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 on.
The easy way to do this is to use the option ‘-p prefix’ (see Invoking Bison). 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 conflict.
The precise list of symbols renamed is yyparse
, yylex
,
yyerror
, yynerrs
, yylval
, yylloc
,
yychar
and yydebug
. If you use a push parser,
yypush_parse
, yypull_parse
, yypstate
,
yypstate_new
and yypstate_delete
will also be renamed.
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 (see Data Types of Semantic Values).
The ‘-p’ option works by adding macro definitions to the
beginning of the parser implementation file, defining yyparse
as prefixparse
, and so on. This effectively substitutes
one name for the other in the entire parser implementation file.