@}
@end group
@group
- | '-' exp %preg NEG @{ $$ = -$2; @}
+ | '-' exp %prec NEG @{ $$ = -$2; @}
| exp '^' exp @{ $$ = pow ($1, $3); @}
| '(' exp ')' @{ $$ = $2; @}
@end group
@findex %requires
@findex %provides
@findex %code-top
+(The prologue alternatives described here are experimental.
+More user feedback will help to determine whether they should become permanent
+features.)
+
The functionality of @var{Prologue} sections can often be subtle and
inflexible.
As an alternative, Bison provides a set of more explicit directives:
@cindex freeing discarded symbols
@findex %destructor
@findex <*>
-@findex <!>
+@findex <>
During error recovery (@pxref{Error Recovery}), symbols already pushed
on the stack and tokens coming from the rest of the file are discarded
until the parser falls on its feet. If the parser runs out of memory,
per-symbol @code{%destructor}.
Finally, you can define two different kinds of default @code{%destructor}s.
-You can place each of @code{<*>} and @code{<!>} in the @var{symbols} list of
+(These default forms are experimental.
+More user feedback will help to determine whether they should become permanent
+features.)
+You can place each of @code{<*>} and @code{<>} in the @var{symbols} list of
exactly one @code{%destructor} declaration in your grammar file.
The parser will invoke the @var{code} associated with one of these whenever it
discards any user-defined grammar symbol that has no per-symbol and no per-type
The parser uses the @var{code} for @code{<*>} in the case of such a grammar
symbol for which you have formally declared a semantic type tag (@code{%type}
counts as such a declaration, but @code{$<tag>$} does not).
-The parser uses the @var{code} for @code{<!>} in the case of such a grammar
+The parser uses the @var{code} for @code{<>} in the case of such a grammar
symbol that has no declared semantic type tag.
@end deffn
%destructor @{ @} <character>
%destructor @{ free ($$); @} <*>
%destructor @{ free ($$); printf ("%d", @@$.first_line); @} STRING1 string1
-%destructor @{ printf ("Discarding tagless symbol.\n"); @} <!>
+%destructor @{ printf ("Discarding tagless symbol.\n"); @} <>
@end smallexample
@noindent
@var{n} is the RHS symbol position of the mid-rule) in any later action in that
rule.
However, if you do reference either, the Bison-generated parser will invoke the
-@code{<!>} @code{%destructor} whenever it discards the mid-rule symbol.
+@code{<>} @code{%destructor} whenever it discards the mid-rule symbol.
@ignore
@noindent
@xref{Table of Symbols, ,%requires}.
@end deffn
+@deffn {Directive} %defines @var{defines-file}
+Same as above, but save in the file @var{defines-file}.
+@end deffn
+
@deffn {Directive} %destructor
Specify how the parser should reclaim the memory associated to
discarded symbols. @xref{Destructor Decl, , Freeing Discarded Symbols}.
@end deffn
-@deffn {Directive} %file-prefix="@var{prefix}"
+@deffn {Directive} %file-prefix "@var{prefix}"
Specify a prefix to use for all Bison output file names. The names are
chosen as if the input file were named @file{@var{prefix}.y}.
@end deffn
accurate syntax error messages.
@end deffn
-@deffn {Directive} %name-prefix="@var{prefix}"
+@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}. For example, if you use
-@samp{%name-prefix="c_"}, the names become @code{c_parse}, @code{c_lex},
+@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}.
@xref{Multiple Parsers, ,Multiple Parsers in the Same Program}.
file in its own right.
@end deffn
-@deffn {Directive} %output="@var{file}"
+@deffn {Directive} %output "@var{file}"
Specify @var{file} for the parser file.
@end deffn
@item -p @var{prefix}
@itemx --name-prefix=@var{prefix}
-Pretend that @code{%name-prefix="@var{prefix}"} was specified.
+Pretend that @code{%name-prefix "@var{prefix}"} was specified.
@xref{Decl Summary}.
@item -l
@node C++ Semantic Values
@subsection C++ Semantic Values
@c - No objects in unions
-@c - YSTYPE
+@c - YYSTYPE
@c - Printer and destructor
The @code{%union} directive works as for C, see @ref{Union Decl, ,The
@deffn {Directive} <*>
Used to define a default tagged @code{%destructor} or default tagged
@code{%printer}.
+
+This feature is experimental.
+More user feedback will help to determine whether it should become a permanent
+feature.
+
@xref{Destructor Decl, , Freeing Discarded Symbols}.
@end deffn
-@deffn {Directive} <!>
+@deffn {Directive} <>
Used to define a default tagless @code{%destructor} or default tagless
@code{%printer}.
+
+This feature is experimental.
+More user feedback will help to determine whether it should become a permanent
+feature.
+
@xref{Destructor Decl, , Freeing Discarded Symbols}.
@end deffn
@deffn {Directive} %code @{@var{code}@}
Other than semantic actions, this is probably the most common place you should
write verbatim code for the parser implementation.
-For C/C++, it replaces the traditional Yacc prologue,
+It replaces the traditional Yacc prologue,
+@comment For C/C++, it replaces the traditional Yacc prologue,
@code{%@{@var{code}%@}}, for most purposes.
-For Java, it inserts code into the parser class.
+@comment For Java, it inserts code into the parser class.
@cindex Prologue
@findex %union
Specifically, @code{%code @{@var{code}@}} always inserts your @var{code} into
the parser code file after the usual contents of the parser header file.
+(Like all the Yacc prologue alternative directives, this directive is
+experimental.
+More user feedback will help to determine whether it should become a permanent
+feature.)
+
@xref{Prologue Alternatives}.
