| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME COMPONENTS -- |
| -- -- |
| -- G N A T . H T A B L E -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1995-2008, 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 2, 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. See the GNU General Public License -- |
| -- for more details. You should have received a copy of the GNU General -- |
| -- Public License distributed with GNAT; see file COPYING. If not, write -- |
| -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- |
| -- Boston, MA 02110-1301, USA. -- |
| -- -- |
| -- As a special exception, if other files instantiate generics from this -- |
| -- unit, or you link this unit with other files to produce an executable, -- |
| -- this unit does not by itself cause the resulting executable to be -- |
| -- covered by the GNU General Public License. This exception does not -- |
| -- however invalidate any other reasons why the executable file might be -- |
| -- covered by the GNU Public License. -- |
| -- -- |
| -- 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. |
| |
| -- Note: actual code is found in System.HTable (s-htable.ads/adb) since |
| -- this facility is accessed from run time routines, but clients should |
| -- always access the version supplied via GNAT.HTable. |
| |
| pragma Warnings (Off); |
| pragma Compiler_Unit; |
| pragma Warnings (On); |
| |
| with System.HTable; |
| |
| package GNAT.HTable is |
| pragma Preelaborate; |
| pragma Elaborate_Body; |
| -- The elaborate body is because we have a dummy body to deal with |
| -- bootstrap path problems (we used to have a real body, and now we don't |
| -- need it any more, but the bootstrap requires that we have a dummy body, |
| -- since otherwise the old body gets picked up. |
| |
| ------------------- |
| -- 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 package Simple_HTable renames System.HTable.Simple_HTable; |
| |
| -- For convenience of reference here is what this package has in it: |
| |
| -- 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 not 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 2 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. |
| -- 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 package Static_HTable renames System.HTable.Static_HTable; |
| |
| -- For convenience of reference here is what this package has in it: |
| |
| -- 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 |
| |
| -- 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. |
| |
| -- 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 2 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 function Hash renames System.HTable.Hash; |
| |
| -- generic |
| -- type Header_Num is range <>; |
| -- function Hash (Key : String) return Header_Num; |
| |
| end GNAT.HTable; |