ch07.029_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 7 of "Perl Best Practices"    ##
##     Copyright (c) O'Reilly & Associates, 2005. All Rights Reserved.      ##
##  See: http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html  ##
##############################################################################


=begin Optimization:
 
     This parser would almost certainly benefit from the use of  
     progressive matching with m/\G.../gcxms, as in:
 
        while (pos $text < length $text) {
            if (m/\G ($TYPENAME)/gcxms) {
                push @tokens, Token::Type->new({ name => $1 });
            }
            elsif (m/\G ($VARNAME)/gcxms) {
                push @tokens, Token::Var->new({ alias => $1 });
            }
            # etc.
            else {
                croak q{Don't understand '}, 
                      substr($text, pos $text, 20),
                      "'\n";
            }
         }
 
     Reconsider when everyone is using at least Perl 5.6.1.
 
=end Optimization
 
=cut