@end deffn
@deffn {Directive} %debug
-In the parser implementation file, define the macro @code{YYDEBUG} to
-1 if it is not already defined, so that the debugging facilities are
-compiled. @xref{Tracing, ,Tracing Your Parser}.
+In the parser implementation file, define the macro @code{YYDEBUG} (or
+@code{@var{prefix}DEBUG} with @samp{%define api.prefix @var{prefix}}), see
+@ref{Multiple Parsers, ,Multiple Parsers in the Same Program}) to 1 if it is
+not already defined, so that the debugging facilities are compiled.
+@xref{Tracing, ,Tracing Your Parser}.
@end deffn
@deffn {Directive} %define @var{variable}
accurate syntax error messages.
@end deffn
-@deffn {Directive} %name-prefix "@var{prefix}"
-Rename the external symbols used in the parser so that they start with
-@var{prefix} instead of @samp{yy}. The precise list of symbols renamed
-in C parsers
-is @code{yyparse}, @code{yylex}, @code{yyerror}, @code{yynerrs},
-@code{yylval}, @code{yychar}, @code{yydebug}, and
-(if locations are used) @code{yylloc}. If you use a push parser,
-@code{yypush_parse}, @code{yypull_parse}, @code{yypstate},
-@code{yypstate_new} and @code{yypstate_delete} will
-also be renamed. For example, if you use @samp{%name-prefix "c_"}, the
-names become @code{c_parse}, @code{c_lex}, and so on.
-For C++ parsers, see the @code{%define namespace} documentation in this
-section.
-@xref{Multiple Parsers, ,Multiple Parsers in the Same Program}.
-@end deffn
-
@ifset defaultprec
@deffn {Directive} %no-default-prec
Do not assign a precedence to rules lacking an explicit @code{%prec}
Some of the accepted @var{variable}s are:
@itemize @bullet
+@c ================================================== api.prefix
+@item @code{api.prefix}
+@findex %define api.prefix
+
+@itemize @bullet
+@item Language(s): All
+
+@item Purpose: Rename exported symbols
+@xref{Multiple Parsers, ,Multiple Parsers in the Same Program}.
+
+@item Accepted Values: String
+
+@item Default Value: @code{yy}
+
+@item History: introduced in Bison 2.6
+@end itemize
+
@c ================================================== api.pure
-@item api.pure
+@item @code{api.pure}
@findex %define api.pure
@itemize @bullet
@item Default Value: @code{false}
@end itemize
-@item api.push-pull
+@c ================================================== api.push-pull
+
+@item @code{api.push-pull}
@findex %define api.push-pull
@itemize @bullet
@c ================================================== lr.default-reductions
-@item lr.default-reductions
+@item @code{lr.default-reductions}
@findex %define lr.default-reductions
@itemize @bullet
@c ============================================ lr.keep-unreachable-states
-@item lr.keep-unreachable-states
+@item @code{lr.keep-unreachable-states}
@findex %define lr.keep-unreachable-states
@itemize @bullet
@c ================================================== lr.type
-@item lr.type
+@item @code{lr.type}
@findex %define lr.type
@itemize @bullet
@item Default Value: @code{lalr}
@end itemize
-@item namespace
+@c ================================================== namespace
+
+@item @code{namespace}
@findex %define namespace
@itemize
@end itemize
@c ================================================== parse.lac
-@item parse.lac
+@item @code{parse.lac}
@findex %define parse.lac
@itemize
@section 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 @code{yyparse}, @code{yylval}, and so on.
-
-The easy way to do this is to use the option @samp{-p @var{prefix}}
-(@pxref{Invocation, ,Invoking Bison}). This renames the interface
-functions and variables of the Bison parser to start with @var{prefix}
-instead of @samp{yy}. You can use this to give each parser distinct
-names that do not conflict.
-
-The precise list of symbols renamed is @code{yyparse}, @code{yylex},
-@code{yyerror}, @code{yynerrs}, @code{yylval}, @code{yylloc},
-@code{yychar} and @code{yydebug}. If you use a push parser,
-@code{yypush_parse}, @code{yypull_parse}, @code{yypstate},
-@code{yypstate_new} and @code{yypstate_delete} will also be renamed.
