1------------------------------------------------------------------------------ 2-- -- 3-- GNAT LIBRARY COMPONENTS -- 4-- -- 5-- A D A . C O N T A I N E R S . H A S H E D _ S E T S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 2004-2021, Free Software Foundation, Inc. -- 10-- -- 11-- This specification is derived from the Ada Reference Manual for use with -- 12-- GNAT. The copyright notice above, and the license provisions that follow -- 13-- apply solely to the contents of the part following the private keyword. -- 14-- -- 15-- GNAT is free software; you can redistribute it and/or modify it under -- 16-- terms of the GNU General Public License as published by the Free Soft- -- 17-- ware Foundation; either version 3, or (at your option) any later ver- -- 18-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 19-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 20-- or FITNESS FOR A PARTICULAR PURPOSE. -- 21-- -- 22-- As a special exception under Section 7 of GPL version 3, you are granted -- 23-- additional permissions described in the GCC Runtime Library Exception, -- 24-- version 3.1, as published by the Free Software Foundation. -- 25-- -- 26-- You should have received a copy of the GNU General Public License and -- 27-- a copy of the GCC Runtime Library Exception along with this program; -- 28-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 29-- <http://www.gnu.org/licenses/>. -- 30-- -- 31-- This unit was originally developed by Matthew J Heaney. -- 32------------------------------------------------------------------------------ 33 34with Ada.Iterator_Interfaces; 35 36private with Ada.Containers.Hash_Tables; 37with Ada.Containers.Helpers; 38private with Ada.Finalization; 39private with Ada.Streams; 40private with Ada.Strings.Text_Buffers; 41 42generic 43 type Element_Type is private; 44 45 with function Hash (Element : Element_Type) return Hash_Type; 46 47 with function Equivalent_Elements 48 (Left, Right : Element_Type) return Boolean; 49 50 with function "=" (Left, Right : Element_Type) return Boolean is <>; 51 52package Ada.Containers.Hashed_Sets with 53 SPARK_Mode => Off 54is 55 pragma Annotate (CodePeer, Skip_Analysis); 56 pragma Preelaborate; 57 pragma Remote_Types; 58 59 type Set is tagged private 60 with 61 Constant_Indexing => Constant_Reference, 62 Default_Iterator => Iterate, 63 Iterator_Element => Element_Type, 64 Aggregate => (Empty => Empty, 65 Add_Unnamed => Include); 66 67 pragma Preelaborable_Initialization (Set); 68 69 type Cursor is private; 70 pragma Preelaborable_Initialization (Cursor); 71 72 function "=" (Left, Right : Cursor) return Boolean; 73 -- The representation of cursors includes a component used to optimize 74 -- iteration over sets. This component may become unreliable after 75 -- multiple set insertions, and must be excluded from cursor equality, 76 -- so we need to provide an explicit definition for it, instead of 77 -- using predefined equality (as implied by a questionable comment 78 -- in the RM). This is also the case for hashed maps, and affects the 79 -- use of Insert primitives in hashed structures. 80 81 Empty_Set : constant Set; 82 -- Set objects declared without an initialization expression are 83 -- initialized to the value Empty_Set. 84 85 No_Element : constant Cursor; 86 -- Cursor objects declared without an initialization expression are 87 -- initialized to the value No_Element. 88 89 function Has_Element (Position : Cursor) return Boolean; 90 -- Equivalent to Position /= No_Element 91 92 package Set_Iterator_Interfaces is new 93 Ada.Iterator_Interfaces (Cursor, Has_Element); 94 95 function Empty (Capacity : Count_Type := 1000) return Set; 96 97 function "=" (Left, Right : Set) return Boolean; 98 -- For each element in Left, set equality attempts to find the equal 99 -- element in Right; if a search fails, then set equality immediately 100 -- returns False. The search works by calling Hash to find the bucket in 101 -- the Right set that corresponds to the Left element. If the bucket is 102 -- non-empty, the search calls the generic formal element equality operator 103 -- to compare the element (in Left) to the element of each node in the 104 -- bucket (in Right); the search terminates when a matching node in the 105 -- bucket is found, or the nodes in the bucket are exhausted. (Note that 106 -- element equality is called here, not Equivalent_Elements. Set equality 107 -- is the only operation in which element equality is used. Compare set 108 -- equality to Equivalent_Sets, which does call Equivalent_Elements.) 