X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/121c498280f96b31a1f90e2012751509e6358a64..dd5611579b3978eff5c4aa22dc8459b8f53c2fc0:/doc/bison.texinfo

diff --git a/doc/bison.texinfo b/doc/bison.texinfo
index ab6486a8..329d81d0 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.
@@ -180,14 +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.
-* 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
 
@@ -206,7 +207,6 @@ Defining Language Semantics
 * Mid-Rule Actions::  Most actions go at the end of a rule.
                       This says when, why and how to use the exceptional
                         action in the middle of a rule.
-* Named References::  Using named references in actions.
 
 Tracking Locations
 
@@ -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
@@ -2621,14 +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.
-* 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
@@ -3388,7 +3390,6 @@ the numbers associated with @var{x} and @var{y}.
 * Mid-Rule Actions::  Most actions go at the end of a rule.
                       This says when, why and how to use the exceptional
                         action in the middle of a rule.
-* Named References::  Using named references in actions.
 @end menu
 
 @node Value Type
@@ -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
@@ -3806,94 +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 Named References
-@subsection Using Named References
-@cindex named references
-
-While every semantic value can be accessed with positional references
-@code{$@var{n}} and @code{$$}, it's often much more convenient to refer to
-them by name.  First of all, original symbol names may be used as named
-references.  For example:
-
-@example
-@group
-invocation: op '(' args ')'
-  @{ $invocation = new_invocation ($op, $args, @@invocation); @}
-@end group
-@end example
-
-@noindent
-The positional @code{$$}, @code{@@$}, @code{$n}, and @code{@@n} can be
-mixed with @code{$name} and @code{@@name} arbitrarily.  For example:
-
-@example
-@group
-invocation: op '(' args ')'
-  @{ $$ = new_invocation ($op, $args, @@$); @}
-@end group
-@end example
-
-@noindent
-However, sometimes regular symbol names are not sufficient due to
-ambiguities:
-
-@example
-@group
-exp: exp '/' exp
-  @{ $exp = $exp / $exp; @} // $exp is ambiguous.
-
-exp: exp '/' exp
-  @{ $$ = $1 / $exp; @} // One usage is ambiguous.
-
-exp: exp '/' exp
-  @{ $$ = $1 / $3; @} // No error.
-@end group
-@end example
-
-@noindent
-When ambiguity occurs, explicitly declared names may be used for values and
-locations.  Explicit names are declared as a bracketed name after a symbol
-appearance in rule definitions.  For example:
-@example
-@group
-exp[result]: exp[left] '/' exp[right]
-  @{ $result = $left / $right; @}
-@end group
-@end example
-
-@noindent
-Explicit names may be declared for RHS and for LHS symbols as well.  In order
-to access a semantic value generated by a mid-rule action, an explicit name
-may also be declared by putting a bracketed name after the closing brace of
-the mid-rule action code:
-@example
-@group
-exp[res]: exp[x] '+' @{$left = $x;@}[left] exp[right]
-  @{ $res = $left + $right; @}
-@end group
-@end example
-
-@noindent
-
-In references, in order to specify names containing dots and dashes, an explicit
-bracketed syntax @code{$[name]} and @code{@@[name]} must be used:
-@example
-@group
-if-stmt: IF '(' expr ')' THEN then.stmt ';'
-  @{ $[if-stmt] = new_if_stmt ($expr, $[then.stmt]); @}
-@end group
-@end example
-
-It often happens that named references are followed by a dot, dash or other
-C punctuation marks and operators.  By default, Bison will read
-@code{$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.
-
-
-@node Locations
+@node Tracking Locations
 @section Tracking Locations
 @cindex location
 @cindex textual location
@@ -3963,8 +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:
 
@@ -4101,6 +4015,99 @@ macro should expand to something that can be used as a single
 statement when it is followed by a semicolon.
 @end itemize
 
