-- Created on: 1992-02-03
-- Created by: Christian CAILLET
-- Copyright (c) 1992-1999 Matra Datavision
-- Copyright (c) 1999-2012 OPEN CASCADE SAS
--
-- The content of this file is subject to the Open CASCADE Technology Public
-- License Version 6.5 (the "License"). You may not use the content of this file
-- except in compliance with the License. Please obtain a copy of the License
-- at http://www.opencascade.org and read it completely before using this file.
--
-- The Initial Developer of the Original Code is Open CASCADE S.A.S., having its
-- main offices at: 1, place des Freres Montgolfier, 78280 Guyancourt, France.
--
-- The Original Code and all software distributed under the License is
-- distributed on an "AS IS" basis, without warranty of any kind, and the
-- Initial Developer hereby disclaims all such warranties, including without
-- limitation, any warranties of merchantability, fitness for a particular
-- purpose or non-infringement. Please see the License for the specific terms
-- and conditions governing the rights and limitations under the License.



deferred generic class Recognizer  from Interface
        (TheKey as any;
    	 TheResul as Transient)
    inherits Transient

    ---Purpose : Defines a correspondance between an object to be recognized,
    --           of type (Kind) TheKey, and a result of the recognition. There
    --           can be no correspondance. When an object is recognized, the
    --           returned result is empty : a Recognizer is not aimed to make
    --           a transfer but to initiate it by giving a correspondant
    --           
    --           A Recognizer can be compound, that is, in addition to its own
    --           Eval method if this one has failed, it can ask another
    --           Recognizer to work, and so on : See method Add

raises NoSuchObject


is

    Initialize;
    ---Purpose : Assumes that no result has yet been recognized

    Evaluate (me : mutable; akey : TheKey; res : out mutable TheResul)
    	returns Boolean;
    ---Purpose : Evaluates if recognition has a result, returns it if yes
    --           In case of success, Returns True and puts result in "res"
    --           In case of Failure, simply Returns False
    --           Works by calling deferred method Eval, and in case of failure,
    --           looks for Added Recognizers to work

    Result (me) returns mutable TheResul  raises NoSuchObject;
    ---Purpose : Returns result of last recognition (call of Evaluate)

    Add (me : mutable; reco : mutable Recognizer);
    ---Purpose : Adds a new Recognizer to the Compound, at the end
    --           Several calls to Add work by adding in the order of calls :
    --           Hence, when Eval has failed to recognize, Evaluate will call
    --	         Evaluate from the first added Recognizer if there is one,
    --	         and to the second if there is still no result, and so on

    SetOK (me : mutable; aresult : mutable TheResul) is protected;
    ---Purpose : Records the result of the recognition. Called by specific
    --           method Eval to record a result : after calling it, Eval has
    --           finished and can return

    SetKO (me : mutable) is protected;
    ---Purpose : Records that recognition gives no result

    Eval (me : mutable; akey : TheKey) is deferred protected;
    ---Purpose : THIS METHOD DEFINES THE RECOGNITION PROTOCOL, it is proper to
    --           each precise type of Recognizer
    --           For a suitable type of akey, it calls SetOK(result) where
    --           result is an empty result of appropriate type, then returns

fields

    theres : TheResul;     -- storing result of last evaluation

    hasnext : Boolean;
    thenext : Recognizer;  -- managing compound definition

end Recognizer;