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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT LIBRARY COMPONENTS                          --

--                                                                          --

--           A D A . C O N T A I N E R S . H A S H E D _ S E T S            --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 2004-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- This specification is derived from the Ada Reference Manual for use with --

-- GNAT. The copyright notice above, and the license provisions that follow --

-- apply solely to the  contents of the part following the private keyword. --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- This unit was originally developed by Matthew J Heaney.                  --

------------------------------------------------------------------------------

private with Ada.Containers.Hash_Tables;

private with Ada.Streams;

private with Ada.Finalization;

generic

   type Element_Type is private;

   with function Hash (Element : Element_Type) return Hash_Type;

   with function Equivalent_Elements

          (Left, Right : Element_Type) return Boolean;

   with function "=" (Left, Right : Element_Type) return Boolean is <>;

package Ada.Containers.Hashed_Sets is

   pragma Preelaborate;

   pragma Remote_Types;

   type Set is tagged private;

   pragma Preelaborable_Initialization (Set);

   type Cursor is private;

   pragma Preelaborable_Initialization (Cursor);

   Empty_Set : constant Set;

   --  Set objects declared without an initialization expression are

   --  initialized to the value Empty_Set.

   No_Element : constant Cursor;

   --  Cursor objects declared without an initialization expression are

   --  initialized to the value No_Element.

   function "=" (Left, Right : Set) return Boolean;

   --  For each element in Left, set equality attempts to find the equal

   --  element in Right; if a search fails, then set equality immediately

   --  returns False. The search works by calling Hash to find the bucket in

   --  the Right set that corresponds to the Left element. If the bucket is

   --  non-empty, the search calls the generic formal element equality operator

   --  to compare the element (in Left) to the element of each node in the

   --  bucket (in Right); the search terminates when a matching node in the

   --  bucket is found, or the nodes in the bucket are exhausted. (Note that

   --  element equality is called here, not Equivalent_Elements. Set equality

   --  is the only operation in which element equality is used. Compare set

   --  equality to Equivalent_Sets, which does call Equivalent_Elements.)

   function Equivalent_Sets (Left, Right : Set) return Boolean;

   --  Similar to set equality, with the difference that the element in Left is

   --  compared to the elements in Right using the generic formal

   --  Equivalent_Elements operation instead of element equality.

   function To_Set (New_Item : Element_Type) return Set;

   --  Constructs a singleton set comprising New_Element. To_Set calls Hash to

   --  determine the bucket for New_Item.

   function Capacity (Container : Set) return Count_Type;

   --  Returns the current capacity of the set. Capacity is the maximum length

   --  before which rehashing in guaranteed not to occur.

   procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type);

   --  Adjusts the current capacity, by allocating a new buckets array. If the

   --  requested capacity is less than the current capacity, then the capacity

   --  is contracted (to a value not less than the current length). If the

   --  requested capacity is greater than the current capacity, then the

   --  capacity is expanded (to a value not less than what is requested). In

   --  either case, the nodes are rehashed from the old buckets array onto the

   --  new buckets array (Hash is called once for each existing element in

   --  order to compute the new index), and then the old buckets array is

   --  deallocated.

   function Length (Container : Set) return Count_Type;

   --  Returns the number of items in the set

   function Is_Empty (Container : Set) return Boolean;

   --  Equivalent to Length (Container) = 0

   procedure Clear (Container : in out Set);

   --  Removes all of the items from the set

   function Element (Position : Cursor) return Element_Type;

   --  Returns the element of the node designated by the cursor

   procedure Replace_Element

     (Container : in out Set;

      Position  : Cursor;

      New_Item  : Element_Type);

   --  If New_Item is equivalent (as determined by calling Equivalent_Elements)

   --  to the element of the node designated by Position, then New_Element is

   --  assigned to that element. Otherwise, it calls Hash to determine the

   --  bucket for New_Item. If the bucket is not empty, then it calls

   --  Equivalent_Elements for each node in that bucket to determine whether

   --  New_Item is equivalent to an element in that bucket. If

   --  Equivalent_Elements returns True then Program_Error is raised (because

   --  an element may appear only once in the set); otherwise, New_Item is

   --  assigned to the node designated by Position, and the node is moved to

   --  its new bucket.

   procedure Query_Element

     (Position : Cursor;

      Process  : not null access procedure (Element : Element_Type));

