn't create any red-red edge between Child and Parent, and we\r | |
| 1106 | // didn't change the black count on any path.\r | |
| 1107 | //\r | |
| 1108 | if (ColorOfUnlinked == RedBlackTreeBlack) {\r | |
| 1109 | //\r | |
| 1110 | // However, if the unlinked node was black, then we have to transfer its\r | |
| 1111 | // "black-increment" to its unique child (pointed-to by Child), lest we\r | |
| 1112 | // break property #4 for its ancestors.\r | |
| 1113 | //\r | |
| 1114 | // If Child is red, we can simply color it black. If Child is black\r | |
| 1115 | // already, we can't technically transfer a black-increment to it, due to\r | |
| 1116 | // property #1.\r | |
| 1117 | //\r | |
| 1118 | // In the following loop we ascend searching for a red node to color black,\r | |
| 1119 | // or until we reach the root (in which case we can drop the\r | |
| 1120 | // black-increment). Inside the loop body, Child has a black value of 2,\r | |
| 1121 | // transitorily breaking property #1 locally, but maintaining property #4\r | |
| 1122 | // globally.\r | |
| 1123 | //\r | |
| 1124 | // Rotations in the loop preserve property #4.\r | |
| 1125 | //\r | |
| 1126 | while (Child != NewRoot && NodeIsNullOrBlack (Child)) {\r | |
| 1127 | RED_BLACK_TREE_NODE *Sibling, *LeftNephew, *RightNephew;\r | |
| 1128 | \r | |
| 1129 | if (Child == Parent->Left) {\r | |
| 1130 | Sibling = Parent->Right;\r | |
| 1131 | //\r | |
| 1132 | // Sibling can never be NULL (ie. a leaf).\r | |
| 1133 | //\r | |
| 1134 | // If Sibling was NULL, then the black count on the path from Parent to\r | |
| 1135 | // Sibling would equal Parent's black value, plus 1 (due to property\r | |
| 1136 | // #2). Whereas the black count on the path from Parent to any leaf via\r | |
| 1137 | // Child would be at least Parent's black value, plus 2 (due to Child's\r | |
| 1138 | // black value of 2). This would clash with property #4.\r | |
| 1139 | //\r | |
| 1140 | // (Sibling can be black of course, but it has to be an internal node.\r | |
| 1141 | // Internality allows Sibling to have children, bumping the black\r | |
| 1142 | // counts of paths that go through it.)\r | |
| 1143 | //\r | |
| 1144 | ASSERT (Sibling != NULL);\r | |
| 1145 | if (Sibling->Color == RedBlackTreeRed) {\r | |
| 1146 | //\r | |
| 1147 | // Sibling's red color implies its children (if any), node C and node\r | |
| 1148 | // E, are black (property #3). It also implies that Parent is black.\r | |
| 1149 | //\r | |
| 1150 | // grandparent grandparent\r | |
| 1151 | // | |\r | |
| 1152 | // Parent,b:B b:D\r | |
| 1153 | // / \ / \_\r | |
| 1154 | // Child,2b:A Sibling,r:D ---> Parent,r:B b:E\r | |
| 1155 | // /\ /\_\r | |
| 1156 | // b:C b:E Child,2b:A Sibling,b:C\r | |
| 1157 | //\r | |
| 1158 | Sibling->Color = RedBlackTreeBlack;\r | |
| 1159 | Parent->Color = RedBlackTreeRed;\r | |
| 1160 | RedBlackTreeRotateLeft (Parent, &NewRoot);\r | |
| 1161 | Sibling = Parent->Right;\r | |
| 1162 | //\r | |
| 1163 | // Same reasoning as above.\r | |
| 1164 | //\r | |
| 1165 | ASSERT (Sibling != NULL);\r | |
| 1166 | }\r | |
| 1167 | \r | |
| 1168 | //\r | |
| 1169 | // Sibling is black, and not NULL. (Ie. Sibling is a black internal\r | |
| 1170 | // node.)\r | |
| 1171 | //\r | |
| 1172 | ASSERT (Sibling->Color == RedBlackTreeBlack);\r | |
| 1173 | LeftNephew = Sibling->Left;\r | |
| 1174 | RightNephew = Sibling->Right;\r | |
| 1175 | if (NodeIsNullOrBlack (LeftNephew) &&\r | |
