text: # Copyright 2013 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.
  
  # This module's classes provide an interface to mojo modules. Modules are
  # collections of interfaces and structs to be used by mojo ipc clients and
  # servers.
  #
  # A simple interface would be created this way:
  # module = mojom.generate.module.Module('Foo')
  # interface = module.AddInterface('Bar')
  # method = interface.AddMethod('Tat', 0)
  # method.AddParameter('baz', 0, mojom.INT32)
  
  import sys
  if sys.version_info.major == 2:
    import cPickle as pickle
  else:
    import pickle
  from uuid import UUID
  
  
  class BackwardCompatibilityChecker(object):
    """Used for memoization while recursively checking two type definitions for
    backward-compatibility."""
  
    def __init__(self):
      self._cache = {}
  
    def IsBackwardCompatible(self, new_kind, old_kind):
      key = (new_kind, old_kind)
      result = self._cache.get(key)
      if result is None:
        # Assume they're compatible at first to effectively ignore recursive
        # checks between these types, e.g. if both kinds are a struct or union
        # that references itself in a field.
        self._cache[key] = True
        result = new_kind.IsBackwardCompatible(old_kind, self)
        self._cache[key] = result
      return result
  
  
  # We use our own version of __repr__ when displaying the AST, as the
  # AST currently doesn't capture which nodes are reference (e.g. to
  # types) and which nodes are definitions. This allows us to e.g. print
  # the definition of a struct when it's defined inside a module, but
  # only print its name when it's referenced in e.g. a method parameter.
  def Repr(obj, as_ref=True):
    """A version of __repr__ that can distinguish references.
  
    Sometimes we like to print an object's full representation
    (e.g. with its fields) and sometimes we just want to reference an
    object that was printed in full elsewhere. This function allows us
    to make that distinction.
  
    Args:
      obj: The object whose string representation we compute.
      as_ref: If True, use the short reference representation.
  
    Returns:
      A str representation of |obj|.
    """
    if hasattr(obj, 'Repr'):
      return obj.Repr(as_ref=as_ref)
    # Since we cannot implement Repr for existing container types, we
    # handle them here.
    elif isinstance(obj, list):
      if not obj:
        return '[]'
      else:
        return ('[\n%s\n]' % (',\n'.join(
            '    %s' % Repr(elem, as_ref).replace('\n', '\n    ')
            for elem in obj)))
    elif isinstance(obj, dict):
      if not obj:
        return '{}'
      else:
        return ('{\n%s\n}' % (',\n'.join(
            '    %s: %s' % (Repr(key, as_ref).replace('\n', '\n    '),
                            Repr(val, as_ref).replace('\n', '\n    '))
            for key, val in obj.items())))
    else:
      return repr(obj)
  
  
  def GenericRepr(obj, names):
    """Compute generic Repr for |obj| based on the attributes in |names|.
  
    Args:
      obj: The object to compute a Repr for.
      names: A dict from attribute names to include, to booleans
          specifying whether those attributes should be shown as
          references or not.
  
    Returns:
      A str representation of |obj|.
    """
  
    def ReprIndent(name, as_ref):
      return '    %s=%s' % (name, Repr(getattr(obj, name), as_ref).replace(
          '\n', '\n    '))
  
    return '%s(\n%s\n)' % (obj.__class__.__name__, ',\n'.join(
        ReprIndent(name, as_ref) for (name, as_ref) in names.items()))
  
  
  class Kind(object):
    """Kind represents a type (e.g. int8, string).
  
    Attributes:
      spec: A string uniquely identifying the type. May be None.
      module: {Module} The defining module. Set to None for built-in types.
      parent_kind: The enclosing type. For example, an enum defined
          inside an interface has that interface as its parent. May be None.
    """
  
    def __init__(self, spec=None, module=None):
      self.spec = spec
      self.module = module
      self.parent_kind = None
  
    def Repr(self, as_ref=True):
      # pylint: disable=unused-argument
      return '<%s spec=%r>' % (self.__class__.__name__, self.spec)
  
    def __repr__(self):
      # Gives us a decent __repr__ for all kinds.
      return self.Repr()
  
    def __eq__(self, rhs):
      # pylint: disable=unidiomatic-typecheck
      return (type(self) == type(rhs)
              and (self.spec, self.parent_kind) == (rhs.spec, rhs.parent_kind))
  
    def __hash__(self):
      # TODO(crbug.com/1060471): Remove this and other __hash__ methods on Kind
      # and its subclasses. This is to support existing generator code which uses
      # some primitive Kinds as dict keys. The default hash (object identity)
      # breaks these dicts when a pickled Module instance is unpickled and used
      # during a subsequent run of the parser.
      return hash((self.spec, self.parent_kind))
  
    # pylint: disable=unused-argument
    def IsBackwardCompatible(self, rhs, checker):
      return self == rhs
  
  
  class ReferenceKind(Kind):
    """ReferenceKind represents pointer and handle types.
  
    A type is nullable if null (for pointer types) or invalid handle (for handle
    types) is a legal value for the type.
  
    Attributes:
      is_nullable: True if the type is nullable.
    """
  
    def __init__(self, spec=None, is_nullable=False, module=None):
      assert spec is None or is_nullable == spec.startswith('?')
      Kind.__init__(self, spec, module)
      self.is_nullable = is_nullable
      self.shared_definition = {}
  
    def Repr(self, as_ref=True):
      return '<%s spec=%r is_nullable=%r>' % (self.__class__.__name__, self.spec,
                                              self.is_nullable)
  
    def MakeNullableKind(self):
      assert not self.is_nullable
  
      if self == STRING:
        return NULLABLE_STRING
      if self == HANDLE:
        return NULLABLE_HANDLE
      if self == DCPIPE:
        return NULLABLE_DCPIPE
      if self == DPPIPE:
        return NULLABLE_DPPIPE
      if self == MSGPIPE:
        return NULLABLE_MSGPIPE
      if self == SHAREDBUFFER:
        return NULLABLE_SHAREDBUFFER
      if self == PLATFORMHANDLE:
        return NULLABLE_PLATFORMHANDLE
  
      nullable_kind = type(self)()
      nullable_kind.shared_definition = self.shared_definition
      if self.spec is not None:
        nullable_kind.spec = '?' + self.spec
      nullable_kind.is_nullable = True
      nullable_kind.parent_kind = self.parent_kind
      nullable_kind.module = self.module
  
      return nullable_kind
  
    @classmethod
    def AddSharedProperty(cls, name):
      """Adds a property |name| to |cls|, which accesses the corresponding item in
         |shared_definition|.
  
