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+/*
+ * Copyright (C) 2003-2014 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 *data;
+
+public:
+ IdTable(unsigned _size):size(_size), next(1), data(new int[size]) {
+ std::fill_n(data, size, -1);
+ }
+
+ ~IdTable() {
+ delete[] data;
+ }
+
+ int IdToPosition(unsigned id) const {
+ return id < size
+ ? data[id]
+ : -1;
+ }
+
+ unsigned GenerateId() {
+ 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) {
+ unsigned id = GenerateId();
+ data[id] = position;
+ return id;
+ }
+
+ void Move(unsigned id, unsigned position) {
+ assert(id < size);
+ assert(data[id] >= 0);
+
+ data[id] = position;
+ }
+
+ void Erase(unsigned id) {
+ assert(id < size);
+ assert(data[id] >= 0);
+
+ data[id] = -1;
+ }
+};
+
+#endif