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) 2004-2019, 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; 40 41generic 42 type Element_Type is private; 43 44 with function Hash (Element : Element_Type) return Hash_Type; 45 46 with function Equivalent_Elements 47 (Left, Right : Element_Type) return Boolean; 48 49 with function "=" (Left, Right : Element_Type) return Boolean is <>; 50 51package Ada.Containers.Hashed_Sets is 52 pragma Annotate (CodePeer, Skip_Analysis); 53 pragma Preelaborate; 54 pragma Remote_Types; 55 56 type Set is tagged private 57 with 58 Constant_Indexing => Constant_Reference, 59 Default_Iterator => Iterate, 60 Iterator_Element => Element_Type; 61 62 pragma Preelaborable_Initialization (Set); 63 64 type Cursor is private; 65 pragma Preelaborable_Initialization (Cursor); 66 67 Empty_Set : constant Set; 68 -- Set objects declared without an initialization expression are 69 -- initialized to the value Empty_Set. 70 71 No_Element : constant Cursor; 72 -- Cursor objects declared without an initialization expression are 73 -- initialized to the value No_Element. 74 75 function Has_Element (Position : Cursor) return Boolean; 76 -- Equivalent to Position /= No_Element 77 78 package Set_Iterator_Interfaces is new 79 Ada.Iterator_Interfaces (Cursor, Has_Element); 80 81 function "=" (Left, Right : Set) return Boolean; 82 -- For each element in Left, set equality attempts to find the equal 83 -- element in Right; if a search fails, then set equality immediately 84 -- returns False. The search works by calling Hash to find the bucket in 85 -- the Right set that corresponds to the Left element. If the bucket is 86 -- non-empty, the search calls the generic formal element equality operator 87 -- to compare the element (in Left) to the element of each node in the 88 -- bucket (in Right); the search terminates when a matching node in the 89 -- bucket is found, or the nodes in the bucket are exhausted. (Note that 90 -- element equality is called here, not Equivalent_Elements. Set equality 91 -- is the only operation in which element equality is used. Compare set 92 -- equality to Equivalent_Sets, which does call Equivalent_Elements.) 93 94 function Equivalent_Sets (Left, Right : Set) return Boolean; 95 -- Similar to set equality, with the difference that the element in Left is 96 -- compared to the elements in Right using the generic formal 97 -- Equivalent_Elements operation instead of element equality. 98 99 function To_Set (New_Item : Element_Type) return Set; 100 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to 101 -- determine the bucket for New_Item. 102 103 function Capacity (Container : Set) return Count_Type; 104 -- Returns the current capacity of the set. Capacity is the maximum length 105 -- before which rehashing in guaranteed not to occur. 106 107 procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type); 108 -- Adjusts the current capacity, by allocating a new buckets array. If the 109 -- requested capacity is less than the current capacity, then the capacity 110 -- is contracted (to a value not less than the current length). If the 111 -- requested capacity is greater than the current capacity, then the 112 -- capacity is expanded (to a value not less than what is requested). In 113 -- either case, the nodes are rehashed from the old buckets array onto the 114 -- new buckets array (Hash is called once for each existing element in 115 -- order to compute the new index), and then the old buckets array is 116 -- deallocated. 