gcc/ada/a-cbhase.ads

   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) 2004-2012, 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
  34 with Ada.Iterator_Interfaces;
  35
  36 private with Ada.Containers.Hash_Tables;
  37 private with Ada.Streams;
  38
  39 generic
  40    type Element_Type is private;
  41
  42    with function Hash (Element : Element_Type) return Hash_Type;
  43
  44    with function Equivalent_Elements
  45           (Left, Right : Element_Type) return Boolean;
  46
  47    with function "=" (Left, Right : Element_Type) return Boolean is <>;
  48
  49 package Ada.Containers.Bounded_Hashed_Sets is
  50    pragma Pure;
  51    pragma Remote_Types;
  52
  53    type Set (Capacity : Count_Type; Modulus : Hash_Type) is tagged private
  54      with Constant_Indexing => Constant_Reference,
  55           Default_Iterator  => Iterate,
  56           Iterator_Element  => Element_Type;
  57
  58    pragma Preelaborable_Initialization (Set);
  59
  60    type Cursor is private;
  61    pragma Preelaborable_Initialization (Cursor);
  62
  63    Empty_Set : constant Set;
  64    --  Set objects declared without an initialization expression are
  65    --  initialized to the value Empty_Set.
  66
  67    No_Element : constant Cursor;
  68    --  Cursor objects declared without an initialization expression are
  69    --  initialized to the value No_Element.
  70
  71    function Has_Element (Position : Cursor) return Boolean;
  72    --  Equivalent to Position /= No_Element
  73
  74    package Set_Iterator_Interfaces is new
  75      Ada.Iterator_Interfaces (Cursor, Has_Element);
  76
  77    function "=" (Left, Right : Set) return Boolean;
  78    --  For each element in Left, set equality attempts to find the equal
  79    --  element in Right; if a search fails, then set equality immediately
  80    --  returns False. The search works by calling Hash to find the bucket in
  81    --  the Right set that corresponds to the Left element. If the bucket is
  82    --  non-empty, the search calls the generic formal element equality operator
  83    --  to compare the element (in Left) to the element of each node in the
  84    --  bucket (in Right); the search terminates when a matching node in the
  85    --  bucket is found, or the nodes in the bucket are exhausted. (Note that
  86    --  element equality is called here, not Equivalent_Elements. Set equality
  87    --  is the only operation in which element equality is used. Compare set
  88    --  equality to Equivalent_Sets, which does call Equivalent_Elements.)
  89
  90    function Equivalent_Sets (Left, Right : Set) return Boolean;
  91    --  Similar to set equality, with the difference that the element in Left is
  92    --  compared to the elements in Right using the generic formal
  93    --  Equivalent_Elements operation instead of element equality.
  94
  95    function To_Set (New_Item : Element_Type) return Set;
  96    --  Constructs a singleton set comprising New_Element. To_Set calls Hash to
  97    --  determine the bucket for New_Item.
  98
  99    function Capacity (Container : Set) return Count_Type;
 100    --  Returns the current capacity of the set. Capacity is the maximum length
 101    --  before which rehashing in guaranteed not to occur.
 102
 103    procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type);
 104    --  If the value of the Capacity actual parameter is less or equal to
 105    --  Container.Capacity, then the operation has no effect.  Otherwise it
 106    --  raises Capacity_Error (as no expansion of capacity is possible for a
 107    --  bounded form).
 108
 109    function Default_Modulus (Capacity : Count_Type) return Hash_Type;
 110    --  Returns a modulus value (hash table size) which is optimal for the
 111    --  specified capacity (which corresponds to the maximum number of items).
 112
 113    function Length (Container : Set) return Count_Type;
 114    --  Returns the number of items in the set
 115
 116    function Is_Empty (Container : Set) return Boolean;
 117    --  Equivalent to Length (Container) = 0
 118
 119    procedure Clear (Container : in out Set);
 120    --  Removes all of the items from the set
 121
 122    function Element (Position : Cursor) return Element_Type;
 123    --  Returns the element of the node designated by the cursor
 124
 125    procedure Replace_Element
 126      (Container : in out Set;
 127       Position  : Cursor;
 128       New_Item  : Element_Type);
 129    --  If New_Item is equivalent (as determined by calling Equivalent_Elements)
 130    --  to the element of the node designated by Position, then New_Element is
 131    --  assigned to that element. Otherwise, it calls Hash to determine the
 132    --  bucket for New_Item. If the bucket is not empty, then it calls
 133    --  Equivalent_Elements for each node in that bucket to determine whether
 134    --  New_Item is equivalent to an element in that bucket. If
 135    --  Equivalent_Elements returns True then Program_Error is raised (because
 136    --  an element may appear only once in the set); otherwise, New_Item is
 137    --  assigned to the node designated by Position, and the node is moved to
 138    --  its new bucket.
