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// Copyright (c) 2012 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.
#include <map>
#include <memory>
#include <set>
#include <vector>
#include "base/macros.h"
#include "components/sync/base/model_type.h"
#include "components/sync/syncable/syncable_id.h"
namespace syncer {
namespace syncable {
struct EntryKernel;
class ParentChildIndex;
// A node ordering function.
struct ChildComparator {
bool operator()(const EntryKernel* a, const EntryKernel* b) const;
// An ordered set of nodes.
using OrderedChildSet = std::set<EntryKernel*, ChildComparator>;
using OrderedChildSetRef = std::shared_ptr<OrderedChildSet>;
// Container that tracks parent-child relationships.
// Provides fast lookup of all items under a given parent.
class ParentChildIndex {
// Returns whether or not this entry belongs in the index.
// True for all non-deleted, non-root entries.
static bool ShouldInclude(const EntryKernel* e);
// Inserts a given child into the index.
bool Insert(EntryKernel* e);
// Removes a given child from the index.
void Remove(EntryKernel* e);
// Returns true if this item is in the index as a child.
bool Contains(EntryKernel* e) const;
// Returns all children of the entry with the given Id. Returns null if the
// node has no children or the Id does not identify a valid directory node.
const OrderedChildSet* GetChildren(const Id& id) const;
// Returns all children of the entry. Returns null if the node has no
// children.
const OrderedChildSet* GetChildren(EntryKernel* e) const;
// Returns all siblings of the entry.
const OrderedChildSet* GetSiblings(EntryKernel* e) const;
// Estimates amount of heap memory used.
size_t EstimateMemoryUsage() const;
friend class ParentChildIndexTest;
using ParentChildrenMap = std::map<Id, OrderedChildSetRef>;
using TypeRootIds = std::vector<Id>;
using TypeRootChildSets = std::vector<OrderedChildSetRef>;
static bool ShouldUseParentId(const Id& parent_id, ModelType model_type);
// Returns OrderedChildSet that should contain the specified entry
// based on the entry's Parent ID or model type.
const OrderedChildSetRef GetChildSet(EntryKernel* e) const;
// Returns OrderedChildSet that contain entries of the |model_type| type.
const OrderedChildSetRef GetModelTypeChildSet(ModelType model_type) const;
// Returns mutable OrderedChildSet that contain entries of the |model_type|
// type. Create one as necessary.
OrderedChildSetRef GetOrCreateModelTypeChildSet(ModelType model_type);
// Returns previously cached model type root ID for the given |model_type|.
const Id& GetModelTypeRootId(ModelType model_type) const;
// A map of parent IDs to children.
// Parents with no children are not included in this map.
ParentChildrenMap parent_children_map_;
// This array tracks model type roots IDs.
TypeRootIds model_type_root_ids_;
// This array contains pre-defined child sets for
// non-hierarchical types (types with flat hierarchy) that support entries
// with implicit parent.
TypeRootChildSets type_root_child_sets_;
} // namespace syncable
} // namespace syncer