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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_FEED_CORE_V2_XSURFACE_DATASTORE_H_
#define COMPONENTS_FEED_CORE_V2_XSURFACE_DATASTORE_H_
#include <map>
#include <string>
#include <vector>
#include "base/observer_list.h"
// This file defines some types related to the XSurface datastore.
// The XSurface datastore is a generic key-value store, which can affect the
// display of UI elements. In some cases, we populate data store with
// information source by the Feed component.
namespace feed {
// Write-access to something that stores data store elements.
class XsurfaceDatastoreDataWriter {
public:
virtual void UpdateDatastoreEntry(const std::string& key,
const std::string& value) = 0;
virtual void RemoveDatastoreEntry(const std::string& key) = 0;
};
// Read-access to something that stores data store elements.
class XsurfaceDatastoreDataReader {
public:
// Observes data that can be read.
class Observer : public base::CheckedObserver {
public:
// An entry has been added or updated.
virtual void DatastoreEntryUpdated(XsurfaceDatastoreDataReader* source,
const std::string& key) = 0;
// An entry has been removed.
virtual void DatastoreEntryRemoved(XsurfaceDatastoreDataReader* source,
const std::string& key) = 0;
};
// Begin observing. Data already present before `AddObserver()` is called can
// be read using `GetAllEntries()`.
virtual void AddObserver(XsurfaceDatastoreDataReader::Observer* o) = 0;
virtual void RemoveObserver(XsurfaceDatastoreDataReader::Observer* o) = 0;
// Find an entry with the given key. Returns nullptr if the entry does not
// exist.
virtual const std::string* FindEntry(const std::string& key) const = 0;
// Return all stored entries.
virtual std::map<std::string, std::string> GetAllEntries() const = 0;
};
// A set of data exported to the XSurface datastore.
class XsurfaceDatastoreSlice : public XsurfaceDatastoreDataReader,
public XsurfaceDatastoreDataWriter {
public:
XsurfaceDatastoreSlice();
~XsurfaceDatastoreSlice();
XsurfaceDatastoreSlice(const XsurfaceDatastoreSlice&) = delete;
XsurfaceDatastoreSlice& operator=(const XsurfaceDatastoreSlice&) = delete;
// XsurfaceDatastoreDataWriter.
void UpdateDatastoreEntry(const std::string& key,
const std::string& value) override;
void RemoveDatastoreEntry(const std::string& key) override;
// XsurfaceDatastoreDataReader.
void AddObserver(Observer* o) override;
void RemoveObserver(Observer* o) override;
const std::string* FindEntry(const std::string& key) const override;
std::map<std::string, std::string> GetAllEntries() const override;
private:
base::ObserverList<Observer> observers_;
std::map<std::string, std::string> entries_;
};
// Combines multiple `XsurfaceDatastoreDataReader`s, to provide access to all
// stored data. This implementation assumes that each contained
// `XsurfaceDatastoreDataReader` provides a disjoint set of keys, so that there
// can be no key collision between `sources`.
class XsurfaceDatastoreAggregate
: public XsurfaceDatastoreDataReader,
public XsurfaceDatastoreDataReader::Observer {
public:
explicit XsurfaceDatastoreAggregate(
std::vector<raw_ptr<XsurfaceDatastoreDataReader>> sources);
~XsurfaceDatastoreAggregate() override;
XsurfaceDatastoreAggregate(const XsurfaceDatastoreAggregate&) = delete;
XsurfaceDatastoreAggregate& operator=(const XsurfaceDatastoreAggregate&) =
delete;
// XsurfaceDatastoreDataReader.
void AddObserver(XsurfaceDatastoreDataReader::Observer* o) override;
void RemoveObserver(XsurfaceDatastoreDataReader::Observer* o) override;
const std::string* FindEntry(const std::string& key) const override;
std::map<std::string, std::string> GetAllEntries() const override;
// XsurfaceDatastoreDataReader::Observer.
void DatastoreEntryUpdated(XsurfaceDatastoreDataReader* source,
const std::string& key) override;
void DatastoreEntryRemoved(XsurfaceDatastoreDataReader* source,
const std::string& key) override;
private:
base::ObserverList<XsurfaceDatastoreDataReader::Observer> observers_;
std::vector<raw_ptr<XsurfaceDatastoreDataReader>> sources_;
};
} // namespace feed
#endif // COMPONENTS_FEED_CORE_V2_XSURFACE_DATASTORE_H_
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