1------------------------------------------------------------------------------ 2-- -- 3-- GNAT LIBRARY COMPONENTS -- 4-- -- 5-- A D A . C O N T A I N E R S . B O U N D E D _ H A S H E D _ S E T S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 2004-2015, 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.Streams; 39private with Ada.Finalization; use Ada.Finalization; 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.Bounded_Hashed_Sets is 52 pragma Annotate (CodePeer, Skip_Analysis); 53 pragma Pure; 54 pragma Remote_Types; 55 56 type Set (Capacity : Count_Type; Modulus : Hash_Type) is tagged private 57 with Constant_Indexing => Constant_Reference, 58 Default_Iterator => Iterate, 59 Iterator_Element => Element_Type; 60 61 pragma Preelaborable_Initialization (Set); 62 63 type Cursor is private; 64 pragma Preelaborable_Initialization (Cursor); 65 66 Empty_Set : constant Set; 67 -- Set objects declared without an initialization expression are 68 -- initialized to the value Empty_Set. 69 70 No_Element : constant Cursor; 71 -- Cursor objects declared without an initialization expression are 72 -- initialized to the value No_Element. 73 74 function Has_Element (Position : Cursor) return Boolean; 75 -- Equivalent to Position /= No_Element 76 77 package Set_Iterator_Interfaces is new 78 Ada.Iterator_Interfaces (Cursor, Has_Element); 79 80 function "=" (Left, Right : Set) return Boolean; 81 -- For each element in Left, set equality attempts to find the equal 82 -- element in Right; if a search fails, then set equality immediately 83 -- returns False. The search works by calling Hash to find the bucket in 84 -- the Right set that corresponds to the Left element. If the bucket is 85 -- non-empty, the search calls the generic formal element equality operator 86 -- to compare the element (in Left) to the element of each node in the 87 -- bucket (in Right); the search terminates when a matching node in the 88 -- bucket is found, or the nodes in the bucket are exhausted. (Note that 89 -- element equality is called here, not Equivalent_Elements. Set equality 90 -- is the only operation in which element equality is used. Compare set 91 -- equality to Equivalent_Sets, which does call Equivalent_Elements.) 92 93 function Equivalent_Sets (Left, Right : Set) return Boolean; 94 -- Similar to set equality, with the difference that the element in Left is 95 -- compared to the elements in Right using the generic formal 96 -- Equivalent_Elements operation instead of element equality. 97 98 function To_Set (New_Item : Element_Type) return Set; 99 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to 100 -- determine the bucket for New_Item. 101 102 function Capacity (Container : Set) return Count_Type; 103 -- Returns the current capacity of the set. Capacity is the maximum length 104 -- before which rehashing in guaranteed not to occur. 105 106 procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type); 107 -- If the value of the Capacity actual parameter is less or equal to 108 -- Container.Capacity, then the operation has no effect. Otherwise it 109 -- raises Capacity_Error (as no expansion of capacity is possible for a 110 -- bounded form). 111 112 function Default_Modulus (Capacity : Count_Type) return Hash_Type; 113 -- Returns a modulus value (hash table size) which is optimal for the 114 -- specified capacity (which corresponds to the maximum number of items). 115 116 function Length (Container : Set) return Count_Type; 117 -- Returns the number of items in the set 118 119 function Is_Empty (Container : Set) return Boolean; 120 -- Equivalent to Length (Container) = 0 121 122 procedure Clear (Container : in out Set); 123 -- Removes all of the items from the set 124 125 function Element (Position : Cursor) return Element_Type; 126 -- Returns the element of the node designated by the cursor 127 128 procedure Replace_Element 129 (Container : in out Set; 130 Position : Cursor; 131 New_Item : Element_Type); 132 -- If New_Item is equivalent (as determined by calling Equivalent_Elements) 133 -- to the element of the node designated by Position, then New_Element is 134 -- assigned to that element. Otherwise, it calls Hash to determine the 135 -- bucket for New_Item. If the bucket is not empty, then it calls 136 -- Equivalent_Elements for each node in that bucket to determine whether 137 -- New_Item is equivalent to an element in that bucket. If 138 -- Equivalent_Elements returns True then Program_Error is raised (because 139 -- an element may appear only once in the set); otherwise, New_Item is 140 -- assigned to the node designated by Position, and the node is moved to 141 -- its new bucket. 