Re: yyerrok is missing in C++ parser

[kogorman]

All this is true, but beside the point.  What's missing is yyerrok, not
yyerror.
I've got the required yyerror and yylex.

I'm using a C++ setup because I don't want to mix FILE* and C++ streams,
and just because it seems the Right Thing To Do (TM).

++ kevin





Laurence Finston wrote:
> 
>> The C examples show using yyerror and the examples compile and run okay. 
>> But my C++ parser
>> won't compile because (it says) yyerror was not declared in this context. 
>> And when I look at 
>> the generated code, the #define I see in the C scanners is missing.  This
>> is
>> a nuisance; is there
>> anything I can do to make it (or the appropriate C++ analogue) appear?
>> 
> 
> I usually use C++ in the actions of my parsers, but I never generate a C++ 
> parser, so there may be some difference that you'll have to account for.
> 
> When generating a C parser, one has to declare `yyerror', `yylex' and 
> possibly `yywrap' in the first section of the parser input file.  They may 
> be defined somewhere else.  `yylex', of course, can be generated by Flex 
> or lex, and I believe there's an option for having at least one of the 
> others generated automatically by Flex and possibly by Bison.  One has to 
> make sure that the declaration matches the function, which can be slightly 
> tricky, if you're passing a parameter to `yyparse' and `yylex' and 
> generating reentrant versions of these functions. 
> 
> Here's an example:
> 
> int 
> yylex(YYSTYPE* lvalp, yyscan_t parameter);
> 
> int
> yywrap(void);
> 
> int
> yyerror(void* v, char const* s);
> 
> For what it's worth, I don't see any particular advantage in generating a 
> C++ parser instead of a C parser, but that's just my opinion and I haven't 
> kept up with developments with respect to this feature.
> 
> Laurence Finston
> 
> On Sun, 10 Aug 2008, kogorman wrote:
> 
>> 
>> I'm developing a very simple parser to frontend to an existing C++ board
>> game
>> (named "six").
>> 
>> I'm following the examples as best I can, but my attempts at syntax error
>> handling are failing.
>> 
>> The C examples show using yyerror and the examples compile and run okay. 
>> But my C++ parser
>> won't compile because (it says) yyerror was not declared in this context. 
>> And when I look at 
>> the generated code, the #define I see in the C scanners is missing.  This
>> is
>> a nuisance; is there
>> anything I can do to make it (or the appropriate C++ analogue) appear?
>> 
>> For reference, the starting point for this project was the C++ example
>> from
>> the Bison docs, and
>> the error processing from the multifunction calculator C example from the
>> same docs.
>> 
>> Here's the scanner spec:
>> http://www.nabble.com/file/p18919947/sixcl-parser.yy sixcl-parser.yy 
>> 
>> 
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>> 
>> 
>> 
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> 
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