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-- File: Interface_GeneralModule.cdl
-- Created: Tue Feb 2 12:20:12 1993
-- Author: Christian CAILLET
-- <cky@phobox>
---Copyright: Matra Datavision 1993
deferred class GeneralModule from Interface inherits TShared
---Purpose : This class defines general services, which must be provided
-- for each type of Entity (i.e. of Transient Object processed
-- by an Interface) : Shared List, Check, Copy, Delete, Category
--
-- To optimise processing (e.g. firstly bind an Entity to a Module
-- then calls Module), each recognized Entity Type corresponds
-- to a Case Number, determined by the Protocol each class of
-- GeneralModule belongs to.
uses Transient, HAsciiString from TCollection,
InterfaceModel, ShareTool, Check, EntityIterator, CopyTool
is
FillShared (me; model : InterfaceModel; CN : Integer; ent : Transient;
iter : in out EntityIterator) is virtual;
---Purpose : Specific filling of the list of Entities shared by an Entity
-- <ent>, according a Case Number <CN> (formerly computed by
-- CaseNum), considered in the context of a Model <model>
-- Default calls FillSharedCase (i.e., ignores the model)
-- Can be redefined to use the model for working
FillSharedCase (me; CN : Integer; ent : Transient;
iter : in out EntityIterator) is deferred;
---Purpose : Specific filling of the list of Entities shared by an Entity
-- <ent>, according a Case Number <CN> (formerly computed by
-- CaseNum). Can use the internal utility method Share, below
Share (me; iter : in out EntityIterator; shared : Transient);
---Purpose : Adds an Entity to a Shared List (uses GetOneItem on <iter>)
ListImplied (me; model : InterfaceModel; CN : Integer; ent : Transient;
iter : in out EntityIterator) is virtual;
---Purpose : List the Implied References of <ent> considered in the context
-- of a Model <model> : i.e. the Entities which are Referenced
-- while not considered as Shared (not copied if <ent> is,
-- references not renewed by CopyCase but by ImpliedCase, only
-- if referenced Entities have been Copied too)
-- FillShared + ListImplied give the complete list of References
-- Default calls ListImpliedCase (i.e. ignores the model)
-- Can be redefined to use the model for working
ListImpliedCase (me; CN : Integer; ent : Transient;
iter : in out EntityIterator) is virtual;
---Purpose : List the Implied References of <ent> (see above)
-- are Referenced while not considered as Shared (not copied if
-- <ent> is, references not renewed by CopyCase but by
-- ImpliedCase, only if referenced Entities have been Copied too)
-- FillSharedCase + ListImpliedCase give the complete list of
-- Referenced Entities
-- The provided default method does nothing (Implied References
-- are specific of a little amount of Entity Classes).
CheckCase (me; CN : Integer; ent : Transient; shares : ShareTool;
ach : in out Check) is deferred;
---Purpose : Specific Checking of an Entity <ent>
-- Can check context queried through a ShareTool, as required
CanCopy (me; CN : Integer; ent : Transient) returns Boolean is virtual;
---Purpose : Specific answer to the question "is Copy properly implemented"
-- Remark that it should be in phase with the implementation of
-- NewVoid+CopyCase/NewCopyCase
-- Default returns always False, can be redefined
Dispatch (me; CN : Integer;
entfrom : Transient; entto : out mutable Transient;
TC : in out CopyTool) returns Boolean is virtual;
---Purpose : Dispatches an entity
-- Returns True if it works by copy, False if it just duplicates
-- the starting Handle
--
-- Dispatching means producing a new entity, image of the
-- starting one, in order to be put into a new Model, this Model
-- being itself the result of a dispatch from an original Model
--
-- According to the cases, dispatch can either
-- * just return <entto> as equating <entfrom>
-- -> the new model designates the starting entity : it is
-- lighter, but the dispatched entity being shared might not be
-- modified for dispatch
-- * copy <entfrom> to <entto>
-- by calling NewVoid+CopyCase (two steps) or NewCopiedCase (1)
-- -> the dispatched entity is a COPY, hence it can be modified
--
-- The provided default just duplicates the handle without
-- copying, then returns False. Can be redefined
NewVoid (me; CN : Integer; entto : out mutable Transient)
returns Boolean is deferred;
---Purpose : Creates a new void entity <entto> according to a Case Number
-- This entity remains to be filled, by reading from a file or
-- by copying from another entity of same type (see CopyCase)
CopyCase (me; CN : Integer;
entfrom : Transient; entto : mutable Transient;
TC : in out CopyTool) is deferred;
---Purpose : Specific Copy ("Deep") from <entfrom> to <entto> (same type)
-- by using a CopyTool which provides its working Map.
-- Use method Transferred from CopyTool to work
NewCopiedCase (me; CN : Integer;
entfrom : Transient; entto : out mutable Transient;
TC : in out CopyTool) returns Boolean is virtual;
---Purpose : Specific operator (create+copy) defaulted to do nothing.
-- It can be redefined : When it is not possible to work in two
-- steps (NewVoid then CopyCase). This can occur when there is
-- no default constructor : hence the result <entto> must be
-- created with an effective definition.
-- Remark : if NewCopiedCase is defined, CopyCase has nothing to do
-- Returns True if it has produced something, false else
RenewImpliedCase (me; CN : Integer;
entfrom : Transient; entto : mutable Transient;
TC : CopyTool) is virtual;
---Purpose : Specific Copying of Implied References
-- A Default is provided which does nothing (must current case !)
-- Already copied references (by CopyFrom) must remain unchanged
-- Use method Search from CopyTool to work
WhenDeleteCase (me; CN : Integer;
ent : mutable Transient; dispatched : Boolean) is virtual;
---Purpose : Prepares an entity to be deleted. What does it mean :
-- Basically, any class of entity may define its own destructor
-- By default, it does nothing but calling destructors on fields
-- With the Memory Manager, it is useless to call destructor,
-- it is done automatically when the Handle is nullified(cleared)
-- BUT this is ineffective in looping structures (whatever these
-- are "Implied" references or not).
--
-- THUS : if no loop may appear in definitions, a class which
-- inherits from TShared is correctly managed by automatic way
-- BUT if there can be loops (or simply back pointers), they must
-- be broken, for instance by clearing fields of one of the nodes
-- The default does nothing, to be redefined if a loop can occur
-- (Implied generally requires WhenDelete, but other cases can
-- occur)
--
-- Warning : <dispatched> tells if the entity to be deleted has been
-- produced by Dispatch or not. Hence WhenDelete must be in
-- coherence with Dispatch
-- Dispatch can either copy or not.
-- If it copies the entity, this one should be deleted
-- If it doesnt (i.e. duplicates the handle) nothing to do
--
-- If <dispatch> is False, normal deletion is to be performed
CategoryNumber (me; CN : Integer; ent : Transient; shares : ShareTool)
returns Integer is virtual;
---Purpose : Returns a category number which characterizes an entity
-- Category Numbers are managed by the class Category
-- <shares> can be used to evaluate this number in the context
-- Default returns 0 which means "unspecified"
Name (me; CN : Integer; ent : Transient; shares : ShareTool)
returns HAsciiString from TCollection is virtual;
---Purpose : Determines if an entity brings a Name (or widerly, if a Name
-- can be attached to it, through the ShareTool
-- By default, returns a Null Handle (no name can be produced)
-- Can be redefined
--
-- Warning : While this string may be edited on the spot, if it is a read
-- field, the returned value must be copied before.
end GeneralModule;
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