Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 1 | ------------------------------------------------------------------------------ |
| 2 | -- -- |
| 3 | -- GNAT LIBRARY COMPONENTS -- |
| 4 | -- -- |
| 5 | -- ADA.CONTAINERS.BOUNDED_DOUBLY_LINKED_LISTS -- |
| 6 | -- -- |
| 7 | -- B o d y -- |
| 8 | -- -- |
| 9 | -- Copyright (C) 2004-2012, 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 | |
| 30 | with Ada.Finalization; use Ada.Finalization; |
| 31 | |
| 32 | with System; use type System.Address; |
| 33 | |
| 34 | package body Ada.Containers.Bounded_Doubly_Linked_Lists is |
| 35 | |
| 36 | type Iterator is new Limited_Controlled and |
| 37 | List_Iterator_Interfaces.Reversible_Iterator with |
| 38 | record |
| 39 | Container : List_Access; |
| 40 | Node : Count_Type; |
| 41 | end record; |
| 42 | |
| 43 | overriding procedure Finalize (Object : in out Iterator); |
| 44 | |
| 45 | overriding function First (Object : Iterator) return Cursor; |
| 46 | overriding function Last (Object : Iterator) return Cursor; |
| 47 | |
| 48 | overriding function Next |
| 49 | (Object : Iterator; |
| 50 | Position : Cursor) return Cursor; |
| 51 | |
| 52 | overriding function Previous |
| 53 | (Object : Iterator; |
| 54 | Position : Cursor) return Cursor; |
| 55 | |
| 56 | ----------------------- |
| 57 | -- Local Subprograms -- |
| 58 | ----------------------- |
| 59 | |
| 60 | procedure Allocate |
| 61 | (Container : in out List; |
| 62 | New_Item : Element_Type; |
| 63 | New_Node : out Count_Type); |
| 64 | |
| 65 | procedure Allocate |
| 66 | (Container : in out List; |
| 67 | New_Node : out Count_Type); |
| 68 | |
| 69 | procedure Allocate |
| 70 | (Container : in out List; |
| 71 | Stream : not null access Root_Stream_Type'Class; |
| 72 | New_Node : out Count_Type); |
| 73 | |
| 74 | procedure Free |
| 75 | (Container : in out List; |
| 76 | X : Count_Type); |
| 77 | |
| 78 | procedure Insert_Internal |
| 79 | (Container : in out List; |
| 80 | Before : Count_Type; |
| 81 | New_Node : Count_Type); |
| 82 | |
| 83 | function Vet (Position : Cursor) return Boolean; |
| 84 | -- Checks invariants of the cursor and its designated container, as a |
| 85 | -- simple way of detecting dangling references (see operation Free for a |
| 86 | -- description of the detection mechanism), returning True if all checks |
| 87 | -- pass. Invocations of Vet are used here as the argument of pragma Assert, |
| 88 | -- so the checks are performed only when assertions are enabled. |
| 89 | |
| 90 | --------- |
| 91 | -- "=" -- |
| 92 | --------- |
| 93 | |
| 94 | function "=" (Left, Right : List) return Boolean is |
| 95 | LN : Node_Array renames Left.Nodes; |
| 96 | RN : Node_Array renames Right.Nodes; |
| 97 | |
| 98 | LI, RI : Count_Type; |
| 99 | |
| 100 | begin |
| 101 | if Left'Address = Right'Address then |
| 102 | return True; |
| 103 | end if; |
| 104 | |
| 105 | if Left.Length /= Right.Length then |
| 106 | return False; |
| 107 | end if; |
| 108 | |
| 109 | LI := Left.First; |
| 110 | RI := Right.First; |
| 111 | for J in 1 .. Left.Length loop |
| 112 | if LN (LI).Element /= RN (RI).Element then |
| 113 | return False; |
| 114 | end if; |
| 115 | |
| 116 | LI := LN (LI).Next; |
| 117 | RI := RN (RI).Next; |
| 118 | end loop; |
| 119 | |
| 120 | return True; |
| 121 | end "="; |
| 122 | |
| 123 | -------------- |
| 124 | -- Allocate -- |
| 125 | -------------- |
| 126 | |
| 127 | procedure Allocate |
| 128 | (Container : in out List; |
| 129 | New_Item : Element_Type; |
| 130 | New_Node : out Count_Type) |
| 131 | is |
| 132 | N : Node_Array renames Container.Nodes; |
| 133 | |
| 134 | begin |
| 135 | if Container.Free >= 0 then |
| 136 | New_Node := Container.Free; |
| 137 | |
| 138 | -- We always perform the assignment first, before we change container |
| 139 | -- state, in order to defend against exceptions duration assignment. |
| 140 | |
| 141 | N (New_Node).Element := New_Item; |
| 142 | Container.Free := N (New_Node).Next; |
| 143 | |
| 144 | else |
| 145 | -- A negative free store value means that the links of the nodes in |
| 146 | -- the free store have not been initialized. In this case, the nodes |
| 147 | -- are physically contiguous in the array, starting at the index that |
| 148 | -- is the absolute value of the Container.Free, and continuing until |
| 149 | -- the end of the array (Nodes'Last). |
| 150 | |
| 151 | New_Node := abs Container.Free; |
| 152 | |
| 153 | -- As above, we perform this assignment first, before modifying any |
| 154 | -- container state. |
| 155 | |
| 156 | N (New_Node).Element := New_Item; |
| 157 | Container.Free := Container.Free - 1; |
| 158 | end if; |
| 159 | end Allocate; |
| 160 | |
| 161 | procedure Allocate |
| 162 | (Container : in out List; |
| 163 | Stream : not null access Root_Stream_Type'Class; |
| 164 | New_Node : out Count_Type) |
| 165 | is |
| 166 | N : Node_Array renames Container.Nodes; |
| 167 | |
| 168 | begin |
| 169 | if Container.Free >= 0 then |
| 170 | New_Node := Container.Free; |
| 171 | |
| 172 | -- We always perform the assignment first, before we change container |
| 173 | -- state, in order to defend against exceptions duration assignment. |
| 174 | |
| 175 | Element_Type'Read (Stream, N (New_Node).Element); |
| 176 | Container.Free := N (New_Node).Next; |
| 177 | |
| 178 | else |
| 179 | -- A negative free store value means that the links of the nodes in |
| 180 | -- the free store have not been initialized. In this case, the nodes |
| 181 | -- are physically contiguous in the array, starting at the index that |
| 182 | -- is the absolute value of the Container.Free, and continuing until |
| 183 | -- the end of the array (Nodes'Last). |
| 184 | |
| 185 | New_Node := abs Container.Free; |
| 186 | |
| 187 | -- As above, we perform this assignment first, before modifying any |
| 188 | -- container state. |
| 189 | |
| 190 | Element_Type'Read (Stream, N (New_Node).Element); |
| 191 | Container.Free := Container.Free - 1; |
| 192 | end if; |
| 193 | end Allocate; |
| 194 | |
| 195 | procedure Allocate |
| 196 | (Container : in out List; |
| 197 | New_Node : out Count_Type) |
| 198 | is |
| 199 | N : Node_Array renames Container.Nodes; |
| 200 | |
| 201 | begin |
| 202 | if Container.Free >= 0 then |
| 203 | New_Node := Container.Free; |
| 204 | Container.Free := N (New_Node).Next; |
| 205 | |
| 206 | else |
| 207 | -- As explained above, a negative free store value means that the |
| 208 | -- links for the nodes in the free store have not been initialized. |
| 209 | |
| 210 | New_Node := abs Container.Free; |
| 211 | Container.Free := Container.Free - 1; |
| 212 | end if; |
| 213 | end Allocate; |
| 214 | |
| 215 | ------------ |
| 216 | -- Append -- |
| 217 | ------------ |
| 218 | |
| 219 | procedure Append |
| 220 | (Container : in out List; |
| 221 | New_Item : Element_Type; |
| 222 | Count : Count_Type := 1) |
| 223 | is |
| 224 | begin |
| 225 | Insert (Container, No_Element, New_Item, Count); |
| 226 | end Append; |
| 227 | |
| 228 | ------------ |
| 229 | -- Assign -- |
| 230 | ------------ |
| 231 | |
| 232 | procedure Assign (Target : in out List; Source : List) is |
| 233 | SN : Node_Array renames Source.Nodes; |
| 234 | J : Count_Type; |
| 235 | |
| 236 | begin |
| 237 | if Target'Address = Source'Address then |
| 238 | return; |
| 239 | end if; |
| 240 | |
| 241 | if Target.Capacity < Source.Length then |
| 242 | raise Capacity_Error -- ??? |
| 243 | with "Target capacity is less than Source length"; |
| 244 | end if; |
| 245 | |
| 246 | Target.Clear; |
| 247 | |
| 248 | J := Source.First; |
| 249 | while J /= 0 loop |
| 250 | Target.Append (SN (J).Element); |
| 251 | J := SN (J).Next; |
| 252 | end loop; |
| 253 | end Assign; |
| 254 | |
| 255 | ----------- |
| 256 | -- Clear -- |
| 257 | ----------- |
| 258 | |
| 259 | procedure Clear (Container : in out List) is |
| 260 | N : Node_Array renames Container.Nodes; |
| 261 | X : Count_Type; |
| 262 | |
| 263 | begin |
| 264 | if Container.Length = 0 then |
| 265 | pragma Assert (Container.First = 0); |
| 266 | pragma Assert (Container.Last = 0); |
| 267 | pragma Assert (Container.Busy = 0); |
| 268 | pragma Assert (Container.Lock = 0); |
| 269 | return; |
| 270 | end if; |
| 271 | |
| 272 | pragma Assert (Container.First >= 1); |
| 273 | pragma Assert (Container.Last >= 1); |
| 274 | pragma Assert (N (Container.First).Prev = 0); |
| 275 | pragma Assert (N (Container.Last).Next = 0); |
| 276 | |
| 277 | if Container.Busy > 0 then |
| 278 | raise Program_Error with |
| 279 | "attempt to tamper with cursors (list is busy)"; |
| 280 | end if; |
| 281 | |
| 282 | while Container.Length > 1 loop |
| 283 | X := Container.First; |
| 284 | pragma Assert (N (N (X).Next).Prev = Container.First); |
| 285 | |
| 286 | Container.First := N (X).Next; |
| 287 | N (Container.First).Prev := 0; |
| 288 | |
| 289 | Container.Length := Container.Length - 1; |
| 290 | |
| 291 | Free (Container, X); |
| 292 | end loop; |
| 293 | |
| 294 | X := Container.First; |
| 295 | pragma Assert (X = Container.Last); |
| 296 | |
| 297 | Container.First := 0; |
| 298 | Container.Last := 0; |
| 299 | Container.Length := 0; |
| 300 | |
| 301 | Free (Container, X); |
| 302 | end Clear; |
| 303 | |
| 304 | ------------------------ |
| 305 | -- Constant_Reference -- |
| 306 | ------------------------ |
| 307 | |
| 308 | function Constant_Reference |
| 309 | (Container : aliased List; |
| 310 | Position : Cursor) return Constant_Reference_Type |
| 311 | is |
