The parse machine

Computational theory is both challenging and essential to the computer science curriculum. Students are exposed to various computer models, but one computer model that is often left out of the subject is the compiler itself. This is unfortunate since students use compilers in most of their classes. The author's goal is to make the subject of parsing more accessible to undergraduates. This paper describes a pedagogical aid called the parse machine, which is similar to a finite automaton. The paper shows how to create a parse machine from a grammar, and how to run it on arbitrary input. The author has used the parse machine concept to teach parsing in computational theory classes. Since the parse machine is designed to be similar to automata the students are already familiar with, they gain confidence that what goes on inside the compiler is not so mysterious after all.