#!/usr/bin/python
"""Semantic Web API Query Module."""

__author__ = 'Sean B. Palmer'
__license__ = 'Copyright (C) 2002 Sean B. Palmer. GNU GPL 2'

import api, ntuples, copy

class Query: 
   def __init__(self): self.result = []

   def mquery(self, store, querytuples, bindings, found=[]): 
      if len(querytuples) > 0: # Now we query
         p = []
         for j in range(len(querytuples[0])): 
            if querytuples[0][j].type == 'Univar': p.append(j)
         res = store.query(querytuples[0])
         for r in res: 
            b = copy.copy(bindings)
            f = copy.copy(found)
            cont = 1
            for j in p: # add the variables to the binding, and query again
               if b[`querytuples[0][j]`] in (None, `r[j]`): 
                  b[`querytuples[0][j]`] = `r[j]`
               else: cont = 0
            if cont: 
               f.append(r)
               self.mquery(store, querytuples[1:], b, f)
      elif None not in bindings.values(): 
         self.result.append((found, bindings))

   def uquery(self, store, querytuples): 
      """Query a set of triples against a store."""
      bindings = {} # Make a dictionary of all the variables in querytuples
      for qtuple in querytuples: 
         for x in qtuple: 
            if x.type == 'Univar': bindings[`x`] = None
      self.mquery(store, querytuples, bindings)
      return self.result

def query(f, q, fmt=0): 
   assert isinstance(f, api.TupleStore)
   assert isinstance(q, api.TupleStore)
   x = Query().uquery(f, q)
   return [x, '\n\n'.join([ntuples.serialize(api.TupleStore(y[0])) 
                             for y in x])][fmt]

if __name__=="__main__": 
   print __doc__