         The reason of adding such indirection is to enable sharing definition
         between a reference kind and its nullable variation. For example:
           a = Struct('test_struct_1')
           b = a.MakeNullableKind()
           a.name = 'test_struct_2'
           print(b.name)  # Outputs 'test_struct_2'.
      """
  
      def Get(self):
        try:
          return self.shared_definition[name]
        except KeyError:  # Must raise AttributeError if property doesn't exist.
          raise AttributeError
  
      def Set(self, value):
        self.shared_definition[name] = value
  
      setattr(cls, name, property(Get, Set))
  
    def __eq__(self, rhs):
      return (isinstance(rhs, ReferenceKind)
              and super(ReferenceKind, self).__eq__(rhs)
              and self.is_nullable == rhs.is_nullable)
  
    def __hash__(self):
      return hash((super(ReferenceKind, self).__hash__(), self.is_nullable))
  
    def IsBackwardCompatible(self, rhs, checker):
      return (super(ReferenceKind, self).IsBackwardCompatible(rhs, checker)
              and self.is_nullable == rhs.is_nullable)
  
  
  # Initialize the set of primitive types. These can be accessed by clients.
  BOOL = Kind('b')
  INT8 = Kind('i8')
  INT16 = Kind('i16')
  INT32 = Kind('i32')
  INT64 = Kind('i64')
  UINT8 = Kind('u8')
  UINT16 = Kind('u16')
  UINT32 = Kind('u32')
  UINT64 = Kind('u64')
  FLOAT = Kind('f')
  DOUBLE = Kind('d')
  STRING = ReferenceKind('s')
  HANDLE = ReferenceKind('h')
  DCPIPE = ReferenceKind('h:d:c')
  DPPIPE = ReferenceKind('h:d:p')
  MSGPIPE = ReferenceKind('h:m')
  SHAREDBUFFER = ReferenceKind('h:s')
  PLATFORMHANDLE = ReferenceKind('h:p')
  NULLABLE_STRING = ReferenceKind('?s', True)
  NULLABLE_HANDLE = ReferenceKind('?h', True)
  NULLABLE_DCPIPE = ReferenceKind('?h:d:c', True)
  NULLABLE_DPPIPE = ReferenceKind('?h:d:p', True)
  NULLABLE_MSGPIPE = ReferenceKind('?h:m', True)
  NULLABLE_SHAREDBUFFER = ReferenceKind('?h:s', True)
  NULLABLE_PLATFORMHANDLE = ReferenceKind('?h:p', True)
  
  # Collection of all Primitive types
  PRIMITIVES = (
      BOOL,
      INT8,
      INT16,
      INT32,
      INT64,
      UINT8,
      UINT16,
      UINT32,
      UINT64,
      FLOAT,
      DOUBLE,
      STRING,
      HANDLE,
      DCPIPE,
      DPPIPE,
      MSGPIPE,
      SHAREDBUFFER,
      PLATFORMHANDLE,
      NULLABLE_STRING,
      NULLABLE_HANDLE,
      NULLABLE_DCPIPE,
      NULLABLE_DPPIPE,
      NULLABLE_MSGPIPE,
      NULLABLE_SHAREDBUFFER,
      NULLABLE_PLATFORMHANDLE,
  )
  
  ATTRIBUTE_MIN_VERSION = 'MinVersion'
  ATTRIBUTE_DEFAULT = 'Default'
  ATTRIBUTE_EXTENSIBLE = 'Extensible'
  ATTRIBUTE_NO_INTERRUPT = 'NoInterrupt'
  ATTRIBUTE_STABLE = 'Stable'
  ATTRIBUTE_SYNC = 'Sync'
  ATTRIBUTE_UNLIMITED_SIZE = 'UnlimitedSize'
  ATTRIBUTE_UUID = 'Uuid'
  ATTRIBUTE_SERVICE_SANDBOX = 'ServiceSandbox'
  
  
  class NamedValue(object):
    def __init__(self, module, parent_kind, mojom_name):
      self.module = module
      self.parent_kind = parent_kind
      self.mojom_name = mojom_name
  
    def GetSpec(self):
      return (self.module.GetNamespacePrefix() +
              (self.parent_kind and
               (self.parent_kind.mojom_name + '.') or "") + self.mojom_name)
  
    def __eq__(self, rhs):
      return (isinstance(rhs, NamedValue)
              and (self.parent_kind, self.mojom_name) == (rhs.parent_kind,
                                                          rhs.mojom_name))
  
    def __hash__(self):
      return hash((self.parent_kind, self.mojom_name))
  
  
  class BuiltinValue(object):
    def __init__(self, value):
      self.value = value
  
    def __eq__(self, rhs):
      return isinstance(rhs, BuiltinValue) and self.value == rhs.value
  
  
  class ConstantValue(NamedValue):
    def __init__(self, module, parent_kind, constant):
      NamedValue.__init__(self, module, parent_kind, constant.mojom_name)
      self.constant = constant
  
    @property
    def name(self):
      return self.constant.name
  
  
  class EnumValue(NamedValue):
    def __init__(self, module, enum, field):
      NamedValue.__init__(self, module, enum.parent_kind, field.mojom_name)
      self.field = field
      self.enum = enum
  
    def GetSpec(self):
      return (self.module.GetNamespacePrefix() +
              (self.parent_kind and (self.parent_kind.mojom_name + '.') or "") +
              self.enum.mojom_name + '.' + self.mojom_name)
  
    @property
    def name(self):
      return self.field.name
  
  
  class Constant(object):
    def __init__(self, mojom_name=None, kind=None, value=None, parent_kind=None):
      self.mojom_name = mojom_name
      self.name = None
      self.kind = kind
      self.value = value
      self.parent_kind = parent_kind
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeConstant(self.mojom_name)
  
    def __eq__(self, rhs):
      return (isinstance(rhs, Constant)
              and (self.mojom_name, self.kind, self.value,
                   self.parent_kind) == (rhs.mojom_name, rhs.kind, rhs.value,
                                         rhs.parent_kind))
  
  
  class Field(object):
    def __init__(self,
                 mojom_name=None,
                 kind=None,
                 ordinal=None,
                 default=None,
                 attributes=None):
      if self.__class__.__name__ == 'Field':
        raise Exception()
      self.mojom_name = mojom_name
      self.name = None
      self.kind = kind
      self.ordinal = ordinal
      self.default = default
      self.attributes = attributes
  
    def Repr(self, as_ref=True):
      # pylint: disable=unused-argument
      # Fields are only referenced by objects which define them and thus
      # they are always displayed as non-references.
      return GenericRepr(self, {'mojom_name': False, 'kind': True})
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeField(self.mojom_name)
  
    @property
    def min_version(self):
      return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
          if self.attributes else None
  
    def __eq__(self, rhs):
      return (isinstance(rhs, Field)
              and (self.mojom_name, self.kind, self.ordinal, self.default,
                   self.attributes) == (rhs.mojom_name, rhs.kind, rhs.ordinal,
                                        rhs.default, rhs.attributes))
  
    def __hash__(self):
      return hash((self.mojom_name, self.kind, self.ordinal, self.default))
  
  
  class StructField(Field):
    def __hash__(self):
      return super(Field, self).__hash__()
  
  
  class UnionField(Field):
    pass
  
  
  def _IsFieldBackwardCompatible(new_field, old_field, checker):
    if (new_field.min_version or 0) != (old_field.min_version or 0):
      return False
  
    return checker.IsBackwardCompatible(new_field.kind, old_field.kind)
  
  
  class Struct(ReferenceKind):
    """A struct with typed fields.
  
