195 lines
7.1 KiB
Python
195 lines
7.1 KiB
Python
# Protocol Buffers - Google's data interchange format
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# Copyright 2008 Google Inc. All rights reserved.
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#
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# Use of this source code is governed by a BSD-style
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# license that can be found in the LICENSE file or at
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# https://developers.google.com/open-source/licenses/bsd
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"""Contains _ExtensionDict class to represent extensions.
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"""
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from google.protobuf.internal import type_checkers
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from google.protobuf.descriptor import FieldDescriptor
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def _VerifyExtensionHandle(message, extension_handle):
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"""Verify that the given extension handle is valid."""
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if not isinstance(extension_handle, FieldDescriptor):
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raise KeyError('HasExtension() expects an extension handle, got: %s' %
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extension_handle)
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if not extension_handle.is_extension:
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raise KeyError('"%s" is not an extension.' % extension_handle.full_name)
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if not extension_handle.containing_type:
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raise KeyError('"%s" is missing a containing_type.'
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% extension_handle.full_name)
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if extension_handle.containing_type is not message.DESCRIPTOR:
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raise KeyError('Extension "%s" extends message type "%s", but this '
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'message is of type "%s".' %
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(extension_handle.full_name,
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extension_handle.containing_type.full_name,
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message.DESCRIPTOR.full_name))
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# TODO: Unify error handling of "unknown extension" crap.
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# TODO: Support iteritems()-style iteration over all
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# extensions with the "has" bits turned on?
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class _ExtensionDict(object):
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"""Dict-like container for Extension fields on proto instances.
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Note that in all cases we expect extension handles to be
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FieldDescriptors.
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"""
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def __init__(self, extended_message):
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"""
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Args:
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extended_message: Message instance for which we are the Extensions dict.
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"""
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self._extended_message = extended_message
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def __getitem__(self, extension_handle):
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"""Returns the current value of the given extension handle."""
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_VerifyExtensionHandle(self._extended_message, extension_handle)
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result = self._extended_message._fields.get(extension_handle)
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if result is not None:
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return result
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if extension_handle.label == FieldDescriptor.LABEL_REPEATED:
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result = extension_handle._default_constructor(self._extended_message)
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elif extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
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message_type = extension_handle.message_type
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if not hasattr(message_type, '_concrete_class'):
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# pylint: disable=g-import-not-at-top
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from google.protobuf import message_factory
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message_factory.GetMessageClass(message_type)
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if not hasattr(extension_handle.message_type, '_concrete_class'):
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from google.protobuf import message_factory
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message_factory.GetMessageClass(extension_handle.message_type)
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result = extension_handle.message_type._concrete_class()
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try:
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result._SetListener(self._extended_message._listener_for_children)
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except ReferenceError:
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pass
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else:
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# Singular scalar -- just return the default without inserting into the
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# dict.
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return extension_handle.default_value
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# Atomically check if another thread has preempted us and, if not, swap
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# in the new object we just created. If someone has preempted us, we
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# take that object and discard ours.
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# WARNING: We are relying on setdefault() being atomic. This is true
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# in CPython but we haven't investigated others. This warning appears
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# in several other locations in this file.
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result = self._extended_message._fields.setdefault(
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extension_handle, result)
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return result
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def __eq__(self, other):
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if not isinstance(other, self.__class__):
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return False
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my_fields = self._extended_message.ListFields()
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other_fields = other._extended_message.ListFields()
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# Get rid of non-extension fields.
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my_fields = [field for field in my_fields if field.is_extension]
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other_fields = [field for field in other_fields if field.is_extension]
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return my_fields == other_fields
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def __ne__(self, other):
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return not self == other
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def __len__(self):
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fields = self._extended_message.ListFields()
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# Get rid of non-extension fields.
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extension_fields = [field for field in fields if field[0].is_extension]
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return len(extension_fields)
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def __hash__(self):
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raise TypeError('unhashable object')
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# Note that this is only meaningful for non-repeated, scalar extension
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# fields. Note also that we may have to call _Modified() when we do
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# successfully set a field this way, to set any necessary "has" bits in the
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# ancestors of the extended message.
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def __setitem__(self, extension_handle, value):
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"""If extension_handle specifies a non-repeated, scalar extension
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field, sets the value of that field.
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"""
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_VerifyExtensionHandle(self._extended_message, extension_handle)
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if (extension_handle.label == FieldDescriptor.LABEL_REPEATED or
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extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE):
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raise TypeError(
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'Cannot assign to extension "%s" because it is a repeated or '
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'composite type.' % extension_handle.full_name)
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# It's slightly wasteful to lookup the type checker each time,
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# but we expect this to be a vanishingly uncommon case anyway.
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type_checker = type_checkers.GetTypeChecker(extension_handle)
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# pylint: disable=protected-access
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self._extended_message._fields[extension_handle] = (
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type_checker.CheckValue(value))
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self._extended_message._Modified()
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def __delitem__(self, extension_handle):
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self._extended_message.ClearExtension(extension_handle)
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def _FindExtensionByName(self, name):
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"""Tries to find a known extension with the specified name.
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Args:
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name: Extension full name.
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Returns:
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Extension field descriptor.
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"""
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descriptor = self._extended_message.DESCRIPTOR
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extensions = descriptor.file.pool._extensions_by_name[descriptor]
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return extensions.get(name, None)
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def _FindExtensionByNumber(self, number):
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"""Tries to find a known extension with the field number.
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Args:
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number: Extension field number.
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Returns:
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Extension field descriptor.
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"""
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descriptor = self._extended_message.DESCRIPTOR
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extensions = descriptor.file.pool._extensions_by_number[descriptor]
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return extensions.get(number, None)
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def __iter__(self):
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# Return a generator over the populated extension fields
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return (f[0] for f in self._extended_message.ListFields()
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if f[0].is_extension)
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def __contains__(self, extension_handle):
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_VerifyExtensionHandle(self._extended_message, extension_handle)
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if extension_handle not in self._extended_message._fields:
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return False
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if extension_handle.label == FieldDescriptor.LABEL_REPEATED:
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return bool(self._extended_message._fields.get(extension_handle))
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if extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
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value = self._extended_message._fields.get(extension_handle)
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# pylint: disable=protected-access
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return value is not None and value._is_present_in_parent
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return True
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