| 312 | begin |
| 313 | if Position.Container = null then |
| 314 | raise Constraint_Error with "Position cursor has no element"; |
| 315 | end if; |
| 316 | |
| 317 | if Position.Container /= Container'Unrestricted_Access then |
| 318 | raise Program_Error with |
| 319 | "Position cursor designates wrong container"; |
| 320 | end if; |
| 321 | |
| 322 | pragma Assert (Vet (Position), "bad cursor in Constant_Reference"); |
| 323 | |
| 324 | declare |
| 325 | N : Node_Type renames Container.Nodes (Position.Node); |
| 326 | begin |
| 327 | return (Element => N.Element'Access); |
| 328 | end; |
| 329 | end Constant_Reference; |
| 330 | |
| 331 | -------------- |
| 332 | -- Contains -- |
| 333 | -------------- |
| 334 | |
| 335 | function Contains |
| 336 | (Container : List; |
| 337 | Item : Element_Type) return Boolean |
| 338 | is |
| 339 | begin |
| 340 | return Find (Container, Item) /= No_Element; |
| 341 | end Contains; |
| 342 | |
| 343 | ---------- |
| 344 | -- Copy -- |
| 345 | ---------- |
| 346 | |
| 347 | function Copy (Source : List; Capacity : Count_Type := 0) return List is |
| 348 | C : Count_Type; |
| 349 | |
| 350 | begin |
| 351 | if Capacity = 0 then |
| 352 | C := Source.Length; |
| 353 | |
| 354 | elsif Capacity >= Source.Length then |
| 355 | C := Capacity; |
| 356 | |
| 357 | else |
| 358 | raise Capacity_Error with "Capacity value too small"; |
| 359 | end if; |
| 360 | |
| 361 | return Target : List (Capacity => C) do |
| 362 | Assign (Target => Target, Source => Source); |
| 363 | end return; |
| 364 | end Copy; |
| 365 | |
| 366 | ------------ |
| 367 | -- Delete -- |
| 368 | ------------ |
| 369 | |
| 370 | procedure Delete |
| 371 | (Container : in out List; |
| 372 | Position : in out Cursor; |
| 373 | Count : Count_Type := 1) |
| 374 | is |
| 375 | N : Node_Array renames Container.Nodes; |
| 376 | X : Count_Type; |
| 377 | |
| 378 | begin |
| 379 | if Position.Node = 0 then |
| 380 | raise Constraint_Error with |
| 381 | "Position cursor has no element"; |
| 382 | end if; |
| 383 | |
| 384 | if Position.Container /= Container'Unrestricted_Access then |
| 385 | raise Program_Error with |
| 386 | "Position cursor designates wrong container"; |
| 387 | end if; |
| 388 | |
| 389 | pragma Assert (Vet (Position), "bad cursor in Delete"); |
| 390 | pragma Assert (Container.First >= 1); |
| 391 | pragma Assert (Container.Last >= 1); |
| 392 | pragma Assert (N (Container.First).Prev = 0); |
| 393 | pragma Assert (N (Container.Last).Next = 0); |
| 394 | |
| 395 | if Position.Node = Container.First then |
| 396 | Delete_First (Container, Count); |
| 397 | Position := No_Element; |
| 398 | return; |
| 399 | end if; |
| 400 | |
| 401 | if Count = 0 then |
| 402 | Position := No_Element; |
| 403 | return; |
| 404 | end if; |
| 405 | |
| 406 | if Container.Busy > 0 then |
| 407 | raise Program_Error with |
| 408 | "attempt to tamper with cursors (list is busy)"; |
| 409 | end if; |
| 410 | |
| 411 | for Index in 1 .. Count loop |
| 412 | pragma Assert (Container.Length >= 2); |
| 413 | |
| 414 | X := Position.Node; |
| 415 | Container.Length := Container.Length - 1; |
| 416 | |
| 417 | if X = Container.Last then |
| 418 | Position := No_Element; |
| 419 | |
| 420 | Container.Last := N (X).Prev; |
| 421 | N (Container.Last).Next := 0; |
| 422 | |
| 423 | Free (Container, X); |
| 424 | return; |
| 425 | end if; |
| 426 | |
| 427 | Position.Node := N (X).Next; |
| 428 | |
| 429 | N (N (X).Next).Prev := N (X).Prev; |
| 430 | N (N (X).Prev).Next := N (X).Next; |
| 431 | |
| 432 | Free (Container, X); |
| 433 | end loop; |
| 434 | |
| 435 | Position := No_Element; |
| 436 | end Delete; |
| 437 | |
| 438 | ------------------ |
| 439 | -- Delete_First -- |
| 440 | ------------------ |
| 441 | |
| 442 | procedure Delete_First |
| 443 | (Container : in out List; |
| 444 | Count : Count_Type := 1) |
| 445 | is |
| 446 | N : Node_Array renames Container.Nodes; |
| 447 | X : Count_Type; |
| 448 | |
| 449 | begin |
| 450 | if Count >= Container.Length then |
| 451 | Clear (Container); |
| 452 | return; |
| 453 | end if; |
| 454 | |
| 455 | if Count = 0 then |
| 456 | return; |
| 457 | end if; |
| 458 | |
| 459 | if Container.Busy > 0 then |
| 460 | raise Program_Error with |
| 461 | "attempt to tamper with cursors (list is busy)"; |
| 462 | end if; |
| 463 | |
| 464 | for I in 1 .. Count loop |
| 465 | X := Container.First; |
| 466 | pragma Assert (N (N (X).Next).Prev = Container.First); |
| 467 | |
| 468 | Container.First := N (X).Next; |
| 469 | N (Container.First).Prev := 0; |
| 470 | |
| 471 | Container.Length := Container.Length - 1; |
| 472 | |
| 473 | Free (Container, X); |
| 474 | end loop; |
| 475 | end Delete_First; |
| 476 | |
| 477 | ----------------- |
| 478 | -- Delete_Last -- |
| 479 | ----------------- |
| 480 | |
| 481 | procedure Delete_Last |
| 482 | (Container : in out List; |
| 483 | Count : Count_Type := 1) |
| 484 | is |
| 485 | N : Node_Array renames Container.Nodes; |
| 486 | X : Count_Type; |
| 487 | |
| 488 | begin |
| 489 | if Count >= Container.Length then |
| 490 | Clear (Container); |
| 491 | return; |
| 492 | end if; |
| 493 | |
| 494 | if Count = 0 then |
| 495 | return; |
| 496 | end if; |
| 497 | |
| 498 | if Container.Busy > 0 then |
| 499 | raise Program_Error with |
| 500 | "attempt to tamper with cursors (list is busy)"; |
| 501 | end if; |
| 502 | |
| 503 | for I in 1 .. Count loop |
| 504 | X := Container.Last; |
| 505 | pragma Assert (N (N (X).Prev).Next = Container.Last); |
| 506 | |
| 507 | Container.Last := N (X).Prev; |
| 508 | N (Container.Last).Next := 0; |
| 509 | |
| 510 | Container.Length := Container.Length - 1; |
| 511 | |
| 512 | Free (Container, X); |
| 513 | end loop; |
| 514 | end Delete_Last; |
| 515 | |
| 516 | ------------- |
| 517 | -- Element -- |
| 518 | ------------- |
| 519 | |
| 520 | function Element (Position : Cursor) return Element_Type is |
| 521 | begin |
| 522 | if Position.Node = 0 then |
| 523 | raise Constraint_Error with |
| 524 | "Position cursor has no element"; |
| 525 | end if; |
| 526 | |
| 527 | pragma Assert (Vet (Position), "bad cursor in Element"); |
| 528 | |
| 529 | return Position.Container.Nodes (Position.Node).Element; |
| 530 | end Element; |
| 531 | |
| 532 | -------------- |
| 533 | -- Finalize -- |
| 534 | -------------- |
| 535 | |
| 536 | procedure Finalize (Object : in out Iterator) is |
| 537 | begin |
| 538 | if Object.Container /= null then |
| 539 | declare |
| 540 | B : Natural renames Object.Container.all.Busy; |
| 541 | |
| 542 | begin |
| 543 | B := B - 1; |
| 544 | end; |
| 545 | end if; |
| 546 | end Finalize; |
| 547 | |
| 548 | ---------- |
| 549 | -- Find -- |
| 550 | ---------- |
| 551 | |
| 552 | function Find |
| 553 | (Container : List; |
| 554 | Item : Element_Type; |
| 555 | Position : Cursor := No_Element) return Cursor |
| 556 | is |
| 557 | Nodes : Node_Array renames Container.Nodes; |
| 558 | Node : Count_Type := Position.Node; |
| 559 | |
| 560 | begin |
| 561 | if Node = 0 then |
| 562 | Node := Container.First; |
| 563 | |
| 564 | else |
| 565 | if Position.Container /= Container'Unrestricted_Access then |
| 566 | raise Program_Error with |
| 567 | "Position cursor designates wrong container"; |
| 568 | end if; |
| 569 | |
| 570 | pragma Assert (Vet (Position), "bad cursor in Find"); |
| 571 | end if; |
| 572 | |
| 573 | while Node /= 0 loop |
| 574 | if Nodes (Node).Element = Item then |
| 575 | return Cursor'(Container'Unrestricted_Access, Node); |
| 576 | end if; |
| 577 | |
| 578 | Node := Nodes (Node).Next; |
| 579 | end loop; |
| 580 | |
| 581 | return No_Element; |
| 582 | end Find; |
| 583 | |
| 584 | ----------- |
| 585 | -- First -- |
| 586 | ----------- |
| 587 | |
| 588 | function First (Container : List) return Cursor is |
| 589 | begin |
| 590 | if Container.First = 0 then |
| 591 | return No_Element; |
| 592 | end if; |
| 593 | |
| 594 | return Cursor'(Container'Unrestricted_Access, Container.First); |
| 595 | end First; |
| 596 | |
| 597 | function First (Object : Iterator) return Cursor is |
| 598 | begin |
| 599 | -- The value of the iterator object's Node component influences the |
| 600 | -- behavior of the First (and Last) selector function. |
| 601 | |
| 602 | -- When the Node component is 0, this means the iterator object was |
| 603 | -- constructed without a start expression, in which case the (forward) |
| 604 | -- iteration starts from the (logical) beginning of the entire sequence |
| 605 | -- of items (corresponding to Container.First, for a forward iterator). |
| 606 | |
| 607 | -- Otherwise, this is iteration over a partial sequence of items. When |
| 608 | -- the Node component is positive, the iterator object was constructed |
| 609 | -- with a start expression, that specifies the position from which the |
| 610 | -- (forward) partial iteration begins. |
| 611 | |
| 612 | if Object.Node = 0 then |
| 613 | return Bounded_Doubly_Linked_Lists.First (Object.Container.all); |
| 614 | else |
| 615 | return Cursor'(Object.Container, Object.Node); |
| 616 | end if; |
| 617 | end First; |
| 618 | |
| 619 | ------------------- |
| 620 | -- First_Element -- |
| 621 | ------------------- |
| 622 | |
| 623 | function First_Element (Container : List) return Element_Type is |
| 624 | begin |
| 625 | if Container.First = 0 then |
| 626 | raise Constraint_Error with "list is empty"; |
| 627 | end if; |
| 628 | |
| 629 | return Container.Nodes (Container.First).Element; |
| 630 | end First_Element; |
| 631 | |