    Attributes:
      mojom_name: {str} The name of the struct type as defined in mojom.
      name: {str} The stylized name.
      native_only: {bool} Does the struct have a body (i.e. any fields) or is it
          purely a native struct.
      custom_serializer: {bool} Should we generate a serializer for the struct or
          will one be provided by non-generated code.
      fields: {List[StructField]} The members of the struct.
      enums: {List[Enum]} The enums defined in the struct scope.
      constants: {List[Constant]} The constants defined in the struct scope.
      attributes: {dict} Additional information about the struct, such as
          if it's a native struct.
    """
  
    ReferenceKind.AddSharedProperty('mojom_name')
    ReferenceKind.AddSharedProperty('name')
    ReferenceKind.AddSharedProperty('native_only')
    ReferenceKind.AddSharedProperty('custom_serializer')
    ReferenceKind.AddSharedProperty('fields')
    ReferenceKind.AddSharedProperty('enums')
    ReferenceKind.AddSharedProperty('constants')
    ReferenceKind.AddSharedProperty('attributes')
  
    def __init__(self, mojom_name=None, module=None, attributes=None):
      if mojom_name is not None:
        spec = 'x:' + mojom_name
      else:
        spec = None
      ReferenceKind.__init__(self, spec, False, module)
      self.mojom_name = mojom_name
      self.name = None
      self.native_only = False
      self.custom_serializer = False
      self.fields = []
      self.enums = []
      self.constants = []
      self.attributes = attributes
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s mojom_name=%r module=%s>' % (self.__class__.__name__,
                                                 self.mojom_name,
                                                 Repr(self.module, as_ref=True))
      else:
        return GenericRepr(self, {
            'mojom_name': False,
            'fields': False,
            'module': True
        })
  
    def AddField(self,
                 mojom_name,
                 kind,
                 ordinal=None,
                 default=None,
                 attributes=None):
      field = StructField(mojom_name, kind, ordinal, default, attributes)
      self.fields.append(field)
      return field
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeStruct(self.mojom_name)
      for field in self.fields:
        field.Stylize(stylizer)
      for enum in self.enums:
        enum.Stylize(stylizer)
      for constant in self.constants:
        constant.Stylize(stylizer)
  
    def IsBackwardCompatible(self, older_struct, checker):
      """This struct is backward-compatible with older_struct if and only if all
      of the following conditions hold:
        - Any newly added field is tagged with a [MinVersion] attribute specifying
          a version number greater than all previously used [MinVersion]
          attributes within the struct.
        - All fields present in older_struct remain present in the new struct,
          with the same ordinal position, same optional or non-optional status,
          same (or backward-compatible) type and where applicable, the same
          [MinVersion] attribute value.
        - All [MinVersion] attributes must be non-decreasing in ordinal order.
        - All reference-typed (string, array, map, struct, or union) fields tagged
          with a [MinVersion] greater than zero must be optional.
      """
  
      def buildOrdinalFieldMap(struct):
        fields_by_ordinal = {}
        for field in struct.fields:
          if field.ordinal in fields_by_ordinal:
            raise Exception('Multiple fields with ordinal %s in struct %s.' %
                            (field.ordinal, struct.mojom_name))
          fields_by_ordinal[field.ordinal] = field
        return fields_by_ordinal
  
      new_fields = buildOrdinalFieldMap(self)
      old_fields = buildOrdinalFieldMap(older_struct)
      if len(new_fields) < len(old_fields):
        # At least one field was removed, which is not OK.
        return False
  
      # If there are N fields, existing ordinal values must exactly cover the
      # range from 0 to N-1.
      num_old_ordinals = len(old_fields)
      max_old_min_version = 0
      for ordinal in range(num_old_ordinals):
        new_field = new_fields[ordinal]
        old_field = old_fields[ordinal]
        if (old_field.min_version or 0) > max_old_min_version:
          max_old_min_version = old_field.min_version
        if not _IsFieldBackwardCompatible(new_field, old_field, checker):
          # Type or min-version mismatch between old and new versions of the same
          # ordinal field.
          return False
  
      # At this point we know all old fields are intact in the new struct
      # definition. Now verify that all new fields have a high enough min version
      # and are appropriately optional where required.
      num_new_ordinals = len(new_fields)
      last_min_version = max_old_min_version
      for ordinal in range(num_old_ordinals, num_new_ordinals):
        new_field = new_fields[ordinal]
        min_version = new_field.min_version or 0
        if min_version <= max_old_min_version:
          # A new field is being added to an existing version, which is not OK.
          return False
        if min_version < last_min_version:
          # The [MinVersion] of a field cannot be lower than the [MinVersion] of
          # a field with lower ordinal value.
          return False
        if IsReferenceKind(new_field.kind) and not IsNullableKind(new_field.kind):
          # New fields whose type can be nullable MUST be nullable.
          return False
  
      return True
  
    @property
    def stable(self):
      return self.attributes.get(ATTRIBUTE_STABLE, False) \
          if self.attributes else False
  
    @property
    def qualified_name(self):
      if self.parent_kind:
        prefix = self.parent_kind.qualified_name + '.'
      else:
        prefix = self.module.GetNamespacePrefix()
      return '%s%s' % (prefix, self.mojom_name)
  
    def _tuple(self):
      return (self.mojom_name, self.native_only, self.fields, self.constants,
              self.attributes)
  
    def __eq__(self, rhs):
      return isinstance(rhs, Struct) and self._tuple() == rhs._tuple()
  
    def __lt__(self, rhs):
      if not isinstance(self, type(rhs)):
        return str(type(self)) < str(type(rhs))
  
      return self._tuple() < rhs._tuple()
  
    def __hash__(self):
      return id(self)
  
  
  class Union(ReferenceKind):
    """A union of several kinds.
  
