------------------------------------------------------------------------------ -- -- -- 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) 2004-2024, 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 -- -- . -- -- -- -- This unit was originally developed by Matthew J Heaney. -- ------------------------------------------------------------------------------ with Ada.Iterator_Interfaces; private with Ada.Containers.Hash_Tables; with Ada.Containers.Helpers; private with Ada.Finalization; private with Ada.Streams; private with Ada.Strings.Text_Buffers; 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 with SPARK_Mode => Off is pragma Annotate (CodePeer, Skip_Analysis); pragma Preelaborate; pragma Remote_Types; type Set is tagged private with Constant_Indexing => Constant_Reference, Default_Iterator => Iterate, Iterator_Element => Element_Type, Aggregate => (Empty => Empty, Add_Unnamed => Include); pragma Preelaborable_Initialization (Set); type Cursor is private; pragma Preelaborable_Initialization (Cursor); function "=" (Left, Right : Cursor) return Boolean; -- The representation of cursors includes a component used to optimize -- iteration over sets. This component may become unreliable after -- multiple set insertions, and must be excluded from cursor equality, -- so we need to provide an explicit definition for it, instead of -- using predefined equality (as implied by a questionable comment -- in the RM). This is also the case for hashed maps, and affects the -- use of Insert primitives in hashed structures. 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 Has_Element (Position : Cursor) return Boolean; -- Equivalent to Position /= No_Element package Set_Iterator_Interfaces is new Ada.Iterator_Interfaces (Cursor, Has_Element); function Empty (Capacity : Count_Type := 1000) return Set; 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. type Constant_Reference_Type (Element : not null access constant Element_Type) is private with Implicit_Dereference => Element; function Constant_Reference (Container : aliased Set; Position : Cursor) return Constant_Reference_Type; pragma Inline (Constant_Reference); procedure Assign (Target : in out Set; Source : Set); function Copy (Source : Set; Capacity : Count_Type := 0) return Set; 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 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 function Iterate (Container : Set) return Set_Iterator_Interfaces.Forward_Iterator'Class; -- Ada 2022 features: function Has_Element (Container : Set; Position : Cursor) return Boolean; function Tampering_With_Cursors_Prohibited (Container : Set) return Boolean; function Element (Container : Set; Position : Cursor) return Element_Type; procedure Query_Element (Container : Set; Position : Cursor; Process : not null access procedure (Element : Element_Type)); function Next (Container : Set; Position : Cursor) return Cursor; procedure Next (Container : Set; Position : in out Cursor); ---------------- 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 Key (Container : Set; Position : Cursor) return Key_Type is (Key (Element (Container, 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 set and -- Program_Error is raised. type Reference_Type (Element : not null access Element_Type) is private with Implicit_Dereference => Element; function Reference_Preserving_Key (Container : aliased in out Set; Position : Cursor) return Reference_Type; function Constant_Reference (Container : aliased Set; Key : Key_Type) return Constant_Reference_Type; function Reference_Preserving_Key (Container : aliased in out Set; Key : Key_Type) return Reference_Type; private use Ada.Streams; type Set_Access is access all Set; for Set_Access'Storage_Size use 0; -- Key_Preserving references must carry information to allow removal -- of elements whose value may have been altered improperly, i.e. have -- been given values incompatible with the hash-code of the previous -- value, and are thus in the wrong bucket. (RM 18.7 (96.6/3)) -- We cannot store the key directly because it is an unconstrained type. -- To avoid using additional dynamic allocation we store the old cursor -- which simplifies possible removal. This is not possible for some -- other set types. -- The mechanism is different for Update_Element_Preserving_Key, as -- in that case the check that buckets have not changed is performed -- at the time of the update, not when the reference is finalized. package Impl is new Helpers.Generic_Implementation; type Reference_Control_Type is new Impl.Reference_Control_Type with record Container : Set_Access; Index : Hash_Type; Old_Pos : Cursor; Old_Hash : Hash_Type; end record; overriding procedure Finalize (Control : in out Reference_Control_Type); pragma Inline (Finalize); type Reference_Type (Element : not null access Element_Type) is record Control : Reference_Control_Type; end record; procedure Read (Stream : not null access Root_Stream_Type'Class; Item : out Reference_Type); for Reference_Type'Read use Read; procedure Write (Stream : not null access Root_Stream_Type'Class; Item : Reference_Type); for Reference_Type'Write use Write; end Generic_Keys; private pragma Inline (Next); type Node_Type; type Node_Access is access Node_Type; type Node_Type is limited record Element : aliased 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 with Put_Image => Put_Image; procedure Put_Image (S : in out Ada.Strings.Text_Buffers.Root_Buffer_Type'Class; V : Set); overriding procedure Adjust (Container : in out Set); overriding procedure Finalize (Container : in out Set); use HT_Types, HT_Types.Implementation; use Ada.Finalization; use Ada.Streams; 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; type Set_Access is access all Set; for Set_Access'Storage_Size use 0; type Cursor is record Container : Set_Access; -- Access to this cursor's container Node : Node_Access; -- Access to the node pointed to by this cursor Position : Hash_Type := Hash_Type'Last; -- Position of the node in the buckets of the container. If this is -- equal to Hash_Type'Last, then it will not be used. Position is -- not requried by the implementation, but improves the efficiency -- of various operations. -- -- However, this value must be maintained so that the predefined -- equality operation acts as required by RM A.18.7-17/2, which -- states: "The predefined "=" operator for type Cursor returns True -- if both cursors are No_Element, or designate the same element -- in the same container." 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; subtype Reference_Control_Type is Implementation.Reference_Control_Type; -- It is necessary to rename this here, so that the compiler can find it type Constant_Reference_Type (Element : not null access constant Element_Type) is record Control : Reference_Control_Type := raise Program_Error with "uninitialized reference"; -- The RM says, "The default initialization of an object of -- type Constant_Reference_Type or Reference_Type propagates -- Program_Error." end record; procedure Read (Stream : not null access Root_Stream_Type'Class; Item : out Constant_Reference_Type); for Constant_Reference_Type'Read use Read; procedure Write (Stream : not null access Root_Stream_Type'Class; Item : Constant_Reference_Type); for Constant_Reference_Type'Write use Write; -- See Ada.Containers.Vectors for documentation on the following procedure _Next (Position : in out Cursor) renames Next; function Pseudo_Reference (Container : aliased Set'Class) return Reference_Control_Type; pragma Inline (Pseudo_Reference); -- Creates an object of type Reference_Control_Type pointing to the -- container, and increments the Lock. Finalization of this object will -- decrement the Lock. type Element_Access is access all Element_Type with Storage_Size => 0; function Get_Element_Access (Position : Cursor) return not null Element_Access; -- Returns a pointer to the element designated by Position. Empty_Set : constant Set := (Controlled with others => <>); No_Element : constant Cursor := (Container => null, Node => null, Position => Hash_Type'Last); type Iterator is new Limited_Controlled and Set_Iterator_Interfaces.Forward_Iterator with record Container : Set_Access; end record with Disable_Controlled => not T_Check; overriding function First (Object : Iterator) return Cursor; overriding function Next (Object : Iterator; Position : Cursor) return Cursor; overriding procedure Finalize (Object : in out Iterator); end Ada.Containers.Hashed_Sets;