142 143 procedure Query_Element 144 (Position : Cursor; 145 Process : not null access procedure (Element : Element_Type)); 146 -- Calls Process with the element (having only a constant view) of the node 147 -- designated by the cursor. 148 149 type Constant_Reference_Type 150 (Element : not null access constant Element_Type) is private 151 with Implicit_Dereference => Element; 152 153 function Constant_Reference 154 (Container : aliased Set; 155 Position : Cursor) return Constant_Reference_Type; 156 157 procedure Assign (Target : in out Set; Source : Set); 158 -- If Target denotes the same object as Source, then the operation has no 159 -- effect. If the Target capacity is less than the Source length, then 160 -- Assign raises Capacity_Error. Otherwise, Assign clears Target and then 161 -- copies the (active) elements from Source to Target. 162 163 function Copy 164 (Source : Set; 165 Capacity : Count_Type := 0; 166 Modulus : Hash_Type := 0) return Set; 167 -- Constructs a new set object whose elements correspond to Source. If the 168 -- Capacity parameter is 0, then the capacity of the result is the same as 169 -- the length of Source. If the Capacity parameter is equal or greater than 170 -- the length of Source, then the capacity of the result is the specified 171 -- value. Otherwise, Copy raises Capacity_Error. If the Modulus parameter 172 -- is 0, then the modulus of the result is the value returned by a call to 173 -- Default_Modulus with the capacity parameter determined as above; 174 -- otherwise the modulus of the result is the specified value. 175 176 procedure Move (Target : in out Set; Source : in out Set); 177 -- Clears Target (if it's not empty), and then moves (not copies) the 178 -- buckets array and nodes from Source to Target. 179 180 procedure Insert 181 (Container : in out Set; 182 New_Item : Element_Type; 183 Position : out Cursor; 184 Inserted : out Boolean); 185 -- Conditionally inserts New_Item into the set. If New_Item is already in 186 -- the set, then Inserted returns False and Position designates the node 187 -- containing the existing element (which is not modified). If New_Item is 188 -- not already in the set, then Inserted returns True and Position 189 -- designates the newly-inserted node containing New_Item. The search for 190 -- an existing element works as follows. Hash is called to determine 191 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements 192 -- is called to compare New_Item to the element of each node in that 193 -- bucket. If the bucket is empty, or there were no equivalent elements in 194 -- the bucket, the search "fails" and the New_Item is inserted in the set 195 -- (and Inserted returns True); otherwise, the search "succeeds" (and 196 -- Inserted returns False). 197 198 procedure Insert (Container : in out Set; New_Item : Element_Type); 199 -- Attempts to insert New_Item into the set, performing the usual insertion 200 -- search (which involves calling both Hash and Equivalent_Elements); if 201 -- the search succeeds (New_Item is equivalent to an element already in the 202 -- set, and so was not inserted), then this operation raises 203 -- Constraint_Error. (This version of Insert is similar to Replace, but 204 -- having the opposite exception behavior. It is intended for use when you 205 -- want to assert that the item is not already in the set.) 206 207 procedure Include (Container : in out Set; New_Item : Element_Type); 208 -- Attempts to insert New_Item into the set. If an element equivalent to 209 -- New_Item is already in the set (the insertion search succeeded, and 210 -- hence New_Item was not inserted), then the value of New_Item is assigned 211 -- to the existing element. (This insertion operation only raises an 212 -- exception if cursor tampering occurs. It is intended for use when you 213 -- want to insert the item in the set, and you don't care whether an 214 -- equivalent element is already present.) 