    Attributes:
      mojom_name: {str} The name of the union type as defined in mojom.
      name: {str} The stylized name.
      fields: {List[UnionField]} The members of the union.
      attributes: {dict} Additional information about the union, such as
          which Java class name to use to represent it in the generated
          bindings.
    """
    ReferenceKind.AddSharedProperty('mojom_name')
    ReferenceKind.AddSharedProperty('name')
    ReferenceKind.AddSharedProperty('fields')
    ReferenceKind.AddSharedProperty('attributes')
  
    def __init__(self, mojom_name=None, module=None, attributes=None):
      if mojom_name is not None:
        spec = 'x:' + mojom_name
      else:
        spec = None
      ReferenceKind.__init__(self, spec, False, module)
      self.mojom_name = mojom_name
      self.name = None
      self.fields = []
      self.attributes = attributes
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s spec=%r is_nullable=%r fields=%s>' % (
            self.__class__.__name__, self.spec, self.is_nullable, Repr(
                self.fields))
      else:
        return GenericRepr(self, {'fields': True, 'is_nullable': False})
  
    def AddField(self, mojom_name, kind, ordinal=None, attributes=None):
      field = UnionField(mojom_name, kind, ordinal, None, attributes)
      self.fields.append(field)
      return field
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeUnion(self.mojom_name)
      for field in self.fields:
        field.Stylize(stylizer)
  
    def IsBackwardCompatible(self, older_union, checker):
      """This union is backward-compatible with older_union if and only if all
      of the following conditions hold:
        - Any newly added field is tagged with a [MinVersion] attribute specifying
          a version number greater than all previously used [MinVersion]
          attributes within the union.
        - All fields present in older_union remain present in the new union,
          with the same ordinal value, same optional or non-optional status,
          same (or backward-compatible) type, and where applicable, the same
          [MinVersion] attribute value.
      """
  
      def buildOrdinalFieldMap(union):
        fields_by_ordinal = {}
        for field in union.fields:
          if field.ordinal in fields_by_ordinal:
            raise Exception('Multiple fields with ordinal %s in union %s.' %
                            (field.ordinal, union.mojom_name))
          fields_by_ordinal[field.ordinal] = field
        return fields_by_ordinal
  
      new_fields = buildOrdinalFieldMap(self)
      old_fields = buildOrdinalFieldMap(older_union)
      if len(new_fields) < len(old_fields):
        # At least one field was removed, which is not OK.
        return False
  
      max_old_min_version = 0
      for ordinal, old_field in old_fields.items():
        new_field = new_fields.get(ordinal)
        if not new_field:
          # A field was removed, which is not OK.
          return False
        if not _IsFieldBackwardCompatible(new_field, old_field, checker):
          # An field changed its type or MinVersion, which is not OK.
          return False
        old_min_version = old_field.min_version or 0
        if old_min_version > max_old_min_version:
          max_old_min_version = old_min_version
  
      new_ordinals = set(new_fields.keys()) - set(old_fields.keys())
      for ordinal in new_ordinals:
        if (new_fields[ordinal].min_version or 0) <= max_old_min_version:
          # New fields must use a MinVersion greater than any old fields.
          return False
  
      return True
  
    @property
    def stable(self):
      return self.attributes.get(ATTRIBUTE_STABLE, False) \
          if self.attributes else False
  
    @property
    def qualified_name(self):
      if self.parent_kind:
        prefix = self.parent_kind.qualified_name + '.'
      else:
        prefix = self.module.GetNamespacePrefix()
      return '%s%s' % (prefix, self.mojom_name)
  
    def _tuple(self):
      return (self.mojom_name, self.fields, self.attributes)
  
    def __eq__(self, rhs):
      return isinstance(rhs, Union) and self._tuple() == rhs._tuple()
  
    def __lt__(self, rhs):
      if not isinstance(self, type(rhs)):
        return str(type(self)) < str(type(rhs))
  
      return self._tuple() < rhs._tuple()
  
    def __hash__(self):
      return id(self)
  
  
  class Array(ReferenceKind):
    """An array.
  
    Attributes:
      kind: {Kind} The type of the elements. May be None.
      length: The number of elements. None if unknown.
    """
  
    ReferenceKind.AddSharedProperty('kind')
    ReferenceKind.AddSharedProperty('length')
  
    def __init__(self, kind=None, length=None):
      if kind is not None:
        if length is not None:
          spec = 'a%d:%s' % (length, kind.spec)
        else:
          spec = 'a:%s' % kind.spec
  
        ReferenceKind.__init__(self, spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind
      self.length = length
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s spec=%r is_nullable=%r kind=%s length=%r>' % (
            self.__class__.__name__, self.spec, self.is_nullable, Repr(
                self.kind), self.length)
      else:
        return GenericRepr(self, {
            'kind': True,
            'length': False,
            'is_nullable': False
        })
  
    def __eq__(self, rhs):
      return (isinstance(rhs, Array)
              and (self.kind, self.length) == (rhs.kind, rhs.length))
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return (isinstance(rhs, Array) and self.length == rhs.length
              and checker.IsBackwardCompatible(self.kind, rhs.kind))
  
  
  class Map(ReferenceKind):
    """A map.
  
    Attributes:
      key_kind: {Kind} The type of the keys. May be None.
      value_kind: {Kind} The type of the elements. May be None.
    """
    ReferenceKind.AddSharedProperty('key_kind')
    ReferenceKind.AddSharedProperty('value_kind')
  
    def __init__(self, key_kind=None, value_kind=None):
      if (key_kind is not None and value_kind is not None):
        ReferenceKind.__init__(
            self, 'm[' + key_kind.spec + '][' + value_kind.spec + ']')
        if IsNullableKind(key_kind):
          raise Exception("Nullable kinds cannot be keys in maps.")
        if IsAnyHandleKind(key_kind):
          raise Exception("Handles cannot be keys in maps.")
        if IsAnyInterfaceKind(key_kind):
          raise Exception("Interfaces cannot be keys in maps.")
        if IsArrayKind(key_kind):
          raise Exception("Arrays cannot be keys in maps.")
      else:
        ReferenceKind.__init__(self)
  
      self.key_kind = key_kind
      self.value_kind = value_kind
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s spec=%r is_nullable=%r key_kind=%s value_kind=%s>' % (
            self.__class__.__name__, self.spec, self.is_nullable,
            Repr(self.key_kind), Repr(self.value_kind))
      else:
        return GenericRepr(self, {'key_kind': True, 'value_kind': True})
  
    def __eq__(self, rhs):
      return (isinstance(rhs, Map) and
              (self.key_kind, self.value_kind) == (rhs.key_kind, rhs.value_kind))
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return (isinstance(rhs, Map)
              and checker.IsBackwardCompatible(self.key_kind, rhs.key_kind)
              and checker.IsBackwardCompatible(self.value_kind, rhs.value_kind))
  
  
  class PendingRemote(ReferenceKind):
    ReferenceKind.AddSharedProperty('kind')
  
    def __init__(self, kind=None):
      if kind is not None:
        if not isinstance(kind, Interface):
          raise Exception(
              'pending_remote<T> requires T to be an interface type. Got %r' %
              kind.spec)
        ReferenceKind.__init__(self, 'rmt:' + kind.spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind
  
    def __eq__(self, rhs):
      return isinstance(rhs, PendingRemote) and self.kind == rhs.kind
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return (isinstance(rhs, PendingRemote)
              and checker.IsBackwardCompatible(self.kind, rhs.kind))
  
  
  class PendingReceiver(ReferenceKind):
    ReferenceKind.AddSharedProperty('kind')
  
    def __init__(self, kind=None):
      if kind is not None:
        if not isinstance(kind, Interface):
          raise Exception(
              'pending_receiver<T> requires T to be an interface type. Got %r' %
              kind.spec)
        ReferenceKind.__init__(self, 'rcv:' + kind.spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind
  