109 110 function Equivalent_Sets (Left, Right : Set) return Boolean; 111 -- Similar to set equality, with the difference that the element in Left is 112 -- compared to the elements in Right using the generic formal 113 -- Equivalent_Elements operation instead of element equality. 114 115 function To_Set (New_Item : Element_Type) return Set; 116 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to 117 -- determine the bucket for New_Item. 118 119 function Capacity (Container : Set) return Count_Type; 120 -- Returns the current capacity of the set. Capacity is the maximum length 121 -- before which rehashing in guaranteed not to occur. 122 123 procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type); 124 -- Adjusts the current capacity, by allocating a new buckets array. If the 125 -- requested capacity is less than the current capacity, then the capacity 126 -- is contracted (to a value not less than the current length). If the 127 -- requested capacity is greater than the current capacity, then the 128 -- capacity is expanded (to a value not less than what is requested). In 129 -- either case, the nodes are rehashed from the old buckets array onto the 130 -- new buckets array (Hash is called once for each existing element in 131 -- order to compute the new index), and then the old buckets array is 132 -- deallocated. 133 134 function Length (Container : Set) return Count_Type; 135 -- Returns the number of items in the set 136 137 function Is_Empty (Container : Set) return Boolean; 138 -- Equivalent to Length (Container) = 0 139 140 procedure Clear (Container : in out Set); 141 -- Removes all of the items from the set 142 143 function Element (Position : Cursor) return Element_Type; 144 -- Returns the element of the node designated by the cursor 145 146 procedure Replace_Element 147 (Container : in out Set; 148 Position : Cursor; 149 New_Item : Element_Type); 150 -- If New_Item is equivalent (as determined by calling Equivalent_Elements) 151 -- to the element of the node designated by Position, then New_Element is 152 -- assigned to that element. Otherwise, it calls Hash to determine the 153 -- bucket for New_Item. If the bucket is not empty, then it calls 154 -- Equivalent_Elements for each node in that bucket to determine whether 155 -- New_Item is equivalent to an element in that bucket. If 156 -- Equivalent_Elements returns True then Program_Error is raised (because 157 -- an element may appear only once in the set); otherwise, New_Item is 158 -- assigned to the node designated by Position, and the node is moved to 159 -- its new bucket. 160 161 procedure Query_Element 162 (Position : Cursor; 163 Process : not null access procedure (Element : Element_Type)); 164 -- Calls Process with the element (having only a constant view) of the node 165 -- designed by the cursor. 166 167 type Constant_Reference_Type 168 (Element : not null access constant Element_Type) is private 169 with Implicit_Dereference => Element; 170 171 function Constant_Reference 172 (Container : aliased Set; 173 Position : Cursor) return Constant_Reference_Type; 174 pragma Inline (Constant_Reference); 175 176 procedure Assign (Target : in out Set; Source : Set); 177 178 function Copy (Source : Set; Capacity : Count_Type := 0) return Set; 179 180 procedure Move (Target : in out Set; Source : in out Set); 181 -- Clears Target (if it's not empty), and then moves (not copies) the 182 -- buckets array and nodes from Source to Target. 183 184 procedure Insert 185 (Container : in out Set; 186 New_Item : Element_Type; 187 Position : out Cursor; 188 Inserted : out Boolean); 189 -- Conditionally inserts New_Item into the set. If New_Item is already in 190 -- the set, then Inserted returns False and Position designates the node 191 -- containing the existing element (which is not modified). If New_Item is 192 -- not already in the set, then Inserted returns True and Position 193 -- designates the newly-inserted node containing New_Item. The search for 194 -- an existing element works as follows. Hash is called to determine 195 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements 196 -- is called to compare New_Item to the element of each node in that 197 -- bucket. If the bucket is empty, or there were no equivalent elements in 198 -- the bucket, the search "fails" and the New_Item is inserted in the set 199 -- (and Inserted returns True); otherwise, the search "succeeds" (and 200 -- Inserted returns False). 