[pro] Is cl-yacc going to cut it?

Matthew D. Swank akopa at charter.net
Fri Feb 4 07:33:56 UTC 2011


It does look nice, and parser combinators are very cool, but I scrape a
lot of semi structured documents.  Sometimes it's hard to operate with
all of it in memory, which is a current requirement of
cl-parser-combinators.

Thank you though,

Matt
On 02/04/2011 01:14 AM, Cyrus Harmon wrote:
> I've been very pleased with cl-parser-combinators. Not sure what you're trying to parse, but it's pretty flexible and powerful. I've used it for parsing a printed representation of molecules, SMILES strings, and have found it to be a pleasure to work with.
>
> Cyrus
>
> On Feb 3, 2011, at 10:33 PM, Matthew D. Swank wrote:
>
>> I suppose this is only marginally related to common lisp, but everything
>> I'm talking about is written in common lisp.
>>
>> I use cl-yacc for a lot of parsing, but one thing that has always seemed
>> harder than it needs to be is writing lexers to feed it. One thing that
>> I've found helpful is the creation of a custom lexer for each parser
>> state by making the action table entry for that state available to the
>> lexer. This provides the terminals the parser is looking for, and
>> narrows the tokens the lexer has to look for at each step.  However,
>> this means I am also maintaining my own fork of cl-yacc. 
>>
>> It seems (from my admittedly limited search) that this is not a common
>> modification of yacc.  Before I start bugging the maintainer about my
>> changes, I want to know: am I abusing yacc? 
>>
>> I do like the separation between low level tokenization the higher level
>> symbol parse, but is there another general parsing technique, available
>> as a lisp library of course, that either works at a lower level than
>> yacc usually does or allows the lexer to access more context about the
>> parse? 
>>
>> Matt
>>
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>





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