 139
 140    procedure Query_Element
 141      (Position : Cursor;
 142       Process  : not null access procedure (Element : Element_Type));
 143    --  Calls Process with the element (having only a constant view) of the node
 144    --  designated by the cursor.
 145
 146    type Constant_Reference_Type
 147      (Element : not null access constant Element_Type) is private
 148         with Implicit_Dereference => Element;
 149
 150    function Constant_Reference
 151      (Container : aliased Set;
 152       Position  : Cursor) return Constant_Reference_Type;
 153
 154    procedure Assign (Target : in out Set; Source : Set);
 155    --  If Target denotes the same object as Source, then the operation has no
 156    --  effect. If the Target capacity is less than the Source length, then
 157    --  Assign raises Capacity_Error.  Otherwise, Assign clears Target and then
 158    --  copies the (active) elements from Source to Target.
 159
 160    function Copy
 161      (Source   : Set;
 162       Capacity : Count_Type := 0;
 163       Modulus  : Hash_Type := 0) return Set;
 164    --  Constructs a new set object whose elements correspond to Source.  If the
 165    --  Capacity parameter is 0, then the capacity of the result is the same as
 166    --  the length of Source. If the Capacity parameter is equal or greater than
 167    --  the length of Source, then the capacity of the result is the specified
 168    --  value. Otherwise, Copy raises Capacity_Error. If the Modulus parameter
 169    --  is 0, then the modulus of the result is the value returned by a call to
 170    --  Default_Modulus with the capacity parameter determined as above;
 171    --  otherwise the modulus of the result is the specified value.
 172
 173    procedure Move (Target : in out Set; Source : in out Set);
 174    --  Clears Target (if it's not empty), and then moves (not copies) the
 175    --  buckets array and nodes from Source to Target.
 176
 177    procedure Insert
 178      (Container : in out Set;
 179       New_Item  : Element_Type;
 180       Position  : out Cursor;
 181       Inserted  : out Boolean);
 182    --  Conditionally inserts New_Item into the set. If New_Item is already in
 183    --  the set, then Inserted returns False and Position designates the node
 184    --  containing the existing element (which is not modified). If New_Item is
 185    --  not already in the set, then Inserted returns True and Position
 186    --  designates the newly-inserted node containing New_Item. The search for
 187    --  an existing element works as follows. Hash is called to determine
 188    --  New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements
 189    --  is called to compare New_Item to the element of each node in that
 190    --  bucket. If the bucket is empty, or there were no equivalent elements in
 191    --  the bucket, the search "fails" and the New_Item is inserted in the set
 192    --  (and Inserted returns True); otherwise, the search "succeeds" (and
 193    --  Inserted returns False).
 194
 195    procedure Insert  (Container : in out Set; New_Item : Element_Type);
 196    --  Attempts to insert New_Item into the set, performing the usual insertion
 197    --  search (which involves calling both Hash and Equivalent_Elements); if
 198    --  the search succeeds (New_Item is equivalent to an element already in the
 199    --  set, and so was not inserted), then this operation raises
 200    --  Constraint_Error. (This version of Insert is similar to Replace, but
 201    --  having the opposite exception behavior. It is intended for use when you
 202    --  want to assert that the item is not already in the set.)
 203
 204    procedure Include (Container : in out Set; New_Item : Element_Type);
 205    --  Attempts to insert New_Item into the set. If an element equivalent to
 206    --  New_Item is already in the set (the insertion search succeeded, and
 207    --  hence New_Item was not inserted), then the value of New_Item is assigned
 208    --  to the existing element. (This insertion operation only raises an
 209    --  exception if cursor tampering occurs. It is intended for use when you
 210    --  want to insert the item in the set, and you don't care whether an
 211    --  equivalent element is already present.)
 212
 213    procedure Replace (Container : in out Set; New_Item : Element_Type);
 214    --  Searches for New_Item in the set; if the search fails (because an
 215    --  equivalent element was not in the set), then it raises
 216    --  Constraint_Error. Otherwise, the existing element is assigned the value
 217    --  New_Item. (This is similar to Insert, but with the opposite exception
 218    --  behavior. It is intended for use when you want to assert that the item
 219    --  is already in the set.)