| 1176 | NodeIsNullOrBlack (RightNephew)) {\r | |
| 1177 | //\r | |
| 1178 | // In this case we can "steal" one black value from Child and Sibling\r | |
| 1179 | // each, and pass it to Parent. "Stealing" means that Sibling (black\r | |
| 1180 | // value 1) becomes red, Child (black value 2) becomes singly-black,\r | |
| 1181 | // and Parent will have to be examined if it can eat the\r | |
| 1182 | // black-increment.\r | |
| 1183 | //\r | |
| 1184 | // Sibling is allowed to become red because both of its children are\r | |
| 1185 | // black (property #3).\r | |
| 1186 | //\r | |
| 1187 | // grandparent Parent\r | |
| 1188 | // | |\r | |
| 1189 | // Parent,x:B Child,x:B\r | |
| 1190 | // / \ / \_\r | |
| 1191 | // Child,2b:A Sibling,b:D ---> b:A r:D\r | |
| 1192 | // /\ /\_\r | |
| 1193 | // LeftNephew,b:C RightNephew,b:E b:C b:E\r | |
| 1194 | //\r | |
| 1195 | Sibling->Color = RedBlackTreeRed;\r | |
| 1196 | Child = Parent;\r | |
| 1197 | Parent = Parent->Parent;\r | |
| 1198 | //\r | |
| 1199 | // Continue ascending.\r | |
| 1200 | //\r | |
| 1201 | } else {\r | |
| 1202 | //\r | |
| 1203 | // At least one nephew is red.\r | |
| 1204 | //\r | |
| 1205 | if (NodeIsNullOrBlack (RightNephew)) {\r | |
| 1206 | //\r | |
| 1207 | // Since the right nephew is black, the left nephew is red. Due to\r | |
| 1208 | // property #3, LeftNephew has two black children, hence node E is\r | |
| 1209 | // black.\r | |
| 1210 | //\r | |
| 1211 | // Together with the rotation, this enables us to color node F red\r | |
| 1212 | // (because property #3 will be satisfied). We flip node D to black\r | |
| 1213 | // to maintain property #4.\r | |
| 1214 | //\r | |
| 1215 | // grandparent grandparent\r | |
| 1216 | // | |\r | |
| 1217 | // Parent,x:B Parent,x:B\r | |
| 1218 | // /\ /\_\r | |
| 1219 | // Child,2b:A Sibling,b:F ---> Child,2b:A Sibling,b:D\r | |
| 1220 | // /\ / \_\r | |
| 1221 | // LeftNephew,r:D RightNephew,b:G b:C RightNephew,r:F\r | |
| 1222 | // /\ /\_\r | |
| 1223 | // b:C b:E b:E b:G\r | |
| 1224 | //\r | |
| 1225 | LeftNephew->Color = RedBlackTreeBlack;\r | |
| 1226 | Sibling->Color = RedBlackTreeRed;\r | |
| 1227 | RedBlackTreeRotateRight (Sibling, &NewRoot);\r | |
| 1228 | Sibling = Parent->Right;\r | |
| 1229 | RightNephew = Sibling->Right;\r | |
| 1230 | //\r | |
| 1231 | // These operations ensure that...\r | |
| 1232 | //\r | |
| 1233 | }\r | |
| 1234 | //\r | |
| 1235 | // ... RightNephew is definitely red here, plus Sibling is (still)\r | |
| 1236 | // black and non-NULL.\r | |
| 1237 | //\r | |
| 1238 | ASSERT (RightNephew != NULL);\r | |
| 1239 | ASSERT (RightNephew->Color == RedBlackTreeRed);\r | |
| 1240 | ASSERT (Sibling != NULL);\r | |
| 1241 | ASSERT (Sibling->Color == RedBlackTreeBlack);\r | |
| 1242 | //\r | |
| 1243 | // In this case we can flush the extra black-increment immediately,\r | |
| 1244 | // restoring property #1 for Child (node A): we color RightNephew\r | |
| 1245 | // (node E) from red to black.\r | |
| 1246 | //\r | |
| 1247 | // In order to maintain property #4, we exchange colors between\r | |
| 1248 | // Parent and Sibling (nodes B and D), and rotate left around Parent\r | |
| 1249 | // (node B). The transformation doesn't change the black count\r | |
| 1250 | // increase incurred by each partial path, eg.\r | |
| 1251 | // - ascending from node A: 2 + x == 1 + 1 + x\r | |
| 1252 | // - ascending from node C: y + 1 + x == y + 1 + x\r | |
