##############################################################################
#
# Copyright (c) 2004, 2005 Zope Corporation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Trusted expression

$Id: TrustedExpression.py 18543 2005-10-14 13:37:26Z regebro $
"""
from sys import modules

from Products.PageTemplates.PythonExpr import PythonExpr

from Products.PageTemplates.Expressions import \
     SubPathExpr, PathExpr, \
     StringExpr, \
     getEngine, installHandlers,\
     SecureModuleImporter

from ReuseUtils import rebindFunction

ModuleImporter = SecureModuleImporter

def trustedTraverse(ob, path, ignored,):
  if not path: return self

  get = getattr
  has = hasattr
  N = None
  M = rebindFunction # artifical marker

  if isinstance(path, str): path = path.split('/')
  else: path=list(path)
  
  REQUEST={'TraversalRequestNameStack': path}
  path.reverse()
  pop=path.pop

  if len(path) > 1 and not path[0]:
    # Remove trailing slash
    path.pop(0)

  if not path[-1]:
    # If the path starts with an empty string, go to the root first.
    pop()
    self=ob.getPhysicalRoot()

  object = ob
  while path:
    name=pop()
    __traceback_info__ = path, name

    if name == '..':
      o=getattr(object, 'aq_parent', M)
      if o is not M:
        object=o
        continue

    t=get(object, '__bobo_traverse__', M)
    if t is not M: o=t(REQUEST, name)
    else:
      o = get(object, name, M)
      if o is M:
        try: o = object[name]
        except (AttributeError, TypeError): # better exception
          raise AttributeError(name)
    object = o

  return object


class SubPathExpr(SubPathExpr):
  _eval = rebindFunction(SubPathExpr._eval.im_func,
                         restrictedTraverse=trustedTraverse,
                         )

class PathExpr(PathExpr):
  __init__ = rebindFunction(PathExpr.__init__.im_func,
                            SubPathExpr=SubPathExpr,
                            )

class StringExpr(StringExpr):
  __init__ = rebindFunction(StringExpr.__init__.im_func,
                            PathExpr=PathExpr,
                            )
  
installHandlers = rebindFunction(installHandlers,
                                 PathExpr=PathExpr,
                                 StringExpr=StringExpr,
                                 PythonExpr=PythonExpr,
                                 )

_engine=None
getEngine = rebindFunction(getEngine,
                           _engine=_engine,
                           installHandlers=installHandlers
                           )


  
