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diff --git a/gcc/ada/libgnat/s-htable.ads b/gcc/ada/libgnat/s-htable.ads new file mode 100644 index 00000000000..b6d9960167b --- /dev/null +++ b/gcc/ada/libgnat/s-htable.ads @@ -0,0 +1,222 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT RUN-TIME COMPONENTS -- +-- -- +-- S Y S T E M . H T A B L E -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 1995-2017, AdaCore -- +-- -- +-- 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/>. -- +-- -- +-- GNAT was originally developed by the GNAT team at New York University. -- +-- Extensive contributions were provided by Ada Core Technologies Inc. -- +-- -- +------------------------------------------------------------------------------ + +-- Hash table searching routines + +-- This package contains two separate packages. The Simple_HTable package +-- provides a very simple abstraction that associates one element to one +-- key value and takes care of all allocations automatically using the heap. +-- The Static_HTable package provides a more complex interface that allows +-- complete control over allocation. + +pragma Compiler_Unit_Warning; + +package System.HTable is + pragma Preelaborate; + + ------------------- + -- Simple_HTable -- + ------------------- + + -- A simple hash table abstraction, easy to instantiate, easy to use. + -- The table associates one element to one key with the procedure Set. + -- Get retrieves the Element stored for a given Key. The efficiency of + -- retrieval is function of the size of the Table parameterized by + -- Header_Num and the hashing function Hash. + + generic + type Header_Num is range <>; + -- An integer type indicating the number and range of hash headers + + type Element is private; + -- The type of element to be stored + + No_Element : Element; + -- The object that is returned by Get when no element has been set for + -- a given key + + type Key is private; + with function Hash (F : Key) return Header_Num; + with function Equal (F1, F2 : Key) return Boolean; + + package Simple_HTable is + + procedure Set (K : Key; E : Element); + -- Associates an element with a given key. Overrides any previously + -- associated element. + + procedure Reset; + -- Removes and frees all elements in the table + + function Get (K : Key) return Element; + -- Returns the Element associated with a key or No_Element if the + -- given key has no associated element. + + procedure Remove (K : Key); + -- Removes the latest inserted element pointer associated with the + -- given key if any, does nothing if none. + + function Get_First return Element; + -- Returns No_Element if the HTable is empty, otherwise returns one + -- non specified element. There is no guarantee that two calls to this + -- function will return the same element. + + function Get_Next return Element; + -- Returns a non-specified element that has not been returned by the + -- same function since the last call to Get_First or No_Element if + -- there is no such element. If there is no call to Set in between + -- Get_Next calls, all the elements of the HTable will be traversed. + + procedure Get_First (K : in out Key; E : out Element); + -- This version of the iterator returns a key/element pair. A non- + -- specified entry is returned, and there is no guarantee that two + -- calls to this procedure will return the same element. If the table + -- is empty, E is set to No_Element, and K is unchanged, otherwise + -- K and E are set to the first returned entry. + + procedure Get_Next (K : in out Key; E : out Element); + -- This version of the iterator returns a key/element pair. It returns + -- a non-specified element that has not been returned since the last + -- call to Get_First. If there is no remaining element, then E is set + -- to No_Element, and the value in K is unchanged, otherwise K and E + -- are set to the next entry. If there is no call to Set in between + -- Get_Next calls, all the elements of the HTable will be traversed. + + end Simple_HTable; + + ------------------- + -- Static_HTable -- + ------------------- + + -- A low-level Hash-Table abstraction, not as easy to instantiate as + -- Simple_HTable but designed to allow complete control over the + -- allocation of necessary data structures. Particularly useful when + -- dynamic allocation is not desired. The model is that each Element + -- contains its own Key that can be retrieved by Get_Key. Furthermore, + -- Element provides a link that can be used by the HTable for linking + -- elements with same hash codes: + + -- Element + + -- +-------------------+ + -- | Key | + -- +-------------------+ + -- : other data : + -- +-------------------+ + -- | Next Elmt | + -- +-------------------+ + + generic + type Header_Num is range <>; + -- An integer type indicating the number and range of hash headers + + type Element (<>) is limited private; + -- The type of element to be stored. This is historically part of the + -- interface, even though it is not used at all in the operations of + -- the package. + + pragma Warnings (Off, Element); + -- We have to kill warnings here, because Element is and always + -- has been unreferenced, but we cannot remove it at this stage, + -- since this unit is in wide use, and it certainly seems harmless. + + type Elmt_Ptr is private; + -- The type used to reference an element (will usually be an access + -- type, but could be some other form of type such as an integer type). + + Null_Ptr : Elmt_Ptr; + -- The null value of the Elmt_Ptr type + + with procedure Set_Next (E : Elmt_Ptr; Next : Elmt_Ptr); + with function Next (E : Elmt_Ptr) return Elmt_Ptr; + -- The type must provide an internal link for the sake of the + -- staticness of the HTable. + + type Key is limited private; + with function Get_Key (E : Elmt_Ptr) return Key; + with function Hash (F : Key) return Header_Num; + with function Equal (F1, F2 : Key) return Boolean; + + package Static_HTable is + + procedure Reset; + -- Resets the hash table by setting all its elements to Null_Ptr. The + -- effect is to clear the hash table so that it can be reused. For the + -- most common case where Elmt_Ptr is an access type, and Null_Ptr is + -- null, this is only needed if the same table is reused in a new + -- context. If Elmt_Ptr is other than an access type, or Null_Ptr is + -- other than null, then Reset must be called before the first use + -- of the hash table. + + procedure Set (E : Elmt_Ptr); + -- Insert the element pointer in the HTable + + function Get (K : Key) return Elmt_Ptr; + -- Returns the latest inserted element pointer with the given Key + -- or null if none. + + function Present (K : Key) return Boolean; + -- True if an element whose Get_Key is K is in the table + + function Set_If_Not_Present (E : Elmt_Ptr) return Boolean; + -- If Present (Get_Key (E)), returns False. Otherwise, does Set (E), and + -- then returns True. Present (Get_Key (E)) is always True afterward, + -- and the result True indicates E is newly Set. + + procedure Remove (K : Key); + -- Removes the latest inserted element pointer associated with the + -- given key if any, does nothing if none. + + function Get_First return Elmt_Ptr; + -- Returns Null_Ptr if the HTable is empty, otherwise returns one + -- non specified element. There is no guarantee that two calls to this + -- function will return the same element. + + function Get_Next return Elmt_Ptr; + -- Returns a non-specified element that has not been returned by the + -- same function since the last call to Get_First or Null_Ptr if + -- there is no such element or Get_First has never been called. If + -- there is no call to 'Set' in between Get_Next calls, all the + -- elements of the HTable will be traversed. + + end Static_HTable; + + ---------- + -- Hash -- + ---------- + + -- A generic hashing function working on String keys + + generic + type Header_Num is range <>; + function Hash (Key : String) return Header_Num; + +end System.HTable; |