    def __eq__(self, rhs):
      return isinstance(rhs, PendingReceiver) and self.kind == rhs.kind
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return isinstance(rhs, PendingReceiver) and checker.IsBackwardCompatible(
          self.kind, rhs.kind)
  
  
  class PendingAssociatedRemote(ReferenceKind):
    ReferenceKind.AddSharedProperty('kind')
  
    def __init__(self, kind=None):
      if kind is not None:
        if not isinstance(kind, Interface):
          raise Exception(
              'pending_associated_remote<T> requires T to be an interface ' +
              'type. Got %r' % kind.spec)
        ReferenceKind.__init__(self, 'rma:' + kind.spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind
  
    def __eq__(self, rhs):
      return isinstance(rhs, PendingAssociatedRemote) and self.kind == rhs.kind
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return isinstance(rhs,
                        PendingAssociatedRemote) and checker.IsBackwardCompatible(
                            self.kind, rhs.kind)
  
  
  class PendingAssociatedReceiver(ReferenceKind):
    ReferenceKind.AddSharedProperty('kind')
  
    def __init__(self, kind=None):
      if kind is not None:
        if not isinstance(kind, Interface):
          raise Exception(
              'pending_associated_receiver<T> requires T to be an interface' +
              'type. Got %r' % kind.spec)
        ReferenceKind.__init__(self, 'rca:' + kind.spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind
  
    def __eq__(self, rhs):
      return isinstance(rhs, PendingAssociatedReceiver) and self.kind == rhs.kind
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return isinstance(
          rhs, PendingAssociatedReceiver) and checker.IsBackwardCompatible(
              self.kind, rhs.kind)
  
  
  class InterfaceRequest(ReferenceKind):
    ReferenceKind.AddSharedProperty('kind')
  
    def __init__(self, kind=None):
      if kind is not None:
        if not isinstance(kind, Interface):
          raise Exception(
              "Interface request requires %r to be an interface." % kind.spec)
        ReferenceKind.__init__(self, 'r:' + kind.spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind
  
    def __eq__(self, rhs):
      return isinstance(rhs, InterfaceRequest) and self.kind == rhs.kind
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return isinstance(rhs, InterfaceRequest) and checker.IsBackwardCompatible(
          self.kind, rhs.kind)
  
  
  class AssociatedInterfaceRequest(ReferenceKind):
    ReferenceKind.AddSharedProperty('kind')
  
    def __init__(self, kind=None):
      if kind is not None:
        if not isinstance(kind, InterfaceRequest):
          raise Exception(
              "Associated interface request requires %r to be an interface "
              "request." % kind.spec)
        assert not kind.is_nullable
        ReferenceKind.__init__(self, 'asso:' + kind.spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind.kind if kind is not None else None
  
    def __eq__(self, rhs):
      return isinstance(rhs, AssociatedInterfaceRequest) and self.kind == rhs.kind
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return isinstance(
          rhs, AssociatedInterfaceRequest) and checker.IsBackwardCompatible(
              self.kind, rhs.kind)
  
  
  class Parameter(object):
    def __init__(self,
                 mojom_name=None,
                 kind=None,
                 ordinal=None,
                 default=None,
                 attributes=None):
      self.mojom_name = mojom_name
      self.name = None
      self.ordinal = ordinal
      self.kind = kind
      self.default = default
      self.attributes = attributes
  
    def Repr(self, as_ref=True):
      # pylint: disable=unused-argument
      return '<%s mojom_name=%r kind=%s>' % (
          self.__class__.__name__, self.mojom_name, self.kind.Repr(as_ref=True))
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeParameter(self.mojom_name)
  
    @property
    def min_version(self):
      return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
          if self.attributes else None
  
    def __eq__(self, rhs):
      return (isinstance(rhs, Parameter)
              and (self.mojom_name, self.ordinal, self.kind, self.default,
                   self.attributes) == (rhs.mojom_name, rhs.ordinal, rhs.kind,
                                        rhs.default, rhs.attributes))
  
  
  class Method(object):
    def __init__(self, interface, mojom_name, ordinal=None, attributes=None):
      self.interface = interface
      self.mojom_name = mojom_name
      self.name = None
      self.explicit_ordinal = ordinal
      self.ordinal = ordinal
      self.parameters = []
      self.param_struct = None
      self.response_parameters = None
      self.response_param_struct = None
      self.attributes = attributes
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s mojom_name=%r>' % (self.__class__.__name__, self.mojom_name)
      else:
        return GenericRepr(self, {
            'mojom_name': False,
            'parameters': True,
            'response_parameters': True
        })
  
    def AddParameter(self,
                     mojom_name,
                     kind,
                     ordinal=None,
                     default=None,
                     attributes=None):
      parameter = Parameter(mojom_name, kind, ordinal, default, attributes)
      self.parameters.append(parameter)
      return parameter
  
    def AddResponseParameter(self,
                             mojom_name,
                             kind,
                             ordinal=None,
                             default=None,
                             attributes=None):
      if self.response_parameters == None:
        self.response_parameters = []
      parameter = Parameter(mojom_name, kind, ordinal, default, attributes)
      self.response_parameters.append(parameter)
      return parameter
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeMethod(self.mojom_name)
      for param in self.parameters:
        param.Stylize(stylizer)
      if self.response_parameters is not None:
        for param in self.response_parameters:
          param.Stylize(stylizer)
  
      if self.param_struct:
        self.param_struct.Stylize(stylizer)
      if self.response_param_struct:
        self.response_param_struct.Stylize(stylizer)
  
    @property
    def min_version(self):
      return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
          if self.attributes else None
  
    @property
    def sync(self):
      return self.attributes.get(ATTRIBUTE_SYNC) \
          if self.attributes else None
  
    @property
    def allow_interrupt(self):
      return not self.attributes.get(ATTRIBUTE_NO_INTERRUPT) \
          if self.attributes else True
  
    @property
    def unlimited_message_size(self):
      return self.attributes.get(ATTRIBUTE_UNLIMITED_SIZE) \
          if self.attributes else False
  
    def _tuple(self):
      return (self.mojom_name, self.ordinal, self.parameters,
              self.response_parameters, self.attributes)
  
    def __eq__(self, rhs):
      return isinstance(rhs, Method) and self._tuple() == rhs._tuple()
  
    def __lt__(self, rhs):
      if not isinstance(self, type(rhs)):
        return str(type(self)) < str(type(rhs))
  
      return self._tuple() < rhs._tuple()
  
  
  class Interface(ReferenceKind):
    ReferenceKind.AddSharedProperty('mojom_name')
    ReferenceKind.AddSharedProperty('name')
    ReferenceKind.AddSharedProperty('methods')
    ReferenceKind.AddSharedProperty('enums')
    ReferenceKind.AddSharedProperty('constants')
    ReferenceKind.AddSharedProperty('attributes')
  
