##############################################################################
# 
# Zope Public License (ZPL) Version 1.0
# -------------------------------------
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# This software consists of contributions made by Digital Creations and
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##############################################################################
"""Provide a function that can find object references in pickles
"""
import cPickle, cStringIO

def referencesf(p,rootl,
                Unpickler=cPickle.Unpickler,
                StringIO=cStringIO.StringIO,
                tt=type(()),
                type=type):

    u=Unpickler(StringIO(p))
    l=len(rootl)
    u.persistent_load=rootl
    u.noload()
    try: u.noload()
    except:
        # Hm.  We failed to do second load.  Maybe there wasn't a
        # second pickle.  Let's check:
        f=StringIO(p)
        u=Unpickler(f)
        u.persistent_load=[]
        u.noload()
        if len(p) > f.tell(): raise ValueError, 'Error unpickling, %s' % p

    # References may have class info, so we need to
    # check for wrapped references.
    for i in range(l, len(rootl)):
        v=rootl[i]
        if v:
            if type(v) is tt: v=v[0]
            rootl[i]=v
                
    return rootl
