Yacc and Bison are tools for generating parsers: programs which recognize the structure grammatical structure of programs. Bison is a faster version of Yacc. In this chapter, Yacc/Bison refers to either of these tools. The sections on Yacc/Bison are a condensation and extension of the document “BISON the Yacc-compatible Parser Generator†by Charles Donnelly and
Richard Stallman.