-For example, if you use @samp{-p c}, the names become @code{cparse},
-@code{clex}, and so on.
-
-@strong{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, @code{YYSTYPE} is not
-renamed, but defining this in different ways in different parsers causes
-no trouble (@pxref{Value Type, ,Data Types of Semantic Values}).
-
-The @samp{-p} option works by adding macro definitions to the
-beginning of the parser implementation file, defining @code{yyparse}
-as @code{@var{prefix}parse}, and so on. This effectively substitutes
-one name for the other in the entire parser implementation file.
+only one Bison parser. But what if you want to parse more than one language
+with the same program? Then you need to avoid name conflicts between
+different definitions of functions and variables such as @code{yyparse},
+@code{yylval}. To use different parsers from the same compilation unit, you
+also need to avoid conflicts on types and macros (e.g., @code{YYSTYPE})
+exported in the generated header.
+
+The easy way to do this is to define the @code{%define} variable
+@code{api.prefix}. With different @code{api.prefix}s it is guaranteed that
+headers do not conflict when included together, and that compiled objects
+can be linked together too. Specifying @samp{%define api.prefix
+@var{prefix}} (or passing the option @samp{-Dapi.prefix=@var{prefix}}, see
+@ref{Invocation, ,Invoking Bison}) renames the interface functions and
+variables of the Bison parser to start with @var{prefix} instead of
+@samp{yy}, and all the macros to start by @var{PREFIX} (i.e., @var{prefix}
+upper-cased) instead of @samp{YY}.
+
+The renamed symbols include @code{yyparse}, @code{yylex}, @code{yyerror},
+@code{yynerrs}, @code{yylval}, @code{yylloc}, @code{yychar} and
+@code{yydebug}. If you use a push parser, @code{yypush_parse},
+@code{yypull_parse}, @code{yypstate}, @code{yypstate_new} and
+@code{yypstate_delete} will also be renamed. The renamed macros include
+@code{YYSTYPE}, @code{YYLTYPE}, and @code{YYDEBUG}, which is treated
+specifically --- more about this below.
+
+For example, if you use @samp{%define api.prefix c}, the names become
+@code{cparse}, @code{clex}, @dots{}, @code{CSTYPE}, @code{CLTYPE}, and so
+on.
+
+The @code{%define} variable @code{api.prefix} works in two different ways.
+In the implementation file, it works by adding macro definitions to the
+beginning of the parser implementation file, defining @code{yyparse} as
+@code{@var{prefix}parse}, and so on:
+
+@example
+#define YYSTYPE CTYPE
+#define yyparse cparse
+#define yylval clval
+...
+YYSTYPE yylval;
+int yyparse (void);
+@end example
+
+This effectively substitutes one name for the other in the entire parser
+implementation file, thus the ``original'' names (@code{yylex},
+@code{YYSTYPE}, @dots{}) are also usable in the parser implementation file.
+
+However, in the parser header file, the symbols are defined renamed, for
+instance:
+
+@example
+extern CSTYPE clval;
+int cparse (void);
+@end example
+
+The macro @code{YYDEBUG} is commonly used to enable the tracing support in
+parsers. To comply with this tradition, when @code{api.prefix} is used,
+@code{YYDEBUG} (not renamed) is used as a default value:
+
+@example
+/* Enabling traces. */
+#ifndef CDEBUG
+# if defined YYDEBUG
+# if YYDEBUG
+# define CDEBUG 1
+# else
+# define CDEBUG 0
+# endif
+# else
+# define CDEBUG 0
+# endif
+#endif
+#if CDEBUG
+extern int cdebug;
+#endif
+@end example
+
+@sp 2
+
+Prior to Bison 2.6, a feature similar to @code{api.prefix} was provided by
+the obsolete directive @code{%name-prefix} (@pxref{Table of Symbols, ,Bison
+Symbols}) and the option @code{--name-prefix} (@pxref{Bison Options}).
