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/*
* Copyright 2003-2017 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_ID_TABLE_HXX
#define MPD_ID_TABLE_HXX
#include "Compiler.h"
#include <algorithm>
#include <assert.h>
/**
* A table that maps id numbers to position numbers.
*/
class IdTable {
unsigned size;
unsigned next;
int *const data;
public:
IdTable(unsigned _size) noexcept
:size(_size), next(1), data(new int[size]) {
std::fill_n(data, size, -1);
}
~IdTable() noexcept {
delete[] data;
}
IdTable(const IdTable &) = delete;
IdTable &operator=(const IdTable &) = delete;
int IdToPosition(unsigned id) const noexcept {
return id < size
? data[id]
: -1;
}
unsigned GenerateId() noexcept {
assert(next > 0);
assert(next < size);
while (true) {
unsigned id = next;
++next;
if (next == size)
next = 1;
if (data[id] < 0)
return id;
}
}
unsigned Insert(unsigned position) noexcept {
unsigned id = GenerateId();
data[id] = position;
return id;
}
void Move(unsigned id, unsigned position) noexcept {
assert(id < size);
assert(data[id] >= 0);
data[id] = position;
}
void Erase(unsigned id) noexcept {
assert(id < size);
assert(data[id] >= 0);
data[id] = -1;
}
};
#endif
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