316 lines
10 KiB
Python
316 lines
10 KiB
Python
#
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# Copyright 2007 Google LLC. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# WARNING: This file is externally viewable by our users. All comments from
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# this file will be stripped. The docstrings will NOT. Do not put sensitive
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# information in docstrings. If you must communicate internal information in
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# this source file, please place them in comments only.
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from __future__ import absolute_import
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from googlecloudsdk.appengine.api import validation
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from googlecloudsdk.appengine.api import yaml_builder
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from googlecloudsdk.appengine.api import yaml_errors
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from googlecloudsdk.appengine.api import yaml_listener
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from ruamel import yaml
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class _ObjectMapper(object):
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"""Wrapper used for mapping attributes from a yaml file to an object.
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This wrapper is required because objects do not know what property they are
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associated with a creation time, and therefore can not be instantiated
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with the correct class until they are mapped to their parents.
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"""
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def __init__(self):
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"""Object mapper starts off with empty value."""
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self.value = None
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self.seen = set()
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def set_value(self, value):
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"""Set value of instance to map to.
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Args:
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value: Instance that this mapper maps to.
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"""
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self.value = value
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def see(self, key):
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if key in self.seen:
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raise yaml_errors.DuplicateAttribute("Duplicate attribute '%s'." % key)
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self.seen.add(key)
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class _ObjectSequencer(object):
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"""Wrapper used for building sequences from a yaml file to a list.
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This wrapper is required because objects do not know what property they are
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associated with a creation time, and therefore can not be instantiated
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with the correct class until they are mapped to their parents.
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"""
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def __init__(self):
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"""Object sequencer starts off with empty value."""
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self.value = []
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self.constructor = None
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def set_constructor(self, constructor):
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"""Set object used for constructing new sequence instances.
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Args:
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constructor: Callable which can accept no arguments. Must return
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an instance of the appropriate class for the container.
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"""
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self.constructor = constructor
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class ObjectBuilder(yaml_builder.Builder):
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"""Builder used for constructing validated objects.
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Given a class that implements validation.ValidatedBase, it will parse a YAML
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document and attempt to build an instance of the class.
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ObjectBuilder will only map YAML fields that are accepted by the
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ValidatedBase's GetValidator function.
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Lists are mapped to validated. Repeated attributes and maps are mapped to
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validated.Type properties.
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For a YAML map to be compatible with a class, the class must have a
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constructor that can be called with no parameters. If the provided type
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does not have such a constructor a parse time error will occur.
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"""
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def __init__(self, default_class):
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"""Initialize validated object builder.
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Args:
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default_class: Class that is instantiated upon the detection of a new
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document. An instance of this class will act as the document itself.
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"""
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self.default_class = default_class
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def _GetRepeated(self, attribute):
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"""Get the ultimate type of a repeated validator.
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Looks for an instance of validation.Repeated, returning its constructor.
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Args:
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attribute: Repeated validator attribute to find type for.
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Returns:
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The expected class of of the Type validator, otherwise object.
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"""
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if isinstance(attribute, validation.Optional):
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attribute = attribute.validator
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if isinstance(attribute, validation.Repeated):
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return attribute.constructor
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return object
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def BuildDocument(self):
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"""Instantiate new root validated object.
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Returns:
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New instance of validated object.
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"""
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return self.default_class()
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def BuildMapping(self, top_value):
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"""New instance of object mapper for opening map scope.
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Args:
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top_value: Parent of nested object.
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Returns:
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New instance of object mapper.
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"""
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result = _ObjectMapper()
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# The first map encountered must be mapped directly to the
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# main document instance.
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if isinstance(top_value, self.default_class):
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result.value = top_value
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return result
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def EndMapping(self, top_value, mapping):
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"""When leaving scope, makes sure new object is initialized.
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This method is mainly for picking up on any missing required attributes.
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Args:
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top_value: Parent of closing mapping object.
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mapping: _ObjectMapper instance that is leaving scope.
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"""
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# make sure that mapping.value is a non-built-in type (i.e. can have
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# 'CheckInitialized' called on it)
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if not hasattr(mapping.value, 'CheckInitialized'):
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raise validation.ValidationError('Cannot convert map to non-map value.')
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try:
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mapping.value.CheckInitialized()
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except validation.ValidationError:
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# These should just pass through.
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raise
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except Exception as e:
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# Some errors may have problematic encoding or other issues.
