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) 2004-2012, 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; 37private with Ada.Streams; 38private with Ada.Finalization; 39 40generic 41 type Element_Type is private; 42 43 with function Hash (Element : Element_Type) return Hash_Type; 44 45 with function Equivalent_Elements 46 (Left, Right : Element_Type) return Boolean; 47 48 with function "=" (Left, Right : Element_Type) return Boolean is <>; 49 50package Ada.Containers.Hashed_Sets is 51 pragma Preelaborate; 52 pragma Remote_Types; 53 54 type Set is tagged private 55 with 56 Constant_Indexing => Constant_Reference, 57 Default_Iterator => Iterate, 58 Iterator_Element => Element_Type; 59 60 pragma Preelaborable_Initialization (Set); 61 62 type Cursor is private; 63 pragma Preelaborable_Initialization (Cursor); 64 65 Empty_Set : constant Set; 66 -- Set objects declared without an initialization expression are 67 -- initialized to the value Empty_Set. 68 69 No_Element : constant Cursor; 70 -- Cursor objects declared without an initialization expression are 71 -- initialized to the value No_Element. 72 73 function Has_Element (Position : Cursor) return Boolean; 74 -- Equivalent to Position /= No_Element 75 76 package Set_Iterator_Interfaces is new 77 Ada.Iterator_Interfaces (Cursor, Has_Element); 78 79 function "=" (Left, Right : Set) return Boolean; 80 -- For each element in Left, set equality attempts to find the equal 81 -- element in Right; if a search fails, then set equality immediately 82 -- returns False. The search works by calling Hash to find the bucket in 83 -- the Right set that corresponds to the Left element. If the bucket is 84 -- non-empty, the search calls the generic formal element equality operator 85 -- to compare the element (in Left) to the element of each node in the 86 -- bucket (in Right); the search terminates when a matching node in the 87 -- bucket is found, or the nodes in the bucket are exhausted. (Note that 88 -- element equality is called here, not Equivalent_Elements. Set equality 89 -- is the only operation in which element equality is used. Compare set 90 -- equality to Equivalent_Sets, which does call Equivalent_Elements.) 91 92 function Equivalent_Sets (Left, Right : Set) return Boolean; 93 -- Similar to set equality, with the difference that the element in Left is 94 -- compared to the elements in Right using the generic formal 95 -- Equivalent_Elements operation instead of element equality. 96 97 function To_Set (New_Item : Element_Type) return Set; 98 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to 99 -- determine the bucket for New_Item. 100 101 function Capacity (Container : Set) return Count_Type; 102 -- Returns the current capacity of the set. Capacity is the maximum length 103 -- before which rehashing in guaranteed not to occur. 104 105 procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type); 106 -- Adjusts the current capacity, by allocating a new buckets array. If the 107 -- requested capacity is less than the current capacity, then the capacity 108 -- is contracted (to a value not less than the current length). If the 109 -- requested capacity is greater than the current capacity, then the 110 -- capacity is expanded (to a value not less than what is requested). In 111 -- either case, the nodes are rehashed from the old buckets array onto the 112 -- new buckets array (Hash is called once for each existing element in 113 -- order to compute the new index), and then the old buckets array is 114 -- deallocated. 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 -- designed 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 pragma Inline (Constant_Reference); 157 158 procedure Assign (Target : in out Set; Source : Set); 159 160 function Copy (Source : Set; Capacity : Count_Type := 0) return Set; 161 162 procedure Move (Target : in out Set; Source : in out Set); 163 -- Clears Target (if it's not empty), and then moves (not copies) the 164 -- buckets array and nodes from Source to Target. 165 166 procedure Insert 167 (Container : in out Set; 168 New_Item : Element_Type; 169 Position : out Cursor; 170 Inserted : out Boolean); 171 -- Conditionally inserts New_Item into the set. If New_Item is already in 172 -- the set, then Inserted returns False and Position designates the node 173 -- containing the existing element (which is not modified). If New_Item is 174 -- not already in the set, then Inserted returns True and Position 175 -- designates the newly-inserted node containing New_Item. The search for 176 -- an existing element works as follows. Hash is called to determine 177 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements 178 -- is called to compare New_Item to the element of each node in that 179 -- bucket. If the bucket is empty, or there were no equivalent elements in 180 -- the bucket, the search "fails" and the New_Item is inserted in the set 181 -- (and Inserted returns True); otherwise, the search "succeeds" (and 182 -- Inserted returns False). 