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/*
* Copyright 2003-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef MPD_TAG_HXX
#define MPD_TAG_HXX
#include "Type.h" // IWYU pragma: export
#include "Item.hxx" // IWYU pragma: export
#include "Chrono.hxx"
#include "util/Compiler.h"
#include "util/DereferenceIterator.hxx"
#include <memory>
#include <utility>
/**
* The meta information about a song file. It is a MPD specific
* subset of tags (e.g. from ID3, vorbis comments, ...).
*/
struct Tag {
/**
* The duration of the song. A negative value means that the
* length is unknown.
*/
SignedSongTime duration = SignedSongTime::Negative();
/**
* Does this file have an embedded playlist (e.g. embedded CUE
* sheet)?
*/
bool has_playlist = false;
/** the total number of tag items in the #items array */
unsigned short num_items = 0;
/** an array of tag items */
TagItem **items = nullptr;
/**
* Create an empty tag.
*/
Tag() = default;
Tag(const Tag &other) noexcept;
Tag(Tag &&other) noexcept
:duration(other.duration), has_playlist(other.has_playlist),
num_items(other.num_items), items(other.items) {
other.items = nullptr;
other.num_items = 0;
}
/**
* Free the tag object and all its items.
*/
~Tag() noexcept {
Clear();
}
Tag &operator=(const Tag &other) = delete;
Tag &operator=(Tag &&other) noexcept {
duration = other.duration;
has_playlist = other.has_playlist;
MoveItemsFrom(std::move(other));
return *this;
}
/**
* Similar to the move operator, but move only the #TagItem
* array.
*/
void MoveItemsFrom(Tag &&other) noexcept {
std::swap(items, other.items);
std::swap(num_items, other.num_items);
}
/**
* Returns true if the tag contains no items. This ignores
* the "duration" attribute.
*/
bool IsEmpty() const noexcept {
return num_items == 0;
}
/**
* Returns true if the tag contains any information.
*/
bool IsDefined() const noexcept {
return !IsEmpty() || !duration.IsNegative();
}
/**
* Clear everything, as if this was a new Tag object.
*/
void Clear() noexcept;
/**
* Merges the data from two tags. If both tags share data for the
* same TagType, only data from "add" is used.
*
* @return a newly allocated tag
*/
static Tag Merge(const Tag &base,
const Tag &add) noexcept;
static std::unique_ptr<Tag> MergePtr(const Tag &base,
const Tag &add) noexcept;
/**
* Merges the data from two tags. Any of the two may be nullptr. Both
* are freed by this function.
*
* @return a newly allocated tag
*/
static std::unique_ptr<Tag> Merge(std::unique_ptr<Tag> base,
std::unique_ptr<Tag> add) noexcept;
/**
* Returns the first value of the specified tag type, or
* nullptr if none is present in this tag object.
*/
gcc_pure
const char *GetValue(TagType type) const noexcept;
/**
* Checks whether the tag contains one or more items with
* the specified type.
*/
gcc_pure
bool HasType(TagType type) const noexcept;
/**
* Returns a value for sorting on the specified type, with
* automatic fallbacks to the next best tag type
* (e.g. #TAG_ALBUM_ARTIST falls back to #TAG_ARTIST). If
* there is no such value, returns an empty string.
*/
gcc_pure gcc_returns_nonnull
const char *GetSortValue(TagType type) const noexcept;
using const_iterator = DereferenceIterator<TagItem *const*,
const TagItem>;
const_iterator begin() const noexcept {
return const_iterator{items};
}
const_iterator end() const noexcept {
return const_iterator{items + num_items};
}
};
#endif
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