| 632 | ---------- |
| 633 | -- Free -- |
| 634 | ---------- |
| 635 | |
| 636 | procedure Free |
| 637 | (Container : in out List; |
| 638 | X : Count_Type) |
| 639 | is |
| 640 | pragma Assert (X > 0); |
| 641 | pragma Assert (X <= Container.Capacity); |
| 642 | |
| 643 | N : Node_Array renames Container.Nodes; |
| 644 | pragma Assert (N (X).Prev >= 0); -- node is active |
| 645 | |
| 646 | begin |
| 647 | -- The list container actually contains two lists: one for the "active" |
| 648 | -- nodes that contain elements that have been inserted onto the list, |
| 649 | -- and another for the "inactive" nodes for the free store. |
| 650 | |
| 651 | -- We desire that merely declaring an object should have only minimal |
| 652 | -- cost; specially, we want to avoid having to initialize the free |
| 653 | -- store (to fill in the links), especially if the capacity is large. |
| 654 | |
| 655 | -- The head of the free list is indicated by Container.Free. If its |
| 656 | -- value is non-negative, then the free store has been initialized in |
| 657 | -- the "normal" way: Container.Free points to the head of the list of |
| 658 | -- free (inactive) nodes, and the value 0 means the free list is empty. |
| 659 | -- Each node on the free list has been initialized to point to the next |
| 660 | -- free node (via its Next component), and the value 0 means that this |
| 661 | -- is the last free node. |
| 662 | |
| 663 | -- If Container.Free is negative, then the links on the free store have |
| 664 | -- not been initialized. In this case the link values are implied: the |
| 665 | -- free store comprises the components of the node array started with |
| 666 | -- the absolute value of Container.Free, and continuing until the end of |
| 667 | -- the array (Nodes'Last). |
| 668 | |
| 669 | -- If the list container is manipulated on one end only (for example if |
| 670 | -- the container were being used as a stack), then there is no need to |
| 671 | -- initialize the free store, since the inactive nodes are physically |
| 672 | -- contiguous (in fact, they lie immediately beyond the logical end |
| 673 | -- being manipulated). The only time we need to actually initialize the |
| 674 | -- nodes in the free store is if the node that becomes inactive is not |
| 675 | -- at the end of the list. The free store would then be discontiguous |
| 676 | -- and so its nodes would need to be linked in the traditional way. |
| 677 | |
| 678 | -- ??? |
| 679 | -- It might be possible to perform an optimization here. Suppose that |
| 680 | -- the free store can be represented as having two parts: one comprising |
| 681 | -- the non-contiguous inactive nodes linked together in the normal way, |
| 682 | -- and the other comprising the contiguous inactive nodes (that are not |
| 683 | -- linked together, at the end of the nodes array). This would allow us |
| 684 | -- to never have to initialize the free store, except in a lazy way as |
| 685 | -- nodes become inactive. |
| 686 | |
| 687 | -- When an element is deleted from the list container, its node becomes |
| 688 | -- inactive, and so we set its Prev component to a negative value, to |
| 689 | -- indicate that it is now inactive. This provides a useful way to |
| 690 | -- detect a dangling cursor reference (and which is used in Vet). |
| 691 | |
| 692 | N (X).Prev := -1; -- Node is deallocated (not on active list) |
| 693 | |
| 694 | if Container.Free >= 0 then |
| 695 | |
| 696 | -- The free store has previously been initialized. All we need to |
| 697 | -- do here is link the newly-free'd node onto the free list. |
| 698 | |
| 699 | N (X).Next := Container.Free; |
| 700 | Container.Free := X; |
| 701 | |
| 702 | elsif X + 1 = abs Container.Free then |
| 703 | |
| 704 | -- The free store has not been initialized, and the node becoming |
| 705 | -- inactive immediately precedes the start of the free store. All |
| 706 | -- we need to do is move the start of the free store back by one. |
| 707 | |
| 708 | -- Note: initializing Next to zero is not strictly necessary but |
| 709 | -- seems cleaner and marginally safer. |
| 710 | |
| 711 | N (X).Next := 0; |
| 712 | Container.Free := Container.Free + 1; |
| 713 | |
| 714 | else |
| 715 | -- The free store has not been initialized, and the node becoming |
| 716 | -- inactive does not immediately precede the free store. Here we |
| 717 | -- first initialize the free store (meaning the links are given |
| 718 | -- values in the traditional way), and then link the newly-free'd |
| 719 | -- node onto the head of the free store. |
| 720 | |
| 721 | -- ??? |
| 722 | -- See the comments above for an optimization opportunity. If the |
| 723 | -- next link for a node on the free store is negative, then this |
| 724 | -- means the remaining nodes on the free store are physically |
| 725 | -- contiguous, starting as the absolute value of that index value. |
| 726 | |
| 727 | Container.Free := abs Container.Free; |
| 728 | |
| 729 | if Container.Free > Container.Capacity then |
| 730 | Container.Free := 0; |
| 731 | |
| 732 | else |
| 733 | for I in Container.Free .. Container.Capacity - 1 loop |
| 734 | N (I).Next := I + 1; |
| 735 | end loop; |
| 736 | |
| 737 | N (Container.Capacity).Next := 0; |
| 738 | end if; |
| 739 | |
| 740 | N (X).Next := Container.Free; |
| 741 | Container.Free := X; |
| 742 | end if; |
| 743 | end Free; |
| 744 | |
| 745 | --------------------- |
| 746 | -- Generic_Sorting -- |
| 747 | --------------------- |
| 748 | |
| 749 | package body Generic_Sorting is |
| 750 | |
| 751 | --------------- |
| 752 | -- Is_Sorted -- |
| 753 | --------------- |
| 754 | |
| 755 | function Is_Sorted (Container : List) return Boolean is |
| 756 | Nodes : Node_Array renames Container.Nodes; |
| 757 | Node : Count_Type := Container.First; |
| 758 | |
| 759 | begin |
| 760 | for J in 2 .. Container.Length loop |
| 761 | if Nodes (Nodes (Node).Next).Element < Nodes (Node).Element then |
| 762 | return False; |
| 763 | end if; |
| 764 | |
| 765 | Node := Nodes (Node).Next; |
| 766 | end loop; |
| 767 | |
| 768 | return True; |
| 769 | end Is_Sorted; |
| 770 | |
| 771 | ----------- |
| 772 | -- Merge -- |
| 773 | ----------- |
| 774 | |
| 775 | procedure Merge |
| 776 | (Target : in out List; |
| 777 | Source : in out List) |
| 778 | is |
| 779 | LN : Node_Array renames Target.Nodes; |
| 780 | RN : Node_Array renames Source.Nodes; |
| 781 | LI, RI : Cursor; |
| 782 | |
| 783 | begin |
| 784 | |
| 785 | -- The semantics of Merge changed slightly per AI05-0021. It was |
| 786 | -- originally the case that if Target and Source denoted the same |
| 787 | -- container object, then the GNAT implementation of Merge did |
| 788 | -- nothing. However, it was argued that RM05 did not precisely |
| 789 | -- specify the semantics for this corner case. The decision of the |
| 790 | -- ARG was that if Target and Source denote the same non-empty |
| 791 | -- container object, then Program_Error is raised. |
| 792 | |
| 793 | if Source.Is_Empty then |
| 794 | return; |
| 795 | end if; |
| 796 | |
| 797 | if Target'Address = Source'Address then |
| 798 | raise Program_Error with |
| 799 | "Target and Source denote same non-empty container"; |
| 800 | end if; |
| 801 | |
| 802 | if Target.Busy > 0 then |
| 803 | raise Program_Error with |
| 804 | "attempt to tamper with cursors of Target (list is busy)"; |
| 805 | end if; |
| 806 | |
| 807 | if Source.Busy > 0 then |
| 808 | raise Program_Error with |
| 809 | "attempt to tamper with cursors of Source (list is busy)"; |
| 810 | end if; |
| 811 | |
| 812 | LI := First (Target); |
| 813 | RI := First (Source); |
| 814 | while RI.Node /= 0 loop |
| 815 | pragma Assert (RN (RI.Node).Next = 0 |
| 816 | or else not (RN (RN (RI.Node).Next).Element < |
| 817 | RN (RI.Node).Element)); |
| 818 | |
| 819 | if LI.Node = 0 then |
| 820 | Splice (Target, No_Element, Source); |
| 821 | return; |
| 822 | end if; |
| 823 | |
| 824 | pragma Assert (LN (LI.Node).Next = 0 |
| 825 | or else not (LN (LN (LI.Node).Next).Element < |
| 826 | LN (LI.Node).Element)); |
| 827 | |
| 828 | if RN (RI.Node).Element < LN (LI.Node).Element then |
| 829 | declare |
| 830 | RJ : Cursor := RI; |
| 831 | begin |
| 832 | RI.Node := RN (RI.Node).Next; |
| 833 | Splice (Target, LI, Source, RJ); |
| 834 | end; |
| 835 | |
| 836 | else |
| 837 | LI.Node := LN (LI.Node).Next; |
| 838 | end if; |
| 839 | end loop; |
| 840 | end Merge; |
| 841 | |
| 842 | ---------- |
| 843 | -- Sort -- |
| 844 | ---------- |
| 845 | |
| 846 | procedure Sort (Container : in out List) is |
| 847 | N : Node_Array renames Container.Nodes; |
| 848 | |
| 849 | procedure Partition (Pivot, Back : Count_Type); |
| 850 | -- What does this do ??? |
| 851 | |
| 852 | procedure Sort (Front, Back : Count_Type); |
| 853 | -- Internal procedure, what does it do??? rename it??? |
| 854 | |
| 855 | --------------- |
| 856 | -- Partition -- |
| 857 | --------------- |
| 858 | |
| 859 | procedure Partition (Pivot, Back : Count_Type) is |
| 860 | Node : Count_Type; |
| 861 | |
| 862 | begin |
| 863 | Node := N (Pivot).Next; |
| 864 | while Node /= Back loop |
| 865 | if N (Node).Element < N (Pivot).Element then |
| 866 | declare |
| 867 | Prev : constant Count_Type := N (Node).Prev; |
| 868 | Next : constant Count_Type := N (Node).Next; |
| 869 | |
| 870 | begin |
| 871 | N (Prev).Next := Next; |
| 872 | |
| 873 | if Next = 0 then |
| 874 | Container.Last := Prev; |
| 875 | else |
| 876 | N (Next).Prev := Prev; |
| 877 | end if; |
