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/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#pragma once
#include <deque>
#include <memory>
#include <mutex>
#include <variant>
#include <vector>
#include "bloom_filter.hpp"
#include "database.hpp"
#include "future_fetcher.hpp"
#include "random.hpp"
#include "track.hpp"
namespace playlist {
/*
* Stateful interface for iterating over a collection of tracks by id.
*/
class ISource {
public:
virtual ~ISource() {}
virtual auto Current() -> std::optional<database::TrackId> = 0;
/*
* Discards the current track id and continues to the next in this source.
* Returns the new current track id.
*/
virtual auto Advance() -> std::optional<database::TrackId> = 0;
/*
* Repeatedly advances until a track with the given id is the current track.
* Returns false if this source ran out of tracks before the requested id
* was encounted, true otherwise.
*/
virtual auto AdvanceTo(database::TrackId id) -> bool {
for (auto t = Current(); t.has_value(); t = Advance()) {
if (*t == id) {
return true;
}
}
return false;
}
/*
* Places the next n tracks into the given vector, in order. Does not change
* the value returned by Current().
*/
virtual auto Peek(std::size_t n, std::vector<database::TrackId>*)
-> std::size_t = 0;
};
/*
* A Source that supports restarting iteration from its original initial
* value.
*/
class IResetableSource : public ISource {
public:
virtual ~IResetableSource() {}
virtual auto Previous() -> std::optional<database::TrackId> = 0;
/*
* Restarts iteration from this source's initial value.
*/
virtual auto Reset() -> void = 0;
};
auto CreateSourceFromResults(
std::weak_ptr<database::Database>,
std::shared_ptr<database::Result<database::IndexRecord>>)
-> std::shared_ptr<IResetableSource>;
class IndexRecordSource : public IResetableSource {
public:
IndexRecordSource(std::weak_ptr<database::Database> db,
std::shared_ptr<database::Result<database::IndexRecord>>);
IndexRecordSource(std::weak_ptr<database::Database> db,
std::shared_ptr<database::Result<database::IndexRecord>>,
std::size_t,
std::shared_ptr<database::Result<database::IndexRecord>>,
std::size_t);
auto Current() -> std::optional<database::TrackId> override;
auto Advance() -> std::optional<database::TrackId> override;
auto Peek(std::size_t n, std::vector<database::TrackId>*)
-> std::size_t override;
auto Previous() -> std::optional<database::TrackId> override;
auto Reset() -> void override;
private:
std::weak_ptr<database::Database> db_;
std::shared_ptr<database::Result<database::IndexRecord>> initial_page_;
ssize_t initial_item_;
std::shared_ptr<database::Result<database::IndexRecord>> current_page_;
ssize_t current_item_;
};
class NestedSource : public IResetableSource {
public:
NestedSource(std::weak_ptr<database::Database> db,
std::shared_ptr<database::Result<database::IndexRecord>>);
auto Current() -> std::optional<database::TrackId> override;
auto Advance() -> std::optional<database::TrackId> override;
auto Peek(std::size_t n, std::vector<database::TrackId>*)
-> std::size_t override;
auto Previous() -> std::optional<database::TrackId> override;
auto Reset() -> void override;
private:
auto CreateChild(std::shared_ptr<database::IndexRecord> page)
-> std::shared_ptr<IResetableSource>;
std::weak_ptr<database::Database> db_;
std::shared_ptr<database::Result<database::IndexRecord>> initial_page_;
ssize_t initial_item_;
std::shared_ptr<database::Result<database::IndexRecord>> current_page_;
ssize_t current_item_;
std::shared_ptr<IResetableSource> current_child_;
};
} // namespace playlist
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