[Zope-Checkins] CVS: Zope2 - Eval.py:1.1.2.1

[shane@digicool.com]

Update of /cvs-repository/Zope2/lib/python/RestrictedPython
In directory korak:/tmp/cvs-serv5392

Added Files:
      Tag: RestrictedPythonBranch
	Eval.py 
Log Message:
Eval, based on VSEval



--- Added File Eval.py in package Zope2 ---
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"""Restricted Python Expressions
"""
__rcs_id__='$Id: Eval.py,v 1.1.2.1 2001/04/19 22:50:59 shane Exp $'
__version__='$Revision: 1.1.2.1 $'[11:-2]

from string import translate, strip
import string
compile_restricted = None

nltosp = string.maketrans('\r\n','  ')

##def careful_mul(env, *factors):
##    # r = result (product of all factors)
##    # c = count (product of all non-sequence factors)
##    # s flags whether any of the factors is a sequence
##    r=c=1
##    s=None
##    for factor in factors:
##        try:
##            l=len(factor)
##            s=1
##        except TypeError:
##            c=c*factor
##        if s and c > 1000:
##            raise TypeError, \
##                  'Illegal sequence repeat (too many repetitions: %d)' % c
##        r=r*factor
##    return r

default_globals={
    '__builtins__': {},
    '_guard': (lambda ob: ob),
    }


class RestrictedEval:
    """Holds a reference to compiled restricted code.
    """

    def __init__(self, expr, globals=default_globals):
        """Create a restricted expression

        where:

          expr -- a string containing the expression to be evaluated.

          globals -- A global namespace.
        """
        global compile_restricted
        if compile_restricted is None:
            # Late binding because this will import the whole
            # compiler suite.
            from RestrictionMutator import compile_restricted

        expr = strip(expr)
        self.__name__ = expr
        expr = translate(expr, nltosp)
        self.expr = expr
        self.globals = globals
        used = {}
        self.code = compile_restricted(expr, '<string>', 'eval', used)
        self.used = tuple(used.keys())

    def eval(self, mapping):
        d = {}
        for name in self.used:
            try:
                d[name] = mapping.getitem(name, 0)
            except KeyError:
                # Swallow KeyErrors since the expression
                # might not actually need the name.  If it
                # does need the name, a NameError will occur.
                pass
        return eval(self.code, self.globals, d)

    def __call__(self, **kw):
        return eval(self.code, self.globals, kw)