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   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --                  ADA.CONTAINERS.INDEFINITE_HASHED_SETS                   --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 2004-2014, 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
  34 with Ada.Iterator_Interfaces;
  35
  36 private with Ada.Containers.Hash_Tables;
  37 private with Ada.Streams;
  38 private with Ada.Finalization;
  39
  40 generic
  41    type Element_Type (<>) is private;
  42
  43    with function Hash (Element : Element_Type) return Hash_Type;
  44
  45    with function Equivalent_Elements (Left, Right : Element_Type)
  46                                      return Boolean;
  47
  48    with function "=" (Left, Right : Element_Type) return Boolean is <>;
  49
  50 package Ada.Containers.Indefinite_Hashed_Sets is
  51    pragma Preelaborate;
  52    pragma Remote_Types;
  53
  54    type Set is tagged private
  55      with Constant_Indexing => Constant_Reference,
  56           Default_Iterator  => Iterate,
  57           Iterator_Element  => Element_Type;
  58
  59    pragma Preelaborable_Initialization (Set);
  60
  61    type Cursor is private;
  62    pragma Preelaborable_Initialization (Cursor);
  63
  64    Empty_Set : constant Set;
  65    --  Set objects declared without an initialization expression are
  66    --  initialized to the value Empty_Set.
  67
  68    No_Element : constant Cursor;
  69    --  Cursor objects declared without an initialization expression are
  70    --  initialized to the value No_Element.
  71
  72    function Has_Element (Position : Cursor) return Boolean;
  73    --  Equivalent to Position /= No_Element
  74
  75    package Set_Iterator_Interfaces is new
  76      Ada.Iterator_Interfaces (Cursor, Has_Element);
  77
  78    function "=" (Left, Right : Set) return Boolean;
  79    --  For each element in Left, set equality attempts to find the equal
  80    --  element in Right; if a search fails, then set equality immediately
  81    --  returns False. The search works by calling Hash to find the bucket in
  82    --  the Right set that corresponds to the Left element. If the bucket is
  83    --  non-empty, the search calls the generic formal element equality operator
  84    --  to compare the element (in Left) to the element of each node in the
  85    --  bucket (in Right); the search terminates when a matching node in the
  86    --  bucket is found, or the nodes in the bucket are exhausted. (Note that
  87    --  element equality is called here, not Equivalent_Elements. Set equality
  88    --  is the only operation in which element equality is used. Compare set
  89    --  equality to Equivalent_Sets, which does call Equivalent_Elements.)
  90
  91    function Equivalent_Sets (Left, Right : Set) return Boolean;
  92    --  Similar to set equality, with the difference that the element in Left is
  93    --  compared to the elements in Right using the generic formal
  94    --  Equivalent_Elements operation instead of element equality.
  95
  96    function To_Set (New_Item : Element_Type) return Set;
  97    --  Constructs a singleton set comprising New_Element. To_Set calls Hash to
  98    --  determine the bucket for New_Item.
  99
 100    function Capacity (Container : Set) return Count_Type;
 101    --  Returns the current capacity of the set. Capacity is the maximum length
 102    --  before which rehashing in guaranteed not to occur.
 103
 104    procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type);
 105    --  Adjusts the current capacity, by allocating a new buckets array. If the
 106    --  requested capacity is less than the current capacity, then the capacity
 107    --  is contracted (to a value not less than the current length). If the
 108    --  requested capacity is greater than the current capacity, then the
 109    --  capacity is expanded (to a value not less than what is requested). In
 110    --  either case, the nodes are rehashed from the old buckets array onto the
 111    --  new buckets array (Hash is called once for each existing element in
 112    --  order to compute the new index), and then the old buckets array is
 113    --  deallocated.