| 1253 | // - ascending from node E: 0 + 1 + x == 1 + x\r | |
| 1254 | //\r | |
| 1255 | // The color exchange is valid, because even if x stands for red,\r | |
| 1256 | // both children of node D are black after the transformation\r | |
| 1257 | // (preserving property #3).\r | |
| 1258 | //\r | |
| 1259 | // grandparent grandparent\r | |
| 1260 | // | |\r | |
| 1261 | // Parent,x:B x:D\r | |
| 1262 | // / \ / \_\r | |
| 1263 | // Child,2b:A Sibling,b:D ---> b:B b:E\r | |
| 1264 | // / \ / \_\r | |
| 1265 | // y:C RightNephew,r:E b:A y:C\r | |
| 1266 | //\r | |
| 1267 | //\r | |
| 1268 | Sibling->Color = Parent->Color;\r | |
| 1269 | Parent->Color = RedBlackTreeBlack;\r | |
| 1270 | RightNephew->Color = RedBlackTreeBlack;\r | |
| 1271 | RedBlackTreeRotateLeft (Parent, &NewRoot);\r | |
| 1272 | Child = NewRoot;\r | |
| 1273 | //\r | |
| 1274 | // This terminates the loop.\r | |
| 1275 | //\r | |
| 1276 | }\r | |
| 1277 | } else {\r | |
| 1278 | //\r | |
| 1279 | // Mirrors the other branch.\r | |
| 1280 | //\r | |
| 1281 | Sibling = Parent->Left;\r | |
| 1282 | ASSERT (Sibling != NULL);\r | |
| 1283 | if (Sibling->Color == RedBlackTreeRed) {\r | |
| 1284 | Sibling->Color = RedBlackTreeBlack;\r | |
| 1285 | Parent->Color = RedBlackTreeRed;\r | |
| 1286 | RedBlackTreeRotateRight (Parent, &NewRoot);\r | |
| 1287 | Sibling = Parent->Left;\r | |
| 1288 | ASSERT (Sibling != NULL);\r | |
| 1289 | }\r | |
| 1290 | \r | |
| 1291 | ASSERT (Sibling->Color == RedBlackTreeBlack);\r | |
| 1292 | RightNephew = Sibling->Right;\r | |
| 1293 | LeftNephew = Sibling->Left;\r | |
| 1294 | if (NodeIsNullOrBlack (RightNephew) &&\r | |
| 1295 | NodeIsNullOrBlack (LeftNephew)) {\r | |
| 1296 | Sibling->Color = RedBlackTreeRed;\r | |
| 1297 | Child = Parent;\r | |
| 1298 | Parent = Parent->Parent;\r | |
| 1299 | } else {\r | |
| 1300 | if (NodeIsNullOrBlack (LeftNephew)) {\r | |
| 1301 | RightNephew->Color = RedBlackTreeBlack;\r | |
| 1302 | Sibling->Color = RedBlackTreeRed;\r | |
| 1303 | RedBlackTreeRotateLeft (Sibling, &NewRoot);\r | |
| 1304 | Sibling = Parent->Left;\r | |
| 1305 | LeftNephew = Sibling->Left;\r | |
| 1306 | }\r | |
| 1307 | ASSERT (LeftNephew != NULL);\r | |
| 1308 | ASSERT (LeftNephew->Color == RedBlackTreeRed);\r | |
| 1309 | ASSERT (Sibling != NULL);\r | |
| 1310 | ASSERT (Sibling->Color == RedBlackTreeBlack);\r | |
| 1311 | Sibling->Color = Parent->Color;\r | |
| 1312 | Parent->Color = RedBlackTreeBlack;\r | |
| 1313 | LeftNephew->Color = RedBlackTreeBlack;\r | |
| 1314 | RedBlackTreeRotateRight (Parent, &NewRoot);\r | |
| 1315 | Child = NewRoot;\r | |
| 1316 | }\r | |
| 1317 | }\r | |
| 1318 | }\r | |
| 1319 | \r | |
| 1320 | if (Child != NULL) {\r | |
| 1321 | Child->Color = RedBlackTreeBlack;\r | |
| 1322 | }\r | |
| 1323 | }\r | |
| 1324 | \r | |
| 1325 | Tree->Root = NewRoot;\r | |
| 1326 | \r | |
| 1327 | if (FeaturePcdGet (PcdValidateOrderedCollection)) {\r | |
| 1328 | RedBlackTreeValidate (Tree);\r | |
| 1329 | }\r | |
| 1330 | }\r | |
| 1331 | \r | |
| 1332 | \r | |
| 1333 | /**\r | |
| 1334 | Recursively check the red-black tree properties #1 to #4 on a node.\r | |
| 1335 | \r | |
| 1336 | @param[in] Node The root of the subtree to validate.\r | |
| 1337 | \r | |
| 1338 | @retval The black-height of Node's parent.\r | |
| 1339 | **/\r | |
| 1340 | STATIC\r | |
| 1341 | UINT32\r | |
| 1342 | RedBlackTreeRecursiveCheck (\r | |
| 1343 | IN CONST RED_BLACK_TREE_NODE *Node\r | |