 220
 221    procedure Exclude (Container : in out Set; Item : Element_Type);
 222    --  Searches for Item in the set, and if found, removes its node from the
 223    --  set and then deallocates it. The search works as follows. The operation
 224    --  calls Hash to determine the item's bucket; if the bucket is not empty,
 225    --  it calls Equivalent_Elements to compare Item to the element of each node
 226    --  in the bucket. (This is the deletion analog of Include. It is intended
 227    --  for use when you want to remove the item from the set, but don't care
 228    --  whether the item is already in the set.)
 229
 230    procedure Delete  (Container : in out Set; Item : Element_Type);
 231    --  Searches for Item in the set (which involves calling both Hash and
 232    --  Equivalent_Elements). If the search fails, then the operation raises
 233    --  Constraint_Error. Otherwise it removes the node from the set and then
 234    --  deallocates it. (This is the deletion analog of non-conditional
 235    --  Insert. It is intended for use when you want to assert that the item is
 236    --  already in the set.)
 237
 238    procedure Delete (Container : in out Set; Position : in out Cursor);
 239    --  Removes the node designated by Position from the set, and then
 240    --  deallocates the node. The operation calls Hash to determine the bucket,
 241    --  and then compares Position to each node in the bucket until there's a
 242    --  match (it does not call Equivalent_Elements).
 243
 244    procedure Union (Target : in out Set; Source : Set);
 245    --  Iterates over the Source set, and conditionally inserts each element
 246    --  into Target.
 247
 248    function Union (Left, Right : Set) return Set;
 249    --  The operation first copies the Left set to the result, and then iterates
 250    --  over the Right set to conditionally insert each element into the result.
 251
 252    function "or" (Left, Right : Set) return Set renames Union;
 253
 254    procedure Intersection (Target : in out Set; Source : Set);
 255    --  Iterates over the Target set (calling First and Next), calling Find to
 256    --  determine whether the element is in Source. If an equivalent element is
 257    --  not found in Source, the element is deleted from Target.
 258
 259    function Intersection (Left, Right : Set) return Set;
 260    --  Iterates over the Left set, calling Find to determine whether the
 261    --  element is in Right. If an equivalent element is found, it is inserted
 262    --  into the result set.
 263
 264    function "and" (Left, Right : Set) return Set renames Intersection;
 265
 266    procedure Difference (Target : in out Set; Source : Set);
 267    --  Iterates over the Source (calling First and Next), calling Find to
 268    --  determine whether the element is in Target. If an equivalent element is
 269    --  found, it is deleted from Target.
 270
 271    function Difference (Left, Right : Set) return Set;
 272    --  Iterates over the Left set, calling Find to determine whether the
 273    --  element is in the Right set. If an equivalent element is not found, the
 274    --  element is inserted into the result set.
 275
 276    function "-" (Left, Right : Set) return Set renames Difference;
 277
 278    procedure Symmetric_Difference (Target : in out Set; Source : Set);
 279    --  The operation iterates over the Source set, searching for the element
 280    --  in Target (calling Hash and Equivalent_Elements). If an equivalent
 281    --  element is found, it is removed from Target; otherwise it is inserted
 282    --  into Target.
 283
 284    function Symmetric_Difference (Left, Right : Set) return Set;
 285    --  The operation first iterates over the Left set. It calls Find to
 286    --  determine whether the element is in the Right set. If no equivalent
 287    --  element is found, the element from Left is inserted into the result. The
 288    --  operation then iterates over the Right set, to determine whether the
 289    --  element is in the Left set. If no equivalent element is found, the Right
 290    --  element is inserted into the result.
 291
 292    function "xor" (Left, Right : Set) return Set
 293      renames Symmetric_Difference;
 294
 295    function Overlap (Left, Right : Set) return Boolean;
 296    --  Iterates over the Left set (calling First and Next), calling Find to
 297    --  determine whether the element is in the Right set. If an equivalent
 298    --  element is found, the operation immediately returns True. The operation
 299    --  returns False if the iteration over Left terminates without finding any
 300    --  equivalent element in Right.
 301
 302    function Is_Subset (Subset : Set; Of_Set : Set) return Boolean;
 303    --  Iterates over Subset (calling First and Next), calling Find to determine
 304    --  whether the element is in Of_Set. If no equivalent element is found in
 305    --  Of_Set, the operation immediately returns False. The operation returns
 306    --  True if the iteration over Subset terminates without finding an element
 307    --  not in Of_Set (that is, every element in Subset is equivalent to an
 308    --  element in Of_Set).