| 878 | |
| 879 | N (Node).Next := Pivot; |
| 880 | N (Node).Prev := N (Pivot).Prev; |
| 881 | |
| 882 | N (Pivot).Prev := Node; |
| 883 | |
| 884 | if N (Node).Prev = 0 then |
| 885 | Container.First := Node; |
| 886 | else |
| 887 | N (N (Node).Prev).Next := Node; |
| 888 | end if; |
| 889 | |
| 890 | Node := Next; |
| 891 | end; |
| 892 | |
| 893 | else |
| 894 | Node := N (Node).Next; |
| 895 | end if; |
| 896 | end loop; |
| 897 | end Partition; |
| 898 | |
| 899 | ---------- |
| 900 | -- Sort -- |
| 901 | ---------- |
| 902 | |
| 903 | procedure Sort (Front, Back : Count_Type) is |
| 904 | Pivot : constant Count_Type := |
Bernhard Rosenkraenzer | ee2ec6d | 2012-10-10 01:40:27 +0159 | [diff] [blame^] | 905 | (if Front = 0 then Container.First else N (Front).Next); |
Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 906 | begin |
| 907 | if Pivot /= Back then |
| 908 | Partition (Pivot, Back); |
| 909 | Sort (Front, Pivot); |
| 910 | Sort (Pivot, Back); |
| 911 | end if; |
| 912 | end Sort; |
| 913 | |
| 914 | -- Start of processing for Sort |
| 915 | |
| 916 | begin |
| 917 | if Container.Length <= 1 then |
| 918 | return; |
| 919 | end if; |
| 920 | |
| 921 | pragma Assert (N (Container.First).Prev = 0); |
| 922 | pragma Assert (N (Container.Last).Next = 0); |
| 923 | |
| 924 | if Container.Busy > 0 then |
| 925 | raise Program_Error with |
| 926 | "attempt to tamper with cursors (list is busy)"; |
| 927 | end if; |
| 928 | |
| 929 | Sort (Front => 0, Back => 0); |
| 930 | |
| 931 | pragma Assert (N (Container.First).Prev = 0); |
| 932 | pragma Assert (N (Container.Last).Next = 0); |
| 933 | end Sort; |
| 934 | |
| 935 | end Generic_Sorting; |
| 936 | |
| 937 | ----------------- |
| 938 | -- Has_Element -- |
| 939 | ----------------- |
| 940 | |
| 941 | function Has_Element (Position : Cursor) return Boolean is |
| 942 | begin |
| 943 | pragma Assert (Vet (Position), "bad cursor in Has_Element"); |
| 944 | return Position.Node /= 0; |
| 945 | end Has_Element; |
| 946 | |
| 947 | ------------ |
| 948 | -- Insert -- |
| 949 | ------------ |
| 950 | |
| 951 | procedure Insert |
| 952 | (Container : in out List; |
| 953 | Before : Cursor; |
| 954 | New_Item : Element_Type; |
| 955 | Position : out Cursor; |
| 956 | Count : Count_Type := 1) |
| 957 | is |
| 958 | New_Node : Count_Type; |
| 959 | |
| 960 | begin |
| 961 | if Before.Container /= null then |
| 962 | if Before.Container /= Container'Unrestricted_Access then |
| 963 | raise Program_Error with |
| 964 | "Before cursor designates wrong list"; |
| 965 | end if; |
| 966 | |
| 967 | pragma Assert (Vet (Before), "bad cursor in Insert"); |
| 968 | end if; |
| 969 | |
| 970 | if Count = 0 then |
| 971 | Position := Before; |
| 972 | return; |
| 973 | end if; |
| 974 | |
| 975 | if Container.Length > Container.Capacity - Count then |
| 976 | raise Constraint_Error with "new length exceeds capacity"; |
| 977 | end if; |
| 978 | |
| 979 | if Container.Busy > 0 then |
| 980 | raise Program_Error with |
| 981 | "attempt to tamper with cursors (list is busy)"; |
| 982 | end if; |
| 983 | |
| 984 | Allocate (Container, New_Item, New_Node); |
| 985 | Insert_Internal (Container, Before.Node, New_Node => New_Node); |
| 986 | Position := Cursor'(Container'Unchecked_Access, Node => New_Node); |
| 987 | |
| 988 | for Index in Count_Type'(2) .. Count loop |
| 989 | Allocate (Container, New_Item, New_Node => New_Node); |
| 990 | Insert_Internal (Container, Before.Node, New_Node => New_Node); |
| 991 | end loop; |
| 992 | end Insert; |
| 993 | |
| 994 | procedure Insert |
| 995 | (Container : in out List; |
| 996 | Before : Cursor; |
| 997 | New_Item : Element_Type; |
| 998 | Count : Count_Type := 1) |
| 999 | is |
| 1000 | Position : Cursor; |
| 1001 | pragma Unreferenced (Position); |
| 1002 | begin |
| 1003 | Insert (Container, Before, New_Item, Position, Count); |
| 1004 | end Insert; |
| 1005 | |
| 1006 | procedure Insert |
| 1007 | (Container : in out List; |
| 1008 | Before : Cursor; |
| 1009 | Position : out Cursor; |
| 1010 | Count : Count_Type := 1) |
| 1011 | is |
| 1012 | New_Node : Count_Type; |
| 1013 | |
| 1014 | begin |
| 1015 | if Before.Container /= null then |
| 1016 | if Before.Container /= Container'Unrestricted_Access then |
| 1017 | raise Program_Error with |
| 1018 | "Before cursor designates wrong list"; |
| 1019 | end if; |
| 1020 | |
| 1021 | pragma Assert (Vet (Before), "bad cursor in Insert"); |
| 1022 | end if; |
| 1023 | |
| 1024 | if Count = 0 then |
| 1025 | Position := Before; |
| 1026 | return; |
| 1027 | end if; |
| 1028 | |
| 1029 | if Container.Length > Container.Capacity - Count then |
| 1030 | raise Constraint_Error with "new length exceeds capacity"; |
| 1031 | end if; |
| 1032 | |
| 1033 | if Container.Busy > 0 then |
| 1034 | raise Program_Error with |
| 1035 | "attempt to tamper with cursors (list is busy)"; |
| 1036 | end if; |
| 1037 | |
| 1038 | Allocate (Container, New_Node => New_Node); |
| 1039 | Insert_Internal (Container, Before.Node, New_Node); |
| 1040 | Position := Cursor'(Container'Unchecked_Access, New_Node); |
| 1041 | |
| 1042 | for Index in Count_Type'(2) .. Count loop |
| 1043 | Allocate (Container, New_Node => New_Node); |
| 1044 | Insert_Internal (Container, Before.Node, New_Node); |
| 1045 | end loop; |
| 1046 | end Insert; |
| 1047 | |
| 1048 | --------------------- |
| 1049 | -- Insert_Internal -- |
| 1050 | --------------------- |
| 1051 | |
| 1052 | procedure Insert_Internal |
| 1053 | (Container : in out List; |
| 1054 | Before : Count_Type; |
| 1055 | New_Node : Count_Type) |
| 1056 | is |
| 1057 | N : Node_Array renames Container.Nodes; |
| 1058 | |
| 1059 | begin |
| 1060 | if Container.Length = 0 then |
| 1061 | pragma Assert (Before = 0); |
| 1062 | pragma Assert (Container.First = 0); |
| 1063 | pragma Assert (Container.Last = 0); |
| 1064 | |
| 1065 | Container.First := New_Node; |
| 1066 | N (Container.First).Prev := 0; |
| 1067 | |
| 1068 | Container.Last := New_Node; |
| 1069 | N (Container.Last).Next := 0; |
| 1070 | |
| 1071 | -- Before = zero means append |
| 1072 | |
| 1073 | elsif Before = 0 then |
| 1074 | pragma Assert (N (Container.Last).Next = 0); |
| 1075 | |
| 1076 | N (Container.Last).Next := New_Node; |
| 1077 | N (New_Node).Prev := Container.Last; |
| 1078 | |
| 1079 | Container.Last := New_Node; |
| 1080 | N (Container.Last).Next := 0; |
| 1081 | |
| 1082 | -- Before = Container.First means prepend |
| 1083 | |
| 1084 | elsif Before = Container.First then |
| 1085 | pragma Assert (N (Container.First).Prev = 0); |
| 1086 | |
| 1087 | N (Container.First).Prev := New_Node; |
| 1088 | N (New_Node).Next := Container.First; |
| 1089 | |
| 1090 | Container.First := New_Node; |
| 1091 | N (Container.First).Prev := 0; |
| 1092 | |
| 1093 | else |
| 1094 | pragma Assert (N (Container.First).Prev = 0); |
| 1095 | pragma Assert (N (Container.Last).Next = 0); |
| 1096 | |
| 1097 | N (New_Node).Next := Before; |
| 1098 | N (New_Node).Prev := N (Before).Prev; |
| 1099 | |
| 1100 | N (N (Before).Prev).Next := New_Node; |
| 1101 | N (Before).Prev := New_Node; |
| 1102 | end if; |
| 1103 | |
| 1104 | Container.Length := Container.Length + 1; |
| 1105 | end Insert_Internal; |
| 1106 | |
| 1107 | -------------- |
| 1108 | -- Is_Empty -- |
| 1109 | -------------- |
| 1110 | |
| 1111 | function Is_Empty (Container : List) return Boolean is |
| 1112 | begin |
| 1113 | return Container.Length = 0; |
| 1114 | end Is_Empty; |
| 1115 | |
| 1116 | ------------- |
| 1117 | -- Iterate -- |
| 1118 | ------------- |
| 1119 | |
| 1120 | procedure Iterate |
| 1121 | (Container : List; |
| 1122 | Process : not null access procedure (Position : Cursor)) |
| 1123 | is |
| 1124 | B : Natural renames Container'Unrestricted_Access.all.Busy; |
| 1125 | Node : Count_Type := Container.First; |
| 1126 | |
| 1127 | begin |
| 1128 | B := B + 1; |
| 1129 | |
| 1130 | begin |
| 1131 | while Node /= 0 loop |
| 1132 | Process (Cursor'(Container'Unrestricted_Access, Node)); |
| 1133 | Node := Container.Nodes (Node).Next; |
| 1134 | end loop; |
| 1135 | |
| 1136 | exception |
| 1137 | when others => |
| 1138 | B := B - 1; |
| 1139 | raise; |
| 1140 | end; |
| 1141 | |
| 1142 | B := B - 1; |
| 1143 | end Iterate; |
| 1144 | |
| 1145 | function Iterate |
| 1146 | (Container : List) |
| 1147 | return List_Iterator_Interfaces.Reversible_Iterator'Class |
| 1148 | is |
| 1149 | B : Natural renames Container'Unrestricted_Access.all.Busy; |
| 1150 | |
| 1151 | begin |
| 1152 | -- The value of the Node component influences the behavior of the First |
| 1153 | -- and Last selector functions of the iterator object. When the Node |
| 1154 | -- component is 0 (as is the case here), this means the iterator |
| 1155 | -- object was constructed without a start expression. This is a |
| 1156 | -- complete iterator, meaning that the iteration starts from the |
| 1157 | -- (logical) beginning of the sequence of items. |
| 1158 | |
| 1159 | -- Note: For a forward iterator, Container.First is the beginning, and |
| 1160 | -- for a reverse iterator, Container.Last is the beginning. |
| 1161 | |
| 1162 | return It : constant Iterator := |
Bernhard Rosenkraenzer | ee2ec6d | 2012-10-10 01:40:27 +0159 | [diff] [blame^] | 1163 | Iterator'(Limited_Controlled with |
| 1164 | Container => Container'Unrestricted_Access, |
| 1165 | Node => 0) |
Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 1166 | do |
| 1167 | B := B + 1; |
| 1168 | end return; |
| 1169 | end Iterate; |
