text: // 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.
  
  #ifndef COMPONENTS_SYNC_DRIVER_MODEL_ASSOCIATOR_H_
  #define COMPONENTS_SYNC_DRIVER_MODEL_ASSOCIATOR_H_
  
  #include "base/basictypes.h"
  #include "base/synchronization/lock.h"
  #include "sync/api/sync_error.h"
  #include "sync/internal_api/public/base/model_type.h"
  
  namespace syncer {
  class BaseNode;
  class SyncMergeResult;
  }
  
  namespace browser_sync {
  
  // This represents the fundamental operations used for model association that
  // are common to all ModelAssociators and do not depend on types of the models
  // being associated.
  class AssociatorInterface {
   public:
    virtual ~AssociatorInterface() {}
  
    // Iterates through both the sync and the chrome model looking for
    // matched pairs of items. After successful completion, the models
    // should be identical and corresponding. Returns true on
    // success. On failure of this step, we should abort the sync
    // operation and report an error to the user.
    virtual syncer::SyncError AssociateModels(
        syncer::SyncMergeResult* local_merge_result,
        syncer::SyncMergeResult* syncer_merge_result) = 0;
  
    // Clears all the associations between the chrome and sync models.
    virtual syncer::SyncError DisassociateModels() = 0;
  
    // The has_nodes out parameter is set to true if the sync model has
    // nodes other than the permanent tagged nodes.  The method may
    // return false if an error occurred.
    virtual bool SyncModelHasUserCreatedNodes(bool* has_nodes) = 0;
  
    // Calling this method while AssociateModels() is in progress will
    // cause the method to exit early with a "false" return value.  This
    // is useful for aborting model associations for shutdown.  This
    // method is only implemented for model associators that are invoked
    // off the main thread.
    virtual void AbortAssociation() = 0;
  
    // Returns whether the datatype is ready for encryption/decryption if the
    // sync service requires it.
    // TODO(zea): This should be implemented automatically for each datatype, see
    // http://crbug.com/76232.
    virtual bool CryptoReadyIfNecessary() = 0;
  };
  
  // In addition to the generic methods, association can refer to operations
  // that depend on the types of the actual IDs we are associating and the
  // underlying node type in the browser.  We collect these into a templatized
  // interface that encapsulates everything you need to implement to have a model
  // associator for a specific data type.
  // This template is appropriate for data types where a Node* makes sense for
  // referring to a particular item.  If we encounter a type that does not fit
  // in this world, we may want to have several PerDataType templates.
  template <class Node, class IDType>
  class PerDataTypeAssociatorInterface : public AssociatorInterface {
   public:
    virtual ~PerDataTypeAssociatorInterface() {}
    // Returns sync id for the given chrome model id.
    // Returns syncer::kInvalidId if the sync node is not found for the given
    // chrome id.
    virtual int64 GetSyncIdFromChromeId(const IDType& id) = 0;
  
    // Returns the chrome node for the given sync id.
    // Returns NULL if no node is found for the given sync id.
    virtual const Node* GetChromeNodeFromSyncId(int64 sync_id) = 0;
  
    // Initializes the given sync node from the given chrome node id.
    // Returns false if no sync node was found for the given chrome node id or
    // if the initialization of sync node fails.
    virtual bool InitSyncNodeFromChromeId(
        const IDType& node_id,
        syncer::BaseNode* sync_node) = 0;
  
    // Associates the given chrome node with the given sync id.
    virtual void Associate(const Node* node, int64 sync_id) = 0;
  
    // Remove the association that corresponds to the given sync id.
    virtual void Disassociate(int64 sync_id) = 0;
  };
  
  }  // namespace browser_sync
  
  #endif  // COMPONENTS_SYNC_DRIVER_MODEL_ASSOCIATOR_H_
  