   --  Calls Process with the element (having only a constant view) of the node

   --  designed by the cursor.

   procedure Move (Target : in out Set; Source : in out Set);

   --  Clears Target (if it's not empty), and then moves (not copies) the

   --  buckets array and nodes from Source to Target.

   procedure Insert

     (Container : in out Set;

      New_Item  : Element_Type;

      Position  : out Cursor;

      Inserted  : out Boolean);

   --  Conditionally inserts New_Item into the set. If New_Item is already in

   --  the set, then Inserted returns False and Position designates the node

   --  containing the existing element (which is not modified). If New_Item is

   --  not already in the set, then Inserted returns True and Position

   --  designates the newly-inserted node containing New_Item. The search for

   --  an existing element works as follows. Hash is called to determine

   --  New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements

   --  is called to compare New_Item to the element of each node in that

   --  bucket. If the bucket is empty, or there were no equivalent elements in

   --  the bucket, the search "fails" and the New_Item is inserted in the set

   --  (and Inserted returns True); otherwise, the search "succeeds" (and

   --  Inserted returns False).

   procedure Insert  (Container : in out Set; New_Item : Element_Type);

   --  Attempts to insert New_Item into the set, performing the usual insertion

   --  search (which involves calling both Hash and Equivalent_Elements); if

   --  the search succeeds (New_Item is equivalent to an element already in the

   --  set, and so was not inserted), then this operation raises

   --  Constraint_Error. (This version of Insert is similar to Replace, but

   --  having the opposite exception behavior. It is intended for use when you

   --  want to assert that the item is not already in the set.)

   procedure Include (Container : in out Set; New_Item : Element_Type);

   --  Attempts to insert New_Item into the set. If an element equivalent to

   --  New_Item is already in the set (the insertion search succeeded, and

   --  hence New_Item was not inserted), then the value of New_Item is assigned

   --  to the existing element. (This insertion operation only raises an

   --  exception if cursor tampering occurs. It is intended for use when you

   --  want to insert the item in the set, and you don't care whether an

   --  equivalent element is already present.)

   procedure Replace (Container : in out Set; New_Item : Element_Type);

   --  Searches for New_Item in the set; if the search fails (because an

   --  equivalent element was not in the set), then it raises

   --  Constraint_Error. Otherwise, the existing element is assigned the value

   --  New_Item. (This is similar to Insert, but with the opposite exception

   --  behavior. It is intended for use when you want to assert that the item

   --  is already in the set.)

   procedure Exclude (Container : in out Set; Item : Element_Type);

   --  Searches for Item in the set, and if found, removes its node from the

   --  set and then deallocates it. The search works as follows. The operation

   --  calls Hash to determine the item's bucket; if the bucket is not empty,

   --  it calls Equivalent_Elements to compare Item to the element of each node

   --  in the bucket. (This is the deletion analog of Include. It is intended

   --  for use when you want to remove the item from the set, but don't care

   --  whether the item is already in the set.)

   procedure Delete  (Container : in out Set; Item : Element_Type);

   --  Searches for Item in the set (which involves calling both Hash and

   --  Equivalent_Elements). If the search fails, then the operation raises

   --  Constraint_Error. Otherwise it removes the node from the set and then

   --  deallocates it. (This is the deletion analog of non-conditional

   --  Insert. It is intended for use when you want to assert that the item is

   --  already in the set.)

   procedure Delete (Container : in out Set; Position : in out Cursor);

   --  Removes the node designated by Position from the set, and then

   --  deallocates the node. The operation calls Hash to determine the bucket,

   --  and then compares Position to each node in the bucket until there's a

   --  match (it does not call Equivalent_Elements).

   procedure Union (Target : in out Set; Source : Set);

   --  The operation first calls Reserve_Capacity if the current capacity is

   --  less than the sum of the lengths of Source and Target. It then iterates

   --  over the Source set, and conditionally inserts each element into Target.

   function Union (Left, Right : Set) return Set;

   --  The operation first copies the Left set to the result, and then iterates

   --  over the Right set to conditionally insert each element into the result.

   function "or" (Left, Right : Set) return Set renames Union;

   procedure Intersection (Target : in out Set; Source : Set);

   --  Iterates over the Target set (calling First and Next), calling Find to

   --  determine whether the element is in Source. If an equivalent element is

   --  not found in Source, the element is deleted from Target.