+@node Named References
+@section Named References
+@cindex named references
+
+As described in the preceding sections, the traditional way to refer to any
+semantic value or location is a @dfn{positional reference}, which takes the
+form @code{$@var{n}}, @code{$$}, @code{@@@var{n}}, and @code{@@$}.  However,
+such a reference is not very descriptive.  Moreover, if you later decide to
+insert or remove symbols in the right-hand side of a grammar rule, the need
+to renumber such references can be tedious and error-prone.
+
+To avoid these issues, you can also refer to a semantic value or location
+using a @dfn{named reference}.  First of all, original symbol names may be
+used as named references.  For example:
+
+@example
+@group
+invocation: op '(' args ')'
+  @{ $invocation = new_invocation ($op, $args, @@invocation); @}
+@end group
+@end example
+
+@noindent
+Positional and named references can be mixed arbitrarily.  For example:
+
+@example
+@group
+invocation: op '(' args ')'
+  @{ $$ = new_invocation ($op, $args, @@$); @}
+@end group
+@end example
+
+@noindent
+However, sometimes regular symbol names are not sufficient due to
+ambiguities:
+
+@example
+@group
+exp: exp '/' exp
+  @{ $exp = $exp / $exp; @} // $exp is ambiguous.
+
+exp: exp '/' exp
+  @{ $$ = $1 / $exp; @} // One usage is ambiguous.
+
+exp: exp '/' exp
+  @{ $$ = $1 / $3; @} // No error.
+@end group
+@end example
+
+@noindent
+When ambiguity occurs, explicitly declared names may be used for values and
+locations.  Explicit names are declared as a bracketed name after a symbol
+appearance in rule definitions.  For example:
+@example
+@group
+exp[result]: exp[left] '/' exp[right]
+  @{ $result = $left / $right; @}
+@end group
+@end example
+
+@noindent
+In order to access a semantic value generated by a mid-rule action, an
+explicit name may also be declared by putting a bracketed name after the
+closing brace of the mid-rule action code:
+@example
+@group
+exp[res]: exp[x] '+' @{$left = $x;@}[left] exp[right]
+  @{ $res = $left + $right; @}
+@end group
+@end example
+
+@noindent
+
+In references, in order to specify names containing dots and dashes, an explicit
+bracketed syntax @code{$[name]} and @code{@@[name]} must be used:
+@example
+@group
+if-stmt: IF '(' expr ')' THEN then.stmt ';'
+  @{ $[if-stmt] = new_if_stmt ($expr, $[then.stmt]); @}
+@end group
+@end example
+
+It often happens that named references are followed by a dot, dash or other
+C punctuation marks and operators.  By default, Bison will read
+@samp{$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
 @cindex declarations, Bison
@@ -4541,12 +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
@@ -4912,9 +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
@@ -5166,11 +5172,11 @@ contain default reductions.  @xref{Default Reductions}.  (The ability to
 specify where default reductions should be used is experimental.  More user
 feedback will help to stabilize it.)
 
-@item Accepted Values: @code{full}, @code{consistent}, @code{accepting}
+@item Accepted Values: @code{most}, @code{consistent}, @code{accepting}
 @item Default Value:
 @itemize
 @item @code{accepting} if @code{lr.type} is @code{canonical-lr}.
-@item @code{full} otherwise.
+@item @code{most} otherwise.
 @end itemize
 @end itemize
 
@@ -5753,12 +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
@@ -6084,9 +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.
 
@@ -6110,9 +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
@@ -7143,7 +7149,7 @@ To adjust which states have default reductions enabled, use the
 Specify the kind of states that are permitted to contain default reductions.
 The accepted values of @var{WHERE} are:
 @itemize
-@item @code{full} (default for LALR and IELR)
+@item @code{most} (default for LALR and IELR)
 @item @code{consistent}
 @item @code{accepting} (default for canonical LR)
 @end itemize
@@ -7256,10 +7262,9 @@ never physically copied.  In our experience, the performance penalty of LAC
 has proven insignificant for practical grammars.
 @end itemize
 
-While the basic premise behind LAC has been recognized in the parser
-community for years, for the first publication that uses the term LAC and
-that discusses Bison's LAC implementation, @pxref{Bibliography,,Denny 2010
-May}.
+While the LAC algorithm shares techniques that have been recognized in the
+parser community for years, for the publication that introduces LAC,
+@pxref{Bibliography,,Denny 2010 May}.
 
 @node Unreachable States
 @subsection Unreachable States
@@ -8427,10 +8432,24 @@ These warnings are not enabled by default since they sometimes prove to
 be false alarms in existing grammars employing the Yacc constructs
 @code{$0} or @code{$-@var{n}} (where @var{n} is some positive integer).
 
-
 @item yacc
 Incompatibilities with POSIX Yacc.
 
+@item conflicts-sr
+@itemx conflicts-rr
+S/R and R/R conflicts.  These warnings are enabled by default.  However, if
+the @code{%expect} or @code{%expect-rr} directive is specified, an
+unexpected number of conflicts is an error, and an expected number of
+conflicts is not reported, so @option{-W} and @option{--warning} then have
+no effect on the conflict report.
+
+@item other
+All warnings not categorized above.  These warnings are enabled by default.
+
+This category is provided merely for the sake of completeness.  Future
+releases of Bison may move warnings from this category to new, more specific
+categories.
+
 @item all
 All the warnings.
 @item none
@@ -8741,10 +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
@@ -9347,8 +9366,8 @@ calcxx_driver::scan_begin ()
     yyin = stdin;
   else if (!(yyin = fopen (file.c_str (), "r")))
     @{
-      error (std::string ("cannot open ") + file);
-      exit (1);
+      error (std::string ("cannot open ") + file + ": " + strerror(errno));
+      exit (EXIT_FAILURE);
     @}
 @}
 
@@ -9496,14 +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
@@ -10027,11 +10045,17 @@ yyparse (char const *file)
 {
   yyin = fopen (file, "r");
   if (!yyin)
-    exit (2);
+  {
+    perror ("fopen");
+    exit (EXIT_FAILURE);
+  }
   /* One token only.  */
   yylex ();
   if (fclose (yyin) != 0)
-    exit (3);
+  {
+    perror ("fclose");
+    exit (EXIT_FAILURE);
+  }
   return 0;
 }
 
@@ -10290,7 +10314,7 @@ 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}.
 
@@ -10343,22 +10367,22 @@ 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} $$