Date: Tue, 9 Apr 2002 21:53:20 -0700 (PDT)
From: Tom Lord <yyyy@xxxxxxxxxxx>
> In other words, to understand what legal constructs are in any of the
> languages, you have to not only read the grammar, but also read the
> text.
I agree that the standard also say "you have to read the text".
However I can't find the reason why the standard doesn't say anything
else.
Let me explain a bit more what I want to say.
The standard says, "Implementations may use other programming languages
or algorithms, as long as the syntax supported is the same as that
represented by the grammar".
(<http://www.opengroup.org/onlinepubs/007904975/utilities/xcu_chap01.html#tag_01_10>)
If RE implementations must use Left-associative grammar, the standard
must say "as long as the grammar is the same", I think.
Then RE implementations may use the grammar except BNF notation.
For example the interpretation (1c) which Paul said is also valid.
And RE implementations may also use Right-associative grammar, since
they describe the same syntax.
On the other hand, perhaps do I miss the sentence which state that
RE implementations must use Left-associative grammar?
If not, I think it isn't necessary to use only Left-associative grammar
as stated above.
Thanks,
--
Isamu Hasegawa
IBM Japan, Ltd.
|