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   virtual ~ReadNode();
  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   virtual InitByLookupResult InitByIdLookup(int64 id) OVERRIDE;
  32   virtual InitByLookupResult InitByClientTagLookup(
  33       ModelType model_type,
  34       const std::string& tag) OVERRIDE;
  35
  36   // There is always a root node, so this can't fail.  The root node is
  37   // never mutable, so root lookup is only possible on a ReadNode.
  38   void InitByRootLookup();
  39
  40   // Each server-created permanent node is tagged with a unique string.
  41   // Look up the node with the particular tag.  If it does not exist,
  42   // return false.
  43   InitByLookupResult InitByTagLookup(const std::string& tag);
  44
  45   // Implementation of BaseNode's abstract virtual accessors.
  46   virtual const syncable::Entry* GetEntry() const OVERRIDE;
  47   virtual const BaseTransaction* GetTransaction() const OVERRIDE;
  48
  49  protected:
  50   ReadNode();
  51
  52  private:
  53   void* operator new(size_t size);  // Node is meant for stack use only.
  54
  55   // The underlying syncable object which this class wraps.
  56   syncable::Entry* entry_;
  57
  58   // The sync API transaction that is the parent of this node.
  59   const BaseTransaction* transaction_;
  60
  61   DISALLOW_COPY_AND_ASSIGN(ReadNode);
  62 };
  63
  64 }  // namespace syncer
  65
  66 #endif  // SYNC_INTERNAL_API_PUBLIC_READ_NODE_H_