117 118 function Length (Container : Set) return Count_Type; 119 -- Returns the number of items in the set 120 121 function Is_Empty (Container : Set) return Boolean; 122 -- Equivalent to Length (Container) = 0 123 124 procedure Clear (Container : in out Set); 125 -- Removes all of the items from the set 126 127 function Element (Position : Cursor) return Element_Type; 128 -- Returns the element of the node designated by the cursor 129 130 procedure Replace_Element 131 (Container : in out Set; 132 Position : Cursor; 133 New_Item : Element_Type); 134 -- If New_Item is equivalent (as determined by calling Equivalent_Elements) 135 -- to the element of the node designated by Position, then New_Element is 136 -- assigned to that element. Otherwise, it calls Hash to determine the 137 -- bucket for New_Item. If the bucket is not empty, then it calls 138 -- Equivalent_Elements for each node in that bucket to determine whether 139 -- New_Item is equivalent to an element in that bucket. If 140 -- Equivalent_Elements returns True then Program_Error is raised (because 141 -- an element may appear only once in the set); otherwise, New_Item is 142 -- assigned to the node designated by Position, and the node is moved to 143 -- its new bucket. 144 145 procedure Query_Element 146 (Position : Cursor; 147 Process : not null access procedure (Element : Element_Type)); 148 -- Calls Process with the element (having only a constant view) of the node 149 -- designed by the cursor. 150 151 type Constant_Reference_Type 152 (Element : not null access constant Element_Type) is private 153 with Implicit_Dereference => Element; 154 155 function Constant_Reference 156 (Container : aliased Set; 157 Position : Cursor) return Constant_Reference_Type; 158 pragma Inline (Constant_Reference); 159 160 procedure Assign (Target : in out Set; Source : Set); 161 162 function Copy (Source : Set; Capacity : Count_Type := 0) return Set; 163 164 procedure Move (Target : in out Set; Source : in out Set); 165 -- Clears Target (if it's not empty), and then moves (not copies) the 166 -- buckets array and nodes from Source to Target. 167 168 procedure Insert 169 (Container : in out Set; 170 New_Item : Element_Type; 171 Position : out Cursor; 172 Inserted : out Boolean); 173 -- Conditionally inserts New_Item into the set. If New_Item is already in 174 -- the set, then Inserted returns False and Position designates the node 175 -- containing the existing element (which is not modified). If New_Item is 176 -- not already in the set, then Inserted returns True and Position 177 -- designates the newly-inserted node containing New_Item. The search for 178 -- an existing element works as follows. Hash is called to determine 179 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements 180 -- is called to compare New_Item to the element of each node in that 181 -- bucket. If the bucket is empty, or there were no equivalent elements in 182 -- the bucket, the search "fails" and the New_Item is inserted in the set 183 -- (and Inserted returns True); otherwise, the search "succeeds" (and 184 -- Inserted returns False). 185 186 procedure Insert (Container : in out Set; New_Item : Element_Type); 187 -- Attempts to insert New_Item into the set, performing the usual insertion 188 -- search (which involves calling both Hash and Equivalent_Elements); if 189 -- the search succeeds (New_Item is equivalent to an element already in the 190 -- set, and so was not inserted), then this operation raises 191 -- Constraint_Error. (This version of Insert is similar to Replace, but 192 -- having the opposite exception behavior. It is intended for use when you 193 -- want to assert that the item is not already in the set.) 194 195 procedure Include (Container : in out Set; New_Item : Element_Type); 196 -- Attempts to insert New_Item into the set. If an element equivalent to 197 -- New_Item is already in the set (the insertion search succeeded, and 198 -- hence New_Item was not inserted), then the value of New_Item is assigned 199 -- to the existing element. (This insertion operation only raises an 200 -- exception if cursor tampering occurs. It is intended for use when you 201 -- want to insert the item in the set, and you don't care whether an 202 -- equivalent element is already present.) 