    def __init__(self, mojom_name=None, module=None, attributes=None):
      if mojom_name is not None:
        spec = 'x:' + mojom_name
      else:
        spec = None
      ReferenceKind.__init__(self, spec, False, module)
      self.mojom_name = mojom_name
      self.name = None
      self.methods = []
      self.enums = []
      self.constants = []
      self.attributes = attributes
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s mojom_name=%r>' % (self.__class__.__name__, self.mojom_name)
      else:
        return GenericRepr(self, {
            'mojom_name': False,
            'attributes': False,
            'methods': False
        })
  
    def AddMethod(self, mojom_name, ordinal=None, attributes=None):
      method = Method(self, mojom_name, ordinal, attributes)
      self.methods.append(method)
      return method
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeInterface(self.mojom_name)
      for method in self.methods:
        method.Stylize(stylizer)
      for enum in self.enums:
        enum.Stylize(stylizer)
      for constant in self.constants:
        constant.Stylize(stylizer)
  
    def IsBackwardCompatible(self, older_interface, checker):
      """This interface is backward-compatible with older_interface if and only
      if all of the following conditions hold:
        - All defined methods in older_interface (when identified by ordinal) have
          backward-compatible definitions in this interface. For each method this
          means:
            - The parameter list is backward-compatible, according to backward-
              compatibility rules for structs, where each parameter is essentially
              a struct field.
            - If the old method definition does not specify a reply message, the
              new method definition must not specify a reply message.
            - If the old method definition specifies a reply message, the new
              method definition must also specify a reply message with a parameter
              list that is backward-compatible according to backward-compatibility
              rules for structs.
        - All newly introduced methods in this interface have a [MinVersion]
          attribute specifying a version greater than any method in
          older_interface.
      """
  
      def buildOrdinalMethodMap(interface):
        methods_by_ordinal = {}
        for method in interface.methods:
          if method.ordinal in methods_by_ordinal:
            raise Exception('Multiple methods with ordinal %s in interface %s.' %
                            (method.ordinal, interface.mojom_name))
          methods_by_ordinal[method.ordinal] = method
        return methods_by_ordinal
  
      new_methods = buildOrdinalMethodMap(self)
      old_methods = buildOrdinalMethodMap(older_interface)
      max_old_min_version = 0
      for ordinal, old_method in old_methods.items():
        new_method = new_methods.get(ordinal)
        if not new_method:
          # A method was removed, which is not OK.
          return False
  
        if not checker.IsBackwardCompatible(new_method.param_struct,
                                            old_method.param_struct):
          # The parameter list is not backward-compatible, which is not OK.
          return False
  
        if old_method.response_param_struct is None:
          if new_method.response_param_struct is not None:
            # A reply was added to a message which didn't have one before, and
            # this is not OK.
            return False
        else:
          if new_method.response_param_struct is None:
            # A reply was removed from a message, which is not OK.
            return False
          if not checker.IsBackwardCompatible(new_method.response_param_struct,
                                              old_method.response_param_struct):
            # The new message's reply is not backward-compatible with the old
            # message's reply, which is not OK.
            return False
  
        if (old_method.min_version or 0) > max_old_min_version:
          max_old_min_version = old_method.min_version
  
      # All the old methods are compatible with their new counterparts. Now verify
      # that newly added methods are properly versioned.
      new_ordinals = set(new_methods.keys()) - set(old_methods.keys())
      for ordinal in new_ordinals:
        new_method = new_methods[ordinal]
        if (new_method.min_version or 0) <= max_old_min_version:
          # A method was added to an existing version, which is not OK.
          return False
  
      return True
  
    @property
    def service_sandbox(self):
      if not self.attributes:
        return None
      return self.attributes.get(ATTRIBUTE_SERVICE_SANDBOX, None)
  
    @property
    def stable(self):
      return self.attributes.get(ATTRIBUTE_STABLE, False) \
          if self.attributes else False
  
    @property
    def qualified_name(self):
      if self.parent_kind:
        prefix = self.parent_kind.qualified_name + '.'
      else:
        prefix = self.module.GetNamespacePrefix()
      return '%s%s' % (prefix, self.mojom_name)
  
    def _tuple(self):
      return (self.mojom_name, self.methods, self.enums, self.constants,
              self.attributes)
  
    def __eq__(self, rhs):
      return isinstance(rhs, Interface) and self._tuple() == rhs._tuple()
  
    def __lt__(self, rhs):
      if not isinstance(self, type(rhs)):
        return str(type(self)) < str(type(rhs))
  
      return self._tuple() < rhs._tuple()
  
    @property
    def uuid(self):
      uuid_str = self.attributes.get(ATTRIBUTE_UUID) if self.attributes else None
      if uuid_str is None:
        return None
  
      try:
        u = UUID(uuid_str)
      except:
        raise ValueError('Invalid format for Uuid attribute on interface {}. '
                         'Expected standard RFC 4122 string representation of '
                         'a UUID.'.format(self.mojom_name))
      return (int(u.hex[:16], 16), int(u.hex[16:], 16))
  
    def __hash__(self):
      return id(self)
  
  
  class AssociatedInterface(ReferenceKind):
    ReferenceKind.AddSharedProperty('kind')
  
    def __init__(self, kind=None):
      if kind is not None:
        if not isinstance(kind, Interface):
          raise Exception(
              "Associated interface requires %r to be an interface." % kind.spec)
        assert not kind.is_nullable
        ReferenceKind.__init__(self, 'asso:' + kind.spec)
      else:
        ReferenceKind.__init__(self)
      self.kind = kind
  
    def __eq__(self, rhs):
      return isinstance(rhs, AssociatedInterface) and self.kind == rhs.kind
  
    def __hash__(self):
      return id(self)
  
    def IsBackwardCompatible(self, rhs, checker):
      return isinstance(rhs,
                        AssociatedInterface) and checker.IsBackwardCompatible(
                            self.kind, rhs.kind)
  
  
  class EnumField(object):
    def __init__(self,
                 mojom_name=None,
                 value=None,
                 attributes=None,
                 numeric_value=None):
      self.mojom_name = mojom_name
      self.name = None
      self.value = value
      self.attributes = attributes
      self.numeric_value = numeric_value
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeEnumField(self.mojom_name)
  
    @property
    def default(self):
      return self.attributes.get(ATTRIBUTE_DEFAULT, False) \
          if self.attributes else False
  
    @property
    def min_version(self):
      return self.attributes.get(ATTRIBUTE_MIN_VERSION) \
          if self.attributes else None
  
    def __eq__(self, rhs):
      return (isinstance(rhs, EnumField)
              and (self.mojom_name, self.value, self.attributes,
                   self.numeric_value) == (rhs.mojom_name, rhs.value,
                                           rhs.attributes, rhs.numeric_value))
  
  
  class Enum(Kind):
    def __init__(self, mojom_name=None, module=None, attributes=None):
      self.mojom_name = mojom_name
      self.name = None
      self.native_only = False
      if mojom_name is not None:
        spec = 'x:' + mojom_name
      else:
        spec = None
      Kind.__init__(self, spec, module)
      self.fields = []
      self.attributes = attributes
      self.min_value = None
      self.max_value = None
      self.default_field = None
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s mojom_name=%r>' % (self.__class__.__name__, self.mojom_name)
      else:
        return GenericRepr(self, {'mojom_name': False, 'fields': False})
  
    def Stylize(self, stylizer):
      self.name = stylizer.StylizeEnum(self.mojom_name)
      for field in self.fields:
        field.Stylize(stylizer)
  
