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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 ...
In computer science, a compiler-compiler or compiler generator is a programming tool that creates a parser, interpreter, or compiler from some form of formal description of a programming language and machine. The most common type of compiler-compiler is called a parser generator. [1] It handles only syntactic analysis.
[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. An equivalent tool is specified as part of the POSIX standard. [3] Lex reads an input stream specifying the lexical analyzer and writes source code which implements the lexical analyzer in the C ...
In general, a syntax and semantic analyzer tries to retrieve the structure of the program from the source code, while a code generator uses this structural information (e.g., data types) to produce code. In other words, the former adds information while the latter loses some of the information.
Here is a very simple program in re2c (example.re). It checks that all input arguments are hexadecimal numbers. The code for re2c is enclosed in comments /*!re2c ... */, all the rest is plain C code. See the official re2c website for more complex examples. [23]
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.
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 ...