203 204 procedure Replace (Container : in out Set; New_Item : Element_Type); 205 -- Searches for New_Item in the set; if the search fails (because an 206 -- equivalent element was not in the set), then it raises 207 -- Constraint_Error. Otherwise, the existing element is assigned the value 208 -- New_Item. (This is similar to Insert, but with the opposite exception 209 -- behavior. It is intended for use when you want to assert that the item 210 -- is already in the set.) 211 212 procedure Exclude (Container : in out Set; Item : Element_Type); 213 -- Searches for Item in the set, and if found, removes its node from the 214 -- set and then deallocates it. The search works as follows. The operation 215 -- calls Hash to determine the item's bucket; if the bucket is not empty, 216 -- it calls Equivalent_Elements to compare Item to the element of each node 217 -- in the bucket. (This is the deletion analog of Include. It is intended 218 -- for use when you want to remove the item from the set, but don't care 219 -- whether the item is already in the set.) 220 221 procedure Delete (Container : in out Set; Item : Element_Type); 222 -- Searches for Item in the set (which involves calling both Hash and 223 -- Equivalent_Elements). If the search fails, then the operation raises 224 -- Constraint_Error. Otherwise it removes the node from the set and then 225 -- deallocates it. (This is the deletion analog of non-conditional 226 -- Insert. It is intended for use when you want to assert that the item is 227 -- already in the set.) 228 229 procedure Delete (Container : in out Set; Position : in out Cursor); 230 -- Removes the node designated by Position from the set, and then 231 -- deallocates the node. The operation calls Hash to determine the bucket, 232 -- and then compares Position to each node in the bucket until there's a 233 -- match (it does not call Equivalent_Elements). 234 235 procedure Union (Target : in out Set; Source : Set); 236 -- The operation first calls Reserve_Capacity if the current capacity is 237 -- less than the sum of the lengths of Source and Target. It then iterates 238 -- over the Source set, and conditionally inserts each element into Target. 239 240 function Union (Left, Right : Set) return Set; 241 -- The operation first copies the Left set to the result, and then iterates 242 -- over the Right set to conditionally insert each element into the result. 243 244 function "or" (Left, Right : Set) return Set renames Union; 245 246 procedure Intersection (Target : in out Set; Source : Set); 247 -- Iterates over the Target set (calling First and Next), calling Find to 248 -- determine whether the element is in Source. If an equivalent element is 249 -- not found in Source, the element is deleted from Target. 250 251 function Intersection (Left, Right : Set) return Set; 252 -- Iterates over the Left set, calling Find to determine whether the 253 -- element is in Right. If an equivalent element is found, it is inserted 254 -- into the result set. 255 256 function "and" (Left, Right : Set) return Set renames Intersection; 257 258 procedure Difference (Target : in out Set; Source : Set); 259 -- Iterates over the Source (calling First and Next), calling Find to 260 -- determine whether the element is in Target. If an equivalent element is 261 -- found, it is deleted from Target. 262 263 function Difference (Left, Right : Set) return Set; 264 -- Iterates over the Left set, calling Find to determine whether the 265 -- element is in the Right set. If an equivalent element is not found, the 266 -- element is inserted into the result set. 267 268 function "-" (Left, Right : Set) return Set renames Difference; 269 270 procedure Symmetric_Difference (Target : in out Set; Source : Set); 271 -- The operation first calls Reserve_Capacity if the current capacity is 272 -- less than the sum of the lengths of Source and Target. It then iterates 273 -- over the Source set, searching for the element in Target (calling Hash 274 -- and Equivalent_Elements). If an equivalent element is found, it is 275 -- removed from Target; otherwise it is inserted into Target. 276 277 function Symmetric_Difference (Left, Right : Set) return Set; 278 -- The operation first iterates over the Left set. It calls Find to 279 -- determine whether the element is in the Right set. If no equivalent 280 -- element is found, the element from Left is inserted into the result. The 281 -- operation then iterates over the Right set, to determine whether the 282 -- element is in the Left set. If no equivalent element is found, the Right 283 -- element is inserted into the result. 