201 202 procedure Insert (Container : in out Set; New_Item : Element_Type); 203 -- Attempts to insert New_Item into the set, performing the usual insertion 204 -- search (which involves calling both Hash and Equivalent_Elements); if 205 -- the search succeeds (New_Item is equivalent to an element already in the 206 -- set, and so was not inserted), then this operation raises 207 -- Constraint_Error. (This version of Insert is similar to Replace, but 208 -- having the opposite exception behavior. It is intended for use when you 209 -- want to assert that the item is not already in the set.) 210 211 procedure Include (Container : in out Set; New_Item : Element_Type); 212 -- Attempts to insert New_Item into the set. If an element equivalent to 213 -- New_Item is already in the set (the insertion search succeeded, and 214 -- hence New_Item was not inserted), then the value of New_Item is assigned 215 -- to the existing element. (This insertion operation only raises an 216 -- exception if cursor tampering occurs. It is intended for use when you 217 -- want to insert the item in the set, and you don't care whether an 218 -- equivalent element is already present.) 219 220 procedure Replace (Container : in out Set; New_Item : Element_Type); 221 -- Searches for New_Item in the set; if the search fails (because an 222 -- equivalent element was not in the set), then it raises 223 -- Constraint_Error. Otherwise, the existing element is assigned the value 224 -- New_Item. (This is similar to Insert, but with the opposite exception 225 -- behavior. It is intended for use when you want to assert that the item 226 -- is already in the set.) 227 228 procedure Exclude (Container : in out Set; Item : Element_Type); 229 -- Searches for Item in the set, and if found, removes its node from the 230 -- set and then deallocates it. The search works as follows. The operation 231 -- calls Hash to determine the item's bucket; if the bucket is not empty, 232 -- it calls Equivalent_Elements to compare Item to the element of each node 233 -- in the bucket. (This is the deletion analog of Include. It is intended 234 -- for use when you want to remove the item from the set, but don't care 235 -- whether the item is already in the set.) 236 237 procedure Delete (Container : in out Set; Item : Element_Type); 238 -- Searches for Item in the set (which involves calling both Hash and 239 -- Equivalent_Elements). If the search fails, then the operation raises 240 -- Constraint_Error. Otherwise it removes the node from the set and then 241 -- deallocates it. (This is the deletion analog of non-conditional 242 -- Insert. It is intended for use when you want to assert that the item is 243 -- already in the set.) 244 245 procedure Delete (Container : in out Set; Position : in out Cursor); 246 -- Removes the node designated by Position from the set, and then 247 -- deallocates the node. The operation calls Hash to determine the bucket, 248 -- and then compares Position to each node in the bucket until there's a 249 -- match (it does not call Equivalent_Elements). 250 251 procedure Union (Target : in out Set; Source : Set); 252 -- The operation first calls Reserve_Capacity if the current capacity is 253 -- less than the sum of the lengths of Source and Target. It then iterates 254 -- over the Source set, and conditionally inserts each element into Target. 255 256 function Union (Left, Right : Set) return Set; 257 -- The operation first copies the Left set to the result, and then iterates 258 -- over the Right set to conditionally insert each element into the result. 259 260 function "or" (Left, Right : Set) return Set renames Union; 261 262 procedure Intersection (Target : in out Set; Source : Set); 263 -- Iterates over the Target set (calling First and Next), calling Find to 264 -- determine whether the element is in Source. If an equivalent element is 265 -- not found in Source, the element is deleted from Target. 266 267 function Intersection (Left, Right : Set) return Set; 268 -- Iterates over the Left set, calling Find to determine whether the 269 -- element is in Right. If an equivalent element is found, it is inserted 270 -- into the result set. 271 272 function "and" (Left, Right : Set) return Set renames Intersection; 273 274 procedure Difference (Target : in out Set; Source : Set); 275 -- Iterates over the Source (calling First and Next), calling Find to 276 -- determine whether the element is in Target. If an equivalent element is 277 -- found, it is deleted from Target. 278 279 function Difference (Left, Right : Set) return Set; 280 -- Iterates over the Left set, calling Find to determine whether the 281 -- element is in the Right set. If an equivalent element is not found, the 282 -- element is inserted into the result set. 283 284 function "-" (Left, Right : Set) return Set renames Difference; 285 286 procedure Symmetric_Difference (Target : in out Set; Source : Set); 287 -- The operation first calls Reserve_Capacity if the current capacity is 288 -- less than the sum of the lengths of Source and Target. It then iterates 289 -- over the Source set, searching for the element in Target (calling Hash 290 -- and Equivalent_Elements). If an equivalent element is found, it is 291 -- removed from Target; otherwise it is inserted into Target. 