Changes in templates needed to enhance pure parser

[Aubin Mahé]

Hello,

I have made some changes in bison templates to enhance pure parser but
bison 1.75 is harder to customize.

1) A question
Where are ‘bison.simple’ and ‘bison.hairy’?
The ‘man’ says:
/usr/local/share/bison/bison.simple   simple parser
/usr/local/share/bison/bison.hairy    complicated parser

Under cygwin, these files don't exist.
I have rebuild bison by hand, from bison-1.75.tar.gz but without any
changes.


2) A suggestion about the YYPARSE_PARAM parameter.
It may be strongly typed. 'void *' is an old "C" stuff which can easily
avoided in C++.
Here a fragment of Makefile to 'sed' the result of bison:

$(YACC_FILES): Expression.y
        bison --debug --output yaccgen/yExpression.cpp
--defines=yaccgen/yExpression.h Expression.y
        sed 's/YYPARSE_PARAM_ARG void \*YYPARSE_PARAM/YYPARSE_PARAM_ARG
YYPARSE_PARAM/g' yaccgen/yExpression.cpp > yaccgen/yExpression.cpp2
        sed 's/int yyparse (void \*)/int yyparse(YYPARSE_PARAM)/g'
yaccgen/yExpression.cpp2 > yaccgen/yExpression.cpp
        rm -f yaccgen/yExpression.cpp2

Here is a fragment of the associated grammar file:

...
#define YYERROR_VERBOSE
#define YYSTYPE            std::string
#define YYPARSE_PARAM      Evaluator & e
#define yyerror( X )       e.setErrorMsg( X )

%}

%pure_parser
%token IDENTIFIER
...
%token BETWEEN
%token SCOPE

%%

Expression
   : Expression OR  Expression { e.push( new Or ( e.popExpression(),
                                                  e.popExpression())); }
   | Expression AND Expression { e.push( new And( e.popExpression(),
                                                  e.popExpression())); }

   | '(' Expression ')'
   ...
   ;
...
Is it possible to change the internally used template to avoid the 'sed'
replacements?


3) Under Solaris, with an antique bsd yacc, I have used '-P myParser'
option after customizing myParser (a copy of bison.simple) to avoid the
'sed' commands in Makefile and it works.
I think it may be easy to change this into bison 1.75 too.

Hope this can be a contribution,
Aubin Mahé