215 216 procedure Replace (Container : in out Set; New_Item : Element_Type); 217 -- Searches for New_Item in the set; if the search fails (because an 218 -- equivalent element was not in the set), then it raises 219 -- Constraint_Error. Otherwise, the existing element is assigned the value 220 -- New_Item. (This is similar to Insert, but with the opposite exception 221 -- behavior. It is intended for use when you want to assert that the item 222 -- is already in the set.) 223 224 procedure Exclude (Container : in out Set; Item : Element_Type); 225 -- Searches for Item in the set, and if found, removes its node from the 226 -- set and then deallocates it. The search works as follows. The operation 227 -- calls Hash to determine the item's bucket; if the bucket is not empty, 228 -- it calls Equivalent_Elements to compare Item to the element of each node 229 -- in the bucket. (This is the deletion analog of Include. It is intended 230 -- for use when you want to remove the item from the set, but don't care 231 -- whether the item is already in the set.) 232 233 procedure Delete (Container : in out Set; Item : Element_Type); 234 -- Searches for Item in the set (which involves calling both Hash and 235 -- Equivalent_Elements). If the search fails, then the operation raises 236 -- Constraint_Error. Otherwise it removes the node from the set and then 237 -- deallocates it. (This is the deletion analog of non-conditional 238 -- Insert. It is intended for use when you want to assert that the item is 239 -- already in the set.) 240 241 procedure Delete (Container : in out Set; Position : in out Cursor); 242 -- Removes the node designated by Position from the set, and then 243 -- deallocates the node. The operation calls Hash to determine the bucket, 244 -- and then compares Position to each node in the bucket until there's a 245 -- match (it does not call Equivalent_Elements). 246 247 procedure Union (Target : in out Set; Source : Set); 248 -- Iterates over the Source set, and conditionally inserts each element 249 -- into Target. 250 251 function Union (Left, Right : Set) return Set; 252 -- The operation first copies the Left set to the result, and then iterates 253 -- over the Right set to conditionally insert each element into the result. 254 255 function "or" (Left, Right : Set) return Set renames Union; 256 257 procedure Intersection (Target : in out Set; Source : Set); 258 -- Iterates over the Target set (calling First and Next), calling Find to 259 -- determine whether the element is in Source. If an equivalent element is 260 -- not found in Source, the element is deleted from Target. 261 262 function Intersection (Left, Right : Set) return Set; 263 -- Iterates over the Left set, calling Find to determine whether the 264 -- element is in Right. If an equivalent element is found, it is inserted 265 -- into the result set. 266 267 function "and" (Left, Right : Set) return Set renames Intersection; 268 269 procedure Difference (Target : in out Set; Source : Set); 270 -- Iterates over the Source (calling First and Next), calling Find to 271 -- determine whether the element is in Target. If an equivalent element is 272 -- found, it is deleted from Target. 273 274 function Difference (Left, Right : Set) return Set; 275 -- Iterates over the Left set, calling Find to determine whether the 276 -- element is in the Right set. If an equivalent element is not found, the 277 -- element is inserted into the result set. 278 279 function "-" (Left, Right : Set) return Set renames Difference; 280 281 procedure Symmetric_Difference (Target : in out Set; Source : Set); 282 -- The operation iterates over the Source set, searching for the element 283 -- in Target (calling Hash and Equivalent_Elements). If an equivalent 284 -- element is found, it is removed from Target; otherwise it is inserted 285 -- into Target. 