 114
 115    function Length (Container : Set) return Count_Type;
 116    --  Returns the number of items in the set
 117
 118    function Is_Empty (Container : Set) return Boolean;
 119    --  Equivalent to Length (Container) = 0
 120
 121    procedure Clear (Container : in out Set);
 122    --  Removes all of the items from the set
 123
 124    function Element (Position : Cursor) return Element_Type;
 125    --  Returns the element of the node designated by the cursor
 126
 127    procedure Replace_Element
 128      (Container : in out Set;
 129       Position  : Cursor;
 130       New_Item  : Element_Type);
 131    --  If New_Item is equivalent (as determined by calling Equivalent_Elements)
 132    --  to the element of the node designated by Position, then New_Element is
 133    --  assigned to that element. Otherwise, it calls Hash to determine the
 134    --  bucket for New_Item. If the bucket is not empty, then it calls
 135    --  Equivalent_Elements for each node in that bucket to determine whether
 136    --  New_Item is equivalent to an element in that bucket. If
 137    --  Equivalent_Elements returns True then Program_Error is raised (because
 138    --  an element may appear only once in the set); otherwise, New_Item is
 139    --  assigned to the node designated by Position, and the node is moved to
 140    --  its new bucket.
 141
 142    procedure Query_Element
 143      (Position : Cursor;
 144       Process  : not null access procedure (Element : Element_Type));
 145    --  Calls Process with the element (having only a constant view) of the node
 146    --  designated by the cursor.
 147
 148    type Constant_Reference_Type
 149      (Element : not null access constant Element_Type) is private
 150         with Implicit_Dereference => Element;
 151
 152    function Constant_Reference
 153      (Container : aliased Set;
 154       Position  : Cursor) return Constant_Reference_Type;
 155    pragma Inline (Constant_Reference);
 156
 157    procedure Assign (Target : in out Set; Source : Set);
 158
 159    function Copy (Source : Set; Capacity : Count_Type := 0) return Set;
 160
 161    procedure Move (Target : in out Set; Source : in out Set);
 162    --  Clears Target (if it's not empty), and then moves (not copies) the
 163    --  buckets array and nodes from Source to Target.
 164
 165    procedure Insert
 166      (Container : in out Set;
 167       New_Item  : Element_Type;
 168       Position  : out Cursor;
 169       Inserted  : out Boolean);
 170    --  Conditionally inserts New_Item into the set. If New_Item is already in
 171    --  the set, then Inserted returns False and Position designates the node
 172    --  containing the existing element (which is not modified). If New_Item is
 173    --  not already in the set, then Inserted returns True and Position
 174    --  designates the newly-inserted node containing New_Item. The search for
 175    --  an existing element works as follows. Hash is called to determine
 176    --  New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements
 177    --  is called to compare New_Item to the element of each node in that
 178    --  bucket. If the bucket is empty, or there were no equivalent elements in
 179    --  the bucket, the search "fails" and the New_Item is inserted in the set
 180    --  (and Inserted returns True); otherwise, the search "succeeds" (and
 181    --  Inserted returns False).
 182
 183    procedure Insert  (Container : in out Set; New_Item : Element_Type);
 184    --  Attempts to insert New_Item into the set, performing the usual insertion
 185    --  search (which involves calling both Hash and Equivalent_Elements); if
 186    --  the search succeeds (New_Item is equivalent to an element already in the
 187    --  set, and so was not inserted), then this operation raises
 188    --  Constraint_Error. (This version of Insert is similar to Replace, but
 189    --  having the opposite exception behavior. It is intended for use when you
 190    --  want to assert that the item is not already in the set.)
 191
 192    procedure Include (Container : in out Set; New_Item : Element_Type);
 193    --  Attempts to insert New_Item into the set. If an element equivalent to
 194    --  New_Item is already in the set (the insertion search succeeded, and
 195    --  hence New_Item was not inserted), then the value of New_Item is assigned
 196    --  to the existing element. (This insertion operation only raises an
 197    --  exception if cursor tampering occurs. It is intended for use when you
 198    --  want to insert the item in the set, and you don't care whether an
 199    --  equivalent element is already present.)
