YACC (Yet Another Compiler-Compiler): An Automatic Parser Generator

Learn about YACC, a powerful tool for automatically generating parser programs from formal grammar specifications. This guide explains YACC's input (formal grammars), output (C source code for a parser), and its significant role in simplifying compiler development.

YACC: An Automatic Parser Generator

What is YACC?

YACC (Yet Another Compiler-Compiler) is a powerful tool used to automatically generate parser programs. Parsers are crucial components of compilers; they take a stream of tokens (the building blocks of a programming language) and determine if the input conforms to the language's grammar rules. YACC simplifies the process of building parsers by taking a formal grammar as input and automatically generating the corresponding parser code. This saves developers significant time and effort in compiler development.

How YACC Works

YACC takes a formal description of a grammar (often expressed in a special notation like BNF - Backus-Naur Form) as input. It then analyzes this grammar and generates a C source code file that implements a parser for that grammar. This parser can then be used to check whether an input string is valid according to the grammar's rules and often to build a parse tree representing the string's syntactic structure.