| 1344 | )\r | |
| 1345 | {\r | |
| 1346 | UINT32 LeftHeight, RightHeight;\r | |
| 1347 | \r | |
| 1348 | //\r | |
| 1349 | // property #2\r | |
| 1350 | //\r | |
| 1351 | if (Node == NULL) {\r | |
| 1352 | return 1;\r | |
| 1353 | }\r | |
| 1354 | \r | |
| 1355 | //\r | |
| 1356 | // property #1\r | |
| 1357 | //\r | |
| 1358 | ASSERT (Node->Color == RedBlackTreeRed || Node->Color == RedBlackTreeBlack);\r | |
| 1359 | \r | |
| 1360 | //\r | |
| 1361 | // property #3\r | |
| 1362 | //\r | |
| 1363 | if (Node->Color == RedBlackTreeRed) {\r | |
| 1364 | ASSERT (NodeIsNullOrBlack (Node->Left));\r | |
| 1365 | ASSERT (NodeIsNullOrBlack (Node->Right));\r | |
| 1366 | }\r | |
| 1367 | \r | |
| 1368 | //\r | |
| 1369 | // property #4\r | |
| 1370 | //\r | |
| 1371 | LeftHeight = RedBlackTreeRecursiveCheck (Node->Left);\r | |
| 1372 | RightHeight = RedBlackTreeRecursiveCheck (Node->Right);\r | |
| 1373 | ASSERT (LeftHeight == RightHeight);\r | |
| 1374 | \r | |
| 1375 | return (Node->Color == RedBlackTreeBlack) + LeftHeight;\r | |
| 1376 | }\r | |
| 1377 | \r | |
| 1378 | \r | |
| 1379 | /**\r | |
| 1380 | A slow function that asserts that the tree is a valid red-black tree, and\r | |
| 1381 | that it orders user structures correctly.\r | |
| 1382 | \r | |
| 1383 | Read-only operation.\r | |
| 1384 | \r | |
| 1385 | This function uses the stack for recursion and is not recommended for\r | |
| 1386 | "production use".\r | |
| 1387 | \r | |
| 1388 | @param[in] Tree The tree to validate.\r | |
| 1389 | **/\r | |
| 1390 | STATIC\r | |
| 1391 | VOID\r | |
| 1392 | RedBlackTreeValidate (\r | |
| 1393 | IN CONST RED_BLACK_TREE *Tree\r | |
| 1394 | )\r | |
| 1395 | {\r | |
| 1396 | UINT32 BlackHeight;\r | |
| 1397 | UINT32 ForwardCount, BackwardCount;\r | |
| 1398 | CONST RED_BLACK_TREE_NODE *Last, *Node;\r | |
| 1399 | \r | |
| 1400 | DEBUG ((DEBUG_VERBOSE, "%a: Tree=%p\n", __FUNCTION__, Tree));\r | |
| 1401 | \r | |
| 1402 | //\r | |
| 1403 | // property #5\r | |
| 1404 | //\r | |
| 1405 | ASSERT (NodeIsNullOrBlack (Tree->Root));\r | |
| 1406 | \r | |
| 1407 | //\r | |
| 1408 | // check the other properties\r | |
| 1409 | //\r | |
| 1410 | BlackHeight = RedBlackTreeRecursiveCheck (Tree->Root) - 1;\r | |
| 1411 | \r | |
| 1412 | //\r | |
| 1413 | // forward ordering\r | |
| 1414 | //\r | |
| 1415 | Last = OrderedCollectionMin (Tree);\r | |
| 1416 | ForwardCount = (Last != NULL);\r | |
| 1417 | for (Node = OrderedCollectionNext (Last); Node != NULL;\r | |
| 1418 | Node = OrderedCollectionNext (Last)) {\r | |
| 1419 | ASSERT (Tree->UserStructCompare (Last->UserStruct, Node->UserStruct) < 0);\r | |
| 1420 | Last = Node;\r | |
| 1421 | ++ForwardCount;\r | |
| 1422 | }\r | |
| 1423 | \r | |
| 1424 | //\r | |
| 1425 | // backward ordering\r | |
| 1426 | //\r | |
| 1427 | Last = OrderedCollectionMax (Tree);\r | |
| 1428 | BackwardCount = (Last != NULL);\r | |
| 1429 | for (Node = OrderedCollectionPrev (Last); Node != NULL;\r | |
| 1430 | Node = OrderedCollectionPrev (Last)) {\r | |
| 1431 | ASSERT (Tree->UserStructCompare (Last->UserStruct, Node->UserStruct) > 0);\r | |
| 1432 | Last = Node;\r | |
| 1433 | ++BackwardCount;\r | |
| 1434 | }\r | |
| 1435 | \r | |
| 1436 | ASSERT (ForwardCount == BackwardCount);\r | |
| 1437 | \r | |
| 1438 | DEBUG ((DEBUG_VERBOSE, "%a: Tree=%p BlackHeight=%Ld Count=%Ld\n",\r | |
| 1439 | __FUNCTION__, Tree, (INT64)BlackHeight, (INT64)ForwardCount));\r | |
| 1440 | }\r |