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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 "Compiler.h"
#include <new>
#include <utility>
#if GCC_OLDER_THAN(4,8)
#include <type_traits>
#endif
#include <assert.h>
#if defined(__clang__) || GCC_CHECK_VERSION(4,7)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
/**
* 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 GCC_OLDER_THAN(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;
}
};
#if defined(__clang__) || GCC_VERSION >= 40700
#pragma GCC diagnostic pop
#endif
#endif
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