@node Interface
@chapter Parser C-Language Interface
YYDEBUG 1} in the prologue of the grammar file (@pxref{Prologue, , The
Prologue}).
-@item the option @option{-t}, @option{--debug}
-Use the @samp{-t} option when you run Bison (@pxref{Invocation,
-,Invoking Bison}). This is POSIX compliant too.
+If the @code{%define} variable @code{api.prefix} is used (@xref{Multiple
+Parsers, ,Multiple Parsers in the Same Program}), for instance @samp{%define
+api.prefix x}, then if @code{CDEBUG} is defined, its value controls the
+tracing feature (enabled iff nonzero); otherwise tracing is enabled iff
+@code{YYDEBUG} is nonzero.
+
+@item the option @option{-t} (POSIX Yacc compliant)
+@itemx the option @option{--debug} (Bison extension)
+Use the @samp{-t} option when you run Bison (@pxref{Invocation, ,Invoking
+Bison}). With @samp{%define api.prefix c}, it defines @code{CDEBUG} to 1,
+otherwise it defines @code{YYDEBUG} to 1.
@item the directive @samp{%debug}
@findex %debug
-Add the @code{%debug} directive (@pxref{Decl Summary, ,Bison
-Declaration Summary}). This is a Bison extension, which will prove
-useful when Bison will output parsers for languages that don't use a
-preprocessor. Unless POSIX and Yacc portability matter to
-you, this is
-the preferred solution.
+Add the @code{%debug} directive (@pxref{Decl Summary, ,Bison Declaration
+Summary}). This is a Bison extension, especially useful for languages that
+don't use a preprocessor. Unless POSIX and Yacc portability matter to you,
+this is the preferred solution.
@end table
We suggest that you always enable the debug option so that debugging is
@item -p @var{prefix}
@itemx --name-prefix=@var{prefix}
-Pretend that @code{%name-prefix "@var{prefix}"} was specified.
-@xref{Decl Summary}.
+Pretend that @code{%name-prefix "@var{prefix}"} was specified (@pxref{Decl
+Summary}). Obsoleted by @code{-Dapi.prefix=@var{prefix}}. @xref{Multiple
+Parsers, ,Multiple Parsers in the Same Program}.
@item -l
@itemx --no-lines
@end deffn
@deffn {Directive} %name-prefix "@var{prefix}"
-Bison declaration to rename the external symbols. @xref{Decl Summary}.
+Obsoleted by the @code{%define} variable @code{api.prefix} (@pxref{Multiple
+Parsers, ,Multiple Parsers in the Same Program}).
+
+Rename the external symbols (variables and functions) used in the parser so
+that they start with @var{prefix} instead of @samp{yy}. Contrary to
+@code{api.prefix}, do no rename types and macros.
+
+The precise list of symbols renamed in C parsers is @code{yyparse},
+@code{yylex}, @code{yyerror}, @code{yynerrs}, @code{yylval}, @code{yychar},
+@code{yydebug}, and (if locations are used) @code{yylloc}. If you use a
+push parser, @code{yypush_parse}, @code{yypull_parse}, @code{yypstate},
+@code{yypstate_new} and @code{yypstate_delete} will also be renamed. For
+example, if you use @samp{%name-prefix "c_"}, the names become
+@code{c_parse}, @code{c_lex}, and so on. For C++ parsers, see the
+@code{%define namespace} documentation in this section.
@end deffn
+
@ifset defaultprec
@deffn {Directive} %no-default-prec
Do not assign a precedence to rules that lack an explicit @samp{%prec}
An obsolete macro that you define with @code{#define} in the prologue
to request verbose, specific error message strings
when @code{yyerror} is called. It doesn't matter what definition you
-use for @code{YYERROR_VERBOSE}, just whether you define it. Using
+use for @code{YYERROR_VERBOSE}, just whether you define it.
+Supported by the C skeletons only; using
@code{%error-verbose} is preferred. @xref{Error Reporting}.
@end deffn
projects / bison.git / blobdiff