[antlr-interest] Re: Local lookahead depth

[John D. Mitchell]

>>>>> "Oliver" == Oliver Zeigermann <oliver at zeigermann.de> writes:
>>>>>> lgcraymer wrote:
[...]

>> Also, as to actions in lookahead code: this is something that Ter
>> supported in PCCTS under the name "guarded predicates" or some such.  I
>> don't know that it saw much use, and I suspect that usage indicates a
>> too early incorporation of semantic information into the
>> translator--tree transformation helps avoid that.

> 1.) You might really increase the set of parseable languages using this
> technique

>>From a theoretical standpoint? Nope, I can't see how you've increased the
power at all.

>>From a "what's easiest/most-efficient to do with tool/framework/etc. XYZ"?
Okay.


> 2.) Sometimes using tree transformation is too expensive

No personal offense intended but... Many people keep saying things like
that and I really don't believe that they understand the problem that they
are nominally trying to solve (let alone understanding the actual problem
that may need to be solved).

For example, if very high speed is so important then what the hell are you
doing using any "language" that needs such complexity to lex, parse,
understand, and act upon to solve the problem?  I.e., why aren't you using
a purpose specific, fixed, highly normalized language that's extremely easy
to robustly deal with rapidly?

[And before y'all jump in and just start walloping me with specific
experiences showing my insanity, please do keep in mind that I've worked on
language projects from 8-bit, hard-real-time systems upto wacky natural
language processing systems.]

Have fun,
	John "Lingua Idiota" Mitchell


 

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