+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNAT RUNTIME COMPONENTS --
--- --
--- G N A T . H T A B L E --
--- --
--- S p e c --
--- --
--- $Revision: 1.1 $
--- --
--- Copyright (C) 1995-2001 Ada Core Technologies, Inc. --
--- --
--- 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, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, 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 is maintained by Ada Core Technologies Inc (http://www.gnat.com). --
--- --
-------------------------------------------------------------------------------
-
--- Hash table searching routines
-
--- This package contains two separate packages. The Simple_Htable package
--- provides a very simple abstraction that asosicates one element to one
--- key values and takes care of all allocation automatically using the heap.
--- The Static_Htable package provides a more complex interface that allows
--- complete control over allocation.
-
-package GNAT.HTable is
-pragma Preelaborate (HTable);
-
- -------------------
- -- 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 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
- 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 bever 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 GNAT.HTable;
projects / msp430-gcc.git / blobdiff