(bison.info)Multiple Parsers

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Multiple Parsers in the Same Program

   Most programs that use Bison parse only one language and therefore
contain only one Bison parser.  But what if you want to parse more than
one language with the same program?  Then you need to avoid a name
conflict between different definitions of `yyparse', `yylval', and so

   The easy way to do this is to use the option `-p PREFIX' (*note
Invoking Bison: Invocation.).  This renames the interface functions and
variables of the Bison parser to start with PREFIX instead of `yy'.
You can use this to give each parser distinct names that do not

   The precise list of symbols renamed is `yyparse', `yylex',
`yyerror', `yylval', `yychar' and `yydebug'.  For example, if you use
`-p c', the names become `cparse', `clex', and so on.

   *All the other variables and macros associated with Bison are not
renamed.* These others are not global; there is no conflict if the same
name is used in different parsers.  For example, `YYSTYPE' is not
renamed, but defining this in different ways in different parsers causes
no trouble (Note: Data Types of Semantic Values.).

   The `-p' option works by adding macro definitions to the beginning
of the parser source file, defining `yyparse' as `PREFIXparse', and so
on.  This effectively substitutes one name for the other in the entire
parser file.

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