While every precaution has been taken in the preparation of this book, the publisher and authors assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein.

Flex and bison are tools designed for writers of compilers and interpreters, although they are also useful for many applications that will interest noncompiler writers. Any application that looks for patterns in its input or has an input or command language is a good candidate for flex and bison. Furthermore, they allow for rapid application prototyping, easy modification, and simple maintenance of programs. To stimulate your imagination, here are a few things people have used flex and bison, or their predecessors lex and yacc, to develop:

, gives an overview of how and why flex and bison are used to create compilers and interpreters and demonstrates some simple applications including a calculator built in flex and bison. It also introduces basic terms we use throughout the book.

, describes how to use flex. It develops flex applications that count words in files, handle multiple and nested input files, and compute statistics on C programs.

, gives a full example using flex and bison to develop a fully functional desktop calculator with variables, procedures, loops, and conditional expressions. It shows the use of abstract syntax trees (ASTs), powerful and easy-to-use data structures for representing parsed input.

, develops a parser for the MySQL dialect of the SQL relational database language. The parser checks the syntax of SQL statements and translates them into an internal form suitable for an interpreter. It shows the use of Reverse Polish Notation (RPN), another powerful form used to represent and interpret parsed input.

, provide detailed descriptions of the features and options available to flex and bison programmers. These chapters and the two that follow provide technical information for the now-experienced flex and bison programmer to use while developing flex and bison applications.

, explains bison ambiguities and conflicts, which are grammar problems that keep bison from creating a parser from a grammar. It then develops methods that can be used to locate and correct such problems.

, discusses techniques that compiler or interpreter designers can use to locate, recognize, and report errors in the compiler input.

, covers reentrant scanners and parsers, Generalized Left to Right (GLR) parsers that can handle grammars that regular bison parsers cant, and interfaces to C++.

The appendix provides the complete grammar and a cross-reference for the SQL parser discussed in .

The glossary lists technical terms from language and compiler theory.

We presume you are familiar with C, because most examples are in C, flex, or bison, with a few in C++ and the remainder in SQL or the special-purpose languages developed within the text.