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What is the .YY File Extension?

.YY File Extension Description:

Bison is a tool for generating a parser that can convert a grammar file into a C source file. The parser's main purpose is to group tokens according to the grammar rules such as building identifiers and operators into expressions.

For Bison to parse a language, it has to define as input a context-free grammar specification, which means one or more syntactic groupings has to be specified and rules have to be provided in order to build them from their parts. As a result, a C language function is produced, and this recognizes the correct instances of the grammar.

To define the language for Bison, a file has to be written that expresses the grammar in the Bison syntax called the Bison grammar file. The Bison grammar file typically has a name ending with the YY file extension.

Each file with the .yy file extension has four main sections:

* C declarations - contain macro definitions and declaration of functions as well as variables copied to the beginning of the file that are used in the actions in the grammar rules.

* Bison declarations - define the symbols used in formulating the grammar and the data types of semantic values.

* Grammar rules - contain at least one set of Bison grammar rules

* additional C code - copied to the end of the file. It cannot contain macros and variables whose names start with yy because the file with the .yy file extension itself contains many of these variables.

Most applications that use Bison can parse only one language and therefore contain only one Bison parser. If you need to parse more than one language with the same program, a name conflict between different definitions of yyparse, yylval, etc. has to be avoided. To do this, the prefix -p can be used to rename the interface functions and variables of files with the .yy file extension to start with -p instead of yy.

On Windows, a Microsoft Program Maintenance Utility that can build projects based on commands contained in the description file called "NMAKE" can, by default, only decode a few specific file extensions such as EXE, CPP, OBJ, ASM, C, CXX, BAS, CBL, FOR, PAS, RES and RC. All other file extensions such as the YY have to be specified with the SUFFIXES directive of Bison.

Author: Robert Corbett
Author URL:
Related Applications: Bison
Common Path: N/A


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Do you have errors with .YY files?

The Frequent Reason for .YY files Errors to Occur:

A common and likely explanation for .YY files errors is failure in the Windows registry - cleaning is needed to prevent additional harm in other software and/or system devices. Receiving these errors puts your personal computer in danger for fatal crashes, blue screen errors as well as device failure.

.YY files Errors - Common Symptoms:

.YY files error symptoms include program lock ups, start up or shut down problems, jerky personal computer operation, laggy behaviour, screen freezing, internal speaker beeps, problems loading documents as well as problems during program installs.

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Repair .YY File Errors    |    Scan for .YY File Extension Errors    |    What is the .YY File Extension?