| 1170 | |
| 1171 | function Iterate |
| 1172 | (Container : List; |
| 1173 | Start : Cursor) |
| 1174 | return List_Iterator_Interfaces.Reversible_Iterator'class |
| 1175 | is |
| 1176 | B : Natural renames Container'Unrestricted_Access.all.Busy; |
| 1177 | |
| 1178 | begin |
| 1179 | -- It was formerly the case that when Start = No_Element, the partial |
| 1180 | -- iterator was defined to behave the same as for a complete iterator, |
| 1181 | -- and iterate over the entire sequence of items. However, those |
| 1182 | -- semantics were unintuitive and arguably error-prone (it is too easy |
| 1183 | -- to accidentally create an endless loop), and so they were changed, |
| 1184 | -- per the ARG meeting in Denver on 2011/11. However, there was no |
| 1185 | -- consensus about what positive meaning this corner case should have, |
| 1186 | -- and so it was decided to simply raise an exception. This does imply, |
| 1187 | -- however, that it is not possible to use a partial iterator to specify |
| 1188 | -- an empty sequence of items. |
| 1189 | |
| 1190 | if Start = No_Element then |
| 1191 | raise Constraint_Error with |
| 1192 | "Start position for iterator equals No_Element"; |
| 1193 | end if; |
| 1194 | |
| 1195 | if Start.Container /= Container'Unrestricted_Access then |
| 1196 | raise Program_Error with |
| 1197 | "Start cursor of Iterate designates wrong list"; |
| 1198 | end if; |
| 1199 | |
| 1200 | pragma Assert (Vet (Start), "Start cursor of Iterate is bad"); |
| 1201 | |
| 1202 | -- The value of the Node component influences the behavior of the First |
| 1203 | -- and Last selector functions of the iterator object. When the Node |
| 1204 | -- component is positive (as is the case here), it means that this |
| 1205 | -- is a partial iteration, over a subset of the complete sequence of |
| 1206 | -- items. The iterator object was constructed with a start expression, |
| 1207 | -- indicating the position from which the iteration begins. Note that |
| 1208 | -- the start position has the same value irrespective of whether this |
| 1209 | -- is a forward or reverse iteration. |
| 1210 | |
| 1211 | return It : constant Iterator := |
Bernhard Rosenkraenzer | ee2ec6d | 2012-10-10 01:40:27 +0159 | [diff] [blame^] | 1212 | Iterator'(Limited_Controlled with |
| 1213 | Container => Container'Unrestricted_Access, |
| 1214 | Node => Start.Node) |
Bernhard Rosenkraenzer | c83ebe5 | 2012-09-18 21:38:03 +0159 | [diff] [blame] | 1215 | do |
| 1216 | B := B + 1; |
| 1217 | end return; |
| 1218 | end Iterate; |
| 1219 | |
| 1220 | ---------- |
| 1221 | -- Last -- |
| 1222 | ---------- |
| 1223 | |
| 1224 | function Last (Container : List) return Cursor is |
| 1225 | begin |
| 1226 | if Container.Last = 0 then |
| 1227 | return No_Element; |
| 1228 | end if; |
| 1229 | |
| 1230 | return Cursor'(Container'Unrestricted_Access, Container.Last); |
| 1231 | end Last; |
| 1232 | |
| 1233 | function Last (Object : Iterator) return Cursor is |
| 1234 | begin |
| 1235 | -- The value of the iterator object's Node component influences the |
| 1236 | -- behavior of the Last (and First) selector function. |
| 1237 | |
| 1238 | -- When the Node component is 0, this means the iterator object was |
| 1239 | -- constructed without a start expression, in which case the (reverse) |
| 1240 | -- iteration starts from the (logical) beginning of the entire sequence |
| 1241 | -- (corresponding to Container.Last, for a reverse iterator). |
| 1242 | |
| 1243 | -- Otherwise, this is iteration over a partial sequence of items. When |
| 1244 | -- the Node component is positive, the iterator object was constructed |
| 1245 | -- with a start expression, that specifies the position from which the |
| 1246 | -- (reverse) partial iteration begins. |
| 1247 | |
| 1248 | if Object.Node = 0 then |
| 1249 | return Bounded_Doubly_Linked_Lists.Last (Object.Container.all); |
| 1250 | else |
| 1251 | return Cursor'(Object.Container, Object.Node); |
| 1252 | end if; |
| 1253 | end Last; |
| 1254 | |
| 1255 | ------------------ |
| 1256 | -- Last_Element -- |
| 1257 | ------------------ |
| 1258 | |
| 1259 | function Last_Element (Container : List) return Element_Type is |
| 1260 | begin |
| 1261 | if Container.Last = 0 then |
| 1262 | raise Constraint_Error with "list is empty"; |
| 1263 | end if; |
| 1264 | |
| 1265 | return Container.Nodes (Container.Last).Element; |
| 1266 | end Last_Element; |
| 1267 | |
| 1268 | ------------ |
| 1269 | -- Length -- |
| 1270 | ------------ |
| 1271 | |
| 1272 | function Length (Container : List) return Count_Type is |
| 1273 | begin |
| 1274 | return Container.Length; |
| 1275 | end Length; |
| 1276 | |
| 1277 | ---------- |
| 1278 | -- Move -- |
| 1279 | ---------- |
| 1280 | |
| 1281 | procedure Move |
| 1282 | (Target : in out List; |
| 1283 | Source : in out List) |
| 1284 | is |
| 1285 | N : Node_Array renames Source.Nodes; |
| 1286 | X : Count_Type; |
| 1287 | |
| 1288 | begin |
| 1289 | if Target'Address = Source'Address then |
| 1290 | return; |
| 1291 | end if; |
| 1292 | |
| 1293 | if Target.Capacity < Source.Length then |
| 1294 | raise Capacity_Error with "Source length exceeds Target capacity"; |
| 1295 | end if; |
| 1296 | |
| 1297 | if Source.Busy > 0 then |
| 1298 | raise Program_Error with |
| 1299 | "attempt to tamper with cursors of Source (list is busy)"; |
| 1300 | end if; |
| 1301 | |
| 1302 | -- Clear target, note that this checks busy bits of Target |
| 1303 | |
| 1304 | Clear (Target); |
| 1305 | |
| 1306 | while Source.Length > 1 loop |
| 1307 | pragma Assert (Source.First in 1 .. Source.Capacity); |
| 1308 | pragma Assert (Source.Last /= Source.First); |
| 1309 | pragma Assert (N (Source.First).Prev = 0); |
| 1310 | pragma Assert (N (Source.Last).Next = 0); |
| 1311 | |
| 1312 | -- Copy first element from Source to Target |
| 1313 | |
| 1314 | X := Source.First; |
| 1315 | Append (Target, N (X).Element); |
| 1316 | |
| 1317 | -- Unlink first node of Source |
| 1318 | |
| 1319 | Source.First := N (X).Next; |
| 1320 | N (Source.First).Prev := 0; |
| 1321 | |
| 1322 | Source.Length := Source.Length - 1; |
| 1323 | |
| 1324 | -- The representation invariants for Source have been restored. It is |
| 1325 | -- now safe to free the unlinked node, without fear of corrupting the |
| 1326 | -- active links of Source. |
| 1327 | |
| 1328 | -- Note that the algorithm we use here models similar algorithms used |
| 1329 | -- in the unbounded form of the doubly-linked list container. In that |
| 1330 | -- case, Free is an instantation of Unchecked_Deallocation, which can |
| 1331 | -- fail (because PE will be raised if controlled Finalize fails), so |
| 1332 | -- we must defer the call until the last step. Here in the bounded |
| 1333 | -- form, Free merely links the node we have just "deallocated" onto a |
| 1334 | -- list of inactive nodes, so technically Free cannot fail. However, |
| 1335 | -- for consistency, we handle Free the same way here as we do for the |
| 1336 | -- unbounded form, with the pessimistic assumption that it can fail. |
| 1337 | |
| 1338 | Free (Source, X); |
| 1339 | end loop; |
| 1340 | |
| 1341 | if Source.Length = 1 then |
| 1342 | pragma Assert (Source.First in 1 .. Source.Capacity); |
| 1343 | pragma Assert (Source.Last = Source.First); |
| 1344 | pragma Assert (N (Source.First).Prev = 0); |
| 1345 | pragma Assert (N (Source.Last).Next = 0); |
| 1346 | |
| 1347 | -- Copy element from Source to Target |
| 1348 | |
| 1349 | X := Source.First; |
| 1350 | Append (Target, N (X).Element); |
| 1351 | |
| 1352 | -- Unlink node of Source |
| 1353 | |
| 1354 | Source.First := 0; |
| 1355 | Source.Last := 0; |
| 1356 | Source.Length := 0; |
| 1357 | |
| 1358 | -- Return the unlinked node to the free store |
| 1359 | |
| 1360 | Free (Source, X); |
| 1361 | end if; |
| 1362 | end Move; |
| 1363 | |
| 1364 | ---------- |
| 1365 | -- Next -- |
| 1366 | ---------- |
| 1367 | |
| 1368 | procedure Next (Position : in out Cursor) is |
| 1369 | begin |
| 1370 | Position := Next (Position); |
| 1371 | end Next; |
| 1372 | |
| 1373 | function Next (Position : Cursor) return Cursor is |
| 1374 | begin |
| 1375 | if Position.Node = 0 then |
| 1376 | return No_Element; |
| 1377 | end if; |
| 1378 | |
| 1379 | pragma Assert (Vet (Position), "bad cursor in Next"); |
| 1380 | |
| 1381 | declare |
| 1382 | Nodes : Node_Array renames Position.Container.Nodes; |
| 1383 | Node : constant Count_Type := Nodes (Position.Node).Next; |
| 1384 | |
| 1385 | begin |
| 1386 | if Node = 0 then |
| 1387 | return No_Element; |
| 1388 | end if; |
| 1389 | |
| 1390 | return Cursor'(Position.Container, Node); |
| 1391 | end; |
| 1392 | end Next; |
| 1393 | |
| 1394 | function Next |
| 1395 | (Object : Iterator; |
| 1396 | Position : Cursor) return Cursor |
| 1397 | is |
| 1398 | begin |
| 1399 | if Position.Container = null then |
| 1400 | return No_Element; |
| 1401 | end if; |
| 1402 | |
| 1403 | if Position.Container /= Object.Container then |
| 1404 | raise Program_Error with |
| 1405 | "Position cursor of Next designates wrong list"; |
| 1406 | end if; |
| 1407 | |
| 1408 | return Next (Position); |
| 1409 | end Next; |
| 1410 | |
| 1411 | ------------- |
| 1412 | -- Prepend -- |
| 1413 | ------------- |
| 1414 | |
| 1415 | procedure Prepend |
| 1416 | (Container : in out List; |
| 1417 | New_Item : Element_Type; |
| 1418 | Count : Count_Type := 1) |
| 1419 | is |
| 1420 | begin |
| 1421 | Insert (Container, First (Container), New_Item, Count); |
