X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/7d31f0928907ccdd647479075d385b5a36c62611..e187b40d317f2bcff21779a774a767f51c0fe276:/doc/bison.texinfo diff --git a/doc/bison.texinfo b/doc/bison.texinfo index 42ea8e28..c121dd4e 100644 --- a/doc/bison.texinfo +++ b/doc/bison.texinfo @@ -33,7 +33,7 @@ This manual (@value{UPDATED}) is for GNU Bison (version @value{VERSION}), the GNU parser generator. -Copyright @copyright{} 1988-1993, 1995, 1998-2011 Free Software +Copyright @copyright{} 1988-1993, 1995, 1998-2012 Free Software Foundation, Inc. @quotation @@ -125,7 +125,7 @@ The Concepts of Bison the name of an identifier, etc.). * Semantic Actions:: Each rule can have an action containing C code. * GLR Parsers:: Writing parsers for general context-free languages. -* Locations Overview:: Tracking Locations. +* Locations:: Overview of location tracking. * Bison Parser:: What are Bison's input and output, how is the output used? * Stages:: Stages in writing and running Bison grammars. @@ -180,15 +180,15 @@ Multi-Function Calculator: @code{mfcalc} Bison Grammar Files -* Grammar Outline:: Overall layout of the grammar file. -* Symbols:: Terminal and nonterminal symbols. -* Rules:: How to write grammar rules. -* Recursion:: Writing recursive rules. -* Semantics:: Semantic values and actions. -* Locations:: Locations and actions. -* Named References:: Using named references in actions. -* Declarations:: All kinds of Bison declarations are described here. -* Multiple Parsers:: Putting more than one Bison parser in one program. +* Grammar Outline:: Overall layout of the grammar file. +* Symbols:: Terminal and nonterminal symbols. +* Rules:: How to write grammar rules. +* Recursion:: Writing recursive rules. +* Semantics:: Semantic values and actions. +* Tracking Locations:: Locations and actions. +* Named References:: Using named references in actions. +* Declarations:: All kinds of Bison declarations are described here. +* Multiple Parsers:: Putting more than one Bison parser in one program. Outline of a Bison Grammar @@ -449,7 +449,7 @@ use Bison or Yacc, we suggest you start by reading this chapter carefully. the name of an identifier, etc.). * Semantic Actions:: Each rule can have an action containing C code. * GLR Parsers:: Writing parsers for general context-free languages. -* Locations Overview:: Tracking Locations. +* Locations:: Overview of location tracking. * Bison Parser:: What are Bison's input and output, how is the output used? * Stages:: Stages in writing and running Bison grammars. @@ -1205,7 +1205,7 @@ will suffice. Otherwise, we suggest %@} @end example -@node Locations Overview +@node Locations @section Locations @cindex location @cindex textual location @@ -1217,9 +1217,10 @@ the @dfn{textual location}, or @dfn{location}, of each syntactic construct. Bison provides a mechanism for handling these locations. Each token has a semantic value. In a similar fashion, each token has an -associated location, but the type of locations is the same for all tokens and -groupings. Moreover, the output parser is equipped with a default data -structure for storing locations (@pxref{Locations}, for more details). +associated location, but the type of locations is the same for all tokens +and groupings. Moreover, the output parser is equipped with a default data +structure for storing locations (@pxref{Tracking Locations}, for more +details). Like semantic values, locations can be reached in actions using a dedicated set of constructs. In the example above, the location of the whole grouping @@ -2621,15 +2622,15 @@ The Bison grammar file conventionally has a name ending in @samp{.y}. @xref{Invocation, ,Invoking Bison}. @menu -* Grammar Outline:: Overall layout of the grammar file. -* Symbols:: Terminal and nonterminal symbols. -* Rules:: How to write grammar rules. -* Recursion:: Writing recursive rules. -* Semantics:: Semantic values and actions. -* Locations:: Locations and actions. -* Named References:: Using named references in actions. -* Declarations:: All kinds of Bison declarations are described here. -* Multiple Parsers:: Putting more than one Bison parser in one program. +* Grammar Outline:: Overall layout of the grammar file. +* Symbols:: Terminal and nonterminal symbols. +* Rules:: How to write grammar rules. +* Recursion:: Writing recursive rules. +* Semantics:: Semantic values and actions. +* Tracking Locations:: Locations and actions. +* Named References:: Using named references in actions. +* Declarations:: All kinds of Bison declarations are described here. +* Multiple Parsers:: Putting more than one Bison parser in one program. @end menu @node Grammar Outline @@ -3509,8 +3510,8 @@ the addition-expression just recognized by the rule. If there were a useful semantic value associated with the @samp{+} token, it could be referred to as @code{$2}. -@xref{Named References,,Using Named References}, for more information -about using the named references construct. +@xref{Named References}, for more information about using the named +references construct. Note that the vertical-bar character @samp{|} is really a rule separator, and actions are attached to a single rule. This is a @@ -3806,7 +3807,7 @@ compound: subroutine Now Bison can execute the action in the rule for @code{subroutine} without deciding which rule for @code{compound} it will eventually use. -@node Locations +@node Tracking Locations @section Tracking Locations @cindex location @cindex textual location @@ -3876,8 +3877,8 @@ The location of the @var{n}th component of the right hand side is In addition, the named references construct @code{@@@var{name}} and @code{@@[@var{name}]} may also be used to address the symbol locations. -@xref{Named References,,Using Named References}, for more information -about using the named references construct. +@xref{Named References}, for more information about using the named +references construct. Here is a basic example using the default data type for locations: @@ -4015,7 +4016,7 @@ statement when it is followed by a semicolon. @end itemize @node Named References -@section Using Named References +@section Named References @cindex named references As described in the preceding sections, the traditional way to refer to any @@ -4075,10 +4076,9 @@ exp[result]: exp[left] '/' exp[right] @end example @noindent -Explicit names may be declared for RHS and for LHS symbols as well. In order -to access a semantic value generated by a mid-rule action, an explicit name -may also be declared by putting a bracketed name after the closing brace of -the mid-rule action code: +In order to access a semantic value generated by a mid-rule action, an +explicit name may also be declared by putting a bracketed name after the +closing brace of the mid-rule action code: @example @group exp[res]: exp[x] '+' @{$left = $x;@}[left] exp[right] @@ -4099,11 +4099,14 @@ if-stmt: IF '(' expr ')' THEN then.stmt ';' It often happens that named references are followed by a dot, dash or other C punctuation marks and operators. By default, Bison will read -@code{$name.suffix} as a reference to symbol value @code{$name} followed by -@samp{.suffix}, i.e., an access to the @samp{suffix} field of the semantic -value. In order to force Bison to recognize @code{name.suffix} in its entirety -as the name of a semantic value, bracketed syntax @code{$[name.suffix]} -must be used. +@samp{$name.suffix} as a reference to symbol value @code{$name} followed by +@samp{.suffix}, i.e., an access to the @code{suffix} field of the semantic +value. In order to force Bison to recognize @samp{name.suffix} in its +entirety as the name of a semantic value, the bracketed syntax +@samp{$[name.suffix]} must be used. + +The named references feature is experimental. More user feedback will help +to stabilize it. @node Declarations @section Bison Declarations @@ -4545,12 +4548,12 @@ redefine it from @code{$end} to, for example, @code{END}: @cindex mid-rule actions Finally, Bison will never invoke a @code{%destructor} for an unreferenced mid-rule semantic value (@pxref{Mid-Rule Actions,,Actions in Mid-Rule}). -That is, Bison does not consider a mid-rule to have a semantic value if you do -not reference @code{$$} in the mid-rule's action or @code{$@var{n}} (where -@var{n} is the RHS symbol position of the mid-rule) in any later action in that -rule. -However, if you do reference either, the Bison-generated parser will invoke the -@code{<>} @code{%destructor} whenever it discards the mid-rule symbol. +That is, Bison does not consider a mid-rule to have a semantic value if you +do not reference @code{$$} in the mid-rule's action or @code{$@var{n}} +(where @var{n} is the right-hand side 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. @ignore @noindent @@ -4916,9 +4919,8 @@ Unless your parser is pure, the parser header file declares (Reentrant) Parser}. If you have also used locations, the parser header file declares -@code{YYLTYPE} and @code{yylloc} using a protocol similar to that of -the @code{YYSTYPE} macro and @code{yylval}. @xref{Locations, -,Tracking Locations}. +@code{YYLTYPE} and @code{yylloc} using a protocol similar to that of the +@code{YYSTYPE} macro and @code{yylval}. @xref{Tracking Locations}. This parser header file is normally essential if you wish to put the definition of @code{yylex} in a separate source file, because @@ -5757,12 +5759,12 @@ then the code in @code{yylex} might look like this: @subsection Textual Locations of Tokens @vindex yylloc -If you are using the @samp{@@@var{n}}-feature (@pxref{Locations, , -Tracking Locations}) in actions to keep track of the textual locations -of tokens and groupings, then you must provide this information in -@code{yylex}. The function @code{yyparse} expects to find the textual -location of a token just parsed in the global variable @code{yylloc}. -So @code{yylex} must store the proper data in that variable. +If you are using the @samp{@@@var{n}}-feature (@pxref{Tracking Locations}) +in actions to keep track of the textual locations of tokens and groupings, +then you must provide this information in @code{yylex}. The function +@code{yyparse} expects to find the textual location of a token just parsed +in the global variable @code{yylloc}. So @code{yylex} must store the proper +data in that variable. By default, the value of @code{yylloc} is a structure and you need only initialize the members that are going to be used by the actions. The @@ -6088,9 +6090,9 @@ Actions}). @deffn {Value} @@$ @findex @@$ -Acts like a structure variable containing information on the textual location -of the grouping made by the current rule. @xref{Locations, , -Tracking Locations}. +Acts like a structure variable containing information on the textual +location of the grouping made by the current rule. @xref{Tracking +Locations}. @c Check if those paragraphs are still useful or not. @@ -6114,9 +6116,9 @@ Tracking Locations}. @deffn {Value} @@@var{n} @findex @@@var{n} -Acts like a structure variable containing information on the textual location -of the @var{n}th component of the current rule. @xref{Locations, , -Tracking Locations}. +Acts like a structure variable containing information on the textual +location of the @var{n}th component of the current rule. @xref{Tracking +Locations}. @end deffn @node Internationalization @@ -8758,10 +8760,10 @@ Symbols}. @c - %define filename_type "const symbol::Symbol" When the directive @code{%locations} is used, the C++ parser supports -location tracking, see @ref{Locations, , Locations Overview}. Two -auxiliary classes define a @code{position}, a single point in a file, -and a @code{location}, a range composed of a pair of -@code{position}s (possibly spanning several files). +location tracking, see @ref{Tracking Locations}. Two auxiliary classes +define a @code{position}, a single point in a file, and a @code{location}, a +range composed of a pair of @code{position}s (possibly spanning several +files). @deftypemethod {position} {std::string*} file The name of the file. It will always be handled as a pointer, the @@ -9513,14 +9515,13 @@ can be used to print the semantic values. This however may change @c - class Position @c - class Location -When the directive @code{%locations} is used, the Java parser -supports location tracking, see @ref{Locations, , Locations Overview}. -An auxiliary user-defined class defines a @dfn{position}, a single point -in a file; Bison itself defines a class representing a @dfn{location}, -a range composed of a pair of positions (possibly spanning several -files). The location class is an inner class of the parser; the name -is @code{Location} by default, and may also be renamed using -@code{%define location_type "@var{class-name}"}. +When the directive @code{%locations} is used, the Java parser supports +location tracking, see @ref{Tracking Locations}. An auxiliary user-defined +class defines a @dfn{position}, a single point in a file; Bison itself +defines a class representing a @dfn{location}, a range composed of a pair of +positions (possibly spanning several files). The location class is an inner +class of the parser; the name is @code{Location} by default, and may also be +renamed using @code{%define location_type "@var{class-name}"}. The location class treats the position as a completely opaque value. By default, the class name is @code{Position}, but this can be changed @@ -10307,7 +10308,7 @@ transcript of the build session, starting with the invocation of send additional files as well (such as `config.h' or `config.cache'). Patches are most welcome, but not required. That is, do not hesitate to -send a bug report just because you can not provide a fix. +send a bug report just because you cannot provide a fix. Send bug reports to @email{bug-bison@@gnu.org}. @@ -10360,22 +10361,22 @@ See @url{http://lists.gnu.org/}. @deffn {Variable} @@$ In an action, the location of the left-hand side of the rule. -@xref{Locations, , Locations Overview}. +@xref{Tracking Locations}. @end deffn @deffn {Variable} @@@var{n} -In an action, the location of the @var{n}-th symbol of the right-hand -side of the rule. @xref{Locations, , Locations Overview}. +In an action, the location of the @var{n}-th symbol of the right-hand side +of the rule. @xref{Tracking Locations}. @end deffn @deffn {Variable} @@@var{name} -In an action, the location of a symbol addressed by name. -@xref{Locations, , Locations Overview}. +In an action, the location of a symbol addressed by name. @xref{Tracking +Locations}. @end deffn @deffn {Variable} @@[@var{name}] -In an action, the location of a symbol addressed by name. -@xref{Locations, , Locations Overview}. +In an action, the location of a symbol addressed by name. @xref{Tracking +Locations}. @end deffn @deffn {Variable} $$