#!/usr/bin/env python
"""
rdfcdb.py - Fast RDF database in pure Python
Author: Sean B. Palmer
License: GPL 2; share and enjoy!

Status: Prototype
Requirements: 
   Python2.4+ - http://www.python.org/
   python-cdb-0.32+ - http://pilcrow.madison.wi.us/python-cdb/
   ntriples.py - http://inamidst.com/proj/rdf/ntriples.py
"""

import sys, urllib
import cdb, ntriples

class Node(unicode): pass
class URI(Node): pass
class bNode(Node): pass
class Literal(Node): 
   def __new__(cls, lit, dtype, lang): 
      return Node.__new__(cls, lit)

def nodeToDB(node): 
   types = {URI: '>', bNode: '_', Literal: '"'}
   for key in types.iterkeys(): 
      if isinstance(node, key): 
         return types[key] + ' ' + node.encode('utf-8')
   raise ValueError("Unknown node type: %s" % type(node))

class Graph(object): 
   def __init__(self, **kargs): 
      self.database = '/desktop/rdfcdb'
      methods = {'uri': self.feedURI, 'ntriples': self.feedNTriples}
      for key in methods.iterkeys(): 
         if kargs.has_key(key): 
            methods[key](kargs[key])

   def feedURI(self, uri): 
      u = urllib.urlopen(uri)
      data = u.read()
      u.close()
      self.feedNTriples(data)

   def feedNTriples(self, nt): 
      ntriples.URI = URI
      ntriples.bNode = bNode
      ntriples.Literal = Literal

      class NTriplesSink(object): 
         def triple(sink, s, p, o): 
            self.append(s, p, o)

      p = ntriples.NTriplesParser(sink=NTriplesSink())
      p.parsestring(nt)

   def append(self, s, p, o): 
      triple = map(nodeToDB, (s, p, o))

def main(): 
   if len(sys.argv) == 2: 
      Graph(uri=sys.argv[1])

if __name__=="__main__": 
   main()