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# Re-raising an error in this block would be very hard to debug
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# for the time being so instead, on error, the value is merely
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# obscured.
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try:
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error_str = str(e)
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except Exception:
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error_str = '<unknown>'
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# Wrap in a ValidationError
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raise validation.ValidationError(error_str, e)
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def BuildSequence(self, top_value):
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"""New instance of object sequence.
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Args:
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top_value: Object that contains the new sequence.
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Returns:
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A new _ObjectSequencer instance.
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"""
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return _ObjectSequencer()
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def MapTo(self, subject, key, value):
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"""Map key-value pair to an objects attribute.
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Args:
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subject: _ObjectMapper of object that will receive new attribute.
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key: Key of attribute.
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value: Value of new attribute.
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Raises:
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UnexpectedAttribute when the key is not a validated attribute of
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the subject value class.
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"""
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assert isinstance(subject.value, validation.ValidatedBase)
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try:
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attribute = subject.value.GetValidator(key)
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except validation.ValidationError as err:
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raise yaml_errors.UnexpectedAttribute(err)
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if isinstance(value, _ObjectMapper):
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# Now know what class the new instance should be.
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# Time to construct it from the attributes expected type.
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value.set_value(attribute.expected_type())
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value = value.value
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elif isinstance(value, _ObjectSequencer):
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# Now know what class new instances within the sequence should be.
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value.set_constructor(self._GetRepeated(attribute))
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value = value.value
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subject.see(key)
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try:
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subject.value.Set(key, value)
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except validation.ValidationError as e:
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# Some errors may have problematic encoding or other issues.
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# Re-raising an error in this block would be very hard to debug
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# for the time being so instead, on error, the value is merely
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# obscured.
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try:
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error_str = str(e)
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except Exception:
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error_str = '<unknown>'
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try:
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value_str = str(value)
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except Exception:
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value_str = '<unknown>'
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# Update error message with a better message.
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e.message = ("Unable to assign value '%s' to attribute '%s':\n%s" %
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(value_str, key, error_str))
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raise e
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except Exception as e:
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try:
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error_str = str(e)
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except Exception:
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error_str = '<unknown>'
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try:
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value_str = str(value)
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except Exception:
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value_str = '<unknown>'
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# Raise a more generic exception message.
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message = ("Unable to assign value '%s' to attribute '%s':\n%s" %
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(value_str, key, error_str))
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raise validation.ValidationError(message, e)
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def AppendTo(self, subject, value):
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"""Append a value to a sequence.
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Args:
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subject: _ObjectSequence that is receiving new value.
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value: Value that is being appended to sequence.
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"""
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if isinstance(value, _ObjectMapper):
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# Construct a new instance of the list.
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value.set_value(subject.constructor())
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subject.value.append(value.value)
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else:
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# Append value to list.
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subject.value.append(value)
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def BuildObjects(default_class, stream, loader=yaml.loader.SafeLoader):
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"""Build objects from stream.
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Handles the basic case of loading all the objects from a stream.
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Args:
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default_class: Class that is instantiated upon the detection of a new
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document. An instance of this class will act as the document itself.
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stream: String document or open file object to process as per the
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yaml.parse method. Any object that implements a 'read()' method which
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returns a string document will work with the YAML parser.
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loader_class: Used for dependency injection.
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Returns:
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List of default_class instances parsed from the stream.
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"""
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builder = ObjectBuilder(default_class)
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handler = yaml_builder.BuilderHandler(builder)
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listener = yaml_listener.EventListener(handler)
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listener.Parse(stream, loader, version=(1, 1))
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return handler.GetResults()
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def BuildSingleObject(default_class, stream, loader=yaml.loader.SafeLoader):
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"""Build object from stream.
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Handles the basic case of loading a single object from a stream.
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Args:
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default_class: Class that is instantiated upon the detection of a new
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document. An instance of this class will act as the document itself.
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stream: String document or open file object to process as per the
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yaml.parse method. Any object that implements a 'read()' method which
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returns a string document will work with the YAML parser.
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loader_class: Used for dependency injection.
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"""
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definitions = BuildObjects(default_class, stream, loader)
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if len(definitions) < 1:
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raise yaml_errors.EmptyConfigurationFile()
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if len(definitions) > 1:
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raise yaml_errors.MultipleConfigurationFile()
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return definitions[0]
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