 200
 201    procedure Replace (Container : in out Set; New_Item : Element_Type);
 202    --  Searches for New_Item in the set; if the search fails (because an
 203    --  equivalent element was not in the set), then it raises
 204    --  Constraint_Error. Otherwise, the existing element is assigned the value
 205    --  New_Item. (This is similar to Insert, but with the opposite exception
 206    --  behavior. It is intended for use when you want to assert that the item
 207    --  is already in the set.)
 208
 209    procedure Exclude (Container : in out Set; Item : Element_Type);
 210    --  Searches for Item in the set, and if found, removes its node from the
 211    --  set and then deallocates it. The search works as follows. The operation
 212    --  calls Hash to determine the item's bucket; if the bucket is not empty,
 213    --  it calls Equivalent_Elements to compare Item to the element of each node
 214    --  in the bucket. (This is the deletion analog of Include. It is intended
 215    --  for use when you want to remove the item from the set, but don't care
 216    --  whether the item is already in the set.)
 217
 218    procedure Delete  (Container : in out Set; Item : Element_Type);
 219    --  Searches for Item in the set (which involves calling both Hash and
 220    --  Equivalent_Elements). If the search fails, then the operation raises
 221    --  Constraint_Error. Otherwise it removes the node from the set and then
 222    --  deallocates it. (This is the deletion analog of non-conditional
 223    --  Insert. It is intended for use when you want to assert that the item is
 224    --  already in the set.)
 225
 226    procedure Delete (Container : in out Set; Position  : in out Cursor);
 227    --  Removes the node designated by Position from the set, and then
 228    --  deallocates the node. The operation calls Hash to determine the bucket,
 229    --  and then compares Position to each node in the bucket until there's a
 230    --  match (it does not call Equivalent_Elements).
 231
 232    procedure Union (Target : in out Set; Source : Set);
 233    --  The operation first calls Reserve_Capacity if the current capacity is
 234    --  less than the sum of the lengths of Source and Target. It then iterates
 235    --  over the Source set, and conditionally inserts each element into Target.
 236
 237    function Union (Left, Right : Set) return Set;
 238    --  The operation first copies the Left set to the result, and then iterates
 239    --  over the Right set to conditionally insert each element into the result.
 240
 241    function "or" (Left, Right : Set) return Set renames Union;
 242
 243    procedure Intersection (Target : in out Set; Source : Set);
 244    --  Iterates over the Target set (calling First and Next), calling Find to
 245    --  determine whether the element is in Source. If an equivalent element is
 246    --  not found in Source, the element is deleted from Target.
 247
 248    function Intersection (Left, Right : Set) return Set;
 249    --  Iterates over the Left set, calling Find to determine whether the
 250    --  element is in Right. If an equivalent element is found, it is inserted
 251    --  into the result set.
 252
 253    function "and" (Left, Right : Set) return Set renames Intersection;
 254
 255    procedure Difference (Target : in out Set; Source : Set);
 256    --  Iterates over the Source (calling First and Next), calling Find to
 257    --  determine whether the element is in Target. If an equivalent element is
 258    --  found, it is deleted from Target.
 259
 260    function Difference (Left, Right : Set) return Set;
 261    --  Iterates over the Left set, calling Find to determine whether the
 262    --  element is in the Right set. If an equivalent element is not found, the
 263    --  element is inserted into the result set.
 264
 265    function "-" (Left, Right : Set) return Set renames Difference;
 266
 267    procedure Symmetric_Difference (Target : in out Set; Source : Set);
 268    --  The operation first calls Reserve_Capacity if the current capacity is
 269    --  less than the sum of the lengths of Source and Target. It then iterates
 270    --  over the Source set, searching for the element in Target (calling Hash
 271    --  and Equivalent_Elements). If an equivalent element is found, it is
 272    --  removed from Target; otherwise it is inserted into Target.
