[Bug 11859] "^" is a valid regular expression

http://www.w3.org/Bugs/Public/show_bug.cgi?id=11859

C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com> changed:

           What    |Removed                     |Added
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           Keywords|                            |needsReview
             Status|NEW                         |ASSIGNED

--- Comment #1 from C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com> 2011-03-08 02:10:50 UTC ---
I think a simpler change would be to replace the initial and final references
to '^' with references to '[^]'. 
Hmm.  Maybe not simpler (it requires other rewordings), but perhaps easier to
follow in context.

To make it a formal proposal, I'll say:  make the second paragraph of the note
read:

    The string '[^]' is unambiguous: the grammar recognizes it as a character 
    class expression containing a positive character group containing just 
    the character '^'.  But the grammatical derivation of the string violates 
    the rule just given, so the string '[^]' must not be accepted as a regular 
    expression.

In addition to changing '^' to '[^]' twice, this changes 'as a positive
character group containing' to 'as a character class expression containing a
positive character group containing just'.

The change suggested by MK would also work; I suggest an alternative because
I'm a little unhappy, now that my attention has been drawn to it, by the note's
saying "the grammar" recognizes '^' as a positive character group.  It's true
(or true-ish) in context, but if '^' is parsed against the regExp non-terminal
(and regExp is after all the natural start symbol, if we are going to refer to
"the grammar"), then, no, it won't be recognized as a positive character group.

This proposal has not been reviewed by the other editors but I'm going to take
the liberty of marking the issue needsReview anyway.

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Received on Tuesday, 8 March 2011 02:10:53 UTC