5541f43903
Mutables in the method params defaults might cause errors and that's why it's anti-pattern in most of the cases and should be removed. Change-Id: I8bc284f12ce72082a0482410ec2c20c2fc087a4b Closes-Bug: #1327473
374 lines
13 KiB
Python
374 lines
13 KiB
Python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import collections
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import copy
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import itertools
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import operator
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from heat.common import exception
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from heat.engine import function
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from heat.engine import properties
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__all__ = ['ResourceDefinition']
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class ResourceDefinitionCore(object):
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"""
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A definition of a resource, independent of any particular template format.
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"""
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DELETION_POLICIES = (
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DELETE, RETAIN, SNAPSHOT,
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) = (
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'Delete', 'Retain', 'Snapshot',
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)
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def __init__(self, name, resource_type, properties=None, metadata=None,
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depends=None, deletion_policy=None, update_policy=None,
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description=''):
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"""
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Initialise with the parsed definition of a resource.
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Any intrinsic functions present in any of the sections should have been
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parsed into Function objects before constructing the definition.
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:param name: The name of the resource (for use in error messages)
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:param resource_type: The resource type
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:param properties: A dictionary of supplied property values
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:param metadata: The supplied metadata
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:param depends: A list of resource names on which this resource depends
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:param deletion_policy: The deletion policy for the resource
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:param update_policy: A dictionary of supplied update policies
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:param description: A string describing the resource
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"""
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depends = depends or []
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self.name = name
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self.resource_type = resource_type
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self.description = description
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self._properties = properties
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self._metadata = metadata
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self._depends = depends
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self._deletion_policy = deletion_policy
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self._update_policy = update_policy
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self._hash = hash(self.resource_type)
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self._rendering = None
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assert isinstance(description, basestring)
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if properties is not None:
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assert isinstance(properties, (collections.Mapping,
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function.Function))
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self._hash ^= _hash_data(properties)
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if metadata is not None:
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assert isinstance(metadata, (collections.Mapping,
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function.Function))
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self._hash ^= _hash_data(metadata)
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assert isinstance(depends, (collections.Sequence,
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function.Function))
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assert not isinstance(depends, basestring)
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self._hash ^= _hash_data(depends)
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if deletion_policy is not None:
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assert deletion_policy in self.DELETION_POLICIES
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self._hash ^= hash(deletion_policy)
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if update_policy is not None:
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assert isinstance(update_policy, (collections.Mapping,
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function.Function))
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self._hash ^= _hash_data(update_policy)
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def reparse(self, stack, template):
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"""
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Reinterpret the resource definition in the context of a new stack.
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This returns a new resource definition, with all of the functions
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parsed in the context of the specified stack and template.
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"""
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def reparse_snippet(snippet):
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return template.parse(stack, copy.deepcopy(snippet))
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return type(self)(self.name, self.resource_type,
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reparse_snippet(self._properties),
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reparse_snippet(self._metadata),
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reparse_snippet(self._depends),
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reparse_snippet(self._deletion_policy),
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reparse_snippet(self._update_policy))
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def dependencies(self, stack):
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"""
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Return the Resource objects in the given stack on which this depends.
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"""
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def path(section):
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return '.'.join([self.name, section])
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def get_resource(res_name):
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if res_name not in stack:
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raise exception.InvalidTemplateReference(resource=res_name,
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key=self.name)
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return stack[res_name]
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def strict_func_deps(data, datapath):
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return itertools.ifilter(lambda r: getattr(r, 'strict_dependency',
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True),
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function.dependencies(data, datapath))
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return itertools.chain((get_resource(dep) for dep in self._depends),
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strict_func_deps(self._properties,
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path(PROPERTIES)),
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strict_func_deps(self._metadata,
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path(METADATA)))
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def properties(self, schema, context=None):
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"""
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Return a Properties object representing the resource properties.
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The Properties object is constructed from the given schema, and may
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require a context to validate constraints.
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"""
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return properties.Properties(schema, self._properties or {},
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function.resolve, self.name, context)
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def deletion_policy(self):
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"""
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Return the deletion policy for the resource.
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The policy will be one of those listed in DELETION_POLICIES.
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"""
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return function.resolve(self._deletion_policy) or self.DELETE
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def update_policy(self, schema, context=None):
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"""
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Return a Properties object representing the resource update policy.
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The Properties object is constructed from the given schema, and may
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require a context to validate constraints.
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"""
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return properties.Properties(schema, self._update_policy or {},
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function.resolve, self.name, context)
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def metadata(self):
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"""
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Return the resource metadata.
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"""
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return function.resolve(self._metadata) or {}
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def render_hot(self):
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"""
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Return a HOT snippet for the resource definition.
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"""
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if self._rendering is None:
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attrs = {
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'type': 'resource_type',
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'properties': '_properties',
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'metadata': '_metadata',
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'deletion_policy': '_deletion_policy',
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'update_policy': '_update_policy',
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'depends_on': '_depends',
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}
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def rawattrs():
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"""Get an attribute with function objects stripped out."""