 273
 274    function Symmetric_Difference (Left, Right : Set) return Set;
 275    --  The operation first iterates over the Left set. It calls Find to
 276    --  determine whether the element is in the Right set. If no equivalent
 277    --  element is found, the element from Left is inserted into the result. The
 278    --  operation then iterates over the Right set, to determine whether the
 279    --  element is in the Left set. If no equivalent element is found, the Right
 280    --  element is inserted into the result.
 281
 282    function "xor" (Left, Right : Set) return Set
 283      renames Symmetric_Difference;
 284
 285    function Overlap (Left, Right : Set) return Boolean;
 286    --  Iterates over the Left set (calling First and Next), calling Find to
 287    --  determine whether the element is in the Right set. If an equivalent
 288    --  element is found, the operation immediately returns True. The operation
 289    --  returns False if the iteration over Left terminates without finding any
 290    --  equivalent element in Right.
 291
 292    function Is_Subset (Subset : Set; Of_Set : Set) return Boolean;
 293    --  Iterates over Subset (calling First and Next), calling Find to determine
 294    --  whether the element is in Of_Set. If no equivalent element is found in
 295    --  Of_Set, the operation immediately returns False. The operation returns
 296    --  True if the iteration over Subset terminates without finding an element
 297    --  not in Of_Set (that is, every element in Subset is equivalent to an
 298    --  element in Of_Set).
 299
 300    function First (Container : Set) return Cursor;
 301    --  Returns a cursor that designates the first non-empty bucket, by
 302    --  searching from the beginning of the buckets array.
 303
 304    function Next (Position : Cursor) return Cursor;
 305    --  Returns a cursor that designates the node that follows the current one
 306    --  designated by Position. If Position designates the last node in its
 307    --  bucket, the operation calls Hash to compute the index of this bucket,
 308    --  and searches the buckets array for the first non-empty bucket, starting
 309    --  from that index; otherwise, it simply follows the link to the next node
 310    --  in the same bucket.
 311
 312    procedure Next (Position : in out Cursor);
 313    --  Equivalent to Position := Next (Position)
 314
 315    function Find (Container : Set; Item : Element_Type) return Cursor;
 316    --  Searches for Item in the set. Find calls Hash to determine the item's
 317    --  bucket; if the bucket is not empty, it calls Equivalent_Elements to
 318    --  compare Item to each element in the bucket. If the search succeeds, Find
 319    --  returns a cursor designating the node containing the equivalent element;
 320    --  otherwise, it returns No_Element.
 321
 322    function Contains (Container : Set; Item : Element_Type) return Boolean;
 323    --  Equivalent to Find (Container, Item) /= No_Element
 324
 325    function Equivalent_Elements (Left, Right : Cursor) return Boolean;
 326    --  Returns the result of calling Equivalent_Elements with the elements of
 327    --  the nodes designated by cursors Left and Right.
 328
 329    function Equivalent_Elements
 330      (Left  : Cursor;
 331       Right : Element_Type) return Boolean;
 332    --  Returns the result of calling Equivalent_Elements with element of the
 333    --  node designated by Left and element Right.
 334
 335    function Equivalent_Elements
 336      (Left  : Element_Type;
 337       Right : Cursor) return Boolean;
 338    --  Returns the result of calling Equivalent_Elements with element Left and
 339    --  the element of the node designated by Right.
 340
 341    procedure Iterate
 342      (Container : Set;
 343       Process   : not null access procedure (Position : Cursor));
 344    --  Calls Process for each node in the set
 345
 346    function Iterate (Container : Set)
 347      return Set_Iterator_Interfaces.Forward_Iterator'Class;
 348
 349    generic
 350       type Key_Type (<>) is private;
 351
 352       with function Key (Element : Element_Type) return Key_Type;
 353
 354       with function Hash (Key : Key_Type) return Hash_Type;
 355
 356       with function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
 357
 358    package Generic_Keys is
 359
 360       function Key (Position : Cursor) return Key_Type;
 361       --  Applies generic formal operation Key to the element of the node
 362       --  designated by Position.
