Not all values of @var{qualifier} are available for all target languages:
@itemize @bullet
-@findex %code requires
@item requires
+@findex %code requires
@itemize @bullet
@item Language(s): C, C++
In this case, Bison selects a default value, which may depend on the selected
target language and/or parser skeleton.
@end enumerate
-@end deffn
-@deffn {Directive} %define push_pull "@var{value}"
-Bison declaration to request a @code{"pull"} parser, a @code{"push"} parser, or
-@code{"both"}.
-The default @code{"@var{value}"} is @code{"pull"}.
-This directive is currently only available for LALR(1) parsers in C.
+Some of the accepted @var{variable}s are:
+
+@itemize @bullet
+@item push_pull
+@findex %define push_pull
+
+@itemize @bullet
+@item Language(s): C (LALR(1) only)
+
+@item Purpose: Requests a pull parser, a push parser, or both.
@xref{Push Decl, ,A Push Parser}.
+
+@item Accepted Values: @code{"pull"}, @code{"push"}, @code{"both"}
+
+@item Default Value: @code{"pull"}
+@end itemize
+
+@item lr.keep_unreachable_states
+@findex %define lr.keep_unreachable_states
+
+@itemize @bullet
+@item Language(s): all
+
+@item Purpose: Requests that Bison allow unreachable parser states to remain in
+the parser tables.
+Bison considers a state to be unreachable if there exists no sequence of
+transitions from the start state to that state.
+A state can become unreachable during conflict resolution if Bison disables a
+shift action leading to it from a predecessor state.
+Keeping unreachable states is sometimes useful for analysis purposes, but they
+are useless in the generated parser.
+
+@item Accepted Values: Boolean
+
+@item Default Value: @code{"false"}
+
+@item Caveats:
+
+@itemize @bullet
+@item Unreachable states may contain conflicts and may reduce rules not
+reduced in any other state.
+Thus, keeping unreachable states may induce warnings that are irrelevant to
+your parser's behavior, and it may eliminate warnings that are relevant.
+Of course, the change in warnings may actually be relevant to a parser table
+analysis that wants to keep unreachable states, so this behavior will likely
+remain in future Bison releases.
+
+@item While Bison is able to remove unreachable states, it is not guaranteed to
+remove other kinds of useless states.
+Specifically, when Bison disables reduce actions during conflict resolution,
+some goto actions may become useless, and thus some additional states may
+become useless.
+If Bison were to compute which goto actions were useless and then disable those
+actions, it could identify such states as unreachable and then remove those
+states.
+However, Bison does not compute which goto actions are useless.
+@end itemize
+@end itemize
+
+@item namespace
+@findex %define namespace
+
+@itemize
+@item Languages(s): C++
+
+@item Purpose: Specifies the namespace for the parser class.
+For example, if you specify:
+
+@smallexample
+%define namespace "foo::bar"
+@end smallexample
+
+Bison uses @code{foo::bar} verbatim in references such as:
+
+@smallexample
+foo::bar::parser::semantic_type
+@end smallexample
+
+However, to open a namespace, Bison removes any leading @code{::} and then
+splits on any remaining occurrences:
+
+@smallexample
+namespace foo @{ namespace bar @{
+ class position;
+ class location;
+@} @}
+@end smallexample
+
+@item Accepted Values: Any absolute or relative C++ namespace reference without
+a trailing @code{"::"}.
+For example, @code{"foo"} or @code{"::foo::bar"}.
+
+@item Default Value: The value specified by @code{%name-prefix}, which defaults
+to @code{yy}.
+This usage of @code{%name-prefix} is for backward compatibility and can be
+confusing since @code{%name-prefix} also specifies the textual prefix for the
+lexical analyzer function.
+Thus, if you specify @code{%name-prefix}, it is best to also specify
+@code{%define namespace} so that @code{%name-prefix} @emph{only} affects the
+lexical analyzer function.
+For example, if you specify:
+
+@smallexample
+%define namespace "foo"
+%name-prefix "bar::"
+@end smallexample
+
+The parser namespace is @code{foo} and @code{yylex} is referenced as
+@code{bar::lex}.
+@end itemize
+@end itemize
+
@end deffn
@deffn {Directive} %defines
@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. In C++ parsers,
-it is only the surrounding namespace which is named @var{prefix} instead
-of @samp{yy}.
+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
@example
state 8
- exp -> exp . '+' exp [$, '+', '-', '/'] (rule 1)
+ exp -> exp . '+' exp (rule 1)
exp -> exp '+' exp . [$, '+', '-', '/'] (rule 1)
exp -> exp . '-' exp (rule 2)
exp -> exp . '*' exp (rule 3)
@item --print-localedir
Print the name of the directory containing locale-dependent data.
+@item --print-datadir
+Print the name of the directory containing skeletons and XSLT.
+
@item -y
@itemx --yacc
Act more like the traditional Yacc command. This can cause
@item @option{--no-lines} @tab @option{-l}
@item @option{--output=@var{outfile}} @tab @option{-o @var{outfile}}
@item @option{--print-localedir} @tab
+@item @option{--print-datadir} @tab
@item @option{--token-table} @tab @option{-k}
@item @option{--verbose} @tab @option{-v}
@item @option{--version} @tab @option{-V}
@option{--language=c++}.
@xref{Decl Summary}.
-When run, @command{bison} will create several
-entities in the @samp{yy} namespace. Use the @samp{%name-prefix}
-directive to change the namespace name, see @ref{Decl Summary}. The
-various classes are generated in the following files:
+When run, @command{bison} will create several entities in the @samp{yy}
+namespace.
+@findex %define namespace
+Use the @samp{%define namespace} directive to change the namespace name, see
+@ref{Decl Summary}.
+The various classes are generated in the following files:
@table @file
@item position.hh
@xref{Decl Summary,,%define}.
@end deffn
-@deffn {Directive} %define push_pull "@var{value}"
-Bison declaration to request a @code{"pull"} parser, a @code{"push"} parser, or
-@code{"both"}.
-@xref{Decl Summary,,%define push_pull}.
-@end deffn
-
@deffn {Directive} %defines
Bison declaration to create a header file meant for the scanner.
@xref{Decl Summary}.
projects / bison.git / blobdiff