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ntriples.py 1.1

From: Aaron Swartz <aswartz@upclink.com>
Date: Sun, 21 Oct 2001 01:51:14 -0500
Cc: www-archive@w3.org
To: "Sean B. Palmer" <sean@mysterylights.com>
Message-Id: <04ECB317-C5F0-11D5-964B-003065D5CE46@upclink.com>
I hope you don't mind but I took the liberty of cleaning up ntriples.py.

I made some small changes:
  - I renamed it "NTriples Tools: Parses and serializes N-Triples 
  - I moved the license down to a __license__ variable.

And a major one: I didn't see the reason it was a class with 
lots of little functions. I really only wanted two things from 
it: take an N-Triples string and give me back an RDF store 
(parse) and take a store and give me back an N-Triples string 
(serialize). So I linearized it into two plain old functions: 
parse(document, store=rdf.Store()) and serialize(store).

I took out the special NTriplesURLopener, since I figured 
calling apps could deal with URIs on their own. I also took out 
the specialized code to deal with file, file names, files, etc.

I also fixed a number of bugs along the way. Resulting code is 
104 lines + command line interface. There still looks like a lot 
of room for tersification, but since I couldn't follow the 
de-commented code very well, I didn't bother (and it's getting 

Let me know if you have questions,
- [ "Aaron Swartz" ; <mailto:me@aaronsw.com> ; 
<http://www.aaronsw.com/> ]

NTriples Tools: Parses and serializes N-Triples documents.
Built on Aaron Swartz's RDF API: http://blogspace.com/rdf/rdfapi.txt
cf. http://www.w3.org/TR/2001/WD-rdf-testcases-20010912/#ntriples

import sys, string, re, urllib
import rdfapi as rdf

__author__ = "Sean B. Palmer with Aaron Swartz"
__version__ = '1.1'
__license__ = """
Copyright (C) 2001 Sean B. Palmer.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.

def parse(document, store=rdf.Store()):
   bNodes = {}
   CTriple = []

   # Uncomprehensible regexps
   t = r'(<[^>]+>|_:[^\s]+|\"(?:\\\"|[^"])*\")'
   rt = re.compile(r'[ \t]*'+t+r'[ \t]+'+t+r'[ \t]+'+t+r'[ \t]*.[ \t]*')
   rc = re.compile(r'(\#[^\n]*)')
   rw = re.compile(r'[ \t]+')

   # Normalize the new lines in document
   if len(document) == 0: raise 'Document has no content'
      document = string.replace(document, '\r\n', '\n')
      document = string.replace(document, '\r', '\n')

   # Parse document into tripleList
   lines = string.split(document, '\n')
   for line in lines:
      if len(line) == 0: continue # line has no content (a double '\n')
      elif rt.match(line):
          terms = rt.findall(line)[0]
          for term in terms:
             if term[0] == '<' and term[-1] == '>': # Term is a URI-view
             elif term[:2] == '_:': # Term is an unlabelled node: bNode
                bNode = term[2:]
                if re.compile(r'[A-Za-z][A-Za-z0-9]*', 
                   if not bNode in bNodes.keys():
                      bNodes[bNode] = rdf.node()
                else: raise 'bnode: "'+bNode+'" is not a valid bNode'
             elif term[0] == '"' and term[-1] == '"':
             else: raise 'Term '+str(term)+' is not a valid 
NTriples term.'
          store.triple(CTriple[0], CTriple[1], CTriple[2])
          CTriple = [] # Reset the current triple
      elif rc.match(line): continue # Line is a comment
      elif rw.match(line): continue # Line is just whitespace
      	SyntaxError = "Line is invalid"
      	raise SyntaxError, line # Validity error
   return store

def serialize(store):
   """Prints out as NTriples (Aaron wrote this function).
   Aaron notes: The code is really ugly and needs to be cleaned up."""
   nodeIdMap, nodeIdNum, output = {}, 0, []
   for t in store.tripleList:
      if (not hasattr(t.subject, 'uri')
        and t.subject not in nodeIdMap.keys()):
         nodeIdNum += 1
         nodeIdMap[t.subject] = 'a' + `nodeIdNum`
      if (not hasattr(t.predicate, 'uri')
        and t.predicate not in nodeIdMap.keys()):
         nodeIdNum += 1
         nodeIdMap[t.predicate] = 'a' + `nodeIdNum`
      if (not hasattr(t.object, 'uri')
        and t.object not in nodeIdMap.keys()):
         nodeIdNum += 1
         nodeIdMap[t.object] = 'a' + `nodeIdNum`
      if t.subject in nodeIdMap.keys(): sub = '_:' + nodeIdMap[t.subject]
      else: sub = '<'+t.subject.uri+'>'
      if t.predicate in nodeIdMap.keys(): prd = '_:' + 
      else: prd = '<'+t.predicate.uri+'>'
      if t.object in nodeIdMap.keys(): obj = '_:' + nodeIdMap[t.object]
      	if t.object.uri[:6] == "data:,":
      		obj = '"'+ rdf.URIToLiteral(t.object.uri) +'"'
      	else: obj = '<'+t.object.uri+'>'
      output.append('%s %s %s .' % (sub, prd, obj))
   return string.join(output, '\n')

def run():
   x = parse(open(sys.argv[1]).read())
   print serialize(x)

# Main program

if __name__ == "__main__":

# Phew
Received on Sunday, 21 October 2001 02:52:06 GMT

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