[San-Diego-pm] Meeting Next Week

[Dave Roe]

On Nov 11, 2004, at 9:13 PM, Christopher Hahn wrote:

> I am trying to use Parse::Recdescent on fairly simple data, but am 
> getting
> stuck on
> capturing an escaped carriage return.

if you turn on $::RD_TRACE, you can see what is going on. it seems the 
answer is to double-up your back-slashes:

EscCR: /\\\\\\\\n/        { print "Escaped CR!\n"; }

from perldoc Parse::RecDescent:

        It is important to remember that, since each grammar is 
specified in a
        Perl string, all instances of the universal escape character '\' 
within
        a grammar must be "doubled", so that they interpolate to single 
'\'s
        when the string is compiled. For example, to use the grammar:

                        word:       /\S+/ | backslash
                        line:       prefix word(s) "\n"
                        backslash:  '\\'

        the following code is required:

                        $parser = new Parse::RecDescent (q{

                                word:       /\\S+/ | backslash
                                line:       prefix word(s) "\\n"
                                backslash:  '\\\\'

                        });

HTH,
/dave