Re: lexing backwards

"Ron Pinkas" <Ron@Profit-Master.com> wrote:
>> Take 2: (I still enjoy take 1, but my educated public demands
>> more sophisticated entertainment.) No comment, no comment:
>> a=b---c;
>> Parse that backwards.
>> ...
>
>Please note that while the subject of the thread is indeed "lexing
>backwards", nothing in my post made any attempt to address *backward*
>lexing. My original post was in reply to a reply, which highlighted
>certain common classes of tokens. My reply addressed that specific
>subject, and attempted to expand and possibly further clarify that
>approach, as the conceptual basis for developing generic lexing
>engine.


          Note that "Once found in the input outside the context of a
Stream, they serve as unconditional terminator of the prior input, and
are also tokens on their own." does not say anything about the reverse
order. If you are in a situation where backwards lexing is being
considered, look-ahead (look-behind?) may be necessary to lex
correctly. It is not enough to lex in reverse.


Sincerely,


Gene Wirchenko
[Here endeth this particular argument. -John]

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