284 285 function "xor" (Left, Right : Set) return Set 286 renames Symmetric_Difference; 287 288 function Overlap (Left, Right : Set) return Boolean; 289 -- Iterates over the Left set (calling First and Next), calling Find to 290 -- determine whether the element is in the Right set. If an equivalent 291 -- element is found, the operation immediately returns True. The operation 292 -- returns False if the iteration over Left terminates without finding any 293 -- equivalent element in Right. 294 295 function Is_Subset (Subset : Set; Of_Set : Set) return Boolean; 296 -- Iterates over Subset (calling First and Next), calling Find to determine 297 -- whether the element is in Of_Set. If no equivalent element is found in 298 -- Of_Set, the operation immediately returns False. The operation returns 299 -- True if the iteration over Subset terminates without finding an element 300 -- not in Of_Set (that is, every element in Subset is equivalent to an 301 -- element in Of_Set). 302 303 function First (Container : Set) return Cursor; 304 -- Returns a cursor that designates the first non-empty bucket, by 305 -- searching from the beginning of the buckets array. 306 307 function Next (Position : Cursor) return Cursor; 308 -- Returns a cursor that designates the node that follows the current one 309 -- designated by Position. If Position designates the last node in its 310 -- bucket, the operation calls Hash to compute the index of this bucket, 311 -- and searches the buckets array for the first non-empty bucket, starting 312 -- from that index; otherwise, it simply follows the link to the next node 313 -- in the same bucket. 314 315 procedure Next (Position : in out Cursor); 316 -- Equivalent to Position := Next (Position) 317 318 function Find 319 (Container : Set; 320 Item : Element_Type) return Cursor; 321 -- Searches for Item in the set. Find calls Hash to determine the item's 322 -- bucket; if the bucket is not empty, it calls Equivalent_Elements to 323 -- compare Item to each element in the bucket. If the search succeeds, Find 324 -- returns a cursor designating the node containing the equivalent element; 325 -- otherwise, it returns No_Element. 326 327 function Contains (Container : Set; Item : Element_Type) return Boolean; 328 -- Equivalent to Find (Container, Item) /= No_Element 329 330 function Equivalent_Elements (Left, Right : Cursor) return Boolean; 331 -- Returns the result of calling Equivalent_Elements with the elements of 332 -- the nodes designated by cursors Left and Right. 333 334 function Equivalent_Elements 335 (Left : Cursor; 336 Right : Element_Type) return Boolean; 337 -- Returns the result of calling Equivalent_Elements with element of the 338 -- node designated by Left and element Right. 339 340 function Equivalent_Elements 341 (Left : Element_Type; 342 Right : Cursor) return Boolean; 343 -- Returns the result of calling Equivalent_Elements with element Left and 344 -- the element of the node designated by Right. 345 346 procedure Iterate 347 (Container : Set; 348 Process : not null access procedure (Position : Cursor)); 349 -- Calls Process for each node in the set 350 351 function Iterate 352 (Container : Set) return Set_Iterator_Interfaces.Forward_Iterator'Class; 353 354 generic 355 type Key_Type (<>) is private; 356 357 with function Key (Element : Element_Type) return Key_Type; 358 359 with function Hash (Key : Key_Type) return Hash_Type; 360 361 with function Equivalent_Keys (Left, Right : Key_Type) return Boolean; 362 363 package Generic_Keys is 364 365 function Key (Position : Cursor) return Key_Type; 366 -- Applies generic formal operation Key to the element of the node 367 -- designated by Position. 368 369 function Element (Container : Set; Key : Key_Type) return Element_Type; 370 -- Searches (as per the key-based Find) for the node containing Key, and 371 -- returns the associated element. 372 373 procedure Replace 374 (Container : in out Set; 375 Key : Key_Type; 376 New_Item : Element_Type); 377 -- Searches (as per the key-based Find) for the node containing Key, and 378 -- then replaces the element of that node (as per the element-based 379 -- Replace_Element). 