-- File:	Interface_Protocol.cdl
-- Created:	Tue Feb  2 11:35:43 1993
-- Author:	Christian CAILLET
--		<cky@phobox>
---Copyright:	 Matra Datavision 1993


deferred class Protocol  from Interface  inherits TShared

    ---Purpose : General description of Interface Protocols. A Protocol defines
    --           a set of Entity types. This class provides also the notion of
    --           Active Protocol, as a working context, defined once then
    --           exploited by various Tools and Libraries.
    --           
    --           It also gives control of type definitions. By default, types
    --           are provided by CDL, but specific implementations, or topics
    --           like multi-typing, may involve another way

uses InterfaceModel, Check, Graph

raises InterfaceError

is

    	--  --    Management of Active Protocol    -- --

    Active (myclass) returns Protocol;
    ---Purpose : Returns the Active Protocol, if defined (else, returns a
    --           Null Handle, which means "no defined active protocol")

    SetActive (myclass; aprotocol : Protocol);
    ---Purpose : Sets a given Protocol to be the Active one (for the users of
    --           Active, see just above). Applies to every sub-type of Protocol

    ClearActive (myclass);
    ---Purpose : Erases the Active Protocol (hence it becomes undefined)

    	-- --    General Definition (complies with Template)    -- --

    NbResources (me) returns Integer  is deferred;
    ---Purpose : Returns count of Protocol used as Resources (level one)

    Resource (me; num : Integer) returns Protocol  is deferred;
    ---Purpose : Returns a Resource, given its rank (between 1 and NbResources)

    CaseNumber (me; obj : any Transient) returns Integer  is virtual;
    ---Purpose : Returns a unique positive CaseNumber for each Recognized
    --           Object. By default, recognition is based on Type(1)
    --           By default, calls the following one which is deferred.

    IsDynamicType (me; obj : any Transient) returns Boolean  is virtual;
    ---Purpose : Returns True if type of <obj> is that defined from CDL
    --           This is the default but it may change according implementation

    NbTypes (me; obj : any Transient) returns Integer  is virtual;
    ---Purpose : Returns the count of DISTINCT types under which an entity may
    --           be processed. Each one is candidate to be recognized by
    --           TypeNumber, <obj> is then processed according it
    --           By default, returns 1 (the DynamicType)

    Type    (me; obj : any Transient; nt : Integer = 1) returns Type;
    ---Purpose : Returns a type under which <obj> can be recognized and
    --           processed, according its rank in its definition list (see
    --           NbTypes).
    --           By default, returns DynamicType

    TypeNumber (me; atype : any Type) returns Integer  is deferred;
    ---Purpose : Returns a unique positive CaseNumber for each Recognized Type,
    --           Returns Zero for "<type> not recognized"

    GlobalCheck (me; G : Graph; ach : in out Check)
    	returns Boolean  is virtual;
    ---Purpose : Evaluates a Global Check for a model (with its Graph)
    --           Returns True when done, False if data in model do not apply
    --           
    --           Very specific of each norm, i.e. of each protocol : the
    --           uppest level Protocol assumes it, it can call GlobalCheck of
    --           its ressources only if it is necessary
    --           
    --           Default does nothing, can be redefined

    	-- --    General Services (defined at Norm level)    -- --

    NewModel (me) returns mutable InterfaceModel  is deferred;
    ---Purpose : Creates an empty Model of the considered Norm

    IsSuitableModel (me; model : InterfaceModel)  returns Boolean  is deferred;
    ---Purpose : Returns True if <model> is a Model of the considered Norm


    UnknownEntity (me) returns mutable Transient  is deferred;
    ---Purpose : Creates a new Unknown Entity for the considered Norm

    IsUnknownEntity (me; ent : Transient) returns Boolean  is deferred;
    ---Purpose : Returns True if <ent> is an Unknown Entity for the Norm, i.e.
    --           same Type as them created by method UnknownEntity
    --           (for an Entity out of the Norm, answer can be unpredicable)

end Protocol;