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Flex (fast lexical analyzer generator) is a free and open-source software alternative to lex. [2] It is a computer program that generates lexical analyzers (also known as "scanners" or "lexers").
Bison: The GNU version of Yacc. Lex (and Flex lexical analyser), a token parser commonly used in conjunction with Yacc (and Bison). BNF is a metasyntax used to express context-free grammars: that is a formal way to describe context-free languages. PLY (Python Lex-Yacc) is an alternative implementation of Lex and Yacc in Python.
RE/flex (regex-centric, fast lexical analyzer) [1] [2] is a free and open source computer program written in C++ that generates fast lexical analyzers (also known as "scanners" or "lexers") [3] [4] in C++. RE/flex offers full Unicode support, indentation anchors, word boundaries, lazy quantifiers (non-greedy, lazy repeats), and performance ...
However, parser generators for context-free grammars often support the ability for user-written code to introduce limited amounts of context-sensitivity. (For example, upon encountering a variable declaration, user-written code could save the name and type of the variable into an external data structure, so that these could be checked against ...
Lex is a computer program that generates lexical analyzers ("scanners" or "lexers"). [ 1 ] [ 2 ] It is commonly used with the yacc parser generator and is the standard lexical analyzer generator on many Unix and Unix-like systems.
Bison has features not found in Yacc, so some projects can be truly said to "use" Bison, since Yacc would not suffice. The following list is of projects which are known to "use" Bison in the looser sense, that they use free software development tools and distribute code which is intended to be fed into Bison or a Bison-compatible package.
Berkeley Yacc (byacc) is a Unix parser generator designed to be compatible with Yacc. It was originally written by Robert Corbett and released in 1989. [ 3 ] Due to its liberal license and because it was faster than the AT&T Yacc, it quickly became the most popular version of Yacc. [ 4 ]
For lexical analysis, Lex (or its replacement Flex) is run via approximately 35,000 lines of lex script. The parsing tool Yacc (or its replacement Bison) is also used, but only for minor tasks. The bulk of parsing is done via native C++ code.