1------------------------------------------------------------------------------ 2-- -- 3-- GNAT LIBRARY COMPONENTS -- 4-- -- 5-- ADA.CONTAINERS.RED_BLACK_TREES.GENERIC_BOUNDED_KEYS -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 2004-2015, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26-- -- 27-- This unit was originally developed by Matthew J Heaney. -- 28------------------------------------------------------------------------------ 29 30package body Ada.Containers.Red_Black_Trees.Generic_Bounded_Keys is 31 32 package Ops renames Tree_Operations; 33 34 ------------- 35 -- Ceiling -- 36 ------------- 37 38 -- AKA Lower_Bound 39 40 function Ceiling 41 (Tree : Tree_Type'Class; 42 Key : Key_Type) return Count_Type 43 is 44 Y : Count_Type; 45 X : Count_Type; 46 N : Nodes_Type renames Tree.Nodes; 47 48 begin 49 Y := 0; 50 51 X := Tree.Root; 52 while X /= 0 loop 53 if Is_Greater_Key_Node (Key, N (X)) then 54 X := Ops.Right (N (X)); 55 else 56 Y := X; 57 X := Ops.Left (N (X)); 58 end if; 59 end loop; 60 61 return Y; 62 end Ceiling; 63 64 ---------- 65 -- Find -- 66 ---------- 67 68 function Find 69 (Tree : Tree_Type'Class; 70 Key : Key_Type) return Count_Type 71 is 72 Y : Count_Type; 73 X : Count_Type; 74 N : Nodes_Type renames Tree.Nodes; 75 76 begin 77 Y := 0; 78 79 X := Tree.Root; 80 while X /= 0 loop 81 if Is_Greater_Key_Node (Key, N (X)) then 82 X := Ops.Right (N (X)); 83 else 84 Y := X; 85 X := Ops.Left (N (X)); 86 end if; 87 end loop; 88 89 if Y = 0 then 90 return 0; 91 end if; 92 93 if Is_Less_Key_Node (Key, N (Y)) then 94 return 0; 95 end if; 96 97 return Y; 98 end Find; 99 100 ----------- 101 -- Floor -- 102 ----------- 103 104 function Floor 105 (Tree : Tree_Type'Class; 106 Key : Key_Type) return Count_Type 107 is 108 Y : Count_Type; 109 X : Count_Type; 110 N : Nodes_Type renames Tree.Nodes; 111 112 begin 113 Y := 0; 114 115 X := Tree.Root; 116 while X /= 0 loop 117 if Is_Less_Key_Node (Key, N (X)) then 118 X := Ops.Left (N (X)); 119 else 120 Y := X; 121 X := Ops.Right (N (X)); 122 end if; 123 end loop; 124 125 return Y; 126 end Floor; 127 128 -------------------------------- 129 -- Generic_Conditional_Insert -- 130 -------------------------------- 131 132 procedure Generic_Conditional_Insert 133 (Tree : in out Tree_Type'Class; 134 Key : Key_Type; 135 Node : out Count_Type; 136 Inserted : out Boolean) 137 is 138 Y : Count_Type; 139 X : Count_Type; 140 N : Nodes_Type renames Tree.Nodes; 141 142 begin 143 -- This is a "conditional" insertion, meaning that the insertion request 144 -- can "fail" in the sense that no new node is created. If the Key is 145 -- equivalent to an existing node, then we return the existing node and 146 -- Inserted is set to False. Otherwise, we allocate a new node (via 147 -- Insert_Post) and Inserted is set to True. 148 149 -- Note that we are testing for equivalence here, not equality. Key must 150 -- be strictly less than its next neighbor, and strictly greater than 151 -- its previous neighbor, in order for the conditional insertion to 152 -- succeed. 153 154 -- We search the tree to find the nearest neighbor of Key, which is 155 -- either the smallest node greater than Key (Inserted is True), or the 156 -- largest node less or equivalent to Key (Inserted is False). 