286 287 function Symmetric_Difference (Left, Right : Set) return Set; 288 -- The operation first iterates over the Left set. It calls Find to 289 -- determine whether the element is in the Right set. If no equivalent 290 -- element is found, the element from Left is inserted into the result. The 291 -- operation then iterates over the Right set, to determine whether the 292 -- element is in the Left set. If no equivalent element is found, the Right 293 -- element is inserted into the result. 294 295 function "xor" (Left, Right : Set) return Set 296 renames Symmetric_Difference; 297 298 function Overlap (Left, Right : Set) return Boolean; 299 -- Iterates over the Left set (calling First and Next), calling Find to 300 -- determine whether the element is in the Right set. If an equivalent 301 -- element is found, the operation immediately returns True. The operation 302 -- returns False if the iteration over Left terminates without finding any 303 -- equivalent element in Right. 304 305 function Is_Subset (Subset : Set; Of_Set : Set) return Boolean; 306 -- Iterates over Subset (calling First and Next), calling Find to determine 307 -- whether the element is in Of_Set. If no equivalent element is found in 308 -- Of_Set, the operation immediately returns False. The operation returns 309 -- True if the iteration over Subset terminates without finding an element 310 -- not in Of_Set (that is, every element in Subset is equivalent to an 311 -- element in Of_Set). 312 313 function First (Container : Set) return Cursor; 314 -- Returns a cursor that designates the first non-empty bucket, by 315 -- searching from the beginning of the buckets array. 316 317 function Next (Position : Cursor) return Cursor; 318 -- Returns a cursor that designates the node that follows the current one 319 -- designated by Position. If Position designates the last node in its 320 -- bucket, the operation calls Hash to compute the index of this bucket, 321 -- and searches the buckets array for the first non-empty bucket, starting 322 -- from that index; otherwise, it simply follows the link to the next node 323 -- in the same bucket. 324 325 procedure Next (Position : in out Cursor); 326 -- Equivalent to Position := Next (Position) 327 328 function Find 329 (Container : Set; 330 Item : Element_Type) return Cursor; 331 -- Searches for Item in the set. Find calls Hash to determine the item's 332 -- bucket; if the bucket is not empty, it calls Equivalent_Elements to 333 -- compare Item to each element in the bucket. If the search succeeds, Find 334 -- returns a cursor designating the node containing the equivalent element; 335 -- otherwise, it returns No_Element. 336 337 function Contains (Container : Set; Item : Element_Type) return Boolean; 338 -- Equivalent to Find (Container, Item) /= No_Element 339 340 function Equivalent_Elements (Left, Right : Cursor) return Boolean; 341 -- Returns the result of calling Equivalent_Elements with the elements of 342 -- the nodes designated by cursors Left and Right. 343 344 function Equivalent_Elements 345 (Left : Cursor; 346 Right : Element_Type) return Boolean; 347 -- Returns the result of calling Equivalent_Elements with element of the 348 -- node designated by Left and element Right. 349 350 function Equivalent_Elements 351 (Left : Element_Type; 352 Right : Cursor) return Boolean; 353 -- Returns the result of calling Equivalent_Elements with element Left and 354 -- the element of the node designated by Right. 355 356 procedure Iterate 357 (Container : Set; 358 Process : not null access procedure (Position : Cursor)); 359 -- Calls Process for each node in the set 360 361 function Iterate 362 (Container : Set) 363 return Set_Iterator_Interfaces.Forward_Iterator'Class; 364 365 generic 366 type Key_Type (<>) is private; 367 368 with function Key (Element : Element_Type) return Key_Type; 369 370 with function Hash (Key : Key_Type) return Hash_Type; 371 372 with function Equivalent_Keys (Left, Right : Key_Type) return Boolean; 373 374 package Generic_Keys is 375 376 function Key (Position : Cursor) return Key_Type; 377 -- Applies generic formal operation Key to the element of the node 378 -- designated by Position. 