How to use the cma.graphnodeexpression.ExpressionContext function in cma

"""
        Evaluate an expression.
        It can be:
            None - return None
            'some-value -- return some-value (it's a constant)
            or an expression to find in values or graphnodes
            or @functionname(args) - for defined functions...

            We may add other kinds of expressions in the future...
        """
        if not isinstance(expression, six.string_types):
            # print('RETURNING NONSTRING:', expression, file=sys.stderr)
            return expression
        expression = str(expression.strip())
        if not hasattr(context, "get") or not hasattr(context, "__setitem__"):
            context = ExpressionContext(context)
        # print('''EVALUATE('%s') (%s):''' % (expression, type(expression))
        # The value of this parameter is a constant...
        if expression.startswith('"'):
            if expression[-1] != '"':
                print("unquoted constant string '%s'" % expression, file=sys.stderr)
            # print('''Constant string: "%s"''' % (expression[1:-1]), file=sys.stderr)
            return expression[1:-1] if expression[-1] == '"' else None
        if (expression.startswith("0x") or expression.startswith("0X")) and len(expression) > 3:
            return int(expression[2:], 16)
        if expression.isdigit():
            return int(expression, 8) if expression.startswith("0") else int(expression)
        if expression.find("(") >= 0:
            value = GraphNodeExpression.functioncall(expression, context)
            context[expression] = value
            return value
        # if expression.startswith('$'):

expressionstring = args[-1]
    if not isinstance(expressionstring, six.string_types):
        print(
            "FOREACH expression must be a string, not %s" % type(expressionstring), file=sys.stderr
        )
        return False
    # print('OBJECTLIST is:', objectlist, file=sys.stderr)
    for obj in objectlist:
        # print('OBJ is:', obj, file=sys.stderr)
        for key in obj:
            item = obj[key]
            if not hasattr(item, "__contains__") or not hasattr(item, "__iter__"):
                print("UNSUITABLE FOREACH CONTEXT[%s]: %s" % (key, item), file=sys.stderr)
                continue
            # print(sys.stderr, 'CREATING CONTEXT[%s]: %s' % (key, item), file=sys.stderr)
            itemcontext = ExpressionContext(item)
            # print('CONTEXT IS:', itemcontext, file=sys.stderr)
            value = GraphNodeExpression.evaluate(expressionstring, itemcontext)
            # print('VALUE of %s IS [%s] in context: %s' % (str(args), value, item), file=sys.stderr)
            if value is None:
                anynone = True
            elif not value:
                return False
    return None if anynone else True

def contexttests():
        "GraphNodeExpression tests that need a context"

        lsattrs = """{
    "/var/log/audit/": {"owner": "root", "group": "root", "type": "d", "perms": {"owner":{"read":true, "write":true, "exec":true, "setid":false}, "group": {"read":true, "write":false, "exec":true, "setid":false}, "other": {"read":false, "write":false, "exec":false}, "sticky":false}, "octal": "0750"},
    "/var/log/audit/audit.log": {"owner": "root", "group": "root", "type": "-", "perms": {"owner":{"read":true, "write":true, "exec":false, "setid":false}, "group": {"read":false, "write":false, "exec":false, "setid":false}, "other": {"read":false, "write":false, "exec":false}, "sticky":false}, "octal": "0600"},
    "/var/log/audit/audit.log.1": {"owner": "root", "group": "root", "type": "-", "perms": {"owner":{"read":true, "write":false, "exec":false, "setid":false}, "group": {"read":false, "write":false, "exec":false, "setid":false}, "other": {"read":false, "write":false, "exec":false}, "sticky":false}, "octal": "0400"}
}"""
        lscontext = ExpressionContext(pyConfigContext(lsattrs))

        Pie_context = ExpressionContext(
            (
                pyConfigContext(
                    {
                        "a": {"b": "c", "pie": 3, "pi": 3, "const": "constant"},
                        "f": {"g": "h", "pie": "3", "pi": 3, "const": "constant"},
                    }
                ),
                pyConfigContext({"math": {"pi": 3.14159, "pie": 3, "const": "constant"}}),
                pyConfigContext({"geography": {"Europe": "big", "const": "constant"}}),
            )
        )
        complicated_context = ExpressionContext(pyConfigContext({"a": {"b": {"pie": 3}}}))
        argcontext = ExpressionContext(
            pyConfigContext('{"argv": ["command-name-suffix", "thing-one", "thang-two"]}')
        )

def contexttests():
        "GraphNodeExpression tests that need a context"

