From: Benoit Daloze <eregontp@...>
Date: 2010-08-07T23:04:04+09:00
Subject: Re: regexp help - substring of a backreference

On 7 August 2010 16:02:31 UTC+2, Benoit Daloze <eregontp@gmail.com> wrote:
> On 7 August 2010 15:33, Bryan Kennerley <me@bryankennerley.co.uk> wrote:
>> I'm putting together a web forum and want to parse web addresses that
>> are part of messages into clickable links. This is my attempt, I'm not
>> claiming its perfect but it works:
>>
>> text.gsub!(/http:?\/*(\w+[\w\-\.\/~\?%&=#;,\+:\@]+)/,
>>          ' <a href="http://\1" target="_blank">http://\1</a>')
>>
>> The problem is that some web addresses are incredibly long, so I want
>> the link text to be limited to, say, 50 chars. i.e. the second \1 needs
>> to be \1[0..49] or something. I can't figure out any easy way of doing
>> it, any ideas?
>> --
>> Posted via http://www.ruby-forum.com/.
>>
>>
>
> $ ri gsub!
>
> Implementation from String
> ------------------------------------------------------------------------------
> str.gsub!(pattern, replacement) -> str or nil
> str.gsub!(pattern) {|match| block } -> str or nil
> str.gsub!(pattern) -> an_enumerator
>
> ------------------------------------------------------------------------------
>
> Performs the substitutions of String#gsub in place, returning
> str, or nil if no substitutions were performed. If no block and
> no replacement is given, an enumerator is returned instead.
> --
>
> text.gsub(/http:?\/*(\w+[\w\-\.\/~\?%&=#;,\+:\@]+)/) { %Q{<a href="http://\1" target="_blank">http://#{$1[0...50]}</a>} }
>
> I am using %Q{str}, as "str" because you already have quotes. You should also use %r{regex} for you Regexp, as it contains '/'.
>
> Benoit Daloze

Missed the first '\1' :
text.gsub(/http:?\/*(\w+[\w\-\.\/~\?%&=#;,\+:\@]+)/) {|match| %Q{<a
href="http://#{$1}" target="_blank">http://#{$1[0...50]}</a>} }