@end deffn
@deffn {Directive} %code-top @{@var{code}@}
-Occasionally for C/C++ it is desirable to insert code near the top of the
+Occasionally it is desirable to insert code near the top of the
+@comment Occasionally for C/C++ it is desirable to insert code near the top of the
parser code file.
For example:
@}
@end smallexample
-@noindent
-For Java, @code{%code-top @{@var{code}@}} is currently unused.
+@comment @noindent
+@comment For Java, @code{%code-top @{@var{code}@}} is currently unused.
@cindex Prologue
@findex %union
on its position in the grammar file relative to any
@code{%union @{@var{code}@}}.
+(Like all the Yacc prologue alternative directives, this directive is
+experimental.
+More user feedback will help to determine whether it should become a permanent
+feature.)
+
@xref{Prologue Alternatives}.
@end deffn
@xref{Decl Summary}.
@end deffn
+@deffn {Directive} %defines @var{defines-file}
+Same as above, but save in the file @var{defines-file}.
+@xref{Decl Summary}.
+@end deffn
+
@deffn {Directive} %destructor
Specify how the parser should reclaim the memory associated to
discarded symbols. @xref{Destructor Decl, , Freeing Discarded Symbols}.
when @code{yyerror} is called.
@end deffn
-@deffn {Directive} %file-prefix="@var{prefix}"
+@deffn {Directive} %file-prefix "@var{prefix}"
Bison declaration to set the prefix of the output files. @xref{Decl
Summary}.
@end deffn
@xref{GLR Parsers, ,Writing @acronym{GLR} Parsers}.
@end deffn
-@deffn {Directive} %name-prefix="@var{prefix}"
+@deffn {Directive} %name-prefix "@var{prefix}"
Bison declaration to rename the external symbols. @xref{Decl Summary}.
@end deffn
@xref{Precedence Decl, ,Operator Precedence}.
@end deffn
-@deffn {Directive} %output="@var{file}"
+@deffn {Directive} %output "@var{file}"
Bison declaration to set the name of the parser file. @xref{Decl
Summary}.
@end deffn
@deffn {Directive} %provides @{@var{code}@}
This is the right place to write additional definitions you would like Bison to
expose externally.
-For C/C++, this directive inserts your @var{code} both into the parser header
+That is, this directive inserts your @var{code} both into the parser header
+@comment For C/C++, this directive inserts your @var{code} both into the parser header
file (if generated; @pxref{Table of Symbols, ,%defines}) and into the parser
code file after Bison's required definitions.
-For Java, it inserts your @var{code} into the parser java file after the parser
-class.
+@comment For Java, it inserts your @var{code} into the parser java file after the parser
+@comment class.
+
+(Like all the Yacc prologue alternative directives, this directive is
+experimental.
+More user feedback will help to determine whether it should become a permanent
+feature.)
@xref{Prologue Alternatives}.
@end deffn
@deffn {Directive} %requires @{@var{code}@}
This is the right place to write dependency code for externally exposed
definitions required by Bison.
-For C/C++, such exposed definitions are those usually appearing in the parser
+Such exposed definitions are those usually appearing in the parser
+@comment For C/C++, such exposed definitions are those usually appearing in the parser
header file.
Thus, this is the right place to define types referenced in
@code{%union @{@var{code}@}} directives, and it is the right place to override
Bison's default @code{YYSTYPE} and @code{YYLTYPE} definitions.
-For Java, this is the right place to write import directives.
+@comment For Java, this is the right place to write import directives.
@cindex Prologue
@findex %union
generated; @pxref{Table of Symbols, ,%defines}) since Bison's required
definitions should depend on it in both places.
+(Like all the Yacc prologue alternative directives, this directive is
+experimental.
+More user feedback will help to determine whether it should become a permanent
+feature.)
+
@xref{Prologue Alternatives}.
@end deffn
@c LocalWords: pre STDC GNUC endif yy YY alloca lf stddef stdlib YYDEBUG
@c LocalWords: NUM exp subsubsection kbd Ctrl ctype EOF getchar isdigit
@c LocalWords: ungetc stdin scanf sc calc ulator ls lm cc NEG prec yyerrok
-@c LocalWords: longjmp fprintf stderr preg yylloc YYLTYPE cos ln
+@c LocalWords: longjmp fprintf stderr yylloc YYLTYPE cos ln
@c LocalWords: smallexample symrec val tptr FNCT fnctptr func struct sym
@c LocalWords: fnct putsym getsym fname arith fncts atan ptr malloc sizeof
@c LocalWords: strlen strcpy fctn strcmp isalpha symbuf realloc isalnum
@c LocalWords: ptypes itype YYPRINT trigraphs yytname expseq vindex dtype
-@c LocalWords: Rhs YYRHSLOC LE nonassoc op deffn typeless typefull yynerrs
+@c LocalWords: Rhs YYRHSLOC LE nonassoc op deffn typeless yynerrs
@c LocalWords: yychar yydebug msg YYNTOKENS YYNNTS YYNRULES YYNSTATES
@c LocalWords: cparse clex deftypefun NE defmac YYACCEPT YYABORT param
@c LocalWords: strncmp intval tindex lvalp locp llocp typealt YYBACKUP
@c LocalWords: hexflag STR exdent itemset asis DYYDEBUG YYFPRINTF args
@c LocalWords: infile ypp yxx outfile itemx tex leaderfill
@c LocalWords: hbox hss hfill tt ly yyin fopen fclose ofirst gcc ll
-@c LocalWords: yyrestart nbar yytext fst snd osplit ntwo strdup AST
+@c LocalWords: nbar yytext fst snd osplit ntwo strdup AST
@c LocalWords: YYSTACK DVI fdl printindex
projects / bison.git / blobdiff