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This dissertation addresses the problem of creating interactive graphical programming environments for visual programming languages that are based on directed graph models of computation. Such programming environments are essential to using these languages but their complexity makes them difficult and time consuming to construct. The dissertation describes a high level specification language, Glide, for defining integrated graphical/textual programming environments for such languages. It also describes the design of a translation system, Glider, which generates an executable representation from specifications in the Glide language. Glider is a programming environment generator; it automates the task of creating the programming environments used for developing programs in graph-based visual languages. The capabilities supported by the synthesized programming environments include both program capture and animation of executing programs.
The significant concepts developed for this work and embodied in the abstractions provided by the Glide language are: an approach to treating programs as structured data in a way that allows an integrated representation of graph and text structure; a means to navigate through the structure to identify program components; a query language to concisely identify collections of components in the structure so that selective views of program components can be specified; a unified means of representing changes to the structure so that editing, execution, and animation semantics associated with the language can all be captured in a uniform way; and a means to associate the graphical capabilities of user interface libraries with displaying components of the language.
The data modeling approach embodied in the Glide specification language is a powerful new way of representing graph-based visual languages. The approach extends the traditional restricted mechanisms for specifying composition of text language structure. The extensions allow programming in visual languages to be expressed as a seamless extension of programming in text-based languages.
A data model of a graph-based visual language specified in Glide forms the basis for specifying the program editing, language execution semantics, and program animation in a concise and abstract way.