title: Will a lookahead in regular expressions always not capture or does it depend?
body: <p>I've been reading some articles on non-capturing groups on this site and on the net
  (such as <a href="http://www.regular-expressions.info/brackets.html" rel="nofollow noreferrer">http://www.regular-expressions.info/brackets.html</a> and <a href="http://www.asiteaboutnothing.net/regexp/regex-disambiguation.html" rel="nofollow noreferrer">http://www.asiteaboutnothing.net/regexp/regex-disambiguation.html</a>, <a href="https://stackoverflow.com/questions/603069/what-does-the-regular-expression-mean">What does the &quot;?:^&quot; regular expression mean?</a>, <a href="https://stackoverflow.com/questions/3512471/non-capturing-group">What is a non-capturing group? What does a question mark followed by a colon (?:) mean?</a>)</p>
  
  <p>I am clear on the meaning of (?:foo). What I am unclear about is (?=foo). Is (?=foo) also always a non-capturing group, or does it depend?</p>