        lsattrs = """{
    "/var/log/audit/": {"owner": "root", "group": "root", "type": "d", "perms": {"owner":{"read":true, "write":true, "exec":true, "setid":false}, "group": {"read":true, "write":false, "exec":true, "setid":false}, "other": {"read":false, "write":false, "exec":false}, "sticky":false}, "octal": "0750"},
    "/var/log/audit/audit.log": {"owner": "root", "group": "root", "type": "-", "perms": {"owner":{"read":true, "write":true, "exec":false, "setid":false}, "group": {"read":false, "write":false, "exec":false, "setid":false}, "other": {"read":false, "write":false, "exec":false}, "sticky":false}, "octal": "0600"},
    "/var/log/audit/audit.log.1": {"owner": "root", "group": "root", "type": "-", "perms": {"owner":{"read":true, "write":false, "exec":false, "setid":false}, "group": {"read":false, "write":false, "exec":false, "setid":false}, "other": {"read":false, "write":false, "exec":false}, "sticky":false}, "octal": "0400"}
}"""
        lscontext = ExpressionContext(pyConfigContext(lsattrs))

        Pie_context = ExpressionContext(
            (
                pyConfigContext(
                    {
                        "a": {"b": "c", "pie": 3, "pi": 3, "const": "constant"},
                        "f": {"g": "h", "pie": "3", "pi": 3, "const": "constant"},
                    }
                ),
                pyConfigContext({"math": {"pi": 3.14159, "pie": 3, "const": "constant"}}),
                pyConfigContext({"geography": {"Europe": "big", "const": "constant"}}),
            )
        )
        complicated_context = ExpressionContext(pyConfigContext({"a": {"b": {"pie": 3}}}))
        argcontext = ExpressionContext(
            pyConfigContext('{"argv": ["command-name-suffix", "thing-one", "thang-two"]}')

return self.values[key]
        for obj in self.objects:
            ret = None
            try:
                # print('GETTING %s in %s: %s' % (key, type(obj), obj), file=sys.stderr)
                ret = obj.get(key, None)
                if ret is None and hasattr(obj, "deepget"):
                    ret = obj.deepget(key, None)
                # print('RETURNED %s' % ret, file=sys.stderr)
            # Too general exception catching...
            # pylint: disable=W0703
            except Exception as e:
                ret = None
                print("OOPS: self.objects = %s / exception %s" % (str(self.objects), e), sys.stderr)
                print("OOPS: OUR object = %s (%s)" % (str(obj), type(obj)), file=sys.stderr)
            ret = ExpressionContext._fixvalue(ret)
            if ret is not None:
                self.values[key] = ret
                return ret
            if self.prefix is not None:
                ret = ExpressionContext._fixvalue(obj.get("%s.%s" % (self.prefix, key), None))
                if ret is not None:
                    self.values[key] = ret
                    return ret
        return alternative

lscontext = ExpressionContext(pyConfigContext(lsattrs))

        Pie_context = ExpressionContext(
            (
                pyConfigContext(
                    {
                        "a": {"b": "c", "pie": 3, "pi": 3, "const": "constant"},
                        "f": {"g": "h", "pie": "3", "pi": 3, "const": "constant"},
                    }
                ),
                pyConfigContext({"math": {"pi": 3.14159, "pie": 3, "const": "constant"}}),
                pyConfigContext({"geography": {"Europe": "big", "const": "constant"}}),
            )
        )
        complicated_context = ExpressionContext(pyConfigContext({"a": {"b": {"pie": 3}}}))
        argcontext = ExpressionContext(
            pyConfigContext('{"argv": ["command-name-suffix", "thing-one", "thang-two"]}')
        )

        assert FOREACH(("EQ(False, $perms.group.write, $perms.other.write)",), lscontext) is True
        assert FOREACH(("EQ($pi, 3)",), Pie_context) is False
        assert FOREACH(("EQ($pie, 3)",), Pie_context) is None
        assert FOREACH(("$a", "EQ($pie, 3)"), complicated_context) is True
        assert FOREACH(("$a", "EQ($pie, 3.14159)"), complicated_context) is False
        assert FOREACH(("$a", "EQ($pi, 3.14159)"), complicated_context) is None
        assert FOREACH(("EQ($const, constant)",), Pie_context) is True
        assert GraphNodeExpression.evaluate("EQ($math.pie, 3)", Pie_context) is True
        assert FOREACH(("EQ($group, root)",), lscontext) is True
        assert FOREACH(("EQ($owner, root)",), lscontext) is True
        assert FOREACH(("AND(EQ($owner, root), EQ($group, root))",), lscontext) is True
        assert argmatch(("thing-(.*)",), argcontext) == "one"
        assert argmatch(("THING-(.*)", "$argv", "I"), argcontext) == "one"