157 158 Y := 0; 159 X := Tree.Root; 160 Inserted := True; 161 while X /= 0 loop 162 Y := X; 163 Inserted := Is_Less_Key_Node (Key, N (X)); 164 X := (if Inserted then Ops.Left (N (X)) else Ops.Right (N (X))); 165 end loop; 166 167 if Inserted then 168 169 -- Either Tree is empty, or Key is less than Y. If Y is the first 170 -- node in the tree, then there are no other nodes that we need to 171 -- search for, and we insert a new node into the tree. 172 173 if Y = Tree.First then 174 Insert_Post (Tree, Y, True, Node); 175 return; 176 end if; 177 178 -- Y is the next nearest-neighbor of Key. We know that Key is not 179 -- equivalent to Y (because Key is strictly less than Y), so we move 180 -- to the previous node, the nearest-neighbor just smaller or 181 -- equivalent to Key. 182 183 Node := Ops.Previous (Tree, Y); 184 185 else 186 -- Y is the previous nearest-neighbor of Key. We know that Key is not 187 -- less than Y, which means either that Key is equivalent to Y, or 188 -- greater than Y. 189 190 Node := Y; 191 end if; 192 193 -- Key is equivalent to or greater than Node. We must resolve which is 194 -- the case, to determine whether the conditional insertion succeeds. 195 196 if Is_Greater_Key_Node (Key, N (Node)) then 197 198 -- Key is strictly greater than Node, which means that Key is not 199 -- equivalent to Node. In this case, the insertion succeeds, and we 200 -- insert a new node into the tree. 201 202 Insert_Post (Tree, Y, Inserted, Node); 203 Inserted := True; 204 return; 205 end if; 206 207 -- Key is equivalent to Node. This is a conditional insertion, so we do 208 -- not insert a new node in this case. We return the existing node and 209 -- report that no insertion has occurred. 210 211 Inserted := False; 212 end Generic_Conditional_Insert; 213 214 ------------------------------------------ 215 -- Generic_Conditional_Insert_With_Hint -- 216 ------------------------------------------ 217 218 procedure Generic_Conditional_Insert_With_Hint 219 (Tree : in out Tree_Type'Class; 220 Position : Count_Type; 221 Key : Key_Type; 222 Node : out Count_Type; 223 Inserted : out Boolean) 224 is 225 N : Nodes_Type renames Tree.Nodes; 226 227 begin 228 -- The purpose of a hint is to avoid a search from the root of 229 -- tree. If we have it hint it means we only need to traverse the 230 -- subtree rooted at the hint to find the nearest neighbor. Note 231 -- that finding the neighbor means merely walking the tree; this 232 -- is not a search and the only comparisons that occur are with 233 -- the hint and its neighbor. 234 235 -- If Position is 0, this is interpreted to mean that Key is 236 -- large relative to the nodes in the tree. If the tree is empty, 237 -- or Key is greater than the last node in the tree, then we're 238 -- done; otherwise the hint was "wrong" and we must search. 239 240 if Position = 0 then -- largest 241 if Tree.Last = 0 242 or else Is_Greater_Key_Node (Key, N (Tree.Last)) 243 then 244 Insert_Post (Tree, Tree.Last, False, Node); 245 Inserted := True; 246 else 247 Conditional_Insert_Sans_Hint (Tree, Key, Node, Inserted); 248 end if; 249 250 return; 251 end if; 252 253 pragma Assert (Tree.Length > 0); 254 255 -- A hint can either name the node that immediately follows Key, 256 -- or immediately precedes Key. We first test whether Key is 257 -- less than the hint, and if so we compare Key to the node that 258 -- precedes the hint. If Key is both less than the hint and 259 -- greater than the hint's preceding neighbor, then we're done; 260 -- otherwise we must search. 