[Bug 1383] [XQuery] some editorial comments on A.2 Lexical structure

http://www.w3.org/Bugs/Public/show_bug.cgi?id=1383





------- Additional Comments From cmsmcq@w3.org  2005-07-20 16:53 -------
While I sympathize in general with the idea of deleting rules 
like the longest-token rule from grammars when they are redundant, 
in this particular case I am inclined to keep this particular 
rule.  There are several reasons:

1 I am not absolutely sure whether it's actually redundant in
this case; I haven't proven that it's not, but I haven't seen
anything that looks like a proof that it is.

2 Considering cases like "<<" vs. "<" + "<" (or similarly
the two-character tokens vs. the two single-character tokens
for "(:", ":)", "/>", ">>", "{{", "}}", "..", "::", ":=",
">=", "?>", "//"), if I have a choice of getting the right
answer by knowing exactly where I am in the grammar or by
following a longest-token rule, it seems clear to me that
the longest-token rule is a lot simpler to understand and
a lot simpler to use in practice.

If we could get rid of the qualification about being valid
in the current context, I'd be even happier, but I don't
see how to eliminate that without more complications.

Received on Wednesday, 20 July 2005 16:53:24 UTC