| 1422 | end Prepend; |
| 1423 | |
| 1424 | -------------- |
| 1425 | -- Previous -- |
| 1426 | -------------- |
| 1427 | |
| 1428 | procedure Previous (Position : in out Cursor) is |
| 1429 | begin |
| 1430 | Position := Previous (Position); |
| 1431 | end Previous; |
| 1432 | |
| 1433 | function Previous (Position : Cursor) return Cursor is |
| 1434 | begin |
| 1435 | if Position.Node = 0 then |
| 1436 | return No_Element; |
| 1437 | end if; |
| 1438 | |
| 1439 | pragma Assert (Vet (Position), "bad cursor in Previous"); |
| 1440 | |
| 1441 | declare |
| 1442 | Nodes : Node_Array renames Position.Container.Nodes; |
| 1443 | Node : constant Count_Type := Nodes (Position.Node).Prev; |
| 1444 | begin |
| 1445 | if Node = 0 then |
| 1446 | return No_Element; |
| 1447 | end if; |
| 1448 | |
| 1449 | return Cursor'(Position.Container, Node); |
| 1450 | end; |
| 1451 | end Previous; |
| 1452 | |
| 1453 | function Previous |
| 1454 | (Object : Iterator; |
| 1455 | Position : Cursor) return Cursor |
| 1456 | is |
| 1457 | begin |
| 1458 | if Position.Container = null then |
| 1459 | return No_Element; |
| 1460 | end if; |
| 1461 | |
| 1462 | if Position.Container /= Object.Container then |
| 1463 | raise Program_Error with |
| 1464 | "Position cursor of Previous designates wrong list"; |
| 1465 | end if; |
| 1466 | |
| 1467 | return Previous (Position); |
| 1468 | end Previous; |
| 1469 | |
| 1470 | ------------------- |
| 1471 | -- Query_Element -- |
| 1472 | ------------------- |
| 1473 | |
| 1474 | procedure Query_Element |
| 1475 | (Position : Cursor; |
| 1476 | Process : not null access procedure (Element : Element_Type)) |
| 1477 | is |
| 1478 | begin |
| 1479 | if Position.Node = 0 then |
| 1480 | raise Constraint_Error with |
| 1481 | "Position cursor has no element"; |
| 1482 | end if; |
| 1483 | |
| 1484 | pragma Assert (Vet (Position), "bad cursor in Query_Element"); |
| 1485 | |
| 1486 | declare |
| 1487 | C : List renames Position.Container.all'Unrestricted_Access.all; |
| 1488 | B : Natural renames C.Busy; |
| 1489 | L : Natural renames C.Lock; |
| 1490 | |
| 1491 | begin |
| 1492 | B := B + 1; |
| 1493 | L := L + 1; |
| 1494 | |
| 1495 | declare |
| 1496 | N : Node_Type renames C.Nodes (Position.Node); |
| 1497 | begin |
| 1498 | Process (N.Element); |
| 1499 | exception |
| 1500 | when others => |
| 1501 | L := L - 1; |
| 1502 | B := B - 1; |
| 1503 | raise; |
| 1504 | end; |
| 1505 | |
| 1506 | L := L - 1; |
| 1507 | B := B - 1; |
| 1508 | end; |
| 1509 | end Query_Element; |
| 1510 | |
| 1511 | ---------- |
| 1512 | -- Read -- |
| 1513 | ---------- |
| 1514 | |
| 1515 | procedure Read |
| 1516 | (Stream : not null access Root_Stream_Type'Class; |
| 1517 | Item : out List) |
| 1518 | is |
| 1519 | N : Count_Type'Base; |
| 1520 | X : Count_Type; |
| 1521 | |
| 1522 | begin |
| 1523 | Clear (Item); |
| 1524 | Count_Type'Base'Read (Stream, N); |
| 1525 | |
| 1526 | if N < 0 then |
| 1527 | raise Program_Error with "bad list length (corrupt stream)"; |
| 1528 | end if; |
| 1529 | |
| 1530 | if N = 0 then |
| 1531 | return; |
| 1532 | end if; |
| 1533 | |
| 1534 | if N > Item.Capacity then |
| 1535 | raise Constraint_Error with "length exceeds capacity"; |
| 1536 | end if; |
| 1537 | |
| 1538 | for Idx in 1 .. N loop |
| 1539 | Allocate (Item, Stream, New_Node => X); |
| 1540 | Insert_Internal (Item, Before => 0, New_Node => X); |
| 1541 | end loop; |
| 1542 | end Read; |
| 1543 | |
| 1544 | procedure Read |
| 1545 | (Stream : not null access Root_Stream_Type'Class; |
| 1546 | Item : out Cursor) |
| 1547 | is |
| 1548 | begin |
| 1549 | raise Program_Error with "attempt to stream list cursor"; |
| 1550 | end Read; |
| 1551 | |
| 1552 | procedure Read |
| 1553 | (Stream : not null access Root_Stream_Type'Class; |
| 1554 | Item : out Reference_Type) |
| 1555 | is |
| 1556 | begin |
| 1557 | raise Program_Error with "attempt to stream reference"; |
| 1558 | end Read; |
| 1559 | |
| 1560 | procedure Read |
| 1561 | (Stream : not null access Root_Stream_Type'Class; |
| 1562 | Item : out Constant_Reference_Type) |
| 1563 | is |
| 1564 | begin |
| 1565 | raise Program_Error with "attempt to stream reference"; |
| 1566 | end Read; |
| 1567 | |
| 1568 | --------------- |
| 1569 | -- Reference -- |
| 1570 | --------------- |
| 1571 | |
| 1572 | function Reference |
| 1573 | (Container : aliased in out List; |
| 1574 | Position : Cursor) return Reference_Type |
| 1575 | is |
| 1576 | begin |
| 1577 | if Position.Container = null then |
| 1578 | raise Constraint_Error with "Position cursor has no element"; |
| 1579 | end if; |
| 1580 | |
| 1581 | if Position.Container /= Container'Unrestricted_Access then |
| 1582 | raise Program_Error with |
| 1583 | "Position cursor designates wrong container"; |
| 1584 | end if; |
| 1585 | |
| 1586 | pragma Assert (Vet (Position), "bad cursor in function Reference"); |
| 1587 | |
| 1588 | declare |
| 1589 | N : Node_Type renames Container.Nodes (Position.Node); |
| 1590 | begin |
| 1591 | return (Element => N.Element'Access); |
| 1592 | end; |
| 1593 | end Reference; |
| 1594 | |
| 1595 | --------------------- |
| 1596 | -- Replace_Element -- |
| 1597 | --------------------- |
| 1598 | |
| 1599 | procedure Replace_Element |
| 1600 | (Container : in out List; |
| 1601 | Position : Cursor; |
| 1602 | New_Item : Element_Type) |
| 1603 | is |
| 1604 | begin |
| 1605 | if Position.Container = null then |
| 1606 | raise Constraint_Error with "Position cursor has no element"; |
| 1607 | end if; |
| 1608 | |
| 1609 | if Position.Container /= Container'Unchecked_Access then |
| 1610 | raise Program_Error with |
| 1611 | "Position cursor designates wrong container"; |
| 1612 | end if; |
| 1613 | |
| 1614 | if Container.Lock > 0 then |
| 1615 | raise Program_Error with |
| 1616 | "attempt to tamper with elements (list is locked)"; |
| 1617 | end if; |
| 1618 | |
| 1619 | pragma Assert (Vet (Position), "bad cursor in Replace_Element"); |
| 1620 | |
| 1621 | Container.Nodes (Position.Node).Element := New_Item; |
| 1622 | end Replace_Element; |
| 1623 | |
| 1624 | ---------------------- |
| 1625 | -- Reverse_Elements -- |
| 1626 | ---------------------- |
| 1627 | |
| 1628 | procedure Reverse_Elements (Container : in out List) is |
| 1629 | N : Node_Array renames Container.Nodes; |
| 1630 | I : Count_Type := Container.First; |
| 1631 | J : Count_Type := Container.Last; |
| 1632 | |
| 1633 | procedure Swap (L, R : Count_Type); |
| 1634 | |
| 1635 | ---------- |
| 1636 | -- Swap -- |
| 1637 | ---------- |
| 1638 | |
| 1639 | procedure Swap (L, R : Count_Type) is |
| 1640 | LN : constant Count_Type := N (L).Next; |
| 1641 | LP : constant Count_Type := N (L).Prev; |
| 1642 | |
| 1643 | RN : constant Count_Type := N (R).Next; |
| 1644 | RP : constant Count_Type := N (R).Prev; |
| 1645 | |
| 1646 | begin |
| 1647 | if LP /= 0 then |
| 1648 | N (LP).Next := R; |
| 1649 | end if; |
| 1650 | |
| 1651 | if RN /= 0 then |
| 1652 | N (RN).Prev := L; |
| 1653 | end if; |
| 1654 | |
| 1655 | N (L).Next := RN; |
| 1656 | N (R).Prev := LP; |
| 1657 | |
| 1658 | if LN = R then |
| 1659 | pragma Assert (RP = L); |
| 1660 | |
| 1661 | N (L).Prev := R; |
| 1662 | N (R).Next := L; |
| 1663 | |
| 1664 | else |
| 1665 | N (L).Prev := RP; |
| 1666 | N (RP).Next := L; |
| 1667 | |
| 1668 | N (R).Next := LN; |
| 1669 | N (LN).Prev := R; |
| 1670 | end if; |
| 1671 | end Swap; |
| 1672 | |
| 1673 | -- Start of processing for Reverse_Elements |
| 1674 | |
| 1675 | begin |
| 1676 | if Container.Length <= 1 then |
| 1677 | return; |
| 1678 | end if; |
| 1679 | |
| 1680 | pragma Assert (N (Container.First).Prev = 0); |
| 1681 | pragma Assert (N (Container.Last).Next = 0); |
| 1682 | |
| 1683 | if Container.Busy > 0 then |
| 1684 | raise Program_Error with |
| 1685 | "attempt to tamper with cursors (list is busy)"; |
| 1686 | end if; |
| 1687 | |
| 1688 | Container.First := J; |
| 1689 | Container.Last := I; |
| 1690 | loop |
| 1691 | Swap (L => I, R => J); |
| 1692 | |
| 1693 | J := N (J).Next; |
| 1694 | exit when I = J; |
| 1695 | |
| 1696 | I := N (I).Prev; |
| 1697 | exit when I = J; |
| 1698 | |
| 1699 | Swap (L => J, R => I); |
| 1700 | |
| 1701 | I := N (I).Next; |
| 1702 | exit when I = J; |
| 1703 | |
| 1704 | J := N (J).Prev; |
| 1705 | exit when I = J; |
| 1706 | end loop; |
| 1707 | |
| 1708 | pragma Assert (N (Container.First).Prev = 0); |
| 1709 | pragma Assert (N (Container.Last).Next = 0); |
| 1710 | end Reverse_Elements; |
| 1711 | |
| 1712 | ------------------ |
| 1713 | -- Reverse_Find -- |
| 1714 | ------------------ |
| 1715 | |
| 1716 | function Reverse_Find |
| 1717 | (Container : List; |
| 1718 | Item : Element_Type; |
| 1719 | Position : Cursor := No_Element) return Cursor |
| 1720 | is |
| 1721 | Node : Count_Type := Position.Node; |
| 1722 | |
| 1723 | begin |
| 1724 | if Node = 0 then |
| 1725 | Node := Container.Last; |
| 1726 | |
| 1727 | else |
| 1728 | if Position.Container /= Container'Unrestricted_Access then |
| 1729 | raise Program_Error with |
| 1730 | "Position cursor designates wrong container"; |
| 1731 | end if; |
| 1732 | |
| 1733 | pragma Assert (Vet (Position), "bad cursor in Reverse_Find"); |
| 1734 | end if; |
| 1735 | |
| 1736 | while Node /= 0 loop |
| 1737 | if Container.Nodes (Node).Element = Item then |
| 1738 | return Cursor'(Container'Unrestricted_Access, Node); |
| 1739 | end if; |
| 1740 | |
| 1741 | Node := Container.Nodes (Node).Prev; |
| 1742 | end loop; |
| 1743 | |
| 1744 | return No_Element; |
