103 lines
3.1 KiB
C++
103 lines
3.1 KiB
C++
/*
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* Copyright 2003-2021 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "VHelper.hxx"
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#include "song/DetachedSong.hxx"
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#include "song/LightSong.hxx"
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#include "song/Filter.hxx"
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#include "tag/Sort.hxx"
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#include <algorithm>
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#include <cassert>
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#include <utility>
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DatabaseVisitorHelper::DatabaseVisitorHelper(DatabaseSelection _selection,
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VisitSong &visit_song) noexcept
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:selection(std::move(_selection))
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{
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// TODO: apply URI and SongFilter
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assert(selection.uri.empty());
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assert(selection.filter == nullptr);
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if (selection.sort != TAG_NUM_OF_ITEM_TYPES) {
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/* the client has asked us to sort the result; this is
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pretty expensive, because instead of streaming the
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result to the client, we need to copy it all into
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this std::vector, and then sort it */
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original_visit_song = std::move(visit_song);
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visit_song = [this](const auto &song){
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songs.emplace_back(song);
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};
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} else if (selection.window != RangeArg::All()) {
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original_visit_song = std::move(visit_song);
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visit_song = [this](const auto &song){
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if (selection.window.Contains(counter++))
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original_visit_song(song);
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};
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}
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}
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DatabaseVisitorHelper::~DatabaseVisitorHelper() noexcept = default;
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void
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DatabaseVisitorHelper::Commit()
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{
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/* only needed if sorting is enabled */
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if (selection.sort == TAG_NUM_OF_ITEM_TYPES)
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return;
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assert(original_visit_song);
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/* sort the song collection */
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const auto sort = selection.sort;
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const auto descending = selection.descending;
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if (sort == TagType(SORT_TAG_LAST_MODIFIED))
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std::stable_sort(songs.begin(), songs.end(),
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[descending](const DetachedSong &a, const DetachedSong &b){
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return descending
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? a.GetLastModified() > b.GetLastModified()
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: a.GetLastModified() < b.GetLastModified();
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});
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else
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std::stable_sort(songs.begin(), songs.end(),
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[sort, descending](const DetachedSong &a,
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const DetachedSong &b){
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return CompareTags(sort, descending,
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a.GetTag(),
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b.GetTag());
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});
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/* apply the "window" */
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if (selection.window.end < songs.size())
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songs.erase(std::next(songs.begin(), selection.window.end),
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songs.end());
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if (selection.window.start >= songs.size())
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return;
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songs.erase(songs.begin(),
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std::next(songs.begin(), selection.window.start));
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/* now pass all songs to the original visitor callback */
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for (const auto &song : songs)
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original_visit_song((LightSong)song);
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}
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