380 381 procedure Exclude (Container : in out Set; Key : Key_Type); 382 -- Searches for Key in the set, and if found, removes its node from the 383 -- set and then deallocates it. The search works by first calling Hash 384 -- (on Key) to determine the bucket; if the bucket is not empty, it 385 -- calls Equivalent_Keys to compare parameter Key to the value of 386 -- generic formal operation Key applied to element of each node in the 387 -- bucket. 388 389 procedure Delete (Container : in out Set; Key : Key_Type); 390 -- Deletes the node containing Key as per Exclude, with the difference 391 -- that Constraint_Error is raised if Key is not found. 392 393 function Find (Container : Set; Key : Key_Type) return Cursor; 394 -- Searches for the node containing Key, and returns a cursor 395 -- designating the node. The search works by first calling Hash (on Key) 396 -- to determine the bucket. If the bucket is not empty, the search 397 -- compares Key to the element of each node in the bucket, and returns 398 -- the matching node. The comparison itself works by applying the 399 -- generic formal Key operation to the element of the node, and then 400 -- calling generic formal operation Equivalent_Keys. 401 402 function Contains (Container : Set; Key : Key_Type) return Boolean; 403 -- Equivalent to Find (Container, Key) /= No_Element 404 405 procedure Update_Element_Preserving_Key 406 (Container : in out Set; 407 Position : Cursor; 408 Process : not null access 409 procedure (Element : in out Element_Type)); 410 -- Calls Process with the element of the node designated by Position, 411 -- but with the restriction that the key-value of the element is not 412 -- modified. The operation first makes a copy of the value returned by 413 -- applying generic formal operation Key on the element of the node, and 414 -- then calls Process with the element. The operation verifies that the 415 -- key-part has not been modified by calling generic formal operation 416 -- Equivalent_Keys to compare the saved key-value to the value returned 417 -- by applying generic formal operation Key to the post-Process value of 418 -- element. If the key values compare equal then the operation 419 -- completes. Otherwise, the node is removed from the set and 420 -- Program_Error is raised. 421 422 type Reference_Type (Element : not null access Element_Type) is private 423 with Implicit_Dereference => Element; 424 425 function Reference_Preserving_Key 426 (Container : aliased in out Set; 427 Position : Cursor) return Reference_Type; 428 429 function Constant_Reference 430 (Container : aliased Set; 431 Key : Key_Type) return Constant_Reference_Type; 432 433 function Reference_Preserving_Key 434 (Container : aliased in out Set; 435 Key : Key_Type) return Reference_Type; 436 437 private 438 use Ada.Streams; 439 type Set_Access is access all Set; 440 for Set_Access'Storage_Size use 0; 441 442 -- Key_Preserving references must carry information to allow removal 443 -- of elements whose value may have been altered improperly, i.e. have 444 -- been given values incompatible with the hash-code of the previous 445 -- value, and are thus in the wrong bucket. (RM 18.7 (96.6/3)) 446 447 -- We cannot store the key directly because it is an unconstrained type. 448 -- To avoid using additional dynamic allocation we store the old cursor 449 -- which simplifies possible removal. This is not possible for some 450 -- other set types. 451 452 -- The mechanism is different for Update_Element_Preserving_Key, as 453 -- in that case the check that buckets have not changed is performed 454 -- at the time of the update, not when the reference is finalized. 