    @property
    def extensible(self):
      return self.attributes.get(ATTRIBUTE_EXTENSIBLE, False) \
          if self.attributes else False
  
    @property
    def stable(self):
      return self.attributes.get(ATTRIBUTE_STABLE, False) \
          if self.attributes else False
  
    @property
    def qualified_name(self):
      if self.parent_kind:
        prefix = self.parent_kind.qualified_name + '.'
      else:
        prefix = self.module.GetNamespacePrefix()
      return '%s%s' % (prefix, self.mojom_name)
  
    # pylint: disable=unused-argument
    def IsBackwardCompatible(self, older_enum, checker):
      """This enum is backward-compatible with older_enum if and only if one of
      the following conditions holds:
          - Neither enum is [Extensible] and both have the exact same set of valid
            numeric values. Field names and aliases for the same numeric value do
            not affect compatibility.
          - older_enum is [Extensible], and for every version defined by
            older_enum, this enum has the exact same set of valid numeric values.
      """
  
      def buildVersionFieldMap(enum):
        fields_by_min_version = {}
        for field in enum.fields:
          if field.min_version not in fields_by_min_version:
            fields_by_min_version[field.min_version] = set()
          fields_by_min_version[field.min_version].add(field.numeric_value)
        return fields_by_min_version
  
      old_fields = buildVersionFieldMap(older_enum)
      new_fields = buildVersionFieldMap(self)
  
      if new_fields.keys() != old_fields.keys() and not older_enum.extensible:
        return False
  
      for min_version, valid_values in old_fields.items():
        if (min_version not in new_fields
            or new_fields[min_version] != valid_values):
          return False
  
      return True
  
    def _tuple(self):
      return (self.mojom_name, self.native_only, self.fields, self.attributes,
              self.min_value, self.max_value, self.default_field)
  
    def __eq__(self, rhs):
      return isinstance(rhs, Enum) and self._tuple() == rhs._tuple()
  
    def __lt__(self, rhs):
      if not isinstance(self, type(rhs)):
        return str(type(self)) < str(type(rhs))
  
      return self._tuple() < rhs._tuple()
  
    def __hash__(self):
      return id(self)
  
  
  class Module(object):
    def __init__(self, path=None, mojom_namespace=None, attributes=None):
      self.path = path
      self.mojom_namespace = mojom_namespace
      self.namespace = None
      self.structs = []
      self.unions = []
      self.interfaces = []
      self.enums = []
      self.constants = []
      self.kinds = {}
      self.attributes = attributes
      self.imports = []
      self.imported_kinds = {}
      self.metadata = {}
  
    def __repr__(self):
      # Gives us a decent __repr__ for modules.
      return self.Repr()
  
    def __eq__(self, rhs):
      return (isinstance(rhs, Module) and
              (self.path, self.attributes, self.mojom_namespace, self.imports,
               self.constants, self.enums, self.structs, self.unions,
               self.interfaces) == (rhs.path, rhs.attributes, rhs.mojom_namespace,
                                    rhs.imports, rhs.constants, rhs.enums,
                                    rhs.structs, rhs.unions, rhs.interfaces))
  
    def __hash__(self):
      return id(self)
  
    def Repr(self, as_ref=True):
      if as_ref:
        return '<%s path=%r mojom_namespace=%r>' % (
            self.__class__.__name__, self.path, self.mojom_namespace)
      else:
        return GenericRepr(
            self, {
                'path': False,
                'mojom_namespace': False,
                'attributes': False,
                'structs': False,
                'interfaces': False,
                'unions': False
            })
  
    def GetNamespacePrefix(self):
      return '%s.' % self.mojom_namespace if self.mojom_namespace else ''
  
    def AddInterface(self, mojom_name, attributes=None):
      interface = Interface(mojom_name, self, attributes)
      self.interfaces.append(interface)
      return interface
  
    def AddStruct(self, mojom_name, attributes=None):
      struct = Struct(mojom_name, self, attributes)
      self.structs.append(struct)
      return struct
  
    def AddUnion(self, mojom_name, attributes=None):
      union = Union(mojom_name, self, attributes)
      self.unions.append(union)
      return union
  
    def Stylize(self, stylizer):
      self.namespace = stylizer.StylizeModule(self.mojom_namespace)
      for struct in self.structs:
        struct.Stylize(stylizer)
      for union in self.unions:
        union.Stylize(stylizer)
      for interface in self.interfaces:
        interface.Stylize(stylizer)
      for enum in self.enums:
        enum.Stylize(stylizer)
      for constant in self.constants:
        constant.Stylize(stylizer)
  
      for imported_module in self.imports:
        imported_module.Stylize(stylizer)
  
    def Dump(self, f):
      pickle.dump(self, f, 2)
  
    @classmethod
    def Load(cls, f):
      result = pickle.load(f)
      assert isinstance(result, Module)
      return result
  
  
  def IsBoolKind(kind):
    return kind.spec == BOOL.spec
  
  
  def IsFloatKind(kind):
    return kind.spec == FLOAT.spec
  
  
  def IsDoubleKind(kind):
    return kind.spec == DOUBLE.spec
  
  
  def IsIntegralKind(kind):
    return (kind.spec == BOOL.spec or kind.spec == INT8.spec
            or kind.spec == INT16.spec or kind.spec == INT32.spec
            or kind.spec == INT64.spec or kind.spec == UINT8.spec
            or kind.spec == UINT16.spec or kind.spec == UINT32.spec
            or kind.spec == UINT64.spec)
  
  
  def IsStringKind(kind):
    return kind.spec == STRING.spec or kind.spec == NULLABLE_STRING.spec
  
  
  def IsGenericHandleKind(kind):
    return kind.spec == HANDLE.spec or kind.spec == NULLABLE_HANDLE.spec
  
  
  def IsDataPipeConsumerKind(kind):
    return kind.spec == DCPIPE.spec or kind.spec == NULLABLE_DCPIPE.spec
  
  
  def IsDataPipeProducerKind(kind):
    return kind.spec == DPPIPE.spec or kind.spec == NULLABLE_DPPIPE.spec
  
  
  def IsMessagePipeKind(kind):
    return kind.spec == MSGPIPE.spec or kind.spec == NULLABLE_MSGPIPE.spec
  
  
  def IsSharedBufferKind(kind):
    return (kind.spec == SHAREDBUFFER.spec
            or kind.spec == NULLABLE_SHAREDBUFFER.spec)
  
  
  def IsPlatformHandleKind(kind):
    return (kind.spec == PLATFORMHANDLE.spec
            or kind.spec == NULLABLE_PLATFORMHANDLE.spec)
  