183 184 procedure Insert (Container : in out Set; New_Item : Element_Type); 185 -- Attempts to insert New_Item into the set, performing the usual insertion 186 -- search (which involves calling both Hash and Equivalent_Elements); if 187 -- the search succeeds (New_Item is equivalent to an element already in the 188 -- set, and so was not inserted), then this operation raises 189 -- Constraint_Error. (This version of Insert is similar to Replace, but 190 -- having the opposite exception behavior. It is intended for use when you 191 -- want to assert that the item is not already in the set.) 192 193 procedure Include (Container : in out Set; New_Item : Element_Type); 194 -- Attempts to insert New_Item into the set. If an element equivalent to 195 -- New_Item is already in the set (the insertion search succeeded, and 196 -- hence New_Item was not inserted), then the value of New_Item is assigned 197 -- to the existing element. (This insertion operation only raises an 198 -- exception if cursor tampering occurs. It is intended for use when you 199 -- want to insert the item in the set, and you don't care whether an 200 -- equivalent element is already present.) 201 202 procedure Replace (Container : in out Set; New_Item : Element_Type); 203 -- Searches for New_Item in the set; if the search fails (because an 204 -- equivalent element was not in the set), then it raises 205 -- Constraint_Error. Otherwise, the existing element is assigned the value 206 -- New_Item. (This is similar to Insert, but with the opposite exception 207 -- behavior. It is intended for use when you want to assert that the item 208 -- is already in the set.) 209 210 procedure Exclude (Container : in out Set; Item : Element_Type); 211 -- Searches for Item in the set, and if found, removes its node from the 212 -- set and then deallocates it. The search works as follows. The operation 213 -- calls Hash to determine the item's bucket; if the bucket is not empty, 214 -- it calls Equivalent_Elements to compare Item to the element of each node 215 -- in the bucket. (This is the deletion analog of Include. It is intended 216 -- for use when you want to remove the item from the set, but don't care 217 -- whether the item is already in the set.) 218 219 procedure Delete (Container : in out Set; Item : Element_Type); 220 -- Searches for Item in the set (which involves calling both Hash and 221 -- Equivalent_Elements). If the search fails, then the operation raises 222 -- Constraint_Error. Otherwise it removes the node from the set and then 223 -- deallocates it. (This is the deletion analog of non-conditional 224 -- Insert. It is intended for use when you want to assert that the item is 225 -- already in the set.) 226 227 procedure Delete (Container : in out Set; Position : in out Cursor); 228 -- Removes the node designated by Position from the set, and then 229 -- deallocates the node. The operation calls Hash to determine the bucket, 230 -- and then compares Position to each node in the bucket until there's a 231 -- match (it does not call Equivalent_Elements). 232 233 procedure Union (Target : in out Set; Source : Set); 234 -- The operation first calls Reserve_Capacity if the current capacity is 235 -- less than the sum of the lengths of Source and Target. It then iterates 236 -- over the Source set, and conditionally inserts each element into Target. 237 238 function Union (Left, Right : Set) return Set; 239 -- The operation first copies the Left set to the result, and then iterates 240 -- over the Right set to conditionally insert each element into the result. 241 242 function "or" (Left, Right : Set) return Set renames Union; 243 244 procedure Intersection (Target : in out Set; Source : Set); 245 -- Iterates over the Target set (calling First and Next), calling Find to 246 -- determine whether the element is in Source. If an equivalent element is 247 -- not found in Source, the element is deleted from Target. 248 249 function Intersection (Left, Right : Set) return Set; 250 -- Iterates over the Left set, calling Find to determine whether the 251 -- element is in Right. If an equivalent element is found, it is inserted 252 -- into the result set. 253 254 function "and" (Left, Right : Set) return Set renames Intersection; 255 256 procedure Difference (Target : in out Set; Source : Set); 257 -- Iterates over the Source (calling First and Next), calling Find to 258 -- determine whether the element is in Target. If an equivalent element is 259 -- found, it is deleted from Target. 260 261 function Difference (Left, Right : Set) return Set; 262 -- Iterates over the Left set, calling Find to determine whether the 263 -- element is in the Right set. If an equivalent element is not found, the 264 -- element is inserted into the result set. 265 266 function "-" (Left, Right : Set) return Set renames Difference; 267 268 procedure Symmetric_Difference (Target : in out Set; Source : Set); 269 -- The operation first calls Reserve_Capacity if the current capacity is 270 -- less than the sum of the lengths of Source and Target. It then iterates 271 -- over the Source set, searching for the element in Target (calling Hash 272 -- and Equivalent_Elements). If an equivalent element is found, it is 273 -- removed from Target; otherwise it is inserted into Target. 