in reply to negative lookaheads doing my 'ead in

The (?!<=) means that the stuff preceeding it mustn't be followed by '<='. Your example is, so it doesn't match. Remove either or both chars or change one or both to something else and it will match. 

/
    ^              # start of line
    \s*            # optional whitespace
    (?!for all)    # NOT "for all"
    (\w+)          # One or more word chars
    \s*            # optional whitespace
    :              # a colon
    \s*            # more optional whitespace
    (\w+)          # another set of one or more word chars
    \s*            # and more optional whitespace
    (?!<=)         # NOT followed by the char sequence '<='
/i

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Nah! You're thinking of Simon Templar, originally played (on UKTV) by Roger Moore and later by Ian Ogilvy

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Re: Re: negative lookaheads doing my 'ead in
by Anonymous Monk on Nov 08, 2002 at 11:24 UTC
    right
    I just re-read my original question and of course what I meant was why does it match?

    When I run the above pattern it does match

[reply]

      The reason it matches is because the immediate preceeding whitespace is optional \s*. Therefore the parser can choose to say that if there is no whitespace, then the next char after the second (\w+) is a space, which isn't '<=' so therefore is can match, so it does.

      Change that to be if (/^\s*(?!for all)(\w+)\s*:\s*(\w+)\s+(?!<=)/i) { and it no longer can match, so it doesn't (if you get my drift.

      I realise that may or may not help you.

      ++Jasper below. I couldn't find a way of doing that. The caveat is that if you wanted to match

      'cidr_enable: en_core_id == NOT(dsp_reset_n) AND <= stuff;'

      your out of luck.

      Nah! You're thinking of Simon Templar, originally played (on UKTV) by Roger Moore and later by Ian Ogilvy
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