[NNTP] wildmat-exact

[Clive D.W. Feather]

Charles Lindsey said:
>>>      wildmat = wildmat-pattern *("," ["!"] wildmat-pattern)
>>>      wildmat-pattern = 1*wildmat-item
>>>        ; must not begin with "!" if not immediately preceded by "!"

> Suppose, for the sake of argument, that '!' were a permitted character in
> newsgroup-names (despite prohibitions to the contrary in RFC 1036 and
> Usefor). Then the following newsgroup-names could legitimately exist.
> 
>     !foo.bar
>     foo.bar
>     foo.baz
>     bar.foo

Right.

> So the wildmat "!foo.bar" matches "!foo.bar", "foo.baz" and "bar.foo",

No: that violates the syntax (the first wildmat-pattern can't have a !
prefix and a wildmat-pattern can't begin with ! if it doesn't have such a
prefix).

> and
> "!!foo.bar" matches "foo.bar", "foo.baz" and "bar.foo".

That violates it as well, because the first wildmat-pattern can't have a !
prefix.

The intent of the comment is that the syntax:

    wildmat = wildmat-pattern *("," ["!"] wildmat-pattern)
    wildmat-pattern = 1*wildmat-item
      ; must not begin with "!" if not immediately preceded by "!"
    wildmat-item = wildmat-exact / wildmat-wild
    wildmat-exact = %x21-29 / %x2B / %x2D-3E / %x40-5A / %x5E-7E /
         UTF8-non-ascii ; exclude * , ? [ \ ]
    wildmat-wild = "*" / "?"

is equivalent to:

    wildmat = wildmat-pattern *("," ["!"] wildmat-pattern)
    wildmat-pattern = wildmat-init-item *wildmat-item
    wildmat-init-item = wildmat-init-exact / wildmat-wild
    wildmat-item = wildmat-exact / wildmat-wild
    wildmat-init-exact = %x22-29 / %x2B / %x2D-3E / %x40-5A / %x5E-7E /
         UTF8-non-ascii ; exclude ! * , ? [ \ ]
    wildmat-exact = "!" / wildmat-init-exact
    wildmat-wild = "*" / "?"

> However, I can see no way to write a wildmat that matches "!foo.bar" and
> nothing else.

That would appear to be so.

> Life would be simpler if '!' was simply excluded from wildmat-exact.
> 
>> On 1st May 2001 you proposed removing it and I said that was "too minimal".
>> I can't find any further comments in the archives. However, if we're going
>> to change this from the then-consensus, such as it was, we need to discuss
>> it first.
> 
> OK. Discussion please.

In the absence of [] and \ metacharacters, I've come to agree with you.
Other opinions?

-- 
Clive D.W. Feather  | Work:  <clive at demon.net>   | Tel:    +44 20 8495 6138
Internet Expert     | Home:  <clive at davros.org>  | Fax:    +44 870 051 9937
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