GNU Bison
general-purpose parser generator
GNU Bison, commonly known as Bison, is a parser generator that is part of the GNU Project. Bison reads a specification in Bison syntax (described as "machine-readable BNF"), warns about any parsing ambiguities, and generates a parser that reads sequences of tokens and decides whether the sequence conforms to the syntax specified by the grammar.
The generated parsers are portable: they do not require any specific compilers. Bison by default generates LALR(1) parsers but it can also generate canonical LR, IELR(1) and GLR parsers.
In POSIX mode, Bison is compatible with Yacc, but also has several extensions over this earlier program, including
Generation of counterexamples for conflicts
Location tracking (e.g., file, line, column)
Rich and internationalizable syntax error messages in the generated parsers
Customizable syntax error generation,
Reentrant parsers
Push parsers, with autocompletion
Support for named references
Several types of reports (graphical, XML) on the generated parser
Support for several programming languages (C, C++, D, or Java)
Flex, an automatic lexical analyser, is often used with Bison, to tokenise input data and provide Bison with tokens.
Bison was originally written by Robert Corbett in 1985. Later, in 1989, Robert Corbett released another parser generator named Berkeley Yacc. Bison was made Yacc-compatible by Richard Stallman.
Bison is free software and is available under the GNU General Public License, with an exception (discussed below) allowing its generated code to be used without triggering the copyleft requirements of the licence.
Features
Counterexample generation
One delicate issue with LR parser generators is the resolution of conflicts (shift/reduce and reduce/reduce conflicts).
The public source identifies “GNU Bison” as general-purpose parser generator. This brief keeps that definition visible, then builds a research path around Bison, general-purpose and parser.
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This entry incorporates text from “GNU Bison” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.