* Alberto Reggiori wrote:
> Bjoern Hoehrmann wrote:
> > 
> > Hi,
> > 
> >    Anyone going to write a Notation3 PerlSAX2 parser?
> 
> yes, I planned to build a N3 and N-triples [1] parser in RDFStore but I
> am not done yet; I just hacked an rdf2n3p.pl util using SiRPAC for the
> moment. Any help/contribution is appreciated :)

N-Triples, as they are currently defined (please see my comments on
www-rdf-comments on the current draft) are quite easy to parse:
  
  #!perl -w
  use strict;
  use warnings;

  # ...
  
  while (<HANDLE> ) {
    chomp;              # remove trailing newline
    s/^[\x20\x09]+//;   # remove leading white space
    s/[\x20\x09]+$//;   # remove trailing white space
    next if /^#/;       # skip comments
    next unless /\S/;   # skip empty lines
  
    # syntax checks
    if (/[^\x20-\x7e\x0d\x0a\x09]/)
    {
      # invalid character(s) found
    }
  
    unless (s/\.$//)
    {
      # syntax error: missing trailing full stop
    }
  
    # parse subject
    if (s/^<([^> ]*)>[\x20\x09]+//)
    {
      # uriref
    }
    elsif (s/^_:([A-Za-z][A-Za-z0-9]*)[\x20\x09]+//)
    {
      # bNode
    }
    else
    {
      # syntax error in <subject>  token
    }
  
    # parse predicate
    if (s/^<([^> ]*)>[\x20\x09]+//)
    {
      # uriref
    }
    else
    {
      # syntax error in predicate
    }
  
    # parse object
    if (s/^<([^> ]*)>[\x20\x09]+//)
    {
      # uriref
    }
    elsif (s/^_:([A-Za-z][A-Za-z0-9]*)[\x20\x09]+//)
    {
      # bNode
    }
    elsif (s/"([^"]*)"[\x20\x09]+//)
    {
      # literal
    }
    else
    {
      # syntax error in <object>  token 
    }
  
    if (length)
    {
      # trash found after <object>  token
    }
  }

You still have to unescape the escapes, but in general you are done with
this. Not very beautiful, but it works.

> [1] http://www.w3.org/2001/sw/RDFCore/ntriples/

This document is AFAICT obsolted by the RDF test cases WD.
-- 
Björn Höhrmann { mailto:bjoern@[...].de } http://www.bjoernsworld.de
am Badedeich 7 } Telefon: +49(0)4667/981028 { http://bjoern.hoehrmann.de
25899 Dagebüll { PGP Pub. KeyID: 0xA4357E78 } http://www.learn.to/quote/
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