| 1745 | end Reverse_Find; |
| 1746 | |
| 1747 | --------------------- |
| 1748 | -- Reverse_Iterate -- |
| 1749 | --------------------- |
| 1750 | |
| 1751 | procedure Reverse_Iterate |
| 1752 | (Container : List; |
| 1753 | Process : not null access procedure (Position : Cursor)) |
| 1754 | is |
| 1755 | C : List renames Container'Unrestricted_Access.all; |
| 1756 | B : Natural renames C.Busy; |
| 1757 | |
| 1758 | Node : Count_Type := Container.Last; |
| 1759 | |
| 1760 | begin |
| 1761 | B := B + 1; |
| 1762 | |
| 1763 | begin |
| 1764 | while Node /= 0 loop |
| 1765 | Process (Cursor'(Container'Unrestricted_Access, Node)); |
| 1766 | Node := Container.Nodes (Node).Prev; |
| 1767 | end loop; |
| 1768 | |
| 1769 | exception |
| 1770 | when others => |
| 1771 | B := B - 1; |
| 1772 | raise; |
| 1773 | end; |
| 1774 | |
| 1775 | B := B - 1; |
| 1776 | end Reverse_Iterate; |
| 1777 | |
| 1778 | ------------ |
| 1779 | -- Splice -- |
| 1780 | ------------ |
| 1781 | |
| 1782 | procedure Splice |
| 1783 | (Target : in out List; |
| 1784 | Before : Cursor; |
| 1785 | Source : in out List) |
| 1786 | is |
| 1787 | begin |
| 1788 | if Before.Container /= null then |
| 1789 | if Before.Container /= Target'Unrestricted_Access then |
| 1790 | raise Program_Error with |
| 1791 | "Before cursor designates wrong container"; |
| 1792 | end if; |
| 1793 | |
| 1794 | pragma Assert (Vet (Before), "bad cursor in Splice"); |
| 1795 | end if; |
| 1796 | |
| 1797 | if Target'Address = Source'Address |
| 1798 | or else Source.Length = 0 |
| 1799 | then |
| 1800 | return; |
| 1801 | end if; |
| 1802 | |
| 1803 | pragma Assert (Source.Nodes (Source.First).Prev = 0); |
| 1804 | pragma Assert (Source.Nodes (Source.Last).Next = 0); |
| 1805 | |
| 1806 | if Target.Length > Count_Type'Last - Source.Length then |
| 1807 | raise Constraint_Error with "new length exceeds maximum"; |
| 1808 | end if; |
| 1809 | |
| 1810 | if Target.Length + Source.Length > Target.Capacity then |
| 1811 | raise Capacity_Error with "new length exceeds target capacity"; |
| 1812 | end if; |
| 1813 | |
| 1814 | if Target.Busy > 0 then |
| 1815 | raise Program_Error with |
| 1816 | "attempt to tamper with cursors of Target (list is busy)"; |
| 1817 | end if; |
| 1818 | |
| 1819 | if Source.Busy > 0 then |
| 1820 | raise Program_Error with |
| 1821 | "attempt to tamper with cursors of Source (list is busy)"; |
| 1822 | end if; |
| 1823 | |
| 1824 | while not Is_Empty (Source) loop |
| 1825 | Insert (Target, Before, Source.Nodes (Source.First).Element); |
| 1826 | Delete_First (Source); |
| 1827 | end loop; |
| 1828 | end Splice; |
| 1829 | |
| 1830 | procedure Splice |
| 1831 | (Container : in out List; |
| 1832 | Before : Cursor; |
| 1833 | Position : Cursor) |
| 1834 | is |
| 1835 | N : Node_Array renames Container.Nodes; |
| 1836 | |
| 1837 | begin |
| 1838 | if Before.Container /= null then |
| 1839 | if Before.Container /= Container'Unchecked_Access then |
| 1840 | raise Program_Error with |
| 1841 | "Before cursor designates wrong container"; |
| 1842 | end if; |
| 1843 | |
| 1844 | pragma Assert (Vet (Before), "bad Before cursor in Splice"); |
| 1845 | end if; |
| 1846 | |
| 1847 | if Position.Node = 0 then |
| 1848 | raise Constraint_Error with "Position cursor has no element"; |
| 1849 | end if; |
| 1850 | |
| 1851 | if Position.Container /= Container'Unrestricted_Access then |
| 1852 | raise Program_Error with |
| 1853 | "Position cursor designates wrong container"; |
| 1854 | end if; |
| 1855 | |
| 1856 | pragma Assert (Vet (Position), "bad Position cursor in Splice"); |
| 1857 | |
| 1858 | if Position.Node = Before.Node |
| 1859 | or else N (Position.Node).Next = Before.Node |
| 1860 | then |
| 1861 | return; |
| 1862 | end if; |
| 1863 | |
| 1864 | pragma Assert (Container.Length >= 2); |
| 1865 | |
| 1866 | if Container.Busy > 0 then |
| 1867 | raise Program_Error with |
| 1868 | "attempt to tamper with cursors (list is busy)"; |
| 1869 | end if; |
| 1870 | |
| 1871 | if Before.Node = 0 then |
| 1872 | pragma Assert (Position.Node /= Container.Last); |
| 1873 | |
| 1874 | if Position.Node = Container.First then |
| 1875 | Container.First := N (Position.Node).Next; |
| 1876 | N (Container.First).Prev := 0; |
| 1877 | else |
| 1878 | N (N (Position.Node).Prev).Next := N (Position.Node).Next; |
| 1879 | N (N (Position.Node).Next).Prev := N (Position.Node).Prev; |
| 1880 | end if; |
| 1881 | |
| 1882 | N (Container.Last).Next := Position.Node; |
| 1883 | N (Position.Node).Prev := Container.Last; |
| 1884 | |
| 1885 | Container.Last := Position.Node; |
| 1886 | N (Container.Last).Next := 0; |
| 1887 | |
| 1888 | return; |
| 1889 | end if; |
| 1890 | |
| 1891 | if Before.Node = Container.First then |
| 1892 | pragma Assert (Position.Node /= Container.First); |
| 1893 | |
| 1894 | if Position.Node = Container.Last then |
| 1895 | Container.Last := N (Position.Node).Prev; |
| 1896 | N (Container.Last).Next := 0; |
| 1897 | else |
| 1898 | N (N (Position.Node).Prev).Next := N (Position.Node).Next; |
| 1899 | N (N (Position.Node).Next).Prev := N (Position.Node).Prev; |
| 1900 | end if; |
| 1901 | |
| 1902 | N (Container.First).Prev := Position.Node; |
| 1903 | N (Position.Node).Next := Container.First; |
| 1904 | |
| 1905 | Container.First := Position.Node; |
| 1906 | N (Container.First).Prev := 0; |
| 1907 | |
| 1908 | return; |
| 1909 | end if; |
| 1910 | |
| 1911 | if Position.Node = Container.First then |
| 1912 | Container.First := N (Position.Node).Next; |
| 1913 | N (Container.First).Prev := 0; |
| 1914 | |
| 1915 | elsif Position.Node = Container.Last then |
| 1916 | Container.Last := N (Position.Node).Prev; |
| 1917 | N (Container.Last).Next := 0; |
| 1918 | |
| 1919 | else |
| 1920 | N (N (Position.Node).Prev).Next := N (Position.Node).Next; |
| 1921 | N (N (Position.Node).Next).Prev := N (Position.Node).Prev; |
| 1922 | end if; |
| 1923 | |
| 1924 | N (N (Before.Node).Prev).Next := Position.Node; |
| 1925 | N (Position.Node).Prev := N (Before.Node).Prev; |
| 1926 | |
| 1927 | N (Before.Node).Prev := Position.Node; |
| 1928 | N (Position.Node).Next := Before.Node; |
| 1929 | |
| 1930 | pragma Assert (N (Container.First).Prev = 0); |
| 1931 | pragma Assert (N (Container.Last).Next = 0); |
| 1932 | end Splice; |
| 1933 | |
| 1934 | procedure Splice |
| 1935 | (Target : in out List; |
| 1936 | Before : Cursor; |
| 1937 | Source : in out List; |
| 1938 | Position : in out Cursor) |
| 1939 | is |
| 1940 | Target_Position : Cursor; |
| 1941 | |
| 1942 | begin |
| 1943 | if Target'Address = Source'Address then |
| 1944 | Splice (Target, Before, Position); |
| 1945 | return; |
| 1946 | end if; |
| 1947 | |
| 1948 | if Before.Container /= null then |
| 1949 | if Before.Container /= Target'Unrestricted_Access then |
| 1950 | raise Program_Error with |
| 1951 | "Before cursor designates wrong container"; |
| 1952 | end if; |
| 1953 | |
| 1954 | pragma Assert (Vet (Before), "bad Before cursor in Splice"); |
| 1955 | end if; |
| 1956 | |
| 1957 | if Position.Node = 0 then |
| 1958 | raise Constraint_Error with "Position cursor has no element"; |
| 1959 | end if; |
| 1960 | |
| 1961 | if Position.Container /= Source'Unrestricted_Access then |
| 1962 | raise Program_Error with |
| 1963 | "Position cursor designates wrong container"; |
| 1964 | end if; |
| 1965 | |
| 1966 | pragma Assert (Vet (Position), "bad Position cursor in Splice"); |
| 1967 | |
| 1968 | if Target.Length >= Target.Capacity then |
| 1969 | raise Capacity_Error with "Target is full"; |
| 1970 | end if; |
| 1971 | |
| 1972 | if Target.Busy > 0 then |
| 1973 | raise Program_Error with |
| 1974 | "attempt to tamper with cursors of Target (list is busy)"; |
| 1975 | end if; |
| 1976 | |
| 1977 | if Source.Busy > 0 then |
| 1978 | raise Program_Error with |
| 1979 | "attempt to tamper with cursors of Source (list is busy)"; |
| 1980 | end if; |
| 1981 | |
| 1982 | Insert |
| 1983 | (Container => Target, |
| 1984 | Before => Before, |
| 1985 | New_Item => Source.Nodes (Position.Node).Element, |
| 1986 | Position => Target_Position); |
| 1987 | |
| 1988 | Delete (Source, Position); |
| 1989 | Position := Target_Position; |
| 1990 | end Splice; |
| 1991 | |
| 1992 | ---------- |
| 1993 | -- Swap -- |
| 1994 | ---------- |
| 1995 | |
| 1996 | procedure Swap |
| 1997 | (Container : in out List; |
| 1998 | I, J : Cursor) |
| 1999 | is |
| 2000 | begin |
| 2001 | if I.Node = 0 then |
| 2002 | raise Constraint_Error with "I cursor has no element"; |
| 2003 | end if; |
| 2004 | |
| 2005 | if J.Node = 0 then |
| 2006 | raise Constraint_Error with "J cursor has no element"; |
| 2007 | end if; |
| 2008 | |
| 2009 | if I.Container /= Container'Unchecked_Access then |
| 2010 | raise Program_Error with "I cursor designates wrong container"; |
| 2011 | end if; |
| 2012 | |
| 2013 | if J.Container /= Container'Unchecked_Access then |
| 2014 | raise Program_Error with "J cursor designates wrong container"; |
| 2015 | end if; |
| 2016 | |
| 2017 | if I.Node = J.Node then |
| 2018 | return; |
| 2019 | end if; |
| 2020 | |
| 2021 | if Container.Lock > 0 then |
| 2022 | raise Program_Error with |
| 2023 | "attempt to tamper with elements (list is locked)"; |
| 2024 | end if; |
| 2025 | |
| 2026 | pragma Assert (Vet (I), "bad I cursor in Swap"); |
| 2027 | pragma Assert (Vet (J), "bad J cursor in Swap"); |
| 2028 | |
| 2029 | declare |
| 2030 | EI : Element_Type renames Container.Nodes (I.Node).Element; |
| 2031 | EJ : Element_Type renames Container.Nodes (J.Node).Element; |
