Pattern Matching Problem

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I have a new perl problem, that I haven't quite figured out the Regular Expression for. We have a web based form that submits data in paragraph form with variables from the form entered into it. A typical set of data may look like this.

Patron @FirstName@ @LastName@ has filled out the @FormName@ form. Plea
+se send them an email at @EmailAddress@.
[download]

Where FirstName, LastName, FormName, and EmailAddress are the actual values, not the variable names. What I need to do, is highlight each of those variables by placing a <B> after the first "@" and a </B> before the second "@", in each one of those variables (without removing the "@"). Best I can come up with is going through the string one character at a time, and watching which "@" I am on. There has got to be a better way to perform this. Iterating over the whole string like that seems sloppy.

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Re: Pattern Matching Problem by Abigail-II (Bishop) on Aug 06, 2003 at 13:01 UTC
`s!\@([^\@]*)\@!\@<B>$1</B>\@!g;` [download] Abigail	[reply] [d/l]
Re: Re: Pattern Matching Problem by allolex (Curate) on Aug 06, 2003 at 13:21 UTC
Ok, so this one catches a string of any length (including zero), using `*`. The string can be any character except "@" `[^\@]`. The matching expression on the left captures the non-@ string and puts it into the variable `$1`, which is then put between bold tags. Abigail-II has used exclamation points here to improve legibility. -- Allolex	[reply] [d/l] [select]
Re: Pattern Matching Problem by allolex (Curate) on Aug 06, 2003 at 13:14 UTC
`#!/usr/bin/perl $_ = 'Patron @FirstName@ @LastName@ has filled out the @FormName@ form +. Please send them an email at @EmailAddress@.'; s/@([a-zA-Z]+?)@/<b>\@$1\@<\/b>/g; print $_ . "\n"; # Output: Patron <b>@FirstName@</b> <b>@LastName@</b> has filled out t +he <b>@FormName@</b> form. Please send them an email at <b>@EmailAddr +ess@</b>.` [download] This gets the right output with the sample data you gave. I hope it helps you along. -- Allolex Update 2003-08-06 15:28:15 CEST: Fixed substitution problem pointed out by Abigail-II (Thanks!).	[reply] [d/l]
Re: Pattern Matching Problem by Abigail-II (Bishop) on Aug 06, 2003 at 13:26 UTC
That removes the `@` signs, of which the OP explicitely mentions they shouldn't be removed. Abigail	[reply]
Re: Pattern Matching Problem by ph0enix (Friar) on Aug 06, 2003 at 13:19 UTC
`my $text = 'Patron @FirstName@ @LastName@ has filled out the @FormName +@ form. Please send them an email at EmailAddress@.'; my $c=0; $text =~ s/\@([^\@]+)/$c++;($c%2)?"\@<b>$1<\/b>":"\@$1"/eg;` [download]	[reply] [d/l]
Re: Pattern Matching Problem by monktim (Friar) on Aug 06, 2003 at 20:23 UTC
Here you go. `use strict; use warnings; my $str = 'Patron @FirstName@ @LastName@ has filled out the @FormName@ + form. Please send them an email at @EmailAddress@.'; print "$str\n"; $str =~ s/\@(.*?)\@/\@<B>$1<\/B>\@/g; print "$str\n";` [download]	[reply] [d/l]
Re: Pattern Matching Problem by eric256 (Parson) on Aug 06, 2003 at 17:04 UTC
Seemed like a good spot for look behind and lookahead :-) `my $test = 'Patron @FirstName@ @LastName@ has filled out the @FormName +@ form. Please send them an email at @EmailAddress@.'; $test =~ s/(?<=@) # starts with @ (but don't grab @) ([a-zA-Z]*) # string of letters (?=@) # ends with @ (but don't grab @) /<b>$1<\/b>/xg; # put $1 back with bold tags around it. @ are + preserved. print $test;` [download] ___________ Eric Hodges	[reply] [d/l]