292 293 function Symmetric_Difference (Left, Right : Set) return Set; 294 -- The operation first iterates over the Left set. It calls Find to 295 -- determine whether the element is in the Right set. If no equivalent 296 -- element is found, the element from Left is inserted into the result. The 297 -- operation then iterates over the Right set, to determine whether the 298 -- element is in the Left set. If no equivalent element is found, the Right 299 -- element is inserted into the result. 300 301 function "xor" (Left, Right : Set) return Set 302 renames Symmetric_Difference; 303 304 function Overlap (Left, Right : Set) return Boolean; 305 -- Iterates over the Left set (calling First and Next), calling Find to 306 -- determine whether the element is in the Right set. If an equivalent 307 -- element is found, the operation immediately returns True. The operation 308 -- returns False if the iteration over Left terminates without finding any 309 -- equivalent element in Right. 310 311 function Is_Subset (Subset : Set; Of_Set : Set) return Boolean; 312 -- Iterates over Subset (calling First and Next), calling Find to determine 313 -- whether the element is in Of_Set. If no equivalent element is found in 314 -- Of_Set, the operation immediately returns False. The operation returns 315 -- True if the iteration over Subset terminates without finding an element 316 -- not in Of_Set (that is, every element in Subset is equivalent to an 317 -- element in Of_Set). 318 319 function First (Container : Set) return Cursor; 320 -- Returns a cursor that designates the first non-empty bucket, by 321 -- searching from the beginning of the buckets array. 322 323 function Next (Position : Cursor) return Cursor; 324 -- Returns a cursor that designates the node that follows the current one 325 -- designated by Position. If Position designates the last node in its 326 -- bucket, the operation calls Hash to compute the index of this bucket, 327 -- and searches the buckets array for the first non-empty bucket, starting 328 -- from that index; otherwise, it simply follows the link to the next node 329 -- in the same bucket. 330 331 procedure Next (Position : in out Cursor); 332 -- Equivalent to Position := Next (Position) 333 334 function Find 335 (Container : Set; 336 Item : Element_Type) return Cursor; 337 -- Searches for Item in the set. Find calls Hash to determine the item's 338 -- bucket; if the bucket is not empty, it calls Equivalent_Elements to 339 -- compare Item to each element in the bucket. If the search succeeds, Find 340 -- returns a cursor designating the node containing the equivalent element; 341 -- otherwise, it returns No_Element. 342 343 function Contains (Container : Set; Item : Element_Type) return Boolean; 344 -- Equivalent to Find (Container, Item) /= No_Element 345 346 function Equivalent_Elements (Left, Right : Cursor) return Boolean; 347 -- Returns the result of calling Equivalent_Elements with the elements of 348 -- the nodes designated by cursors Left and Right. 349 350 function Equivalent_Elements 351 (Left : Cursor; 352 Right : Element_Type) return Boolean; 353 -- Returns the result of calling Equivalent_Elements with element of the 354 -- node designated by Left and element Right. 355 356 function Equivalent_Elements 357 (Left : Element_Type; 358 Right : Cursor) return Boolean; 359 -- Returns the result of calling Equivalent_Elements with element Left and 360 -- the element of the node designated by Right. 361 362 procedure Iterate 363 (Container : Set; 364 Process : not null access procedure (Position : Cursor)); 365 -- Calls Process for each node in the set 366 367 function Iterate 368 (Container : Set) return Set_Iterator_Interfaces.Forward_Iterator'Class; 369 370 generic 371 type Key_Type (<>) is private; 372 373 with function Key (Element : Element_Type) return Key_Type; 374 375 with function Hash (Key : Key_Type) return Hash_Type; 376 377 with function Equivalent_Keys (Left, Right : Key_Type) return Boolean; 378 379 package Generic_Keys is 380 381 function Key (Position : Cursor) return Key_Type; 382 -- Applies generic formal operation Key to the element of the node 383 -- designated by Position. 384 385 function Element (Container : Set; Key : Key_Type) return Element_Type; 386 -- Searches (as per the key-based Find) for the node containing Key, and 387 -- returns the associated element. 