Incremental Type Checking in OCL Compilers

In software engineering, modeling tools have become widely accepted to increase application reliability and decrease development time. The UML and the OCL became industry standards and are supported by many Computer-Aided Software Engineering tools. The increasing number of modeled functionalities results in complex models that need more and more textual constraints to express the hidden restrictions applying to the systems. The usual scenario of model development is to create an initial model of the system, and then fine-tune it with simple modifications. During development, rebuilding all the constraints is unnecessary when only a few changes have been applied. In this paper, we present an algorithm that handles changes incrementally on expression level, thus required rebuilds are kept to a minimum. The background and implementation framework for the discussed compiler is the Visual Modeling and Transformation System, but the algorithm is general enough to support any tree-based compiler integrated into an IDE.