cl-ppcre-devel August 2005

cl-ppcre-devel@common-lisp.net

2 participants
4 discussions

Re: [cl-ppcre-devel] Roles of scanner vs. parser vs. lexer?
by Edi Weitz 04 Aug '05

04 Aug '05

[You forgot to Cc the mailing list.] On Wed, 3 Aug 2005 15:49:58 -0700, Derek Peschel <dpeschel(a)eskimo.com> wrote: > CL-PPCRE makes a start, with a grammar and a set of token types that > the lexer produces. The problem, as you know, is how to make sure > the specification is complete while stating it in a way that's not > tied to a particular implementation. All the context-sensitive > tricks (extended mode, backreference vs. octal constants, \Q and \E) > make the spec harder to check too. Definitely. I'm afraid I won't be able to help very much, though. CL-PPCRE's parser/lexer is very much an ad hoc implementation and it's the first parser I ever wrote. > Climacs's syntax highlighters work with parse trees, so CL-PPCRE's > use of them seemed to make it a good match for Climacs. I think > Climacs needs to reconstruct the original text from the parse tree, > and it parses the text incrementally, and a good syntax module will > flag errors yet allow further changes to the text. So I don't know > if the Climacs parse tree could be ready to pass to CL-PPCRE. But > that would be ideal. Without knowing anything about Climacs' internals: How about using CL-PPCRE::PARSE-STRING and feeding the result to Climacs? > Are dangling \Es legal in Perl too? Yep. edi@vmware:~$ perl -le '$a = "\Q*\E\E"; print $a' \* Cheers, Edi.

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[cl-ppcre-devel] Roles of scanner vs. parser vs. lexer?
by Derek Peschel 03 Aug '05

03 Aug '05

Hi everybody, I've been reading the CL-PPCRE docs and code to get a clear specification of the syntax. Ultimately I'd like to add syntax highlighting for CL-PPCRE regexps to the Climacs text editor. But there seems to be a certain amount of defensive or sloppy programming (things being done in more than one place). The scanner knows something about skipping # comments but the lexer does too. The lexer has code to ignore \E markers but I get the impression the scanner removes them before the lexer starts. If this kind of duplication does exist, is there a useful reason for it? -- Derek

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[cl-ppcre-devel] Typo in documentation string for parser function GROUP?
by Derek Peschel 03 Aug '05

03 Aug '05

Hi everybody, I only have version 1.2.10. Since the change log for 1.2.11 doesn't mention this problem, I assume it hasn't been fixed yet. In parser.lisp, the documentation string for function GROUP starts out "Parses and consumes a <group>. The productions are: <group> -> \"(\"<regex>\")\" \"(?:\"<regex>\")\" \"(?<\"<regex>\")\" But shouldn't the last line read \"(?>\"<regex>\")\" ? After all, (?< tokens always have something else after the angle bracket. -- Derek

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[cl-ppcre-devel] New version 1.2.11
by Edi Weitz 01 Aug '05

01 Aug '05

ChangeLog: Version 1.2.11 2005-08-01 Added external format for SBCL in ppcre-tests.lisp (thanks to Christophe Rhodes) Download: <http://weitz.de/files/cl-ppcre.tar.gz> Cheers, Edi.

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cl-ppcre-devel August 2005