chrome/browser/ui/app_list/search/mixer.h

// Copyright 2013 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 CHROME_BROWSER_UI_APP_LIST_SEARCH_MIXER_H_
#define CHROME_BROWSER_UI_APP_LIST_SEARCH_MIXER_H_

#include <stddef.h>

#include <memory>
#include <vector>

#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "chrome/browser/ui/app_list/search/history_types.h"

class AppListModelUpdater;

namespace app_list {

namespace test {
FORWARD_DECLARE_TEST(MixerTest, Publish);
}

class SearchProvider;
class SearchResult;

// Mixer collects results from providers, sorts them and publishes them to the
// SearchResults UI model. The targeted results have 6 slots to hold the
// result. The search controller can specify any number of groups, each with a
// different number of results and priority boost.
class Mixer {
 public:
  explicit Mixer(AppListModelUpdater* model_updater);
  ~Mixer();

  // Adds a new mixer group. A "soft" maximum of |max_results| results will be
  // chosen from this group (if 0, will allow unlimited results from this
  // group). If there aren't enough results from all groups, more than
  // |max_results| may be chosen from this group. Each result in the group will
  // have its score multiplied by |multiplier| and added by |boost|. Returns the
  // group's group_id.
  size_t AddGroup(size_t max_results, double multiplier, double boost);

  // Associates a provider with a mixer group.
  void AddProviderToGroup(size_t group_id, SearchProvider* provider);

  // Collects the results, sorts and publishes them.
  void MixAndPublish(const KnownResults& known_results, size_t num_max_results);

 private:
  FRIEND_TEST_ALL_PREFIXES(test::MixerTest, Publish);

  // Used for sorting and mixing results.
  struct SortData {
    SortData();
    SortData(SearchResult* result, double score);

    bool operator<(const SortData& other) const;

    SearchResult* result;  // Not owned.
    double score;
  };
  typedef std::vector<Mixer::SortData> SortedResults;

  class Group;
  typedef std::vector<std::unique_ptr<Group>> Groups;

  // Removes entries from |results| with duplicate IDs. When two or more results
  // have the same ID, the earliest one in the |results| list is kept.
  // NOTE: This is not necessarily the one with the highest *score*, as
  // |results| may not have been sorted yet.
  static void RemoveDuplicates(SortedResults* results);

  void FetchResults(const KnownResults& known_results);

  AppListModelUpdater* const model_updater_;  // Not owned.

  Groups groups_;

  DISALLOW_COPY_AND_ASSIGN(Mixer);
};

}  // namespace app_list

#endif  // CHROME_BROWSER_UI_APP_LIST_SEARCH_MIXER_H_