379 380 function Element (Container : Set; Key : Key_Type) return Element_Type; 381 -- Searches (as per the key-based Find) for the node containing Key, and 382 -- returns the associated element. 383 384 procedure Replace 385 (Container : in out Set; 386 Key : Key_Type; 387 New_Item : Element_Type); 388 -- Searches (as per the key-based Find) for the node containing Key, and 389 -- then replaces the element of that node (as per the element-based 390 -- Replace_Element). 391 392 procedure Exclude (Container : in out Set; Key : Key_Type); 393 -- Searches for Key in the set, and if found, removes its node from the 394 -- set and then deallocates it. The search works by first calling Hash 395 -- (on Key) to determine the bucket; if the bucket is not empty, it 396 -- calls Equivalent_Keys to compare parameter Key to the value of 397 -- generic formal operation Key applied to element of each node in the 398 -- bucket. 399 400 procedure Delete (Container : in out Set; Key : Key_Type); 401 -- Deletes the node containing Key as per Exclude, with the difference 402 -- that Constraint_Error is raised if Key is not found. 403 404 function Find (Container : Set; Key : Key_Type) return Cursor; 405 -- Searches for the node containing Key, and returns a cursor 406 -- designating the node. The search works by first calling Hash (on Key) 407 -- to determine the bucket. If the bucket is not empty, the search 408 -- compares Key to the element of each node in the bucket, and returns 409 -- the matching node. The comparison itself works by applying the 410 -- generic formal Key operation to the element of the node, and then 411 -- calling generic formal operation Equivalent_Keys. 412 413 function Contains (Container : Set; Key : Key_Type) return Boolean; 414 -- Equivalent to Find (Container, Key) /= No_Element 415 416 procedure Update_Element_Preserving_Key 417 (Container : in out Set; 418 Position : Cursor; 419 Process : not null access 420 procedure (Element : in out Element_Type)); 421 -- Calls Process with the element of the node designated by Position, 422 -- but with the restriction that the key-value of the element is not 423 -- modified. The operation first makes a copy of the value returned by 424 -- applying generic formal operation Key on the element of the node, and 425 -- then calls Process with the element. The operation verifies that the 426 -- key-part has not been modified by calling generic formal operation 427 -- Equivalent_Keys to compare the saved key-value to the value returned 428 -- by applying generic formal operation Key to the post-Process value of 429 -- element. If the key values compare equal then the operation 430 -- completes. Otherwise, the node is removed from the map and 431 -- Program_Error is raised. 432 433 type Reference_Type (Element : not null access Element_Type) is private 434 with Implicit_Dereference => Element; 435 436 function Reference_Preserving_Key 437 (Container : aliased in out Set; 438 Position : Cursor) return Reference_Type; 439 440 function Constant_Reference 441 (Container : aliased Set; 442 Key : Key_Type) return Constant_Reference_Type; 443 444 function Reference_Preserving_Key 445 (Container : aliased in out Set; 446 Key : Key_Type) return Reference_Type; 447 448 private 449 type Set_Access is access all Set; 450 for Set_Access'Storage_Size use 0; 451 452 package Impl is new Helpers.Generic_Implementation; 453 454 type Reference_Control_Type is 455 new Impl.Reference_Control_Type with 456 record 457 Container : Set_Access; 458 Index : Hash_Type; 459 Old_Pos : Cursor; 460 Old_Hash : Hash_Type; 461 end record; 462 463 overriding procedure Finalize (Control : in out Reference_Control_Type); 464 pragma Inline (Finalize); 465 466 type Reference_Type (Element : not null access Element_Type) is record 467 Control : Reference_Control_Type; 468 end record; 469 470 use Ada.Streams; 471 472 procedure Read 473 (Stream : not null access Root_Stream_Type'Class; 