261 262 -- Note also that a hint can either be an anterior node or a leaf 263 -- node. A new node is always inserted at the bottom of the tree 264 -- (at least prior to rebalancing), becoming the new left or 265 -- right child of leaf node (which prior to the insertion must 266 -- necessarily be null, since this is a leaf). If the hint names 267 -- an anterior node then its neighbor must be a leaf, and so 268 -- (here) we insert after the neighbor. If the hint names a leaf 269 -- then its neighbor must be anterior and so we insert before the 270 -- hint. 271 272 if Is_Less_Key_Node (Key, N (Position)) then 273 declare 274 Before : constant Count_Type := Ops.Previous (Tree, Position); 275 276 begin 277 if Before = 0 then 278 Insert_Post (Tree, Tree.First, True, Node); 279 Inserted := True; 280 281 elsif Is_Greater_Key_Node (Key, N (Before)) then 282 if Ops.Right (N (Before)) = 0 then 283 Insert_Post (Tree, Before, False, Node); 284 else 285 Insert_Post (Tree, Position, True, Node); 286 end if; 287 288 Inserted := True; 289 290 else 291 Conditional_Insert_Sans_Hint (Tree, Key, Node, Inserted); 292 end if; 293 end; 294 295 return; 296 end if; 297 298 -- We know that Key isn't less than the hint so we try again, 299 -- this time to see if it's greater than the hint. If so we 300 -- compare Key to the node that follows the hint. If Key is both 301 -- greater than the hint and less than the hint's next neighbor, 302 -- then we're done; otherwise we must search. 303 304 if Is_Greater_Key_Node (Key, N (Position)) then 305 declare 306 After : constant Count_Type := Ops.Next (Tree, Position); 307 308 begin 309 if After = 0 then 310 Insert_Post (Tree, Tree.Last, False, Node); 311 Inserted := True; 312 313 elsif Is_Less_Key_Node (Key, N (After)) then 314 if Ops.Right (N (Position)) = 0 then 315 Insert_Post (Tree, Position, False, Node); 316 else 317 Insert_Post (Tree, After, True, Node); 318 end if; 319 320 Inserted := True; 321 322 else 323 Conditional_Insert_Sans_Hint (Tree, Key, Node, Inserted); 324 end if; 325 end; 326 327 return; 328 end if; 329 330 -- We know that Key is neither less than the hint nor greater 331 -- than the hint, and that's the definition of equivalence. 332 -- There's nothing else we need to do, since a search would just 333 -- reach the same conclusion. 334 335 Node := Position; 336 Inserted := False; 337 end Generic_Conditional_Insert_With_Hint; 338 339 ------------------------- 340 -- Generic_Insert_Post -- 341 ------------------------- 342 343 procedure Generic_Insert_Post 344 (Tree : in out Tree_Type'Class; 345 Y : Count_Type; 346 Before : Boolean; 347 Z : out Count_Type) 348 is 349 N : Nodes_Type renames Tree.Nodes; 350 351 begin 352 TC_Check (Tree.TC); 353 354 if Checks and then Tree.Length >= Tree.Capacity then 355 raise Capacity_Error with "not enough capacity to insert new item"; 356 end if; 357 358 Z := New_Node; 359 pragma Assert (Z /= 0); 360 361 if Y = 0 then 362 pragma Assert (Tree.Length = 0); 363 pragma Assert (Tree.Root = 0); 364 pragma Assert (Tree.First = 0); 365 pragma Assert (Tree.Last = 0); 366 367 Tree.Root := Z; 368 Tree.First := Z; 369 Tree.Last := Z; 370 371 elsif Before then 372 pragma Assert (Ops.Left (N (Y)) = 0); 373 374 Ops.Set_Left (N (Y), Z); 375 376 if Y = Tree.First then 377 Tree.First := Z; 378 end if; 379 380 else 381 pragma Assert (Ops.Right (N (Y)) = 0); 382 383 Ops.Set_Right (N (Y), Z); 384 385 if Y = Tree.Last then 386 Tree.Last := Z; 387 end if; 388 end if; 389 