 363
 364       function Element (Container : Set; Key : Key_Type) return Element_Type;
 365       --  Searches (as per the key-based Find) for the node containing Key, and
 366       --  returns the associated element.
 367
 368       procedure Replace
 369         (Container : in out Set;
 370          Key       : Key_Type;
 371          New_Item  : Element_Type);
 372       --  Searches (as per the key-based Find) for the node containing Key, and
 373       --  then replaces the element of that node (as per the element-based
 374       --  Replace_Element).
 375
 376       procedure Exclude (Container : in out Set; Key : Key_Type);
 377       --  Searches for Key in the set, and if found, removes its node from the
 378       --  set and then deallocates it. The search works by first calling Hash
 379       --  (on Key) to determine the bucket; if the bucket is not empty, it
 380       --  calls Equivalent_Keys to compare parameter Key to the value of
 381       --  generic formal operation Key applied to element of each node in the
 382       --  bucket.
 383
 384       procedure Delete (Container : in out Set; Key : Key_Type);
 385       --  Deletes the node containing Key as per Exclude, with the difference
 386       --  that Constraint_Error is raised if Key is not found.
 387
 388       function Find (Container : Set; Key : Key_Type) return Cursor;
 389       --  Searches for the node containing Key, and returns a cursor
 390       --  designating the node. The search works by first calling Hash (on Key)
 391       --  to determine the bucket. If the bucket is not empty, the search
 392       --  compares Key to the element of each node in the bucket, and returns
 393       --  the matching node. The comparison itself works by applying the
 394       --  generic formal Key operation to the element of the node, and then
 395       --  calling generic formal operation Equivalent_Keys.
 396
 397       function Contains (Container : Set; Key : Key_Type) return Boolean;
 398       --  Equivalent to Find (Container, Key) /= No_Element
 399
 400       procedure Update_Element_Preserving_Key
 401         (Container : in out Set;
 402          Position  : Cursor;
 403          Process   : not null access
 404                        procedure (Element : in out Element_Type));
 405       --  Calls Process with the element of the node designated by Position,
 406       --  but with the restriction that the key-value of the element is not
 407       --  modified. The operation first makes a copy of the value returned by
 408       --  applying generic formal operation Key on the element of the node, and
 409       --  then calls Process with the element. The operation verifies that the
 410       --  key-part has not been modified by calling generic formal operation
 411       --  Equivalent_Keys to compare the saved key-value to the value returned
 412       --  by applying generic formal operation Key to the post-Process value of
 413       --  element. If the key values compare equal then the operation
 414       --  completes. Otherwise, the node is removed from the map and
 415       --  Program_Error is raised.
 416
 417       type Reference_Type (Element : not null access Element_Type) is private
 418         with Implicit_Dereference => Element;
 419
 420       function Reference_Preserving_Key
 421         (Container : aliased in out Set;
 422          Position  : Cursor) return Reference_Type;
 423
 424       function Constant_Reference
 425         (Container : aliased Set;
 426          Key       : Key_Type) return Constant_Reference_Type;
 427
 428       function Reference_Preserving_Key
 429         (Container : aliased in out Set;
 430          Key       : Key_Type) return Reference_Type;
 431
 432    private
 433       type Set_Access is access all Set;
 434       for Set_Access'Storage_Size use 0;
 435
 436       type Reference_Control_Type is
 437         new Ada.Finalization.Controlled with
 438       record
 439          Container : Set_Access;
 440          Index     : Hash_Type;
 441          Old_Pos   : Cursor;
 442          Old_Hash  : Hash_Type;
