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


CSolver - enforces connector semantics


#include <Unidraw/csolver.h>


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 connectivity 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.


Create a new instance. Application programs do not normally instantiate CSolver explicitly.
Specify a connection between two connectors, optionally with a piece of CGlue interposed. Omitting the CGlue parameter is equivalent to specifying a connection with CGlue having zero natural size, elasticity, and deformation limits.
Destroy the connection(s) established between two connectors (the two-parameter form), or destroy all connections to a given connector (the one-parameter form).
Solve instructs the CSolver to reorient connected connectors to conform to their connectivity semantics as reflected by its connection specifications. Normally this function is called automatically and only in response to Unidraw::Update.
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 connector, 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).
Explicitly read/write the csolver's contents from/to disk. Normally only a catalog calls these operations.


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

20 November 1990 Unidraw