#  $Id$
#
#  Copyright (C) 2003 Rational Discovery LLC
#     All Rights Reserved
#
import sys

from rdkit.VLib.Node import VLibNode

class FilterNode(VLibNode):
  """ base class for nodes which filter their input

  Assumptions:

    - filter function takes a number of arguments equal to the
      number of inputs we have.  It returns a bool

    - inputs (parents) can be stepped through in lockstep

    - we return a tuple if there's more than one input
  
  Usage Example:
    >>> from rdkit.VLib.Supply import SupplyNode
    >>> def func(a,b):
    ...   return a+b < 5
    >>> filt = FilterNode(func=func)
    >>> suppl1 = SupplyNode(contents=[1,2,3,3])
    >>> suppl2 = SupplyNode(contents=[1,2,3,1])
    >>> filt.AddParent(suppl1)
    >>> filt.AddParent(suppl2)
    >>> v = [x for x in filt]
    >>> v
    [(1, 1), (2, 2), (3, 1)]
    >>> filt.reset()
    >>> v = [x for x in filt]
    >>> v
    [(1, 1), (2, 2), (3, 1)]
    >>> filt.Destroy()
    
    Negation is also possible:
    >>> filt = FilterNode(func=func,negate=1)
    >>> suppl1 = SupplyNode(contents=[1,2,3,3])
    >>> suppl2 = SupplyNode(contents=[1,2,3,1])
    >>> filt.AddParent(suppl1)
    >>> filt.AddParent(suppl2)
    >>> v = [x for x in filt]
    >>> v
    [(3, 3)]
    >>> filt.Destroy()

    With no function, just return the inputs:
    >>> filt = FilterNode()
    >>> suppl1 = SupplyNode(contents=[1,2,3,3])
    >>> filt.AddParent(suppl1)
    >>> v = [x for x in filt]
    >>> v
    [1, 2, 3, 3]
    >>> filt.Destroy()



  """
  def __init__(self,func=None,negate=0,**kwargs):
    VLibNode.__init__(self,**kwargs)
    self._func = func
    self._negate = negate
  def SetNegate(self,state):
    self._negate = state
  def Negate(self):
    return self._negate

  def next(self):
    done = 0
    parents = self.GetParents()
    while 1:
      args = []
      try:
        for parent in parents:
          args.append(parent.next())
      except StopIteration:
        raise StopIteration
      args = tuple(args)
      if self._func is not None:
        r = apply(self._func,args)
        if self._negate:
          r = not r
          #sys.stderr.write('\t\tNEGATE -> %d\n'%(r))
        if r:
          res = args
          break
      else:
        res = args
        break
    if len(parents)==1:
      res = res[0]
    return res
  

  
#------------------------------------
#
#  doctest boilerplate
#
def _test():
  import doctest,sys
  return doctest.testmod(sys.modules["__main__"])

if __name__ == '__main__':
  import sys
  failed,tried = _test()
  sys.exit(failed)

  
