Language Definition in the Schütz Semantic Editor

Abstract

The Schütz semantic editor intends to perform semantic analysis, incrementally during editing, on possibly incomplete and incorrect programs. Currently, the project is addressing a prerequisite problem of maintaining an internal tree representation, necessary for semantic analysis, while presenting the user with a text-editor style interface, essential for programmer acceptance. Prior papers have addressed the language-independent aspects of our data structure and algorithms. Here, we discuss our specifications of the language to be edited. These are initially written in a purpose-designed Language Definition Language (LDL), then transformed into internal form needed by the editor. Our approach is to first build a syntactic editor for its own LDL, then use this to define an editor for its own implementation language, i.e., Modula-3, add incremental semantics, and finally to define editors for other programming languages. We summarize our language-independent data structure and algorithms and how they are specialized for a specific language. We describe our LDL in detail and how it has evolved to support Modula-3. The current implementation supports editing of LDL descriptions. The principal contribution of this paper is that LDL is an essential part of our method of providing an acceptable user-interface, without which semantic editing would be irrelevant.