Parse::RecDescent and operators with quotes

Question

I have something like the following:

((x=2 or y=3 ) and (r=3 and c=3) or (x=5 and g=6))

I defined:

Token : /\w \= \d/
operator or|and
expression : token operator(s)
quoted_expression : "("expression")"
query : expression (s)|quoted_expression(s)

But I have a problem with parsing the above condition any idea how to parse the above?

Answer 1

At the core, you want

expr    : log_or

log_or  : log_or 'or' log_and
        | log_and

log_and : log_and 'and' cmp
        | cmp

cmp     : cmp /=|<[>=]?|>=?/ term
        | term

term    : '(' expr ')'
        | IDENT
        | NUMBER

After eliminating left-recursion and adding the necessary code blocks, you get the following:

my $grammar = <<'__EOS__';

   {
      # The code in rules is also covered by these pragmas.
      use strict;
      use warnings;
   }

   parse    : expr /\Z/ { $item[1] }

   # ----------------------------------------
   # Rules

   expr     : log_or { $item[1] }

   # ---vvv--- Lowest precedence ---vvv---

   log_or   : log_and log_or_[ $item[1] ]
   log_or_  : 'or' log_and log_or_[ [ $item[1], $arg[0], $item[2] ] ]
            | { $arg[0] }

   log_and  : cmp log_and_[ $item[1] ]
   log_and_ : 'and' cmp log_and_[ [ $item[1], $arg[0], $item[2] ] ]
            | { $arg[0] }

   cmp      : term cmp_[ $item[1] ]
   cmp_     : /=|<[>=]?|>=?/ term cmp_[ [ $item[1], $arg[0], $item[2] ] ]
            | { $arg[0] }

   # ---^^^--- Highest precedence ---^^^---

   term     : '(' expr ')' { $item[2] }
            | IDENT  { [ $item[0], $item[1] ] }
            | NUMBER { [ $item[0], $item[1] ] }

   # ----------------------------------------
   # Tokens

   IDENT    : /\w+/
   NUMBER   : /\d+/

__EOS__