Reg Expression translation

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Re: Reg Expression translation by danger (Priest) on Nov 14, 2003 at 19:39 UTC
Please help me understand the below reg expressions: `/^\s*$/` [download] means check for all spaces in the entry. Check for beginning spaces and spaces in the middle and ending with a space?? It means: match the beginning of the string, followed by zero or more whitespace characters, followed by the end of the string. Essentially, it matches what we often think of as a "blank" line. `/^\w{1,}@/` [download] Check for beginning with one word only and a '@' ?? Match beginning of string, followed by 1 or more word characters (those being of the class: `[a-zA-Z0-9_]`) followed by the '@' character. To really understand regular expressions better, please see the following documents: perlrequick, perlretut, perlre. Also, Jeffrey Friedl's "Mastering Regular Expressions" is an excellent resource.	[reply] [d/l] [select]
Re: Reg Expression translation by Anonymous Monk on Nov 14, 2003 at 19:52 UTC
Use YAPE::Regex::Explain. $ perl -MYAPE::Regex::Explain -e 'print YAPE::Regex::Explain->new(q(^\ +s$))->explain' The regular expression: (?-imsx:^\s$) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ^ the beginning of the string ---------------------------------------------------------------------- \s* whitespace (\n, \r, \t, \f, and " ") (0 or more times (matching the most amount possible)) ---------------------------------------------------------------------- $ before an optional \n, and the end of the string ---------------------------------------------------------------------- ) end of grouping ---------------------------------------------------------------------- $ perl -MYAPE::Regex::Explain -e 'print YAPE::Regex::Explain->new(q(^\ +w{1,}@))->explain' The regular expression: (?-imsx:^\w{1,}@) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ^ the beginning of the string ---------------------------------------------------------------------- \w{1,} word characters (a-z, A-Z, 0-9, _) (at least 1 times (matching the most amount possible)) ---------------------------------------------------------------------- @ '@' ---------------------------------------------------------------------- ) end of grouping ---------------------------------------------------------------------- [download]	[reply] [d/l]
Re: Reg Expression translation by Albannach (Monsignor) on Nov 14, 2003 at 19:54 UTC
Provided you do read perlre and the other fine references so that you have a basis for understanding, you might find YAPE::Regex::Explain (by our own japhy) to be of use. `perl -MYAPE::Regex::Explain -e "print YAPE::Regex::Explain->new(shift)->explain;" "^\s$"` yields The regular expression: (?-imsx:^\s$) matches as follows: NODE EXPLANATION ---------------------------------------------------------------------- (?-imsx: group, but do not capture (case-sensitive) (with ^ and $ matching normally) (with . not matching \n) (matching whitespace and # normally): ---------------------------------------------------------------------- ^ the beginning of the string ---------------------------------------------------------------------- \s* whitespace (\n, \r, \t, \f, and " ") (0 or more times (matching the most amount possible)) ---------------------------------------------------------------------- $ before an optional \n, and the end of the string ---------------------------------------------------------------------- ) end of grouping ---------------------------------------------------------------------- [download] -- I'd like to be able to assign to an luser	[reply] [d/l] [select]
Re: Reg Expression translation by fletcher_the_dog (Friar) on Nov 14, 2003 at 19:54 UTC
`/^\s$/` is a common way of seeing if a string is empty or has just white space. Basically it matches if from the beginning ("^") to the end ("$") where there is nothing or only white space ("\s") between. `/^\w{1,}@/` is just another way of writing `/^\w+@/` which matches one or more "word" characters ("\w+") followed by "@" at the beginning of the line ("^")	[reply] [d/l] [select]
Re: Re: Reg Expression translation by Anonymous Monk on Nov 14, 2003 at 20:07 UTC
thanks to everyone.	[reply]
Re: Reg Expression translation by meetraz (Hermit) on Nov 14, 2003 at 20:10 UTC
One thing you can try is YAPE-Regex-Explain. It works like this: `use strict; use YAPE::Regex::Explain; my $regex1 = qr/^\s$/; my $regex2 = qr/^\w{1,}@/; print YAPE::Regex::Explain->new($regex1)->explain; print YAPE::Regex::Explain->new($regex2)->explain;` [download] (Its a cool module from japhy) UPDATE*: Whoops, looks like everybody beat me to it!	[reply] [d/l]
Re: Reg Expression translation by hardburn (Abbot) on Nov 14, 2003 at 19:31 UTC
perlre ---- I wanted to explore how Perl's closures can be manipulated, and ended up creating an object system by accident. -- Schemer `: () { :\|:& };:` Note: All code is untested, unless otherwise stated	[reply] [d/l]


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