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Yacc (Yet Another Compiler-Compiler) is a computer program for the Unix operating system developed by Stephen C. Johnson.It is a lookahead left-to-right rightmost derivation (LALR) parser generator, generating a LALR parser (the part of a compiler that tries to make syntactic sense of the source code) based on a formal grammar, written in a notation similar to Backus–Naur form (BNF). [1]
It is used to parse source code into concrete syntax trees usable in compilers, interpreters, text editors, and static analyzers. [1] [2] It is specialized for use in text editors, as it supports incremental parsing for updating parse trees while code is edited in real time, [3] and provides a built-in S-expression query system for analyzing ...
It is the lexer generator adopted by projects such as PHP, [4] SpamAssassin, [5] Ninja build system [6] and others. Together with the Lemon parser generator, re2c is used in BRL-CAD. [7] This combination is also used with STEPcode, an implementation of ISO 10303 standard. [8]
Compiler-compilers exist in many flavors, including bottom-up rewrite machine generators (see JBurg) used to tile syntax trees according to a rewrite grammar for code generation, and attribute grammar parser generators (e.g. ANTLR can be used for simultaneous type checking, constant propagation, and more during the parsing stage).
As a result, an implementation of the Engine written for Visual Basic 6 will differ greatly from one written for ANSI C. Currently, Engines for GOLD have been implemented for the following programming languages / platforms. New Engines can be implemented using the source code for the existing Engines as the starting point. Assembly - Intel x86 ...
Lemon is a parser generator, maintained as part of the SQLite project, that generates a look-ahead LR parser (LALR parser) in the programming language C from an input context-free grammar. The generator is quite simple, implemented in one C source file with another file used as a template for output. Lexical analysis is performed externally.
A lookahead LR parser (LALR) generator is a software tool that reads a context-free grammar (CFG) and creates an LALR parser which is capable of parsing files written in the context-free language defined by the CFG. LALR parsers are desirable because they are very fast and small in comparison to other types of parsers.
For example, YACC (Yet Another Compiler-Compiler) takes input in Backus–Naur form and converts it to a parser in C. Though it was originally created for automatic generation of a parser for a compiler, yacc is also often used to automate writing code that needs to be modified each time specifications are changed. [3]