388 389 procedure Replace 390 (Container : in out Set; 391 Key : Key_Type; 392 New_Item : Element_Type); 393 -- Searches (as per the key-based Find) for the node containing Key, and 394 -- then replaces the element of that node (as per the element-based 395 -- Replace_Element). 396 397 procedure Exclude (Container : in out Set; Key : Key_Type); 398 -- Searches for Key in the set, and if found, removes its node from the 399 -- set and then deallocates it. The search works by first calling Hash 400 -- (on Key) to determine the bucket; if the bucket is not empty, it 401 -- calls Equivalent_Keys to compare parameter Key to the value of 402 -- generic formal operation Key applied to element of each node in the 403 -- bucket. 404 405 procedure Delete (Container : in out Set; Key : Key_Type); 406 -- Deletes the node containing Key as per Exclude, with the difference 407 -- that Constraint_Error is raised if Key is not found. 408 409 function Find (Container : Set; Key : Key_Type) return Cursor; 410 -- Searches for the node containing Key, and returns a cursor 411 -- designating the node. The search works by first calling Hash (on Key) 412 -- to determine the bucket. If the bucket is not empty, the search 413 -- compares Key to the element of each node in the bucket, and returns 414 -- the matching node. The comparison itself works by applying the 415 -- generic formal Key operation to the element of the node, and then 416 -- calling generic formal operation Equivalent_Keys. 417 418 function Contains (Container : Set; Key : Key_Type) return Boolean; 419 -- Equivalent to Find (Container, Key) /= No_Element 420 421 procedure Update_Element_Preserving_Key 422 (Container : in out Set; 423 Position : Cursor; 424 Process : not null access 425 procedure (Element : in out Element_Type)); 426 -- Calls Process with the element of the node designated by Position, 427 -- but with the restriction that the key-value of the element is not 428 -- modified. The operation first makes a copy of the value returned by 429 -- applying generic formal operation Key on the element of the node, and 430 -- then calls Process with the element. The operation verifies that the 431 -- key-part has not been modified by calling generic formal operation 432 -- Equivalent_Keys to compare the saved key-value to the value returned 433 -- by applying generic formal operation Key to the post-Process value of 434 -- element. If the key values compare equal then the operation 435 -- completes. Otherwise, the node is removed from the set and 436 -- Program_Error is raised. 437 438 type Reference_Type (Element : not null access Element_Type) is private 439 with Implicit_Dereference => Element; 440 441 function Reference_Preserving_Key 442 (Container : aliased in out Set; 443 Position : Cursor) return Reference_Type; 444 445 function Constant_Reference 446 (Container : aliased Set; 447 Key : Key_Type) return Constant_Reference_Type; 448 449 function Reference_Preserving_Key 450 (Container : aliased in out Set; 451 Key : Key_Type) return Reference_Type; 452 453 private 454 use Ada.Streams; 455 type Set_Access is access all Set; 456 for Set_Access'Storage_Size use 0; 457 458 -- Key_Preserving references must carry information to allow removal 459 -- of elements whose value may have been altered improperly, i.e. have 460 -- been given values incompatible with the hash-code of the previous 461 -- value, and are thus in the wrong bucket. (RM 18.7 (96.6/3)) 462 463 -- We cannot store the key directly because it is an unconstrained type. 464 -- To avoid using additional dynamic allocation we store the old cursor 465 -- which simplifies possible removal. This is not possible for some 466 -- other set types. 467 468 -- The mechanism is different for Update_Element_Preserving_Key, as 469 -- in that case the check that buckets have not changed is performed 470 -- at the time of the update, not when the reference is finalized. 