A Pattern Language For Parsing

Abstract

Parsing is the core of the front end of a compiler. The predictive recursive-descent parsing technology is most widely used in a traditional compiler design. It is straightforward and easy to implement. But since predictive recursive-descent parsing degrades into a structural programming, it results in a parser that is very hard to change, extend and maintain.

A pattern language is a set of related patterns that solve a common problem in a problem domain. This paper presents a pattern language for developing a framework for parsing in object-oriented compiler design based on the principle of the predictive recursive-descent parsing technology. It describes four patterns that address three design aspects in developing an object-oriented parser. Two alternative patterns are presented to provide alternative solutions to solve the recursion problem in the object-oriented software design. One is based on the Builder design pattern, and the other is based on the meta-programming technology. The parsers developed from this pattern language are easy to implement, easy to extend, and easy to maintain. This pattern language is intended to express a flexible and extensible design for parsing that can accommodate variations to its most extent.