311 lines
10 KiB
Python
311 lines
10 KiB
Python
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# 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 FieldMask class."""
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from google.protobuf.descriptor import FieldDescriptor
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class FieldMask(object):
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"""Class for FieldMask message type."""
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__slots__ = ()
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def ToJsonString(self):
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"""Converts FieldMask to string according to proto3 JSON spec."""
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camelcase_paths = []
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for path in self.paths:
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camelcase_paths.append(_SnakeCaseToCamelCase(path))
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return ','.join(camelcase_paths)
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def FromJsonString(self, value):
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"""Converts string to FieldMask according to proto3 JSON spec."""
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if not isinstance(value, str):
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raise ValueError('FieldMask JSON value not a string: {!r}'.format(value))
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self.Clear()
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if value:
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for path in value.split(','):
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self.paths.append(_CamelCaseToSnakeCase(path))
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def IsValidForDescriptor(self, message_descriptor):
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"""Checks whether the FieldMask is valid for Message Descriptor."""
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for path in self.paths:
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if not _IsValidPath(message_descriptor, path):
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return False
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return True
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def AllFieldsFromDescriptor(self, message_descriptor):
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"""Gets all direct fields of Message Descriptor to FieldMask."""
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self.Clear()
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for field in message_descriptor.fields:
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self.paths.append(field.name)
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def CanonicalFormFromMask(self, mask):
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"""Converts a FieldMask to the canonical form.
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Removes paths that are covered by another path. For example,
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"foo.bar" is covered by "foo" and will be removed if "foo"
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is also in the FieldMask. Then sorts all paths in alphabetical order.
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Args:
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mask: The original FieldMask to be converted.
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"""
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tree = _FieldMaskTree(mask)
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tree.ToFieldMask(self)
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def Union(self, mask1, mask2):
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"""Merges mask1 and mask2 into this FieldMask."""
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_CheckFieldMaskMessage(mask1)
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_CheckFieldMaskMessage(mask2)
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tree = _FieldMaskTree(mask1)
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tree.MergeFromFieldMask(mask2)
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tree.ToFieldMask(self)
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def Intersect(self, mask1, mask2):
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"""Intersects mask1 and mask2 into this FieldMask."""
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_CheckFieldMaskMessage(mask1)
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_CheckFieldMaskMessage(mask2)
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tree = _FieldMaskTree(mask1)
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intersection = _FieldMaskTree()
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for path in mask2.paths:
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tree.IntersectPath(path, intersection)
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intersection.ToFieldMask(self)
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def MergeMessage(
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self, source, destination,
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replace_message_field=False, replace_repeated_field=False):
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"""Merges fields specified in FieldMask from source to destination.
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Args:
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source: Source message.
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destination: The destination message to be merged into.
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replace_message_field: Replace message field if True. Merge message
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field if False.
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replace_repeated_field: Replace repeated field if True. Append
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elements of repeated field if False.
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"""
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tree = _FieldMaskTree(self)
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tree.MergeMessage(
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source, destination, replace_message_field, replace_repeated_field)
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def _IsValidPath(message_descriptor, path):
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"""Checks whether the path is valid for Message Descriptor."""
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parts = path.split('.')
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last = parts.pop()
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for name in parts:
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field = message_descriptor.fields_by_name.get(name)
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if (field is None or
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field.label == FieldDescriptor.LABEL_REPEATED or
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field.type != FieldDescriptor.TYPE_MESSAGE):
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return False
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message_descriptor = field.message_type
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return last in message_descriptor.fields_by_name
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def _CheckFieldMaskMessage(message):
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"""Raises ValueError if message is not a FieldMask."""
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message_descriptor = message.DESCRIPTOR
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if (message_descriptor.name != 'FieldMask' or
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message_descriptor.file.name != 'google/protobuf/field_mask.proto'):
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raise ValueError('Message {0} is not a FieldMask.'.format(
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message_descriptor.full_name))
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def _SnakeCaseToCamelCase(path_name):
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"""Converts a path name from snake_case to camelCase."""
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result = []
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after_underscore = False
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for c in path_name:
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if c.isupper():
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raise ValueError(
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'Fail to print FieldMask to Json string: Path name '
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'{0} must not contain uppercase letters.'.format(path_name))
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if after_underscore:
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if c.islower():
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result.append(c.upper())
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after_underscore = False
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else:
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raise ValueError(
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'Fail to print FieldMask to Json string: The '
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'character after a "_" must be a lowercase letter '
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'in path name {0}.'.format(path_name))
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elif c == '_':
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after_underscore = True
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else:
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result += c
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if after_underscore:
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raise ValueError('Fail to print FieldMask to Json string: Trailing "_" '
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'in path name {0}.'.format(path_name))
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return ''.join(result)
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def _CamelCaseToSnakeCase(path_name):
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"""Converts a field name from camelCase to snake_case."""
