Developing a Back-end Compatibility Check for the BNF Converter

Abstract

There exist various architectural models for structuring large-scale software projects. A common pattern employed in various systems involves decomposing the application into a user-facing front-end component, responsible for input validation, and several back-end components, which perform subsequent processing and generate output. In such a system, each back-end may target a distinct output format. Communication between the front-end and the back-ends is typically conducted by means of a well-defined interface.

It is often desired that the front-end be responsible for all input validation, so as to promote encapsulation and enforce uniform communication to the user. However, difficulties may arise when the back-ends impose different requirements on the input that they process.

This thesis examines this problem in the context of the BNF Converter – a compiler construction tool that transforms a common grammar specification into software components used for implementing a compiler for the language of said grammar. The BNF Converter adheres to the aforementioned architectural model and supports multiple back-ends that target various output formats and are characterized by distinct capabilities and requirements with respect to the input.

In order to address these discrepancies, a so-called back-end compatibility check was developed. This check enables the front-end to validate whether a given input conforms to the requirements imposed by a particular back-end. The methodology used for this purpose is expected to generalize to other systems exhibiting a similar structure. Additionally, a new back-end was implemented, both to evaluate the usefulness of the interface and to contribute to the development of the BNF Converter itself.