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<p class=MsoNormal>ABNF is documented here:<span style='font-size:11.0pt;
font-family:"Calibri","sans-serif";color:#1F497D'> </span><a
href="http://en.wikipedia.org/wiki/Augmented_Backus%E2%80%93Naur_Form">http://en.wikipedia.org/wiki/Augmented_Backus–Naur_Form</a><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>You will first have to understand the differences and convert
in to a LL ANTLR grammar.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I’m not sure but ABNF might allow left recursion. In
that case you need to remove left recursions from the grammar. There are
standard methods to do it. Here is the theory behind it : <a
href="http://www-und.ida.liu.se/~TDDA89/Notes/left.rec.pdf">http://www-und.ida.liu.se/~TDDA89/Notes/left.rec.pdf</a>.
And here is an article from ANTLR wiki: <a
href="http://www.antlr.org/wiki/display/ANTLR3/Left-Recursion+Removal+-+Print+Edition">http://www.antlr.org/wiki/display/ANTLR3/Left-Recursion+Removal+-+Print+Edition</a><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Replacing backtracking by Left factoring can also be done
very methodologically. You just have to remove the necessity for infinite
lookahead. Refer <a
href="http://www.cse.iitk.ac.in/research/mtech1998/9811115/node29.html">http://www.cse.iitk.ac.in/research/mtech1998/9811115/node29.html</a>
to understand what left factoring is.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>If you still have doubts, send us a small segment that you
are not able to left factor along with what you have tried. <o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Regards,<o:p></o:p></p>
<p class=MsoNormal>Indhu<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>PS: Please address the mail to the group to get quicker and better
replies.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Bharath R
[mailto:r.bharath@huawei.com] <br>
<b>Sent:</b> Friday, September 11, 2009 11:47 AM<br>
<b>To:</b> 'Indhu Bharathi'<br>
<b>Subject:</b> RE: [antlr-interest] Optimized code generation<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Hi , </span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Thanx a lot for ur reply. </span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Sorry for asking the question on basic of ANTLR , could you pls
tell me how should I left factor my grammar. </span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Currently I am working in SIP Protocol , where the RFC 3966 defines
the TEL URI Grammar in ABNF format. </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>This format need to be converted into the parser understandable
way. </span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>So I have used antlrworks for writing my grammar file.</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'> </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>And eventually end up with a complex state where I could not able
to compile the grammar without "backtrack=true". </span><o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal> <o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Regards</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:blue'>Bharath R </span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
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<p class=MsoNormal><br>
<span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:gray'>Address:
Huawei Industrial Base<br>
Bantian Longgang<br>
Shenzhen 518129, P.R.China<br>
www.huawei.com<br>
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This e-mail and its attachments contain confidential information from HUAWEI,
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use of the <br>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> Indhu Bharathi
[mailto:indhu.b@s7software.com] <br>
<b>Sent:</b> Thursday, September 10, 2009 10:37 PM<br>
<b>To:</b> r.bharath@huawei.com; 'antlr-interest'<br>
<b>Subject:</b> RE: [antlr-interest] Optimized code generation</span><o:p></o:p></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Yes, backtracking will affect performance. If you are concerned
about performance, don’t use backtrack and try left factoring your
grammar instead. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
antlr-interest-bounces@antlr.org [mailto:antlr-interest-bounces@antlr.org] <b>On
Behalf Of </b>Bharath R<br>
<b>Sent:</b> Thursday, September 10, 2009 5:25 PM<br>
<b>To:</b> 'antlr-interest'<br>
<b>Subject:</b> [antlr-interest] Optimized code generation<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Hi
All , </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Pls
let me know what are all the option that I could use , to get the generated
code with more performance. ( Need to be fast in parsing ). </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>I
have enabled " backtracking = true " , will this hits the
performance ??? </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Without
this option some ambiquity is coming. </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Pls
help me in providing any better performace tuning option that I could set for
code generation. </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Thanx
in advance</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Bharath
R </span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
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<p class=MsoNormal><br>
<span style='font-size:7.5pt;font-family:"Arial","sans-serif";color:gray'>Address:
Huawei Industrial Base<br>
Bantian Longgang<br>
Shenzhen 518129, P.R.China<br>
www.huawei.com<br>
-------------------------------------------------------------------------------------------------------------------------------------<br>
This e-mail and its attachments contain confidential information from HUAWEI,
which <br>
is intended only for the person or entity whose address is listed above. Any
use of the <br>
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