 309
 310    function First (Container : Set) return Cursor;
 311    --  Returns a cursor that designates the first non-empty bucket, by
 312    --  searching from the beginning of the buckets array.
 313
 314    function Next (Position : Cursor) return Cursor;
 315    --  Returns a cursor that designates the node that follows the current one
 316    --  designated by Position. If Position designates the last node in its
 317    --  bucket, the operation calls Hash to compute the index of this bucket,
 318    --  and searches the buckets array for the first non-empty bucket, starting
 319    --  from that index; otherwise, it simply follows the link to the next node
 320    --  in the same bucket.
 321
 322    procedure Next (Position : in out Cursor);
 323    --  Equivalent to Position := Next (Position)
 324
 325    function Find
 326      (Container : Set;
 327       Item      : Element_Type) return Cursor;
 328    --  Searches for Item in the set. Find calls Hash to determine the item's
 329    --  bucket; if the bucket is not empty, it calls Equivalent_Elements to
 330    --  compare Item to each element in the bucket. If the search succeeds, Find
 331    --  returns a cursor designating the node containing the equivalent element;
 332    --  otherwise, it returns No_Element.
 333
 334    function Contains (Container : Set; Item : Element_Type) return Boolean;
 335    --  Equivalent to Find (Container, Item) /= No_Element
 336
 337    function Equivalent_Elements (Left, Right : Cursor) return Boolean;
 338    --  Returns the result of calling Equivalent_Elements with the elements of
 339    --  the nodes designated by cursors Left and Right.
 340
 341    function Equivalent_Elements
 342      (Left  : Cursor;
 343       Right : Element_Type) return Boolean;
 344    --  Returns the result of calling Equivalent_Elements with element of the
 345    --  node designated by Left and element Right.
 346
 347    function Equivalent_Elements
 348      (Left  : Element_Type;
 349       Right : Cursor) return Boolean;
 350    --  Returns the result of calling Equivalent_Elements with element Left and
 351    --  the element of the node designated by Right.
 352
 353    procedure Iterate
 354      (Container : Set;
 355       Process   : not null access procedure (Position : Cursor));
 356    --  Calls Process for each node in the set
 357
 358    function Iterate
 359      (Container : Set)
 360       return Set_Iterator_Interfaces.Forward_Iterator'Class;
 361
 362    generic
 363       type Key_Type (<>) is private;
 364
 365       with function Key (Element : Element_Type) return Key_Type;
 366
 367       with function Hash (Key : Key_Type) return Hash_Type;
 368
 369       with function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
 370
 371    package Generic_Keys is
 372
 373       function Key (Position : Cursor) return Key_Type;
 374       --  Applies generic formal operation Key to the element of the node
 375       --  designated by Position.
 376
 377       function Element (Container : Set; Key : Key_Type) return Element_Type;
 378       --  Searches (as per the key-based Find) for the node containing Key, and
 379       --  returns the associated element.
 380
 381       procedure Replace
 382         (Container : in out Set;
 383          Key       : Key_Type;
 384          New_Item  : Element_Type);
 385       --  Searches (as per the key-based Find) for the node containing Key, and
 386       --  then replaces the element of that node (as per the element-based
 387       --  Replace_Element).
 388
 389       procedure Exclude (Container : in out Set; Key : Key_Type);
 390       --  Searches for Key in the set, and if found, removes its node from the
 391       --  set and then deallocates it. The search works by first calling Hash
 392       --  (on Key) to determine the bucket; if the bucket is not empty, it
 393       --  calls Equivalent_Keys to compare parameter Key to the value of
 394       --  generic formal operation Key applied to element of each node in the
 395       --  bucket.
 396
 397       procedure Delete (Container : in out Set; Key : Key_Type);
 398       --  Deletes the node containing Key as per Exclude, with the difference
 399       --  that Constraint_Error is raised if Key is not found.
 400
 401       function Find (Container : Set; Key : Key_Type) return Cursor;
 402       --  Searches for the node containing Key, and returns a cursor
 403       --  designating the node. The search works by first calling Hash (on Key)
 404       --  to determine the bucket. If the bucket is not empty, the search
 405       --  compares Key to the element of each node in the bucket, and returns
 406       --  the matching node. The comparison itself works by applying the
 407       --  generic formal Key operation to the element of the node, and then
 408       --  calling generic formal operation Equivalent_Keys.
