Syntax-directed editor for subset of VAS VMS Pascal

Syntax-Directed editor, SYNED is designed for a subset of VAX VMS Pascal 8350 mini computer system at De La Salle University. SYNED is designed to detect syntax errors as the source program is edited. The theory of syntax direction for the languages is well supported by the reference we have included and in fact there are several Syntax-Directed editors implemented on various systems. It involves the theory and concepts on Editor and Compiler building. We shall briefly discuss only the important theories and concepts being used in design and implementation of SYNED. The single most important theory used is the incremental parsing concept. The crux of the incremental parsing is still the LR parsing algorithm. LR parsing is extended by the following ways: suitable design of a special editor data structure, special treatment of the symbol table, mechanism of saving the shift-reduce stacks for all lines parsed, and extension of LR parsing algorithm to deal with this new demand of incremental parsing. It uses the LALR parsing tables generated by YACC. SYNED is only capable of detecting simple type errors. Not withstanding the importance of incremental parsing, the design of the editor is equally important in the areas of windowing system, file functions, help features, diagnostic capabilities, and an integrated environment of Compile and Run. Lastly, the SYNED test results of diagnostic capability and speed indicate that the requirements were successfully met