CSolver(3U)						    InterViews Reference Manual 					       CSolver(3U)

NAME

       CSolver - enforces connector semantics

SYNOPSIS

       #include <Unidraw/csolver.h>

DESCRIPTION

       A CSolver object defines and implements a model for specifying connectivity semantics that connector subclasses can build upon to implement
       their specialized semantics.  Normally, only one CSolver instance is used per application, and only connector subclasses  need  access  it.
       The  Unidraw  class  constructor  initializes  the  csolver global to point to a CSolver instance it creates.  Thus applications should not
       instantiate CSolver directly.

       CSolver models a connection between two connectors (regardless of their particular subclass or semantics) as a pair of  generic	connectors
       with  a	piece  of  CGlue  interposed.  The CGlue characterizes the relationship between the connectors' centers in terms of a natural size
       (which corresponds to the distance between the centers), elasticity, and deformation limits.  Connector subclasses specify their connectiv-
       ity  behavior with a CGlue instance and subsequently rely on the CSolver to reorient them to conform to that behavior.  For example, when a
       pin is told to connect itself to another pin, it registers with the global csolver a connection containing the  two  connectors	(the  pins
       themselves)  and  a piece of CGlue having zero natural size, elasticity, and deformation limits.  This specification effectively constrains
       the connectors' centers to coincide.  The connectivity semantics of other connector combinations, including  those  involving  application-
       specific connectors, must be specified using CGlue.

PUBLIC OPERATIONS

       CSolver()
	      Create a new instance.  Application programs do not normally instantiate CSolver explicitly.

       virtual void Connect(Connector*, Connector*, CGlue* = nil)
	      Specify  a  connection between two connectors, optionally with a piece of CGlue interposed.  Omitting the CGlue parameter is equiva-
	      lent to specifying a connection with CGlue having zero natural size, elasticity, and deformation limits.

       void Disconnect(Connector*, Connector*)
       void Disconnect(Connector*)
	      Destroy the connection(s) established between two connectors (the two-parameter form), or destroy all connections to a given connec-
	      tor (the one-parameter form).

       void Solve()
	      Solve  instructs the CSolver to reorient connected connectors to conform to their connectivity semantics as reflected by its connec-
	      tion specifications.  Normally this function is called automatically and only in response to Unidraw::Update.

       CSolverState* GetState(Connector*)
       void SetState(CSolverState*)
	      CSolverState is a class that encapsulates all the information about the connections in which a connector participates.  Only CSolver
	      can  create or do anything with a CSolverState instance. GetState initializes and returns a CSolverState instance for the given con-
	      nector, and SetState establishes the connections that a CSolverState instance specifies  without	disturbing  existing  connections.
	      These operations are useful when it is necessary to reestablish a connector's connections after they have been lost, for example, by
	      removing the connector from the component hierarchy (as caused by a command to delete the component).

       void Read(istream&)
       void Write(ostream&)
	      Explicitly read/write the csolver's contents from/to disk.  Normally only a catalog calls these operations.

SEE ALSO

       Catalog(3U), GGlue(3U), Connector(3U), globals(3U)

Unidraw 							 20 November 1990						       CSolver(3U)