| 2032 | |
| 2033 | EI_Copy : constant Element_Type := EI; |
| 2034 | |
| 2035 | begin |
| 2036 | EI := EJ; |
| 2037 | EJ := EI_Copy; |
| 2038 | end; |
| 2039 | end Swap; |
| 2040 | |
| 2041 | ---------------- |
| 2042 | -- Swap_Links -- |
| 2043 | ---------------- |
| 2044 | |
| 2045 | procedure Swap_Links |
| 2046 | (Container : in out List; |
| 2047 | I, J : Cursor) |
| 2048 | is |
| 2049 | begin |
| 2050 | if I.Node = 0 then |
| 2051 | raise Constraint_Error with "I cursor has no element"; |
| 2052 | end if; |
| 2053 | |
| 2054 | if J.Node = 0 then |
| 2055 | raise Constraint_Error with "J cursor has no element"; |
| 2056 | end if; |
| 2057 | |
| 2058 | if I.Container /= Container'Unrestricted_Access then |
| 2059 | raise Program_Error with "I cursor designates wrong container"; |
| 2060 | end if; |
| 2061 | |
| 2062 | if J.Container /= Container'Unrestricted_Access then |
| 2063 | raise Program_Error with "J cursor designates wrong container"; |
| 2064 | end if; |
| 2065 | |
| 2066 | if I.Node = J.Node then |
| 2067 | return; |
| 2068 | end if; |
| 2069 | |
| 2070 | if Container.Busy > 0 then |
| 2071 | raise Program_Error with |
| 2072 | "attempt to tamper with cursors (list is busy)"; |
| 2073 | end if; |
| 2074 | |
| 2075 | pragma Assert (Vet (I), "bad I cursor in Swap_Links"); |
| 2076 | pragma Assert (Vet (J), "bad J cursor in Swap_Links"); |
| 2077 | |
| 2078 | declare |
| 2079 | I_Next : constant Cursor := Next (I); |
| 2080 | |
| 2081 | begin |
| 2082 | if I_Next = J then |
| 2083 | Splice (Container, Before => I, Position => J); |
| 2084 | |
| 2085 | else |
| 2086 | declare |
| 2087 | J_Next : constant Cursor := Next (J); |
| 2088 | |
| 2089 | begin |
| 2090 | if J_Next = I then |
| 2091 | Splice (Container, Before => J, Position => I); |
| 2092 | |
| 2093 | else |
| 2094 | pragma Assert (Container.Length >= 3); |
| 2095 | |
| 2096 | Splice (Container, Before => I_Next, Position => J); |
| 2097 | Splice (Container, Before => J_Next, Position => I); |
| 2098 | end if; |
| 2099 | end; |
| 2100 | end if; |
| 2101 | end; |
| 2102 | end Swap_Links; |
| 2103 | |
| 2104 | -------------------- |
| 2105 | -- Update_Element -- |
| 2106 | -------------------- |
| 2107 | |
| 2108 | procedure Update_Element |
| 2109 | (Container : in out List; |
| 2110 | Position : Cursor; |
| 2111 | Process : not null access procedure (Element : in out Element_Type)) |
| 2112 | is |
| 2113 | begin |
| 2114 | if Position.Node = 0 then |
| 2115 | raise Constraint_Error with "Position cursor has no element"; |
| 2116 | end if; |
| 2117 | |
| 2118 | if Position.Container /= Container'Unchecked_Access then |
| 2119 | raise Program_Error with |
| 2120 | "Position cursor designates wrong container"; |
| 2121 | end if; |
| 2122 | |
| 2123 | pragma Assert (Vet (Position), "bad cursor in Update_Element"); |
| 2124 | |
| 2125 | declare |
| 2126 | B : Natural renames Container.Busy; |
| 2127 | L : Natural renames Container.Lock; |
| 2128 | |
| 2129 | begin |
| 2130 | B := B + 1; |
| 2131 | L := L + 1; |
| 2132 | |
| 2133 | declare |
| 2134 | N : Node_Type renames Container.Nodes (Position.Node); |
| 2135 | begin |
| 2136 | Process (N.Element); |
| 2137 | exception |
| 2138 | when others => |
| 2139 | L := L - 1; |
| 2140 | B := B - 1; |
| 2141 | raise; |
| 2142 | end; |
| 2143 | |
| 2144 | L := L - 1; |
| 2145 | B := B - 1; |
| 2146 | end; |
| 2147 | end Update_Element; |
| 2148 | |
| 2149 | --------- |
| 2150 | -- Vet -- |
| 2151 | --------- |
| 2152 | |
| 2153 | function Vet (Position : Cursor) return Boolean is |
| 2154 | begin |
| 2155 | if Position.Node = 0 then |
| 2156 | return Position.Container = null; |
| 2157 | end if; |
| 2158 | |
| 2159 | if Position.Container = null then |
| 2160 | return False; |
| 2161 | end if; |
| 2162 | |
| 2163 | declare |
| 2164 | L : List renames Position.Container.all; |
| 2165 | N : Node_Array renames L.Nodes; |
| 2166 | |
| 2167 | begin |
| 2168 | if L.Length = 0 then |
| 2169 | return False; |
| 2170 | end if; |
| 2171 | |
| 2172 | if L.First = 0 or L.First > L.Capacity then |
| 2173 | return False; |
| 2174 | end if; |
| 2175 | |
| 2176 | if L.Last = 0 or L.Last > L.Capacity then |
| 2177 | return False; |
| 2178 | end if; |
| 2179 | |
| 2180 | if N (L.First).Prev /= 0 then |
| 2181 | return False; |
| 2182 | end if; |
| 2183 | |
| 2184 | if N (L.Last).Next /= 0 then |
| 2185 | return False; |
| 2186 | end if; |
| 2187 | |
| 2188 | if Position.Node > L.Capacity then |
| 2189 | return False; |
| 2190 | end if; |
| 2191 | |
| 2192 | -- An invariant of an active node is that its Previous and Next |
| 2193 | -- components are non-negative. Operation Free sets the Previous |
| 2194 | -- component of the node to the value -1 before actually deallocating |
| 2195 | -- the node, to mark the node as inactive. (By "dellocating" we mean |
| 2196 | -- only that the node is linked onto a list of inactive nodes used |
| 2197 | -- for storage.) This marker gives us a simple way to detect a |
| 2198 | -- dangling reference to a node. |
| 2199 | |
| 2200 | if N (Position.Node).Prev < 0 then -- see Free |
| 2201 | return False; |
| 2202 | end if; |
| 2203 | |
| 2204 | if N (Position.Node).Prev > L.Capacity then |
| 2205 | return False; |
| 2206 | end if; |
| 2207 | |
| 2208 | if N (Position.Node).Next = Position.Node then |
| 2209 | return False; |
| 2210 | end if; |
| 2211 | |
| 2212 | if N (Position.Node).Prev = Position.Node then |
| 2213 | return False; |
| 2214 | end if; |
| 2215 | |
| 2216 | if N (Position.Node).Prev = 0 |
| 2217 | and then Position.Node /= L.First |
| 2218 | then |
| 2219 | return False; |
| 2220 | end if; |
| 2221 | |
| 2222 | pragma Assert (N (Position.Node).Prev /= 0 |
| 2223 | or else Position.Node = L.First); |
| 2224 | |
| 2225 | if N (Position.Node).Next = 0 |
| 2226 | and then Position.Node /= L.Last |
| 2227 | then |
| 2228 | return False; |
| 2229 | end if; |
| 2230 | |
| 2231 | pragma Assert (N (Position.Node).Next /= 0 |
| 2232 | or else Position.Node = L.Last); |
| 2233 | |
| 2234 | if L.Length = 1 then |
| 2235 | return L.First = L.Last; |
| 2236 | end if; |
| 2237 | |
| 2238 | if L.First = L.Last then |
| 2239 | return False; |
| 2240 | end if; |
| 2241 | |
| 2242 | if N (L.First).Next = 0 then |
| 2243 | return False; |
| 2244 | end if; |
| 2245 | |
| 2246 | if N (L.Last).Prev = 0 then |
| 2247 | return False; |
| 2248 | end if; |
| 2249 | |
| 2250 | if N (N (L.First).Next).Prev /= L.First then |
| 2251 | return False; |
| 2252 | end if; |
| 2253 | |
| 2254 | if N (N (L.Last).Prev).Next /= L.Last then |
| 2255 | return False; |
| 2256 | end if; |
| 2257 | |
| 2258 | if L.Length = 2 then |
| 2259 | if N (L.First).Next /= L.Last then |
| 2260 | return False; |
| 2261 | end if; |
| 2262 | |
| 2263 | if N (L.Last).Prev /= L.First then |
| 2264 | return False; |
| 2265 | end if; |
| 2266 | |
| 2267 | return True; |
| 2268 | end if; |
| 2269 | |
| 2270 | if N (L.First).Next = L.Last then |
| 2271 | return False; |
| 2272 | end if; |
| 2273 | |
| 2274 | if N (L.Last).Prev = L.First then |
| 2275 | return False; |
| 2276 | end if; |
| 2277 | |
| 2278 | -- Eliminate earlier possibility |
| 2279 | |
| 2280 | if Position.Node = L.First then |
| 2281 | return True; |
| 2282 | end if; |
| 2283 | |
| 2284 | pragma Assert (N (Position.Node).Prev /= 0); |
| 2285 | |
| 2286 | -- ELiminate another possibility |
| 2287 | |
| 2288 | if Position.Node = L.Last then |
| 2289 | return True; |
| 2290 | end if; |
| 2291 | |
| 2292 | pragma Assert (N (Position.Node).Next /= 0); |
| 2293 | |
| 2294 | if N (N (Position.Node).Next).Prev /= Position.Node then |
| 2295 | return False; |
| 2296 | end if; |
| 2297 | |
| 2298 | if N (N (Position.Node).Prev).Next /= Position.Node then |
| 2299 | return False; |
| 2300 | end if; |
| 2301 | |
| 2302 | if L.Length = 3 then |
| 2303 | if N (L.First).Next /= Position.Node then |
| 2304 | return False; |
| 2305 | end if; |
| 2306 | |
| 2307 | if N (L.Last).Prev /= Position.Node then |
| 2308 | return False; |
| 2309 | end if; |
| 2310 | end if; |
| 2311 | |
| 2312 | return True; |
| 2313 | end; |
| 2314 | end Vet; |
| 2315 | |
| 2316 | ----------- |
| 2317 | -- Write -- |
| 2318 | ----------- |
| 2319 | |
| 2320 | procedure Write |
| 2321 | (Stream : not null access Root_Stream_Type'Class; |
| 2322 | Item : List) |
| 2323 | is |
| 2324 | Node : Count_Type; |
| 2325 | |
| 2326 | begin |
| 2327 | Count_Type'Base'Write (Stream, Item.Length); |
| 2328 | |
| 2329 | Node := Item.First; |
| 2330 | while Node /= 0 loop |
| 2331 | Element_Type'Write (Stream, Item.Nodes (Node).Element); |
| 2332 | Node := Item.Nodes (Node).Next; |
| 2333 | end loop; |
| 2334 | end Write; |
| 2335 | |
| 2336 | procedure Write |
| 2337 | (Stream : not null access Root_Stream_Type'Class; |
| 2338 | Item : Cursor) |
| 2339 | is |
| 2340 | begin |
| 2341 | raise Program_Error with "attempt to stream list cursor"; |
| 2342 | end Write; |
| 2343 | |
| 2344 | procedure Write |
| 2345 | (Stream : not null access Root_Stream_Type'Class; |
| 2346 | Item : Reference_Type) |
| 2347 | is |
| 2348 | begin |
| 2349 | raise Program_Error with "attempt to stream reference"; |
| 2350 | end Write; |
| 2351 | |
| 2352 | procedure Write |
| 2353 | (Stream : not null access Root_Stream_Type'Class; |
| 2354 | Item : Constant_Reference_Type) |
| 2355 | is |
| 2356 | begin |
| 2357 | raise Program_Error with "attempt to stream reference"; |
| 2358 | end Write; |
| 2359 | |
| 2360 | end Ada.Containers.Bounded_Doubly_Linked_Lists; |