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/*
* Copyright 2003-2018 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.
*/
#include "VHelper.hxx"
#include "song/LightSong.hxx"
#include "song/Filter.hxx"
#include <assert.h>
#include <stdlib.h>
#include <string.h>
DatabaseVisitorHelper::DatabaseVisitorHelper(const DatabaseSelection &_selection,
VisitSong &visit_song) noexcept
:selection(_selection)
{
// TODO: apply URI and SongFilter
assert(selection.uri.empty());
assert(selection.filter == nullptr);
if (selection.sort != TAG_NUM_OF_ITEM_TYPES) {
/* the client has asked us to sort the result; this is
pretty expensive, because instead of streaming the
result to the client, we need to copy it all into
this std::vector, and then sort it */
original_visit_song = std::move(visit_song);
visit_song = [this](const auto &song){
songs.emplace_back(song);
};
} else if (selection.window != RangeArg::All()) {
original_visit_song = std::move(visit_song);
visit_song = [this](const auto &song){
if (selection.window.Contains(counter++))
original_visit_song(song);
};
}
}
DatabaseVisitorHelper::~DatabaseVisitorHelper() noexcept = default;
gcc_pure
static bool
CompareNumeric(const char *a, const char *b) noexcept
{
long a_value = strtol(a, nullptr, 10);
long b_value = strtol(b, nullptr, 10);
return a_value < b_value;
}
gcc_pure
static bool
CompareTags(TagType type, bool descending, const Tag &a, const Tag &b) noexcept
{
const char *a_value = a.GetSortValue(type);
const char *b_value = b.GetSortValue(type);
if (descending) {
using std::swap;
swap(a_value, b_value);
}
switch (type) {
case TAG_DISC:
case TAG_TRACK:
return CompareNumeric(a_value, b_value);
default:
return strcmp(a_value, b_value) < 0;
}
}
void
DatabaseVisitorHelper::Commit()
{
/* only needed if sorting is enabled */
if (selection.sort == TAG_NUM_OF_ITEM_TYPES)
return;
assert(original_visit_song);
/* sort the song collection */
const auto sort = selection.sort;
const auto descending = selection.descending;
if (sort == TagType(SORT_TAG_LAST_MODIFIED))
std::stable_sort(songs.begin(), songs.end(),
[descending](const DetachedSong &a, const DetachedSong &b){
return descending
? a.GetLastModified() > b.GetLastModified()
: a.GetLastModified() < b.GetLastModified();
});
else
std::stable_sort(songs.begin(), songs.end(),
[sort, descending](const DetachedSong &a,
const DetachedSong &b){
return CompareTags(sort, descending,
a.GetTag(),
b.GetTag());
});
/* apply the "window" */
if (selection.window.end < songs.size())
songs.erase(std::next(songs.begin(), selection.window.end),
songs.end());
if (selection.window.start >= songs.size())
return;
songs.erase(songs.begin(),
std::next(songs.begin(), selection.window.start));
/* now pass all songs to the original visitor callback */
for (const auto &song : songs)
original_visit_song((LightSong)song);
}
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