Textmate whitespace highlighting

Question

I want to modify the solution for highlighting trailing whitespace described here by NOT highlighting whitespace on otherwise empty lines.

I've modified this in my Python language file:

     { match = '(\s+)$';
  captures = { 1 = { name = 'invalid.whitespace'; }; };
 },

To this:

     { match = '\S(\s+)$';
  captures = { 1 = { name = 'invalid.whitespace'; }; };
 },

This new expression doesn't seem to match anything anymore. What am I doing wrong ?

Answer 1

Try assertions:

(?<=\S)\s+$

They're described nicely in PHP manual (they're not PHP-specific of course, just php.net happens to have quite readable version of the document).

Answer 2

The problem with your pattern is that the preceding non-space character is presumably already matched by another rule, and thus is not available to your rule. Using an assertion as porneL suggests is the correct wayt to do this.