  
  def IsStructKind(kind):
    return isinstance(kind, Struct)
  
  
  def IsUnionKind(kind):
    return isinstance(kind, Union)
  
  
  def IsArrayKind(kind):
    return isinstance(kind, Array)
  
  
  def IsInterfaceKind(kind):
    return isinstance(kind, Interface)
  
  
  def IsAssociatedInterfaceKind(kind):
    return isinstance(kind, AssociatedInterface)
  
  
  def IsInterfaceRequestKind(kind):
    return isinstance(kind, InterfaceRequest)
  
  
  def IsAssociatedInterfaceRequestKind(kind):
    return isinstance(kind, AssociatedInterfaceRequest)
  
  
  def IsPendingRemoteKind(kind):
    return isinstance(kind, PendingRemote)
  
  
  def IsPendingReceiverKind(kind):
    return isinstance(kind, PendingReceiver)
  
  
  def IsPendingAssociatedRemoteKind(kind):
    return isinstance(kind, PendingAssociatedRemote)
  
  
  def IsPendingAssociatedReceiverKind(kind):
    return isinstance(kind, PendingAssociatedReceiver)
  
  
  def IsEnumKind(kind):
    return isinstance(kind, Enum)
  
  
  def IsReferenceKind(kind):
    return isinstance(kind, ReferenceKind)
  
  
  def IsNullableKind(kind):
    return IsReferenceKind(kind) and kind.is_nullable
  
  
  def IsMapKind(kind):
    return isinstance(kind, Map)
  
  
  def IsObjectKind(kind):
    return IsPointerKind(kind) or IsUnionKind(kind)
  
  
  def IsPointerKind(kind):
    return (IsStructKind(kind) or IsArrayKind(kind) or IsStringKind(kind)
            or IsMapKind(kind))
  
  
  # Please note that it doesn't include any interface kind.
  def IsAnyHandleKind(kind):
    return (IsGenericHandleKind(kind) or IsDataPipeConsumerKind(kind)
            or IsDataPipeProducerKind(kind) or IsMessagePipeKind(kind)
            or IsSharedBufferKind(kind) or IsPlatformHandleKind(kind))
  
  
  def IsAnyInterfaceKind(kind):
    return (IsInterfaceKind(kind) or IsInterfaceRequestKind(kind)
            or IsAssociatedKind(kind) or IsPendingRemoteKind(kind)
            or IsPendingReceiverKind(kind))
  
  
  def IsAnyHandleOrInterfaceKind(kind):
    return IsAnyHandleKind(kind) or IsAnyInterfaceKind(kind)
  
  
  def IsAssociatedKind(kind):
    return (IsAssociatedInterfaceKind(kind)
            or IsAssociatedInterfaceRequestKind(kind)
            or IsPendingAssociatedRemoteKind(kind)
            or IsPendingAssociatedReceiverKind(kind))
  
  
  def HasCallbacks(interface):
    for method in interface.methods:
      if method.response_parameters != None:
        return True
    return False
  
  
  # Finds out whether an interface passes associated interfaces and associated
  # interface requests.
  def PassesAssociatedKinds(interface):
    visited_kinds = set()
    for method in interface.methods:
      if MethodPassesAssociatedKinds(method, visited_kinds):
        return True
    return False
  
  
  def _AnyMethodParameterRecursive(method, predicate, visited_kinds=None):
    def _HasProperty(kind):
      if kind in visited_kinds:
        # No need to examine the kind again.
        return False
      visited_kinds.add(kind)
      if predicate(kind):
        return True
      if IsArrayKind(kind):
        return _HasProperty(kind.kind)
      if IsStructKind(kind) or IsUnionKind(kind):
        for field in kind.fields:
          if _HasProperty(field.kind):
            return True
      if IsMapKind(kind):
        if _HasProperty(kind.key_kind) or _HasProperty(kind.value_kind):
          return True
      return False
  
    if visited_kinds is None:
      visited_kinds = set()
  
    for param in method.parameters:
      if _HasProperty(param.kind):
        return True
    if method.response_parameters != None:
      for param in method.response_parameters:
        if _HasProperty(param.kind):
          return True
    return False
  
  
  # Finds out whether a method passes associated interfaces and associated
  # interface requests.
  def MethodPassesAssociatedKinds(method, visited_kinds=None):
    return _AnyMethodParameterRecursive(
        method, IsAssociatedKind, visited_kinds=visited_kinds)
  
  
  # Determines whether a method passes interfaces.
  def MethodPassesInterfaces(method):
    return _AnyMethodParameterRecursive(method, IsInterfaceKind)
  
  
  def HasSyncMethods(interface):
    for method in interface.methods:
      if method.sync:
        return True
    return False
  
  
  def HasUninterruptableMethods(interface):
    for method in interface.methods:
      if not method.allow_interrupt:
        return True
    return False
  
  
  def ContainsHandlesOrInterfaces(kind):
    """Check if the kind contains any handles.
  
    This check is recursive so it checks all struct fields, containers elements,
    etc.
  
    Args:
      struct: {Kind} The kind to check.
  
    Returns:
      {bool}: True if the kind contains handles.
    """
    # We remember the types we already checked to avoid infinite recursion when
    # checking recursive (or mutually recursive) types:
    checked = set()
  
    def Check(kind):
      if kind.spec in checked:
        return False
      checked.add(kind.spec)
      if IsStructKind(kind):
        return any(Check(field.kind) for field in kind.fields)
      elif IsUnionKind(kind):
        return any(Check(field.kind) for field in kind.fields)
      elif IsAnyHandleKind(kind):
        return True
      elif IsAnyInterfaceKind(kind):
        return True
      elif IsArrayKind(kind):
        return Check(kind.kind)
      elif IsMapKind(kind):
        return Check(kind.key_kind) or Check(kind.value_kind)
      else:
        return False
  
    return Check(kind)
  
  
  def ContainsNativeTypes(kind):
    """Check if the kind contains any native type (struct or enum).
  
    This check is recursive so it checks all struct fields, scoped interface
    enums, etc.
  
    Args:
      struct: {Kind} The kind to check.
  
    Returns:
      {bool}: True if the kind contains native types.
    """
    # We remember the types we already checked to avoid infinite recursion when
    # checking recursive (or mutually recursive) types:
    checked = set()
  
    def Check(kind):
      if kind.spec in checked:
        return False
      checked.add(kind.spec)
      if IsEnumKind(kind):
        return kind.native_only
      elif IsStructKind(kind):
        if kind.native_only:
          return True
        if any(enum.native_only for enum in kind.enums):
          return True
        return any(Check(field.kind) for field in kind.fields)
      elif IsUnionKind(kind):
        return any(Check(field.kind) for field in kind.fields)
      elif IsInterfaceKind(kind):
        return any(enum.native_only for enum in kind.enums)
      elif IsArrayKind(kind):
        return Check(kind.kind)
      elif IsMapKind(kind):
        return Check(kind.key_kind) or Check(kind.value_kind)
      else:
        return False
  
    return Check(kind)
  