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for key, attr in attrs.items():
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value = getattr(self, attr)
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if value is not None:
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yield key, copy.deepcopy(value)
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self._rendering = dict(rawattrs())
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return self._rendering
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def __eq__(self, other):
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"""
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Compare this resource definition for equality with another.
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Two resource definitions are considered to be equal if they can be
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generated from the same template snippet. The name of the resource is
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ignored, as are the actual values that any included functions resolve
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to.
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"""
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if not isinstance(other, ResourceDefinitionCore):
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return NotImplemented
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return self.render_hot() == other.render_hot()
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def __ne__(self, other):
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"""
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Compare this resource definition for inequality with another.
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See __eq__() for the definition of equality.
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"""
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equal = self.__eq__(other)
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if equal is NotImplemented:
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return NotImplemented
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return not equal
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def __hash__(self):
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"""
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Return a hash value for this resource definition.
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Resource definitions that compare equal will have the same hash. (In
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particular, the resource name is *not* taken into account.) See
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the __eq__() method for the definition of equality.
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"""
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return self._hash
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def __repr__(self):
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"""
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Return a string representation of the resource definition.
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"""
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def arg_repr(arg_name):
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return '='.join([arg_name, repr(getattr(self, '_%s' % arg_name))])
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args = ('properties', 'metadata', 'depends',
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'deletion_policy', 'update_policy')
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data = {
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'classname': type(self).__name__,
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'name': repr(self.name),
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'type': repr(self.type),
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'args': ', '.join(arg_repr(n) for n in args)
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}
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return '%(classname)s(%(name)s, %(type)s, %(args)s)' % data
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_KEYS = (
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TYPE, PROPERTIES, METADATA, DELETION_POLICY, UPDATE_POLICY,
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DEPENDS_ON, DESCRIPTION,
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) = (
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'Type', 'Properties', 'Metadata', 'DeletionPolicy', 'UpdatePolicy',
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'DependsOn', 'Description',
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)
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class ResourceDefinition(ResourceDefinitionCore, collections.Mapping):
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"""
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A resource definition that also acts like a cfn template snippet.
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This class exists only for backwards compatibility with existing resource
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plugins and unit tests; it will at some point be deprecated and then
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replaced with ResourceDefinitionCore.
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"""
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def __eq__(self, other):
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"""
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Compare this resource definition for equality with another.
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Two resource definitions are considered to be equal if they can be
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generated from the same template snippet. The name of the resource is
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ignored, as are the actual values that any included functions resolve
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to.
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This method can also compare the resource definition to a template
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snippet. In this case, two snippets are considered equal if they
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compare equal in a dictionary comparison. (Specifically, this means
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that intrinsic functions are compared by their results.) This exists
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solely to not break existing unit tests.
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"""
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if not isinstance(other, ResourceDefinitionCore):
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if isinstance(other, collections.Mapping):
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return dict(self) == other
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return super(ResourceDefinition, self).__eq__(other)
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def __iter__(self):
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"""
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Iterate over the available CFN template keys.
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This is for backwards compatibility with existing code that expects a
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parsed-JSON template snippet.
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"""
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yield TYPE
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if self._properties is not None:
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yield PROPERTIES
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if self._metadata is not None:
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yield METADATA
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if self._deletion_policy is not None:
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yield DELETION_POLICY
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if self._update_policy is not None:
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yield UPDATE_POLICY
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if self._depends:
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yield DEPENDS_ON
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if self.description:
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yield DESCRIPTION
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def __getitem__(self, key):
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"""
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Get the specified item from a CFN template snippet.
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This is for backwards compatibility with existing code that expects a
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parsed-JSON template snippet.
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"""
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if key == TYPE:
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return self.resource_type
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elif key == PROPERTIES:
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if self._properties is not None:
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return self._properties
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elif key == METADATA:
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if self._metadata is not None:
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return self._metadata
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elif key == DELETION_POLICY:
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if self._deletion_policy is not None:
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return self._deletion_policy
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elif key == UPDATE_POLICY:
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if self._update_policy is not None:
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return self._update_policy
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elif key == DEPENDS_ON:
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if self._depends:
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if len(self._depends) == 1:
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return self._depends[0]
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return self._depends
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elif key == DESCRIPTION:
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if self.description:
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return self.description
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raise KeyError(key)
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def __len__(self):
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"""
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Return the number of available CFN template keys.
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This is for backwards compatibility with existing code that expects a
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parsed-JSON template snippet.
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"""
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return len(list(iter(self)))
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def __repr__(self):
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"""
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Return a string representation of the resource definition.
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"""
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return 'ResourceDefinition %s' % repr(dict(self))
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def _hash_data(data):
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"""
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Return a stable hash value for an arbitrary parsed-JSON data snippet.
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"""
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if isinstance(data, function.Function):
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data = copy.deepcopy(data)
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if not isinstance(data, basestring):
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if isinstance(data, collections.Sequence):
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return hash(tuple(_hash_data(d) for d in data))
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if isinstance(data, collections.Mapping):
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item_hashes = (hash(k) ^ _hash_data(v) for k, v in data.items())
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return reduce(operator.xor, item_hashes, 0L)
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return hash(data)
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