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result = []
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for c in path_name:
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if c == '_':
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raise ValueError('Fail to parse FieldMask: Path name '
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'{0} must not contain "_"s.'.format(path_name))
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if c.isupper():
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result += '_'
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result += c.lower()
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else:
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result += c
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return ''.join(result)
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class _FieldMaskTree(object):
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"""Represents a FieldMask in a tree structure.
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For example, given a FieldMask "foo.bar,foo.baz,bar.baz",
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the FieldMaskTree will be:
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[_root] -+- foo -+- bar
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+- bar --- baz
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In the tree, each leaf node represents a field path.
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"""
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__slots__ = ('_root',)
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def __init__(self, field_mask=None):
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"""Initializes the tree by FieldMask."""
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self._root = {}
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if field_mask:
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self.MergeFromFieldMask(field_mask)
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def MergeFromFieldMask(self, field_mask):
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"""Merges a FieldMask to the tree."""
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for path in field_mask.paths:
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self.AddPath(path)
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def AddPath(self, path):
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"""Adds a field path into the tree.
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If the field path to add is a sub-path of an existing field path
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in the tree (i.e., a leaf node), it means the tree already matches
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the given path so nothing will be added to the tree. If the path
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matches an existing non-leaf node in the tree, that non-leaf node
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will be turned into a leaf node with all its children removed because
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the path matches all the node's children. Otherwise, a new path will
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be added.
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Args:
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path: The field path to add.
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"""
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node = self._root
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for name in path.split('.'):
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if name not in node:
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node[name] = {}
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elif not node[name]:
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# Pre-existing empty node implies we already have this entire tree.
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return
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node = node[name]
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# Remove any sub-trees we might have had.
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node.clear()
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def ToFieldMask(self, field_mask):
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"""Converts the tree to a FieldMask."""
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field_mask.Clear()
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_AddFieldPaths(self._root, '', field_mask)
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def IntersectPath(self, path, intersection):
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"""Calculates the intersection part of a field path with this tree.
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Args:
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path: The field path to calculates.
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intersection: The out tree to record the intersection part.
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"""
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node = self._root
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for name in path.split('.'):
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if name not in node:
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return
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elif not node[name]:
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intersection.AddPath(path)
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return
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node = node[name]
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intersection.AddLeafNodes(path, node)
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def AddLeafNodes(self, prefix, node):
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"""Adds leaf nodes begin with prefix to this tree."""
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if not node:
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self.AddPath(prefix)
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for name in node:
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child_path = prefix + '.' + name
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self.AddLeafNodes(child_path, node[name])
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def MergeMessage(
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self, source, destination,
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replace_message, replace_repeated):
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"""Merge all fields specified by this tree from source to destination."""
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_MergeMessage(
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self._root, source, destination, replace_message, replace_repeated)
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def _StrConvert(value):
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"""Converts value to str if it is not."""
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# This file is imported by c extension and some methods like ClearField
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# requires string for the field name. py2/py3 has different text
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# type and may use unicode.
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if not isinstance(value, str):
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return value.encode('utf-8')
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return value
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def _MergeMessage(
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node, source, destination, replace_message, replace_repeated):
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"""Merge all fields specified by a sub-tree from source to destination."""
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source_descriptor = source.DESCRIPTOR
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for name in node:
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child = node[name]
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field = source_descriptor.fields_by_name[name]
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if field is None:
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raise ValueError('Error: Can\'t find field {0} in message {1}.'.format(
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name, source_descriptor.full_name))
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if child:
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# Sub-paths are only allowed for singular message fields.
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if (field.label == FieldDescriptor.LABEL_REPEATED or
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field.cpp_type != FieldDescriptor.CPPTYPE_MESSAGE):
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raise ValueError('Error: Field {0} in message {1} is not a singular '
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'message field and cannot have sub-fields.'.format(
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name, source_descriptor.full_name))
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if source.HasField(name):
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_MergeMessage(
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child, getattr(source, name), getattr(destination, name),
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replace_message, replace_repeated)
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continue
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if field.label == FieldDescriptor.LABEL_REPEATED:
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if replace_repeated:
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destination.ClearField(_StrConvert(name))
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repeated_source = getattr(source, name)
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repeated_destination = getattr(destination, name)
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repeated_destination.MergeFrom(repeated_source)
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else:
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if field.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
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if replace_message:
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destination.ClearField(_StrConvert(name))
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if source.HasField(name):
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getattr(destination, name).MergeFrom(getattr(source, name))
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else:
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setattr(destination, name, getattr(source, name))
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def _AddFieldPaths(node, prefix, field_mask):
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"""Adds the field paths descended from node to field_mask."""
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if not node and prefix:
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field_mask.paths.append(prefix)
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return
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for name in sorted(node):
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if prefix:
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child_path = prefix + '.' + name
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else:
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child_path = name
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_AddFieldPaths(node[name], child_path, field_mask)
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