sync/internal_api/public/read_node.h

   1 // Copyright 2012 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 SYNC_INTERNAL_API_PUBLIC_READ_NODE_H_
   6 #define SYNC_INTERNAL_API_PUBLIC_READ_NODE_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/compiler_specific.h"
  12 #include "sync/base/sync_export.h"
  13 #include "sync/internal_api/public/base/model_type.h"
  14 #include "sync/internal_api/public/base_node.h"
  15
  16 namespace syncer {
  17
  18 // ReadNode wraps a syncable::Entry to provide the functionality of a
  19 // read-only BaseNode.
  20 class SYNC_EXPORT ReadNode : public BaseNode {
  21  public:
  22   // Create an unpopulated ReadNode on the given transaction.  Call some flavor
  23   // of Init to populate the ReadNode with a database entry.
  24   explicit ReadNode(const BaseTransaction* transaction);
  25   ~ReadNode() override;
  26
  27   // A client must use one (and only one) of the following Init variants to
  28   // populate the node.
  29
  30   // BaseNode implementation.
  31   InitByLookupResult InitByIdLookup(int64 id) override;
  32   InitByLookupResult InitByClientTagLookup(ModelType model_type,
  33                                            const std::string& tag) override;
  34
  35   // There is always a root node, so this can't fail.  The root node is
  36   // never mutable, so root lookup is only possible on a ReadNode.
  37   void InitByRootLookup();
  38
  39   // Returns the type root node, if it exists.  This is usually created by the
  40   // server during first sync.  Eventually, we plan to remove support for it
  41   // from the protocol and have the client create the node instead.
  42   InitByLookupResult InitTypeRoot(ModelType type);
  43
  44   // Returns a server-created and unique-server-tagged item.
  45   //
  46   // This functionality is only useful for bookmarks because only bookmarks
  47   // have server-tagged items.  All other server-tagged items are type root
  48   // nodes, which should be looked up with InitTypeRoot().
  49   InitByLookupResult InitByTagLookupForBookmarks(const std::string& tag);
  50
  51   // Returns transaction version of the last transaction where this node has
  52   // been modified.
  53   int64 GetTransactionVersion() const;
  54
  55   // Implementation of BaseNode's abstract virtual accessors.
  56   const syncable::Entry* GetEntry() const override;
  57   const BaseTransaction* GetTransaction() const override;
  58
  59  protected:
  60   ReadNode();
  61
  62  private:
  63   void* operator new(size_t size);  // Node is meant for stack use only.
  64
  65   // The underlying syncable object which this class wraps.
  66   syncable::Entry* entry_;
  67
  68   // The sync API transaction that is the parent of this node.
  69   const BaseTransaction* transaction_;
  70
  71   DISALLOW_COPY_AND_ASSIGN(ReadNode);
  72 };
  73
  74 }  // namespace syncer
  75
  76 #endif  // SYNC_INTERNAL_API_PUBLIC_READ_NODE_H_