/[bison]/bison/doc/bison.texinfo
ViewVC logotype

Diff of /bison/doc/bison.texinfo

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 1.95 by eggert, Tue Dec 24 07:43:43 2002 UTC revision 1.96 by eggert, Sat Dec 28 08:37:17 2002 UTC
# Line 3186  Actually, actions are not the best place Line 3186  Actually, actions are not the best place
3186  locations are much more general than semantic values, there is room in  locations are much more general than semantic values, there is room in
3187  the output parser to redefine the default action to take for each  the output parser to redefine the default action to take for each
3188  rule.  The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is  rule.  The @code{YYLLOC_DEFAULT} macro is invoked each time a rule is
3189  matched, before the associated action is run.  matched, before the associated action is run.  It is also invoked
3190    while processing a syntax error, to compute the error's location.
3191    
3192  Most of the time, this macro is general enough to suppress location  Most of the time, this macro is general enough to suppress location
3193  dedicated code from semantic actions.  dedicated code from semantic actions.
3194    
3195  The @code{YYLLOC_DEFAULT} macro takes three parameters.  The first one is  The @code{YYLLOC_DEFAULT} macro takes three parameters.  The first one is
3196  the location of the grouping (the result of the computation).  The second one  the location of the grouping (the result of the computation).  When a
3197  is an array holding locations of all right hand side elements of the rule  rule is matched, the second parameter is an array holding locations of
3198  being matched.  The last one is the size of the right hand side rule.  all right hand side elements of the rule being matched, and the third
3199    parameter is the size of the rule's right hand side.  When processing
3200    a syntax error, the second parameter is an array holding locations of
3201    the symbols that were discarded during error processing, and the third
3202    parameter is the number of discarded symbols.
3203    
3204  By default, it is defined this way for simple @acronym{LALR}(1) parsers:  By default, @code{YYLLOC_DEFAULT} is defined this way for simple
3205    @acronym{LALR}(1) parsers:
3206    
3207  @example  @example
3208  @group  @group
# Line 3491  should use @code{$$} to designate the se Line 3497  should use @code{$$} to designate the se
3497  (@pxref{Parser Function, , The Parser Function @code{yyparse}}).  (@pxref{Parser Function, , The Parser Function @code{yyparse}}).
3498    
3499  @strong{Warning:} as of Bison 1.875, this feature is still considered as  @strong{Warning:} as of Bison 1.875, this feature is still considered as
3500  experimental, as there was not enough users feedback.  In particular,  experimental, as there was not enough user feedback.  In particular,
3501  the syntax might still change.  the syntax might still change.
3502  @end deffn  @end deffn
3503    

Legend:
Removed from v.1.95  
changed lines
  Added in v.1.96

savannah-hackers-public@gnu.org
ViewVC Help
Powered by ViewVC 1.1.26