390 Ops.Set_Color (N (Z), Red); 391 Ops.Set_Parent (N (Z), Y); 392 Ops.Rebalance_For_Insert (Tree, Z); 393 Tree.Length := Tree.Length + 1; 394 end Generic_Insert_Post; 395 396 ----------------------- 397 -- Generic_Iteration -- 398 ----------------------- 399 400 procedure Generic_Iteration 401 (Tree : Tree_Type'Class; 402 Key : Key_Type) 403 is 404 procedure Iterate (Index : Count_Type); 405 406 ------------- 407 -- Iterate -- 408 ------------- 409 410 procedure Iterate (Index : Count_Type) is 411 J : Count_Type; 412 N : Nodes_Type renames Tree.Nodes; 413 414 begin 415 J := Index; 416 while J /= 0 loop 417 if Is_Less_Key_Node (Key, N (J)) then 418 J := Ops.Left (N (J)); 419 elsif Is_Greater_Key_Node (Key, N (J)) then 420 J := Ops.Right (N (J)); 421 else 422 Iterate (Ops.Left (N (J))); 423 Process (J); 424 J := Ops.Right (N (J)); 425 end if; 426 end loop; 427 end Iterate; 428 429 -- Start of processing for Generic_Iteration 430 431 begin 432 Iterate (Tree.Root); 433 end Generic_Iteration; 434 435 ------------------------------- 436 -- Generic_Reverse_Iteration -- 437 ------------------------------- 438 439 procedure Generic_Reverse_Iteration 440 (Tree : Tree_Type'Class; 441 Key : Key_Type) 442 is 443 procedure Iterate (Index : Count_Type); 444 445 ------------- 446 -- Iterate -- 447 ------------- 448 449 procedure Iterate (Index : Count_Type) is 450 J : Count_Type; 451 N : Nodes_Type renames Tree.Nodes; 452 453 begin 454 J := Index; 455 while J /= 0 loop 456 if Is_Less_Key_Node (Key, N (J)) then 457 J := Ops.Left (N (J)); 458 elsif Is_Greater_Key_Node (Key, N (J)) then 459 J := Ops.Right (N (J)); 460 else 461 Iterate (Ops.Right (N (J))); 462 Process (J); 463 J := Ops.Left (N (J)); 464 end if; 465 end loop; 466 end Iterate; 467 468 -- Start of processing for Generic_Reverse_Iteration 469 470 begin 471 Iterate (Tree.Root); 472 end Generic_Reverse_Iteration; 473 474 ---------------------------------- 475 -- Generic_Unconditional_Insert -- 476 ---------------------------------- 477 478 procedure Generic_Unconditional_Insert 479 (Tree : in out Tree_Type'Class; 480 Key : Key_Type; 481 Node : out Count_Type) 482 is 483 Y : Count_Type; 484 X : Count_Type; 485 N : Nodes_Type renames Tree.Nodes; 486 487 Before : Boolean; 488 489 begin 490 Y := 0; 491 Before := False; 492 493 X := Tree.Root; 494 while X /= 0 loop 495 Y := X; 496 Before := Is_Less_Key_Node (Key, N (X)); 497 X := (if Before then Ops.Left (N (X)) else Ops.Right (N (X))); 498 end loop; 499 500 Insert_Post (Tree, Y, Before, Node); 501 end Generic_Unconditional_Insert; 502 503 -------------------------------------------- 504 -- Generic_Unconditional_Insert_With_Hint -- 505 -------------------------------------------- 506 507 procedure Generic_Unconditional_Insert_With_Hint 508 (Tree : in out Tree_Type'Class; 509 Hint : Count_Type; 510 Key : Key_Type; 511 Node : out Count_Type) 512 is 513 N : Nodes_Type renames Tree.Nodes; 514 515 begin 516 -- There are fewer constraints for an unconditional insertion 517 -- than for a conditional insertion, since we allow duplicate 518 -- keys. So instead of having to check (say) whether Key is 519 -- (strictly) greater than the hint's previous neighbor, here we 520 -- allow Key to be equal to or greater than the previous node. 521 522 -- There is the issue of what to do if Key is equivalent to the 523 -- hint. Does the new node get inserted before or after the hint? 524 -- We decide that it gets inserted after the hint, reasoning that 525 -- this is consistent with behavior for non-hint insertion, which 526 -- inserts a new node after existing nodes with equivalent keys. 527 528 -- First we check whether the hint is null, which is interpreted 529 -- to mean that Key is large relative to existing nodes. 