Regex: match everything before image

Question

url1: /dir-images/no1/top-left.gif
url2: /test-1/test-2/test

I want to match the path before the last slash if it is an image file(url1), aka /dir-images/no1/ and match the whole path if it is not(url2), /test-1/test-2/test

tried ^([\=\/\.\w-]+\/)+ this could get path before the last slash no matter what is after it..

Answer 1

Try:

^([\=/.\w-]+/)+((?!.*\.gif$).*|)

The part with (?!) is a lookahead. This is something like an if statement. There are two different lookaheads, ?= and ?!. The first one is a normal if, the second one is an 'if not'.

In your case, I just ask if the ending is not gif? And then I match everything.

Answer 2

One way (with perl flavour):

m|\A(.*/(?(?!.*\.gif$).*))|

Explanation:

m| ... |              # Regexp.
\A                    # Begin of line.
(                     # Group 1.
  .*/                 # All characters until last slash.
  (?                  # Conditional expression.
    (?!.*\.gif$)      # If line doesn't end with '.gif', match...
    .*)               # ... until end of line.
)

---

Testing...

Content of script.pl:

use warnings;
use strict;

while ( <DATA> ) { 
    printf qq[%s\n], $1 if m|\A(.*/(?(?!.*\.gif$).*))|;
}

__DATA__
/dir-images/no1/top-left.gif
/test-1/test-2/test

Run it like:

perl script.pl

And following result:

/dir-images/no1/
/test-1/test-2/test