zh:zh|yacc yacc（Yet Another Compiler Compiler），是Unix/Linux上一个用来生成编译器的编译器（编译器代码生成器）。yacc生成的编译器主要是用C语言写成的语法解析器（Parser），需要与词法解析器Lex一起使用，再把两部份产生出来的C进程一并编译。yacc本来只在Unix系统上才有，但现时已普遍移植往Windows及其他平台。

yacc的输入是巴科斯范式（BNF）表达的语法规则以及语法规约的处理代码，Yacc输出的是基于表驱动的编译器，包含输入的语法规约的处理代码部分。

Yacc is a computer program for the Unix operating system. It is a LALR parser generator, generating a parser, the part of a compiler that tries to make syntactic sense of the source code, specifically a LALR parser, based on an analytic grammar written in a notation similar to BNF. Yacc itself used to be available as the default parser generator on most Unix systems, though it has since been supplanted as the default by more recent, largely compatible, programs.