Some aspects of error correction of programming languages

Abstract

The thesis treats the problem of error correction in a context free language, and the design of an error correcting parser for the BASIC language.

Two important things can be said about this thesis. First, it presents the problem of error correction in a context free language, and the existing results in the field. The concept of a context free language as a model for a programming language, and the definitions and results used later are presented or reviewed. A distance between two strings is defined and used to develop a “minimum distance error correcting parser”.

Second, the thesis develops two global error correcting parsers. The first one is the top-down global error correcting parser, obtained by transforming Unger’s top-down parser into an error correcting one.

Then the idea of Graham and Rhodes, of condensing the surrounding context of error, is extended, and a global simple precedence error correcting parser is obtained by analysing the whole content of the error, available from the input string.

These parsers, and other known methods are then used to design and partially implement an error correcting parser for BASIC.