471 472 package Impl is new Helpers.Generic_Implementation; 473 474 type Reference_Control_Type is 475 new Impl.Reference_Control_Type with 476 record 477 Container : Set_Access; 478 Index : Hash_Type; 479 Old_Pos : Cursor; 480 Old_Hash : Hash_Type; 481 end record; 482 483 overriding procedure Finalize (Control : in out Reference_Control_Type); 484 pragma Inline (Finalize); 485 486 type Reference_Type (Element : not null access Element_Type) is record 487 Control : Reference_Control_Type; 488 end record; 489 490 procedure Read 491 (Stream : not null access Root_Stream_Type'Class; 492 Item : out Reference_Type); 493 494 for Reference_Type'Read use Read; 495 496 procedure Write 497 (Stream : not null access Root_Stream_Type'Class; 498 Item : Reference_Type); 499 500 for Reference_Type'Write use Write; 501 end Generic_Keys; 502 503private 504 pragma Inline (Next); 505 506 type Node_Type; 507 type Node_Access is access Node_Type; 508 509 type Node_Type is limited record 510 Element : aliased Element_Type; 511 Next : Node_Access; 512 end record; 513 514 package HT_Types is 515 new Hash_Tables.Generic_Hash_Table_Types (Node_Type, Node_Access); 516 517 type Set is new Ada.Finalization.Controlled with record 518 HT : HT_Types.Hash_Table_Type; 519 end record with Put_Image => Put_Image; 520 521 procedure Put_Image 522 (S : in out Ada.Strings.Text_Buffers.Root_Buffer_Type'Class; V : Set); 523 524 overriding procedure Adjust (Container : in out Set); 525 526 overriding procedure Finalize (Container : in out Set); 527 528 use HT_Types, HT_Types.Implementation; 529 use Ada.Finalization; 530 use Ada.Streams; 531 532 procedure Write 533 (Stream : not null access Root_Stream_Type'Class; 534 Container : Set); 535 536 for Set'Write use Write; 537 538 procedure Read 539 (Stream : not null access Root_Stream_Type'Class; 540 Container : out Set); 541 542 for Set'Read use Read; 543 544 type Set_Access is access all Set; 545 for Set_Access'Storage_Size use 0; 546 547 type Cursor is record 548 Container : Set_Access; 549 -- Access to this cursor's container 550 551 Node : Node_Access; 552 -- Access to the node pointed to by this cursor 553 554 Position : Hash_Type := Hash_Type'Last; 555 -- Position of the node in the buckets of the container. If this is 556 -- equal to Hash_Type'Last, then it will not be used. Position is 557 -- not requried by the implementation, but improves the efficiency 558 -- of various operations. 559 -- 560 -- However, this value must be maintained so that the predefined 561 -- equality operation acts as required by RM A.18.7-17/2, which 562 -- states: "The predefined "=" operator for type Cursor returns True 563 -- if both cursors are No_Element, or designate the same element 564 -- in the same container." 565 end record; 566 567 procedure Write 568 (Stream : not null access Root_Stream_Type'Class; 569 Item : Cursor); 570 571 for Cursor'Write use Write; 572 573 procedure Read 574 (Stream : not null access Root_Stream_Type'Class; 575 Item : out Cursor); 576 577 for Cursor'Read use Read; 578 579 subtype Reference_Control_Type is Implementation.Reference_Control_Type; 580 -- It is necessary to rename this here, so that the compiler can find it 581 582 type Constant_Reference_Type 583 (Element : not null access constant Element_Type) is 584 record 585 Control : Reference_Control_Type := 586 raise Program_Error with "uninitialized reference"; 587 -- The RM says, "The default initialization of an object of 588 -- type Constant_Reference_Type or Reference_Type propagates 589 -- Program_Error." 590 end record; 591 592 procedure Read 593 (Stream : not null access Root_Stream_Type'Class; 594 Item : out Constant_Reference_Type); 595 596 for Constant_Reference_Type'Read use Read; 597 598 procedure Write 599 (Stream : not null access Root_Stream_Type'Class; 600 Item : Constant_Reference_Type); 601 602 for Constant_Reference_Type'Write use Write; 603 604 -- Three operations are used to optimize in the expansion of "for ... of" 605 -- loops: the Next(Cursor) procedure in the visible part, and the following 606 -- Pseudo_Reference and Get_Element_Access functions. See Sem_Ch5 for 607 -- details. 608 609 function Pseudo_Reference 610 (Container : aliased Set'Class) return Reference_Control_Type; 611 pragma Inline (Pseudo_Reference); 612 -- Creates an object of type Reference_Control_Type pointing to the 613 -- container, and increments the Lock. Finalization of this object will 614 -- decrement the Lock. 615 616 type Element_Access is access all Element_Type with 617 Storage_Size => 0; 618 619 function Get_Element_Access 620 (Position : Cursor) return not null Element_Access; 621 -- Returns a pointer to the element designated by Position. 622 623 Empty_Set : constant Set := (Controlled with others => <>); 624 625 No_Element : constant Cursor := 626 (Container => null, Node => null, Position => Hash_Type'Last); 627 628 type Iterator is new Limited_Controlled and 629 Set_Iterator_Interfaces.Forward_Iterator with 630 record 631 Container : Set_Access; 632 end record 633 with Disable_Controlled => not T_Check; 634 635 overriding function First (Object : Iterator) return Cursor; 636 637 overriding function Next 638 (Object : Iterator; 639 Position : Cursor) return Cursor; 640 overriding procedure Finalize (Object : in out Iterator); 641 642end Ada.Containers.Hashed_Sets; 643