#!/usr/bin/python
"""
NTriples Tools: Parses and serializes N-Triples documents.
http://infomesh.net/2001/10/ntriples/
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
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 = {}, []
   # Comprehensible 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'
   else:
      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
                CTriple.append(term[1:-1])
             elif term[:2] == '_:': # Term is an unlabelled node: bNode
                bNode = term[2:]
                if re.compile(r'[A-Za-z][A-Za-z0-9]*', re.S).match(bNode):
                   if not bNode in bNodes.keys(): bNodes[bNode] = rdf.node()
                   CTriple.append(bNodes[bNode])
                else: raise 'bnode: "'+bNode+'" is not a valid bNode'
             elif term[0] == '"' and term[-1] == '"': 
                CTriple.append(unicode(term[1:-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
      else: raise "Line is invalid", line # Validity error
   return store

def serialize(store):
   """Prints out as NTriples (co-written)."""
   nodeIdMap, nodeIdNum, nt, utol = {}, 0, '', rdf.URIToLiteral
   for t in store.tripleList: 
      for pos in [t.subject, t.predicate, t.object]: 
         if (not hasattr(pos, 'uri') and pos not in nodeIdMap.keys()): 
            nodeIdNum += 1; nodeIdMap[pos] = 's'+`nodeIdNum`
      for pos in [t.subject, t.predicate, t.object]: 
         if pos in nodeIdMap.keys(): nt += '_:'+nodeIdMap[pos]+' '
         elif pos.uri[:6] == 'data:,': nt += '"'+utol(pos.uri)+'" '
         else: nt += '<'+pos.uri+'> '
      nt += '.\n'
   return string.rstrip(nt)

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

# Main program

if __name__ == "__main__":
     run()

# Phew