   function Intersection (Left, Right : Set) return Set;

   --  Iterates over the Left set, calling Find to determine whether the

   --  element is in Right. If an equivalent element is found, it is inserted

   --  into the result set.

   function "and" (Left, Right : Set) return Set renames Intersection;

   procedure Difference (Target : in out Set; Source : Set);

   --  Iterates over the Source (calling First and Next), calling Find to

   --  determine whether the element is in Target. If an equivalent element is

   --  found, it is deleted from Target.

   function Difference (Left, Right : Set) return Set;

   --  Iterates over the Left set, calling Find to determine whether the

   --  element is in the Right set. If an equivalent element is not found, the

   --  element is inserted into the result set.

   function "-" (Left, Right : Set) return Set renames Difference;

   procedure Symmetric_Difference (Target : in out Set; Source : Set);

   --  The operation first calls Reserve_Capacity if the current capacity is

   --  less than the sum of the lengths of Source and Target. It then iterates

   --  over the Source set, searching for the element in Target (calling Hash

   --  and Equivalent_Elements). If an equivalent element is found, it is

   --  removed from Target; otherwise it is inserted into Target.

   function Symmetric_Difference (Left, Right : Set) return Set;

   --  The operation first iterates over the Left set. It calls Find to

   --  determine whether the element is in the Right set. If no equivalent

   --  element is found, the element from Left is inserted into the result. The

   --  operation then iterates over the Right set, to determine whether the

   --  element is in the Left set. If no equivalent element is found, the Right

   --  element is inserted into the result.

   function "xor" (Left, Right : Set) return Set

     renames Symmetric_Difference;

   function Overlap (Left, Right : Set) return Boolean;

   --  Iterates over the Left set (calling First and Next), calling Find to

   --  determine whether the element is in the Right set. If an equivalent

   --  element is found, the operation immediately returns True. The operation

   --  returns False if the iteration over Left terminates without finding any

   --  equivalent element in Right.

   function Is_Subset (Subset : Set; Of_Set : Set) return Boolean;

   --  Iterates over Subset (calling First and Next), calling Find to determine

   --  whether the element is in Of_Set. If no equivalent element is found in

   --  Of_Set, the operation immediately returns False. The operation returns

   --  True if the iteration over Subset terminates without finding an element

   --  not in Of_Set (that is, every element in Subset is equivalent to an

   --  element in Of_Set).

   function First (Container : Set) return Cursor;

   --  Returns a cursor that designates the first non-empty bucket, by

   --  searching from the beginning of the buckets array.

   function Next (Position : Cursor) return Cursor;

   --  Returns a cursor that designates the node that follows the current one

   --  designated by Position. If Position designates the last node in its

   --  bucket, the operation calls Hash to compute the index of this bucket,

   --  and searches the buckets array for the first non-empty bucket, starting

   --  from that index; otherwise, it simply follows the link to the next node

   --  in the same bucket.

   procedure Next (Position : in out Cursor);

   --  Equivalent to Position := Next (Position)

   function Find

     (Container : Set;

      Item      : Element_Type) return Cursor;

   --  Searches for Item in the set. Find calls Hash to determine the item's

   --  bucket; if the bucket is not empty, it calls Equivalent_Elements to

   --  compare Item to each element in the bucket. If the search succeeds, Find

   --  returns a cursor designating the node containing the equivalent element;

   --  otherwise, it returns No_Element.

   function Contains (Container : Set; Item : Element_Type) return Boolean;

   --  Equivalent to Find (Container, Item) /= No_Element

   function Has_Element (Position : Cursor) return Boolean;

   --  Equivalent to Position /= No_Element

   function Equivalent_Elements (Left, Right : Cursor) return Boolean;

   --  Returns the result of calling Equivalent_Elements with the elements of

   --  the nodes designated by cursors Left and Right.

   function Equivalent_Elements

     (Left  : Cursor;

      Right : Element_Type) return Boolean;

   --  Returns the result of calling Equivalent_Elements with element of the

   --  node designated by Left and element Right.

   function Equivalent_Elements

     (Left  : Element_Type;

      Right : Cursor) return Boolean;

   --  Returns the result of calling Equivalent_Elements with element Left and

   --  the element of the node designated by Right.

   procedure Iterate

     (Container : Set;

      Process   : not null access procedure (Position : Cursor));

