murano/murano/dsl/lhs_expression.py

#    Copyright (c) 2014 Mirantis, Inc.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

import itertools

import six
from yaql.language import specs
from yaql.language import utils
from yaql.language import yaqltypes

from murano.dsl import constants
from murano.dsl import dsl
from murano.dsl import dsl_types
from murano.dsl import exceptions
from murano.dsl import yaql_functions
from murano.dsl import yaql_integration


class LhsExpression(object):
    class Property(object):
        def __init__(self, getter, setter):
            self._getter = getter
            self._setter = setter

        def get(self):
            return self._getter()

        def set(self, value):
            self._setter(value)

    def __init__(self, expression):
        self._expression = expression

    def _create_context(self, root_context):
        @specs.parameter('name', yaqltypes.StringConstant())
        def get_context_data(name):

            def set_data(value):
                if not name or name == '$' or name == '$this':
                    raise ValueError('Cannot assign to {0}'.format(name))
                ctx = root_context
                while constants.CTX_VARIABLE_SCOPE not in ctx:
                    ctx = ctx.parent
                ctx[name] = value

            return LhsExpression.Property(
                lambda: root_context[name], set_data)

        @specs.parameter('this', LhsExpression.Property)
        @specs.parameter('key', yaqltypes.Keyword())
        def attribution(this, key):
            def setter(src_property, value):
                src = src_property.get()
                if isinstance(src, utils.MappingType):
                    src_property.set(
                        utils.FrozenDict(
                            itertools.chain(
                                six.iteritems(src),
                                ((key, value),))))
                elif isinstance(src, dsl_types.MuranoObject):
                    src.set_property(key, value, root_context)
                elif isinstance(src, (
                        dsl_types.MuranoTypeReference,
                        dsl_types.MuranoType)):
                    if isinstance(src, dsl_types.MuranoTypeReference):
                        mc = src.type
                    else:
                        mc = src
                    mc.set_property(key, value, root_context)
                else:
                    raise ValueError(
                        'attribution may only be applied to '
                        'objects and dictionaries')

            def getter(src):
                if isinstance(src, utils.MappingType):
                    return src.get(key, {})
                elif isinstance(src, dsl_types.MuranoObject):
                    self._current_obj = src
                    self._current_obj_name = key
                    try:
                        return src.get_property(key, root_context)
                    except exceptions.UninitializedPropertyAccessError:
                        return {}

                else:
                    raise ValueError(
                        'attribution may only be applied to '
                        'objects and dictionaries')

            return LhsExpression.Property(
                lambda: getter(this.get()),
                lambda value: setter(this, value))

        @specs.parameter('this', LhsExpression.Property)
        @specs.parameter('index', yaqltypes.Lambda(with_context=True))
        def indexation(this, index):
            index = index(root_context)

            def getter(src):
                if utils.is_sequence(src):
                    return src[index]
                else:
                    raise ValueError('indexation may only be applied to lists')

            def setter(src_property, value):
                src = src_property.get()
                if utils.is_sequence(src):
                    src_property.set(src[:index] + (value,) + src[index + 1:])
                elif isinstance(src, utils.MappingType):
                    attribution(src_property, index).set(value)

            if isinstance(index, int):
                return LhsExpression.Property(
                    lambda: getter(this.get()),
                    lambda value: setter(this, value))
            else:
                return attribution(this, index)

        def _wrap_type_reference(tr):
            return LhsExpression.Property(lambda: tr, self._invalid_target)

        @specs.parameter('prefix', yaqltypes.Keyword())
        @specs.parameter('name', yaqltypes.Keyword())
        @specs.name('#operator_:')
        def ns_resolve(prefix, name):
            return _wrap_type_reference(
                yaql_functions.ns_resolve(context, prefix, name))

        @specs.parameter('name', yaqltypes.Keyword())
        @specs.name('#unary_operator_:')
        def ns_resolve_unary(context, name):
            return _wrap_type_reference(
                yaql_functions.ns_resolve_unary(context, name))

        @specs.parameter('object_', dsl_types.MuranoObject)
        def type_(object_):
            return _wrap_type_reference(yaql_functions.type_(object_))

        @specs.name('type')
        @specs.parameter('cls', dsl.MuranoTypeParameter())
        def type_from_name(cls):
            return _wrap_type_reference(cls)

        context = yaql_integration.create_empty_context()
        context.register_function(get_context_data, '#get_context_data')
        context.register_function(attribution, '#operator_.')
        context.register_function(indexation, '#indexer')
        context.register_function(ns_resolve)
        context.register_function(ns_resolve_unary)
        context.register_function(type_)
        context.register_function(type_from_name)
        return context

    def _invalid_target(self, *args, **kwargs):
        raise exceptions.InvalidLhsTargetError(self._expression)

    def __call__(self, value, context):
        new_context = self._create_context(context)
        new_context[''] = context['$']
        for name in (constants.CTX_NAMES_SCOPE,):
            new_context[name] = context[name]
        self._current_obj = None
        self._current_obj_name = None
        property = self._expression(context=new_context)
        if not isinstance(property, LhsExpression.Property):
            self._invalid_target()
        property.set(value)