474 Item : out Reference_Type); 475 476 for Reference_Type'Read use Read; 477 478 procedure Write 479 (Stream : not null access Root_Stream_Type'Class; 480 Item : Reference_Type); 481 482 for Reference_Type'Write use Write; 483 484 end Generic_Keys; 485 486private 487 pragma Inline (Next); 488 489 type Node_Type is record 490 Element : aliased Element_Type; 491 Next : Count_Type; 492 end record; 493 494 package HT_Types is 495 new Hash_Tables.Generic_Bounded_Hash_Table_Types (Node_Type); 496 497 type Set (Capacity : Count_Type; Modulus : Hash_Type) is 498 new HT_Types.Hash_Table_Type (Capacity, Modulus) with null record; 499 500 use HT_Types, HT_Types.Implementation; 501 use Ada.Streams; 502 503 procedure Write 504 (Stream : not null access Root_Stream_Type'Class; 505 Container : Set); 506 507 for Set'Write use Write; 508 509 procedure Read 510 (Stream : not null access Root_Stream_Type'Class; 511 Container : out Set); 512 513 for Set'Read use Read; 514 515 type Set_Access is access all Set; 516 for Set_Access'Storage_Size use 0; 517 518 -- Note: If a Cursor object has no explicit initialization expression, 519 -- it must default initialize to the same value as constant No_Element. 520 -- The Node component of type Cursor has scalar type Count_Type, so it 521 -- requires an explicit initialization expression of its own declaration, 522 -- in order for objects of record type Cursor to properly initialize. 523 524 type Cursor is record 525 Container : Set_Access; 526 Node : Count_Type := 0; 527 end record; 528 529 procedure Write 530 (Stream : not null access Root_Stream_Type'Class; 531 Item : Cursor); 532 533 for Cursor'Write use Write; 534 535 procedure Read 536 (Stream : not null access Root_Stream_Type'Class; 537 Item : out Cursor); 538 539 for Cursor'Read use Read; 540 541 subtype Reference_Control_Type is Implementation.Reference_Control_Type; 542 -- It is necessary to rename this here, so that the compiler can find it 543 544 type Constant_Reference_Type 545 (Element : not null access constant Element_Type) is 546 record 547 Control : Reference_Control_Type := 548 raise Program_Error with "uninitialized reference"; 549 -- The RM says, "The default initialization of an object of 550 -- type Constant_Reference_Type or Reference_Type propagates 551 -- Program_Error." 552 end record; 553 554 procedure Read 555 (Stream : not null access Root_Stream_Type'Class; 556 Item : out Constant_Reference_Type); 557 558 for Constant_Reference_Type'Read use Read; 559 560 procedure Write 561 (Stream : not null access Root_Stream_Type'Class; 562 Item : Constant_Reference_Type); 563 564 for Constant_Reference_Type'Write use Write; 565 566 -- Three operations are used to optimize in the expansion of "for ... of" 567 -- loops: the Next(Cursor) procedure in the visible part, and the following 568 -- Pseudo_Reference and Get_Element_Access functions. See Sem_Ch5 for 569 -- details. 570 571 function Pseudo_Reference 572 (Container : aliased Set'Class) return Reference_Control_Type; 573 pragma Inline (Pseudo_Reference); 574 -- Creates an object of type Reference_Control_Type pointing to the 575 -- container, and increments the Lock. Finalization of this object will 576 -- decrement the Lock. 577 578 type Element_Access is access all Element_Type with 579 Storage_Size => 0; 580 581 function Get_Element_Access 582 (Position : Cursor) return not null Element_Access; 583 -- Returns a pointer to the element designated by Position. 584 585 Empty_Set : constant Set := 586 (Hash_Table_Type with Capacity => 0, Modulus => 0); 587 588 No_Element : constant Cursor := (Container => null, Node => 0); 589 590 type Iterator is new Limited_Controlled and 591 Set_Iterator_Interfaces.Forward_Iterator with 592 record 593 Container : Set_Access; 594 end record 595 with Disable_Controlled => not T_Check; 596 597 overriding procedure Finalize (Object : in out Iterator); 598 599 overriding function First (Object : Iterator) return Cursor; 600 601 overriding function Next 602 (Object : Iterator; 603 Position : Cursor) return Cursor; 604 605end Ada.Containers.Bounded_Hashed_Sets; 606