530 -- Following our rule above, if Key is equal to or greater than 531 -- the last node, then we insert the new node immediately after 532 -- last. (We don't have an operation for testing whether a key is 533 -- "equal to or greater than" a node, so we must say instead "not 534 -- less than", which is equivalent.) 535 536 if Hint = 0 then -- largest 537 if Tree.Last = 0 then 538 Insert_Post (Tree, 0, False, Node); 539 elsif Is_Less_Key_Node (Key, N (Tree.Last)) then 540 Unconditional_Insert_Sans_Hint (Tree, Key, Node); 541 else 542 Insert_Post (Tree, Tree.Last, False, Node); 543 end if; 544 545 return; 546 end if; 547 548 pragma Assert (Tree.Length > 0); 549 550 -- We decide here whether to insert the new node prior to the 551 -- hint. Key could be equivalent to the hint, so in theory we 552 -- could write the following test as "not greater than" (same as 553 -- "less than or equal to"). If Key were equivalent to the hint, 554 -- that would mean that the new node gets inserted before an 555 -- equivalent node. That wouldn't break any container invariants, 556 -- but our rule above says that new nodes always get inserted 557 -- after equivalent nodes. So here we test whether Key is both 558 -- less than the hint and equal to or greater than the hint's 559 -- previous neighbor, and if so insert it before the hint. 560 561 if Is_Less_Key_Node (Key, N (Hint)) then 562 declare 563 Before : constant Count_Type := Ops.Previous (Tree, Hint); 564 begin 565 if Before = 0 then 566 Insert_Post (Tree, Hint, True, Node); 567 elsif Is_Less_Key_Node (Key, N (Before)) then 568 Unconditional_Insert_Sans_Hint (Tree, Key, Node); 569 elsif Ops.Right (N (Before)) = 0 then 570 Insert_Post (Tree, Before, False, Node); 571 else 572 Insert_Post (Tree, Hint, True, Node); 573 end if; 574 end; 575 576 return; 577 end if; 578 579 -- We know that Key isn't less than the hint, so it must be equal 580 -- or greater. So we just test whether Key is less than or equal 581 -- to (same as "not greater than") the hint's next neighbor, and 582 -- if so insert it after the hint. 583 584 declare 585 After : constant Count_Type := Ops.Next (Tree, Hint); 586 begin 587 if After = 0 then 588 Insert_Post (Tree, Hint, False, Node); 589 elsif Is_Greater_Key_Node (Key, N (After)) then 590 Unconditional_Insert_Sans_Hint (Tree, Key, Node); 591 elsif Ops.Right (N (Hint)) = 0 then 592 Insert_Post (Tree, Hint, False, Node); 593 else 594 Insert_Post (Tree, After, True, Node); 595 end if; 596 end; 597 end Generic_Unconditional_Insert_With_Hint; 598 599 ----------------- 600 -- Upper_Bound -- 601 ----------------- 602 603 function Upper_Bound 604 (Tree : Tree_Type'Class; 605 Key : Key_Type) return Count_Type 606 is 607 Y : Count_Type; 608 X : Count_Type; 609 N : Nodes_Type renames Tree.Nodes; 610 611 begin 612 Y := 0; 613 614 X := Tree.Root; 615 while X /= 0 loop 616 if Is_Less_Key_Node (Key, N (X)) then 617 Y := X; 618 X := Ops.Left (N (X)); 619 else 620 X := Ops.Right (N (X)); 621 end if; 622 end loop; 623 624 return Y; 625 end Upper_Bound; 626 627end Ada.Containers.Red_Black_Trees.Generic_Bounded_Keys; 628