 443       end record;
 444
 445       overriding procedure Adjust (Control : in out Reference_Control_Type);
 446       pragma Inline (Adjust);
 447
 448       overriding procedure Finalize (Control : in out Reference_Control_Type);
 449       pragma Inline (Finalize);
 450
 451       type Reference_Type (Element : not null access Element_Type) is record
 452          Control : Reference_Control_Type;
 453       end record;
 454
 455       use Ada.Streams;
 456
 457       procedure Read
 458         (Stream : not null access Root_Stream_Type'Class;
 459          Item   : out Reference_Type);
 460
 461       for Reference_Type'Read use Read;
 462
 463       procedure Write
 464         (Stream : not null access Root_Stream_Type'Class;
 465          Item   : Reference_Type);
 466
 467       for Reference_Type'Write use Write;
 468    end Generic_Keys;
 469
 470 private
 471    pragma Inline (Next);
 472
 473    type Node_Type;
 474    type Node_Access is access Node_Type;
 475
 476    type Element_Access is access Element_Type;
 477
 478    type Node_Type is limited record
 479       Element : Element_Access;
 480       Next    : Node_Access;
 481    end record;
 482
 483    package HT_Types is
 484      new Hash_Tables.Generic_Hash_Table_Types (Node_Type, Node_Access);
 485
 486    type Set is new Ada.Finalization.Controlled with record
 487       HT : HT_Types.Hash_Table_Type;
 488    end record;
 489
 490    overriding procedure Adjust (Container : in out Set);
 491
 492    overriding procedure Finalize (Container : in out Set);
 493
 494    use HT_Types;
 495    use Ada.Finalization;
 496    use Ada.Streams;
 497
 498    procedure Write
 499      (Stream    : not null access Root_Stream_Type'Class;
 500       Container : Set);
 501
 502    for Set'Write use Write;
 503
 504    procedure Read
 505      (Stream    : not null access Root_Stream_Type'Class;
 506       Container : out Set);
 507
 508    for Set'Read use Read;
 509
 510    type Set_Access is access all Set;
 511    for Set_Access'Storage_Size use 0;
 512
 513    type Cursor is record
 514       Container : Set_Access;
 515       Node      : Node_Access;
 516    end record;
 517
 518    procedure Write
 519      (Stream : not null access Root_Stream_Type'Class;
 520       Item   : Cursor);
 521
 522    for Cursor'Write use Write;
 523
 524    procedure Read
 525      (Stream : not null access Root_Stream_Type'Class;
 526       Item   : out Cursor);
 527
 528    for Cursor'Read use Read;
 529
 530    type Reference_Control_Type is
 531       new Controlled with record
 532          Container : Set_Access;
 533       end record;
 534
 535    overriding procedure Adjust (Control : in out Reference_Control_Type);
 536    pragma Inline (Adjust);
 537
 538    overriding procedure Finalize (Control : in out Reference_Control_Type);
 539    pragma Inline (Finalize);
 540
 541    type Constant_Reference_Type
 542      (Element : not null access constant Element_Type) is
 543       record
 544          Control : Reference_Control_Type;
 545       end record;
 546
 547    procedure Read
 548      (Stream : not null access Root_Stream_Type'Class;
 549       Item   : out Constant_Reference_Type);
 550
 551    for Constant_Reference_Type'Read use Read;
 552
 553    procedure Write
 554      (Stream : not null access Root_Stream_Type'Class;
 555       Item   : Constant_Reference_Type);
 556
 557    for Constant_Reference_Type'Write use Write;
 558
 559    Empty_Set : constant Set := (Controlled with HT => (null, 0, 0, 0));
 560
 561    No_Element : constant Cursor := (Container => null, Node => null);
 562
 563    type Iterator is new Limited_Controlled and
 564      Set_Iterator_Interfaces.Forward_Iterator with
 565    record
 566       Container : Set_Access;
 567    end record;
 568
 569    overriding procedure Finalize (Object : in out Iterator);
 570
 571    overriding function First (Object : Iterator) return Cursor;
 572
 573    overriding function Next
 574      (Object   : Iterator;
 575       Position : Cursor) return Cursor;
 576
 577 end Ada.Containers.Indefinite_Hashed_Sets;