455 456 package Impl is new Helpers.Generic_Implementation; 457 458 type Reference_Control_Type is 459 new Impl.Reference_Control_Type with 460 record 461 Container : Set_Access; 462 Index : Hash_Type; 463 Old_Pos : Cursor; 464 Old_Hash : Hash_Type; 465 end record; 466 467 overriding procedure Finalize (Control : in out Reference_Control_Type); 468 pragma Inline (Finalize); 469 470 type Reference_Type (Element : not null access Element_Type) is record 471 Control : Reference_Control_Type; 472 end record; 473 474 procedure Read 475 (Stream : not null access Root_Stream_Type'Class; 476 Item : out Reference_Type); 477 478 for Reference_Type'Read use Read; 479 480 procedure Write 481 (Stream : not null access Root_Stream_Type'Class; 482 Item : Reference_Type); 483 484 for Reference_Type'Write use Write; 485 end Generic_Keys; 486 487private 488 pragma Inline (Next); 489 490 type Node_Type; 491 type Node_Access is access Node_Type; 492 493 type Node_Type is limited record 494 Element : aliased Element_Type; 495 Next : Node_Access; 496 end record; 497 498 package HT_Types is 499 new Hash_Tables.Generic_Hash_Table_Types (Node_Type, Node_Access); 500 501 type Set is new Ada.Finalization.Controlled with record 502 HT : HT_Types.Hash_Table_Type; 503 end record; 504 505 overriding procedure Adjust (Container : in out Set); 506 507 overriding procedure Finalize (Container : in out Set); 508 509 use HT_Types, HT_Types.Implementation; 510 use Ada.Finalization; 511 use Ada.Streams; 512 513 procedure Write 514 (Stream : not null access Root_Stream_Type'Class; 515 Container : Set); 516 517 for Set'Write use Write; 518 519 procedure Read 520 (Stream : not null access Root_Stream_Type'Class; 521 Container : out Set); 522 523 for Set'Read use Read; 524 525 type Set_Access is access all Set; 526 for Set_Access'Storage_Size use 0; 527 528 type Cursor is record 529 Container : Set_Access; 530 Node : Node_Access; 531 Position : Hash_Type := Hash_Type'Last; 532 end record; 533 534 procedure Write 535 (Stream : not null access Root_Stream_Type'Class; 536 Item : Cursor); 537 538 for Cursor'Write use Write; 539 540 procedure Read 541 (Stream : not null access Root_Stream_Type'Class; 542 Item : out Cursor); 543 544 for Cursor'Read use Read; 545 546 subtype Reference_Control_Type is Implementation.Reference_Control_Type; 547 -- It is necessary to rename this here, so that the compiler can find it 548 549 type Constant_Reference_Type 550 (Element : not null access constant Element_Type) is 551 record 552 Control : Reference_Control_Type := 553 raise Program_Error with "uninitialized reference"; 554 -- The RM says, "The default initialization of an object of 555 -- type Constant_Reference_Type or Reference_Type propagates 556 -- Program_Error." 557 end record; 558 559 procedure Read 560 (Stream : not null access Root_Stream_Type'Class; 561 Item : out Constant_Reference_Type); 562 563 for Constant_Reference_Type'Read use Read; 564 565 procedure Write 566 (Stream : not null access Root_Stream_Type'Class; 567 Item : Constant_Reference_Type); 568 569 for Constant_Reference_Type'Write use Write; 570 571 -- Three operations are used to optimize in the expansion of "for ... of" 572 -- loops: the Next(Cursor) procedure in the visible part, and the following 573 -- Pseudo_Reference and Get_Element_Access functions. See Sem_Ch5 for 574 -- details. 575 576 function Pseudo_Reference 577 (Container : aliased Set'Class) return Reference_Control_Type; 578 pragma Inline (Pseudo_Reference); 579 -- Creates an object of type Reference_Control_Type pointing to the 580 -- container, and increments the Lock. Finalization of this object will 581 -- decrement the Lock. 582 583 type Element_Access is access all Element_Type with 584 Storage_Size => 0; 585 586 function Get_Element_Access 587 (Position : Cursor) return not null Element_Access; 588 -- Returns a pointer to the element designated by Position. 589 590 Empty_Set : constant Set := (Controlled with others => <>); 591 592 No_Element : constant Cursor := 593 (Container => null, Node => null, Position => Hash_Type'Last); 594 595 type Iterator is new Limited_Controlled and 596 Set_Iterator_Interfaces.Forward_Iterator with 597 record 598 Container : Set_Access; 599 end record 600 with Disable_Controlled => not T_Check; 601 602 overriding function First (Object : Iterator) return Cursor; 603 604 overriding function Next 605 (Object : Iterator; 606 Position : Cursor) return Cursor; 607 overriding procedure Finalize (Object : in out Iterator); 608 609end Ada.Containers.Hashed_Sets; 610