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Full Discussion: Regular Expression matching in PERL
Top Forums Programming Regular Expression matching in PERL Post 302320300 by Feliix1956 on Wednesday 27th of May 2009 03:16:25 PM
Old 05-27-2009
I know its quite late to reply but this is how I would do what is described here:
Code:
#open file, read only
open(DATA, "<filename.txt");

open(SUBJECT, ">subject.txt");
open(COMMENT, ">comment.txt");
open(LENGTH, ">length.txt");

my $filetoprint = "";

#start a run through the file
while(<DATA>)
{
 #grab next line
 my $line = $_;
 # trim line breaks from $line and return it to the variable
 chomp($line);

 # Check start of line
 if ($line =~ m/^SUBJECT(.+)/)
 {
  # set variable indicator to Subject
  $filetoprint = "Subject";
  # remove first word from $line by passing the matched portion back into it
  $line "$1";
 }

 # Check start of line
 if ($line =~ m/^LENGTH(.+)/)
 {
  # set variable indicator to Length
  $filetoprint = "Length";
  # remove first word from $line by passing the matched portion back into it
  $line "$1";
 }


 # Check start of line
 if ($line =~ m/^COMMENT(.+)/)
 {
  # set variable indicator to Comment
  $filetoprint = "Comment";
  # remove first word from $line by passing the matched portion back into it
  $line "$1";
 }

# if there has been a previous match (this line or any following print out to the appropriate file
 if ($filetoprint eq "Subject") {print SUBJECT "$line\n";}
 if ($filetoprint eq "Comment") {print COMMENT "$line\n";}
 if ($filetoprint eq "Length")  {print LENGTH  "$line\n";}

}

close SUBJECT;
close COMMENT;
close LENGTH ;

Hope this helps anyone with a similar problem. you can also add a "terminating" string by writing a regular expression match for the desired character/string then set $filetoprint back to "" and printing anything from the line leading up to the match into the output file so it isnt lost.

to discern between one block and another you could add a variable that you increase by 1 each time you match a new chunk indicator (like for example a subject line) then you could add the number to the beginning of the line in the output file.

An advanced version might be to store the data in an array of hashes, reference the array by the number that iterates while reading the file and store the data from each line in the named part of the hash corresponding to the data type. eg in pseudo code:
Code:
if ($filetoprint eq detail)
{
 #print the detail content to the detail element of the current hash in the array
 $arrayofhashes[$i]->[detail] = "${$arrayofhashes[$i]->[detail]}$line\n";
}
etc

then you can count the array and print out in the format you want for webmail or forum software
 

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LEARN ABOUT MOJAVE

ppi::token::comment5.18

PPI::Token::Comment(3)					User Contributed Perl Documentation				    PPI::Token::Comment(3)

NAME

       PPI::Token::Comment - A comment in Perl source code

INHERITANCE

	 PPI::Token::Comment
	 isa PPI::Token
	     isa PPI::Element

SYNOPSIS

	 # This is a PPI::Token::Comment

	 print "Hello World!"; # So it this

	 $string =~ s/ foo  # This, unfortunately, is not :(
	       bar
	       /w;

DESCRIPTION

       In PPI, comments are represented by "PPI::Token::Comment" objects.

       These come in two flavours, line comment and inline comments.

       A "line comment" is a comment that stands on its own line. These comments hold their own newline and whitespace (both leading and trailing)
       as part of the one "PPI::Token::Comment" object.

       An inline comment is a comment that appears after some code, and continues to the end of the line. This does not include whitespace, and
       the terminating newlines is considered a separate PPI::Token::Whitespace token.

       This is largely a convenience, simplifying a lot of normal code relating to the common things people do with comments.

       Most commonly, it means when you "prune" or "delete" a comment, a line comment disappears taking the entire line with it, and an inline
       comment is removed from the inside of the line, allowing the newline to drop back onto the end of the code, as you would expect.

       It also means you can move comments around in blocks much more easily.

       For now, this is a suitably handy way to do things. However, I do reserve the right to change my mind on this one if it gets dangerously
       anachronistic somewhere down the line.

METHODS

       Only very limited methods are available, beyond those provided by our parent PPI::Token and PPI::Element classes.

   line
       The "line" accessor returns true if the "PPI::Token::Comment" is a line comment, or false if it is an inline comment.

SUPPORT

       See the support section in the main module.

AUTHOR

       Adam Kennedy <adamk@cpan.org>

COPYRIGHT

       Copyright 2001 - 2011 Adam Kennedy.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

       The full text of the license can be found in the LICENSE file included with this module.

perl v5.18.2							    2011-02-25						    PPI::Token::Comment(3)
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