A Compact Guide to Lex & Yacc

This document explains how to construct a compiler using lex and yacc. Lex and yacc are tools used to generate lexical analyzers and parsers. I assume you can program in C, and understand data structures such as linked-lists and trees.

The Overview describes the basic building blocks of a compiler and explains the interaction between lex and yacc. The next two sections describe lex and yacc in more detail. With this background we can construct a sophisticated calculator. Conventional arithmetic operations and control statements, such as if-else and while, are implemented. With minor changes we will convert the calculator into a compiler for a stack-based machine. The remaining sections discuss issues that commonly arise in compiler writing. Right-click on the following links for additional downloads:

Permission to reproduce portions of this document is given provided the web site listed below is referenced, and no additional restrictions apply. Source code, when part of a software project, may be used freely without reference to the author.

Tom Niemann
Portland, Oregon