Move //mojo/{public, edk} underneath //third_party

mojo/public/python/mojo_bindings/serialization.py

-# Copyright 2014 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-"""Utility classes for serialization"""
-
-import struct
-
-
-# Format of a header for a struct or an array.
-HEADER_STRUCT = struct.Struct("<II")
-
-
-class SerializationException(Exception):
-  """Error when strying to serialize a struct."""
-  pass
-
-
-class DeserializationException(Exception):
-  """Error when strying to deserialize a struct."""
-  pass
-
-
-class DeserializationContext(object):
-
-  def ClaimHandle(self, handle):
-    raise NotImplementedError()
-
-  def ClaimMemory(self, start, size):
-    raise NotImplementedError()
-
-  def GetSubContext(self, offset):
-    raise NotImplementedError()
-
-  def IsInitialContext(self):
-    raise NotImplementedError()
-
-
-class RootDeserializationContext(DeserializationContext):
-  def __init__(self, data, handles):
-    if isinstance(data, buffer):
-      self.data = data
-    else:
-      self.data = buffer(data)
-    self._handles = handles
-    self._next_handle = 0;
-    self._next_memory = 0;
-
-  def ClaimHandle(self, handle):
-    if handle < self._next_handle:
-      raise DeserializationException('Accessing handles out of order.')
-    self._next_handle = handle + 1
-    return self._handles[handle]
-
-  def ClaimMemory(self, start, size):
-    if start < self._next_memory:
-      raise DeserializationException('Accessing buffer out of order.')
-    self._next_memory = start + size
-
-  def GetSubContext(self, offset):
-    return _ChildDeserializationContext(self, offset)
-
-  def IsInitialContext(self):
-    return True
-
-
-class _ChildDeserializationContext(DeserializationContext):
-  def __init__(self, parent, offset):
-    self._parent = parent
-    self._offset = offset
-    self.data = buffer(parent.data, offset)
-
-  def ClaimHandle(self, handle):
-    return self._parent.ClaimHandle(handle)
-
-  def ClaimMemory(self, start, size):
-    return self._parent.ClaimMemory(self._offset + start, size)
-
-  def GetSubContext(self, offset):
-    return self._parent.GetSubContext(self._offset + offset)
-
-  def IsInitialContext(self):
-    return False
-
-
-class Serialization(object):
-  """
-  Helper class to serialize/deserialize a struct.
-  """
-  def __init__(self, groups):
-    self.version = _GetVersion(groups)
-    self._groups = groups
-    main_struct = _GetStruct(groups)
-    self.size = HEADER_STRUCT.size + main_struct.size
-    self._struct_per_version = {
-        self.version: main_struct,
-    }
-    self._groups_per_version = {
-        self.version: groups,
-    }
-
-  def _GetMainStruct(self):
-    return self._GetStruct(self.version)
-
-  def _GetGroups(self, version):
-    # If asking for a version greater than the last known.
-    version = min(version, self.version)
-    if version not in self._groups_per_version:
-      self._groups_per_version[version] = _FilterGroups(self._groups, version)
-    return self._groups_per_version[version]
-
-  def _GetStruct(self, version):
-    # If asking for a version greater than the last known.
-    version = min(version, self.version)
-    if version not in self._struct_per_version:
-      self._struct_per_version[version] = _GetStruct(self._GetGroups(version))
-    return self._struct_per_version[version]
-
-  def Serialize(self, obj, handle_offset):
-    """
-    Serialize the given obj. handle_offset is the the first value to use when
-    encoding handles.
-    """
-    handles = []
-    data = bytearray(self.size)
-    HEADER_STRUCT.pack_into(data, 0, self.size, self.version)
-    position = HEADER_STRUCT.size
-    to_pack = []
-    for group in self._groups:
-      position = position + NeededPaddingForAlignment(position,
-                                                      group.GetByteSize())
-      (entry, new_handles) = group.Serialize(
-          obj,
-          len(data) - position,
-          data,
-          handle_offset + len(handles))
-      to_pack.append(entry)
-      handles.extend(new_handles)
-      position = position + group.GetByteSize()
-    self._GetMainStruct().pack_into(data, HEADER_STRUCT.size, *to_pack)
-    return (data, handles)
-
-  def Deserialize(self, fields, context):
-    if len(context.data) < HEADER_STRUCT.size:
-      raise DeserializationException(
-          'Available data too short to contain header.')
-    (size, version) = HEADER_STRUCT.unpack_from(context.data)
-    if len(context.data) < size or size < HEADER_STRUCT.size:
-      raise DeserializationException('Header size is incorrect.')
-    if context.IsInitialContext():
-      context.ClaimMemory(0, size)
-    version_struct = self._GetStruct(version)
-    entitities = version_struct.unpack_from(context.data, HEADER_STRUCT.size)
-    filtered_groups = self._GetGroups(version)
-    position = HEADER_STRUCT.size
-    for (group, value) in zip(filtered_groups, entitities):
-      position = position + NeededPaddingForAlignment(position,
-                                                      group.GetByteSize())
-      fields.update(group.Deserialize(value, context.GetSubContext(position)))
-      position += group.GetByteSize()
-
-
-def NeededPaddingForAlignment(value, alignment=8):
-  """Returns the padding necessary to align value with the given alignment."""
-  if value % alignment:
-    return alignment - (value % alignment)
-  return 0
-
-
-def _GetVersion(groups):
-  return sum([len(x.descriptors) for x in groups])
-
-
-def _FilterGroups(groups, version):
-  return [group for group in groups if group.GetVersion() < version]
-
-
-def _GetStruct(groups):
-  index = 0
-  codes = [ '<' ]
-  for group in groups:
-    code = group.GetTypeCode()
-    size = group.GetByteSize()
-    needed_padding = NeededPaddingForAlignment(index, size)
-    if needed_padding:
-      codes.append('x' * needed_padding)
-      index = index + needed_padding
-    codes.append(code)
-    index = index + size
-  alignment_needed = NeededPaddingForAlignment(index)
-  if alignment_needed:
-    codes.append('x' * alignment_needed)
-  return struct.Struct(''.join(codes))