components/mus/ids.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_MUS_IDS_H_
   6 #define COMPONENTS_MUS_IDS_H_
   7
   8 #include "components/mus/public/cpp/types.h"
   9 #include "components/mus/public/cpp/util.h"
  10
  11 namespace mus {
  12
  13 // Connection id is used to indicate no connection. That is, no ViewTreeImpl
  14 // ever gets this id.
  15 const ConnectionSpecificId kInvalidConnectionId = 0;
  16
  17 // Adds a bit of type safety to view ids.
  18 struct ViewId {
  19   ViewId(ConnectionSpecificId connection_id, ConnectionSpecificId view_id)
  20       : connection_id(connection_id), view_id(view_id) {}
  21   ViewId() : connection_id(0), view_id(0) {}
  22
  23   bool operator==(const ViewId& other) const {
  24     return other.connection_id == connection_id && other.view_id == view_id;
  25   }
  26
  27   bool operator!=(const ViewId& other) const { return !(*this == other); }
  28
  29   ConnectionSpecificId connection_id;
  30   ConnectionSpecificId view_id;
  31 };
  32
  33 inline ViewId ViewIdFromTransportId(Id id) {
  34   return ViewId(HiWord(id), LoWord(id));
  35 }
  36
  37 inline Id ViewIdToTransportId(const ViewId& id) {
  38   return (id.connection_id << 16) | id.view_id;
  39 }
  40
  41 // Returns a ViewId that is reserved to indicate no view. That is, no view will
  42 // ever be created with this id.
  43 inline ViewId InvalidViewId() {
  44   return ViewId(kInvalidConnectionId, 0);
  45 }
  46
  47 // Returns a root view id with a given index offset.
  48 inline ViewId RootViewId(uint16_t index) {
  49   return ViewId(kInvalidConnectionId, 2 + index);
  50 }
  51
  52 }  // namespace mus
  53
  54 #endif  // COMPONENTS_MUS_IDS_H_