   --  Calls Process for each node in the set

   generic

      type Key_Type (<>) is private;

      with function Key (Element : Element_Type) return Key_Type;

      with function Hash (Key : Key_Type) return Hash_Type;

      with function Equivalent_Keys (Left, Right : Key_Type) return Boolean;

   package Generic_Keys is

      function Key (Position : Cursor) return Key_Type;

      --  Applies generic formal operation Key to the element of the node

      --  designated by Position.

      function Element (Container : Set; Key : Key_Type) return Element_Type;

      --  Searches (as per the key-based Find) for the node containing Key, and

      --  returns the associated element.

      procedure Replace

        (Container : in out Set;

         Key       : Key_Type;

         New_Item  : Element_Type);

      --  Searches (as per the key-based Find) for the node containing Key, and

      --  then replaces the element of that node (as per the element-based

      --  Replace_Element).

      procedure Exclude (Container : in out Set; Key : Key_Type);

      --  Searches for Key in the set, and if found, removes its node from the

      --  set and then deallocates it. The search works by first calling Hash

      --  (on Key) to determine the bucket; if the bucket is not empty, it

      --  calls Equivalent_Keys to compare parameter Key to the value of

      --  generic formal operation Key applied to element of each node in the

      --  bucket.

      procedure Delete (Container : in out Set; Key : Key_Type);

      --  Deletes the node containing Key as per Exclude, with the difference

      --  that Constraint_Error is raised if Key is not found.

      function Find (Container : Set; Key : Key_Type) return Cursor;

      --  Searches for the node containing Key, and returns a cursor

      --  designating the node. The search works by first calling Hash (on Key)

      --  to determine the bucket. If the bucket is not empty, the search

      --  compares Key to the element of each node in the bucket, and returns

      --  the matching node. The comparison itself works by applying the

      --  generic formal Key operation to the element of the node, and then

      --  calling generic formal operation Equivalent_Keys.

      function Contains (Container : Set; Key : Key_Type) return Boolean;

      --  Equivalent to Find (Container, Key) /= No_Element

      procedure Update_Element_Preserving_Key

        (Container : in out Set;

         Position  : Cursor;

         Process   : not null access

                       procedure (Element : in out Element_Type));

      --  Calls Process with the element of the node designated by Position,

      --  but with the restriction that the key-value of the element is not

      --  modified. The operation first makes a copy of the value returned by

      --  applying generic formal operation Key on the element of the node, and

      --  then calls Process with the element. The operation verifies that the

      --  key-part has not been modified by calling generic formal operation

      --  Equivalent_Keys to compare the saved key-value to the value returned

      --  by applying generic formal operation Key to the post-Process value of

      --  element. If the key values compare equal then the operation

      --  completes. Otherwise, the node is removed from the map and

      --  Program_Error is raised.

   end Generic_Keys;

private

   pragma Inline (Next);

   type Node_Type;

   type Node_Access is access Node_Type;

   type Node_Type is limited record

      Element : Element_Type;

      Next    : Node_Access;

   end record;

   package HT_Types is

     new Hash_Tables.Generic_Hash_Table_Types (Node_Type, Node_Access);

   type Set is new Ada.Finalization.Controlled with record

      HT : HT_Types.Hash_Table_Type;

   end record;

   overriding

   procedure Adjust (Container : in out Set);

   overriding

   procedure Finalize (Container : in out Set);

   use HT_Types;

   use Ada.Finalization;

   use Ada.Streams;

   type Set_Access is access all Set;

   for Set_Access'Storage_Size use 0;

   type Cursor is record

      Container : Set_Access;

      Node      : Node_Access;

   end record;

   procedure Write

     (Stream : not null access Root_Stream_Type'Class;

      Item   : Cursor);

   for Cursor'Write use Write;

   procedure Read

     (Stream : not null access Root_Stream_Type'Class;

      Item   : out Cursor);

   for Cursor'Read use Read;

   No_Element : constant Cursor := (Container => null, Node => null);

   procedure Write

     (Stream    : not null access Root_Stream_Type'Class;

      Container : Set);

   for Set'Write use Write;

   procedure Read

     (Stream    : not null access Root_Stream_Type'Class;

      Container : out Set);

   for Set'Read use Read;

   Empty_Set : constant Set := (Controlled with HT => (null, 0, 0, 0));

end Ada.Containers.Hashed_Sets;