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+/*
+ * Copyright (C) 2013 Max Kellermann <max@duempel.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef MPD_MANUAL_HXX
+#define MPD_MANUAL_HXX
+
+#include "gcc.h"
+
+#include <new>
+
+#if !defined(__clang__) && __GNUC__ && !GCC_CHECK_VERSION(4,8)
+#include <type_traits>
+#endif
+
+#include <assert.h>
+
+/**
+ * Container for an object that gets constructed and destructed
+ * manually. The object is constructed in-place, and therefore
+ * without allocation overhead. It can be constructed and destructed
+ * repeatedly.
+ */
+template<class T>
+class Manual {
+#if !defined(__clang__) && __GNUC__ && !GCC_CHECK_VERSION(4,8)
+ /* no alignas() on gcc < 4.8: apply worst-case fallback */
+ __attribute__((aligned(8)))
+#else
+ alignas(T)
+#endif
+ char data[sizeof(T)];
+
+#ifndef NDEBUG
+ bool initialized;
+#endif
+
+public:
+#ifndef NDEBUG
+ Manual():initialized(false) {}
+ ~Manual() {
+ assert(!initialized);
+ }
+#endif
+
+ template<typename... Args>
+ void Construct(Args&&... args) {
+ assert(!initialized);
+
+ void *p = data;
+ new(p) T(std::forward<Args>(args)...);
+
+#ifndef NDEBUG
+ initialized = true;
+#endif
+ }
+
+ void Destruct() {
+ assert(initialized);
+
+ T *t = (T *)data;
+ t->T::~T();
+
+#ifndef NDEBUG
+ initialized = false;
+#endif
+ }
+
+ operator T &() {
+ return *(T *)data;
+ }
+
+ operator const T &() const {
+ return *(const T *)data;
+ }
+
+ T *operator->() {
+ return (T *)data;
+ }
+
+ const T *operator->() const {
+ return (T *)data;
+ }
+};
+
+#endif