[pro] Lexer wanted

[Frank Huttner]

buffalo is an LALR(1) parser generator in pure Lisp that performs roughly on
par with its large cousin on the "torture" tests from the GNU Bison test
suite (https://github.com/fhuttner/buffalo-testsuite). What I find really
missing is an equivalent, open-sourced lexer; is there such a project?

[Paul Tarvydas]

Esrap is a PEG parser. PEG is Lex and Yacc combined. I'm sure that you
could use esrap as a lexer-only, if you wish to.

http://nikodemus.github.io/esrap/

On my github there's an experimental PEG syntax overlaid over esrap
syntax, if you care. https://github.com/guitarvydas

Ping me if you need ref's to papers about PEG.

pt

[Marc Battyani]

I agree with Paul: Esrap is nice and Paul's PEG syntax parser is great
if you want to use a PEG like syntax. I use them both and this works well.
Otherwise there is cl-yacc which I was using before.

BTW Paul, this reminds me I have to send you a few fixes/additions I've
done to your PEG parser.

Marc

Post by Paul Tarvydas
Esrap is a PEG parser. PEG is Lex and Yacc combined. I'm sure that
you could use esrap as a lexer-only, if you wish to.
http://nikodemus.github.io/esrap/
On my github there's an experimental PEG syntax overlaid over esrap
syntax, if you care. https://github.com/guitarvydas
Ping me if you need ref's to papers about PEG.
pt
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[Gary King]

Hi Paul,

What is the performance of Esrap vis-a-vis something like cl-yac? Given a BN grammar, how hard is it to build up a PEG parser?

thanks,

Esrap is a PEG parser. PEG is Lex and Yacc combined. I'm sure that you could use esrap as a lexer-only, if you wish to.
http://nikodemus.github.io/esrap/
On my github there's an experimental PEG syntax overlaid over esrap syntax, if you care. https://github.com/guitarvydas
Ping me if you need ref's to papers about PEG.
pt
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--
Gary Warren King, metabang.com
Cell: [phone]
Fax: [phone]
gwkkwg on Skype * garethsan on AIM * gwking on twitter

[Paul Tarvydas]

I wish that I’d had PEG 20 years ago,

PEG parses a wider set of grammars than YACC can.

PEG is backtracking, but, it uses a trick, memoizing, that minimizes the cost of backtracking.

Given the hardware we have these days, I don’t see why anyone would use anything but PEG and packrat parsing.

Google phrase “bryan ford peg”

Building a PEG parser is way, way easier than dealing with Lex and YACC.

I’m not sure if I’ve answered all of your questions … please feel free to ask again....

pt

Post by Gary King
Hi Paul,
What is the performance of Esrap vis-a-vis something like cl-yac? Given a BN grammar, how hard is it to build up a PEG parser?
thanks,

Esrap is a PEG parser. PEG is Lex and Yacc combined. I'm sure that you could use esrap as a lexer-only, if you wish to.
http://nikodemus.github.io/esrap/
On my github there's an experimental PEG syntax overlaid over esrap syntax, if you care. https://github.com/guitarvydas
Ping me if you need ref's to papers about PEG.
pt
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pro mailing list
https://mailman.common-lisp.net/cgi-bin/mailman/listinfo/pro

--
Gary Warren King, metabang.com
Cell: [phone]
Fax: [phone]
gwkkwg on Skype * garethsan on AIM * gwking on twitter
_______________________________________________
pro mailing list
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[Marc Battyani]

The original question was about a lexer do use with buffalo. PEG parsers
do the equivalent of yacc + lex but it should be possible to use a PEG
parser to do only the lexer part to use with buffalo.
Optima (and optima.ppcre) is another library that can be used for lexers.

Marc

I wish that I’d had PEG 20 years ago,
PEG parses a wider set of grammars than YACC can.
PEG is backtracking, but, it uses a trick, memoizing, that minimizes the cost of backtracking.
Given the hardware we have these days, I don’t see why anyone would use anything but PEG and packrat parsing.
Google phrase “bryan ford peg”
Building a PEG parser is way, way easier than dealing with Lex and YACC.
I’m not sure if I’ve answered all of your questions 
 please feel free to ask again....
pt

Post by Gary King
Hi Paul,
What is the performance of Esrap vis-a-vis something like cl-yac? Given a BN grammar, how hard is it to build up a PEG parser?
thanks,

Esrap is a PEG parser. PEG is Lex and Yacc combined. I'm sure that you could use esrap as a lexer-only, if you wish to.
http://nikodemus.github.io/esrap/
On my github there's an experimental PEG syntax overlaid over esrap syntax, if you care. https://github.com/guitarvydas
Ping me if you need ref's to papers about PEG.
pt
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pro mailing list
https://mailman.common-lisp.net/cgi-bin/mailman/listinfo/pro

--
Gary Warren King, metabang.com
Cell: [phone]
Fax: [phone]
gwkkwg on Skype * garethsan on AIM * gwking on twitter
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