 409
 410       function Contains (Container : Set; Key : Key_Type) return Boolean;
 411       --  Equivalent to Find (Container, Key) /= No_Element
 412
 413       procedure Update_Element_Preserving_Key
 414         (Container : in out Set;
 415          Position  : Cursor;
 416          Process   : not null access
 417                        procedure (Element : in out Element_Type));
 418       --  Calls Process with the element of the node designated by Position,
 419       --  but with the restriction that the key-value of the element is not
 420       --  modified. The operation first makes a copy of the value returned by
 421       --  applying generic formal operation Key on the element of the node, and
 422       --  then calls Process with the element. The operation verifies that the
 423       --  key-part has not been modified by calling generic formal operation
 424       --  Equivalent_Keys to compare the saved key-value to the value returned
 425       --  by applying generic formal operation Key to the post-Process value of
 426       --  element. If the key values compare equal then the operation
 427       --  completes. Otherwise, the node is removed from the map and
 428       --  Program_Error is raised.
 429
 430       type Reference_Type (Element : not null access Element_Type) is private
 431         with Implicit_Dereference => Element;
 432
 433       function Reference_Preserving_Key
 434         (Container : aliased in out Set;
 435          Position  : Cursor) return Reference_Type;
 436
 437       function Constant_Reference
 438         (Container : aliased Set;
 439          Key       : Key_Type) return Constant_Reference_Type;
 440
 441       function Reference_Preserving_Key
 442         (Container : aliased in out Set;
 443          Key       : Key_Type) return Reference_Type;
 444
 445    private
 446       type Reference_Type (Element : not null access Element_Type)
 447          is null record;
 448
 449       use Ada.Streams;
 450
 451       procedure Read
 452         (Stream : not null access Root_Stream_Type'Class;
 453          Item   : out Reference_Type);
 454
 455       for Reference_Type'Read use Read;
 456
 457       procedure Write
 458         (Stream : not null access Root_Stream_Type'Class;
 459          Item   : Reference_Type);
 460
 461       for Reference_Type'Write use Write;
 462
 463    end Generic_Keys;
 464
 465 private
 466    pragma Inline (Next);
 467
 468    type Node_Type is record
 469       Element : aliased Element_Type;
 470       Next    : Count_Type;
 471    end record;
 472
 473    package HT_Types is
 474      new Hash_Tables.Generic_Bounded_Hash_Table_Types (Node_Type);
 475
 476    type Set (Capacity : Count_Type; Modulus : Hash_Type) is
 477       new HT_Types.Hash_Table_Type (Capacity, Modulus) with null record;
 478
 479    use HT_Types;
 480    use Ada.Streams;
 481
 482    procedure Write
 483      (Stream    : not null access Root_Stream_Type'Class;
 484       Container : Set);
 485
 486    for Set'Write use Write;
 487
 488    procedure Read
 489      (Stream    : not null access Root_Stream_Type'Class;
 490       Container : out Set);
 491
 492    for Set'Read use Read;
 493
 494    type Set_Access is access all Set;
 495    for Set_Access'Storage_Size use 0;
 496
 497    --  Note: If a Cursor object has no explicit initialization expression,
 498    --  it must default initialize to the same value as constant No_Element.
 499    --  The Node component of type Cursor has scalar type Count_Type, so it
 500    --  requires an explicit initialization expression of its own declaration,
 501    --  in order for objects of record type Cursor to properly initialize.
 502
 503    type Cursor is record
 504       Container : Set_Access;
 505       Node      : Count_Type := 0;
 506    end record;
 507
 508    procedure Write
 509      (Stream : not null access Root_Stream_Type'Class;
 510       Item   : Cursor);
 511
 512    for Cursor'Write use Write;
 513
 514    procedure Read
 515      (Stream : not null access Root_Stream_Type'Class;
 516       Item   : out Cursor);
 517
 518    for Cursor'Read use Read;
 519
 520    type Constant_Reference_Type
 521      (Element : not null access constant Element_Type) is null record;
 522
 523    procedure Read
 524      (Stream : not null access Root_Stream_Type'Class;
 525       Item   : out Constant_Reference_Type);
 526
 527    for Constant_Reference_Type'Read use Read;
 528
 529    procedure Write
 530      (Stream : not null access Root_Stream_Type'Class;
 531       Item   : Constant_Reference_Type);
 532
 533    for Constant_Reference_Type'Write use Write;
 534
 535    Empty_Set : constant Set :=
 536                  (Hash_Table_Type with Capacity => 0, Modulus => 0);
 537
 538    No_Element : constant Cursor := (Container => null, Node => 0);
 539
 540 end Ada.Containers.Bounded_Hashed_Sets;