274 275 function Symmetric_Difference (Left, Right : Set) return Set; 276 -- The operation first iterates over the Left set. It calls Find to 277 -- determine whether the element is in the Right set. If no equivalent 278 -- element is found, the element from Left is inserted into the result. The 279 -- operation then iterates over the Right set, to determine whether the 280 -- element is in the Left set. If no equivalent element is found, the Right 281 -- element is inserted into the result. 282 283 function "xor" (Left, Right : Set) return Set 284 renames Symmetric_Difference; 285 286 function Overlap (Left, Right : Set) return Boolean; 287 -- Iterates over the Left set (calling First and Next), calling Find to 288 -- determine whether the element is in the Right set. If an equivalent 289 -- element is found, the operation immediately returns True. The operation 290 -- returns False if the iteration over Left terminates without finding any 291 -- equivalent element in Right. 292 293 function Is_Subset (Subset : Set; Of_Set : Set) return Boolean; 294 -- Iterates over Subset (calling First and Next), calling Find to determine 295 -- whether the element is in Of_Set. If no equivalent element is found in 296 -- Of_Set, the operation immediately returns False. The operation returns 297 -- True if the iteration over Subset terminates without finding an element 298 -- not in Of_Set (that is, every element in Subset is equivalent to an 299 -- element in Of_Set). 300 301 function First (Container : Set) return Cursor; 302 -- Returns a cursor that designates the first non-empty bucket, by 303 -- searching from the beginning of the buckets array. 304 305 function Next (Position : Cursor) return Cursor; 306 -- Returns a cursor that designates the node that follows the current one 307 -- designated by Position. If Position designates the last node in its 308 -- bucket, the operation calls Hash to compute the index of this bucket, 309 -- and searches the buckets array for the first non-empty bucket, starting 310 -- from that index; otherwise, it simply follows the link to the next node 311 -- in the same bucket. 312 313 procedure Next (Position : in out Cursor); 314 -- Equivalent to Position := Next (Position) 315 316 function Find 317 (Container : Set; 318 Item : Element_Type) return Cursor; 319 -- Searches for Item in the set. Find calls Hash to determine the item's 320 -- bucket; if the bucket is not empty, it calls Equivalent_Elements to 321 -- compare Item to each element in the bucket. If the search succeeds, Find 322 -- returns a cursor designating the node containing the equivalent element; 323 -- otherwise, it returns No_Element. 324 325 function Contains (Container : Set; Item : Element_Type) return Boolean; 326 -- Equivalent to Find (Container, Item) /= No_Element 327 328 function Equivalent_Elements (Left, Right : Cursor) return Boolean; 329 -- Returns the result of calling Equivalent_Elements with the elements of 330 -- the nodes designated by cursors Left and Right. 331 332 function Equivalent_Elements 333 (Left : Cursor; 334 Right : Element_Type) return Boolean; 335 -- Returns the result of calling Equivalent_Elements with element of the 336 -- node designated by Left and element Right. 337 338 function Equivalent_Elements 339 (Left : Element_Type; 340 Right : Cursor) return Boolean; 341 -- Returns the result of calling Equivalent_Elements with element Left and 342 -- the element of the node designated by Right. 343 344 procedure Iterate 345 (Container : Set; 346 Process : not null access procedure (Position : Cursor)); 347 -- Calls Process for each node in the set 348 349 function Iterate 350 (Container : Set) return Set_Iterator_Interfaces.Forward_Iterator'Class; 351 352 generic 353 type Key_Type (<>) is private; 354 355 with function Key (Element : Element_Type) return Key_Type; 356 357 with function Hash (Key : Key_Type) return Hash_Type; 358 359 with function Equivalent_Keys (Left, Right : Key_Type) return Boolean; 360 361 package Generic_Keys is 362 363 function Key (Position : Cursor) return Key_Type; 364 -- Applies generic formal operation Key to the element of the node 365 -- designated by Position. 366 367 function Element (Container : Set; Key : Key_Type) return Element_Type; 368 -- Searches (as per the key-based Find) for the node containing Key, and 369 -- returns the associated element. 370 371 procedure Replace 372 (Container : in out Set; 373 Key : Key_Type; 374 New_Item : Element_Type); 375 -- Searches (as per the key-based Find) for the node containing Key, and 376 -- then replaces the element of that node (as per the element-based 377 -- Replace_Element). 378 379 procedure Exclude (Container : in out Set; Key : Key_Type); 380 -- Searches for Key in the set, and if found, removes its node from the 381 -- set and then deallocates it. The search works by first calling Hash 382 -- (on Key) to determine the bucket; if the bucket is not empty, it 383 -- calls Equivalent_Keys to compare parameter Key to the value of 384 -- generic formal operation Key applied to element of each node in the 385 -- bucket. 386 387 procedure Delete (Container : in out Set; Key : Key_Type); 388 -- Deletes the node containing Key as per Exclude, with the difference 389 -- that Constraint_Error is raised if Key is not found. 390 391 function Find (Container : Set; Key : Key_Type) return Cursor; 392 -- Searches for the node containing Key, and returns a cursor 393 -- designating the node. The search works by first calling Hash (on Key) 394 -- to determine the bucket. If the bucket is not empty, the search 395 -- compares Key to the element of each node in the bucket, and returns 396 -- the matching node. The comparison itself works by applying the 397 -- generic formal Key operation to the element of the node, and then 398 -- calling generic formal operation Equivalent_Keys. 399 400 function Contains (Container : Set; Key : Key_Type) return Boolean; 401 -- Equivalent to Find (Container, Key) /= No_Element 402 403 procedure Update_Element_Preserving_Key 404 (Container : in out Set; 405 Position : Cursor; 406 Process : not null access 407 procedure (Element : in out Element_Type)); 408 -- Calls Process with the element of the node designated by Position, 409 -- but with the restriction that the key-value of the element is not 410 -- modified. The operation first makes a copy of the value returned by 411 -- applying generic formal operation Key on the element of the node, and 412 -- then calls Process with the element. The operation verifies that the 413 -- key-part has not been modified by calling generic formal operation 414 -- Equivalent_Keys to compare the saved key-value to the value returned 415 -- by applying generic formal operation Key to the post-Process value of 416 -- element. If the key values compare equal then the operation 417 -- completes. Otherwise, the node is removed from the set and 418 -- Program_Error is raised. 419 420 type Reference_Type (Element : not null access Element_Type) is private 421 with Implicit_Dereference => Element; 422 423 function Reference_Preserving_Key 424 (Container : aliased in out Set; 425 Position : Cursor) return Reference_Type; 426 427 function Constant_Reference 428 (Container : aliased Set; 429 Key : Key_Type) return Constant_Reference_Type; 430 431 function Reference_Preserving_Key 432 (Container : aliased in out Set; 433 Key : Key_Type) return Reference_Type; 434 435 private 436 type Reference_Type (Element : not null access Element_Type) 437 is null record; 438 439 use Ada.Streams; 440 441 procedure Read 442 (Stream : not null access Root_Stream_Type'Class; 443 Item : out Reference_Type); 444 445 for Reference_Type'Read use Read; 446 447 procedure Write 448 (Stream : not null access Root_Stream_Type'Class; 449 Item : Reference_Type); 450 451 for Reference_Type'Write use Write; 452 453 end Generic_Keys; 454 455private 456 pragma Inline (Next); 457 458 type Node_Type; 459 type Node_Access is access Node_Type; 460 461 type Node_Type is limited record 462 Element : aliased Element_Type; 463 Next : Node_Access; 464 end record; 465 466 package HT_Types is 467 new Hash_Tables.Generic_Hash_Table_Types (Node_Type, Node_Access); 468 469 type Set is new Ada.Finalization.Controlled with record 470 HT : HT_Types.Hash_Table_Type; 471 end record; 472 473 overriding procedure Adjust (Container : in out Set); 474 475 overriding procedure Finalize (Container : in out Set); 476 477 use HT_Types; 478 use Ada.Finalization; 479 use Ada.Streams; 480 481 procedure Write 482 (Stream : not null access Root_Stream_Type'Class; 483 Container : Set); 484 485 for Set'Write use Write; 486 487 procedure Read 488 (Stream : not null access Root_Stream_Type'Class; 489 Container : out Set); 490 491 for Set'Read use Read; 492 493 type Set_Access is access all Set; 494 for Set_Access'Storage_Size use 0; 495 496 type Cursor is record 497 Container : Set_Access; 498 Node : Node_Access; 499 end record; 500 501 procedure Write 502 (Stream : not null access Root_Stream_Type'Class; 503 Item : Cursor); 504 505 for Cursor'Write use Write; 506 507 procedure Read 508 (Stream : not null access Root_Stream_Type'Class; 509 Item : out Cursor); 510 511 for Cursor'Read use Read; 512 513 type Reference_Control_Type is 514 new Controlled with record 515 Container : Set_Access; 516 end record; 517 518 overriding procedure Adjust (Control : in out Reference_Control_Type); 519 pragma Inline (Adjust); 520 521 overriding procedure Finalize (Control : in out Reference_Control_Type); 522 pragma Inline (Finalize); 523 524 type Constant_Reference_Type 525 (Element : not null access constant Element_Type) is 526 record 527 Control : Reference_Control_Type; 528 end record; 529 530 procedure Read 531 (Stream : not null access Root_Stream_Type'Class; 532 Item : out Constant_Reference_Type); 533 534 for Constant_Reference_Type'Read use Read; 535 536 procedure Write 537 (Stream : not null access Root_Stream_Type'Class; 538 Item : Constant_Reference_Type); 539 540 for Constant_Reference_Type'Write use Write; 541 542 Empty_Set : constant Set := (Controlled with HT => (null, 0, 0, 0)); 543 544 No_Element : constant Cursor := (Container => null, Node => null); 545 546end Ada.Containers.Hashed_Sets; 547