122 lines
2.8 KiB
C++
122 lines
2.8 KiB
C++
/*
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* Copyright (C) 2013 Max Kellermann <max@duempel.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef MPD_MANUAL_HXX
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#define MPD_MANUAL_HXX
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#include "Compiler.h"
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#include <new>
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#include <utility>
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#if GCC_OLDER_THAN(4,8)
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#include <type_traits>
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#endif
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#include <assert.h>
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#if defined(__clang__) || GCC_CHECK_VERSION(4,7)
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wstrict-aliasing"
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#endif
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/**
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* Container for an object that gets constructed and destructed
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* manually. The object is constructed in-place, and therefore
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* without allocation overhead. It can be constructed and destructed
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* repeatedly.
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*/
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template<class T>
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class Manual {
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#if GCC_OLDER_THAN(4,8)
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/* no alignas() on gcc < 4.8: apply worst-case fallback */
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__attribute__((aligned(8)))
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#else
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alignas(T)
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#endif
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char data[sizeof(T)];
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#ifndef NDEBUG
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bool initialized;
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#endif
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public:
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#ifndef NDEBUG
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Manual():initialized(false) {}
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~Manual() {
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assert(!initialized);
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}
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#endif
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template<typename... Args>
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void Construct(Args&&... args) {
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assert(!initialized);
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void *p = data;
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new(p) T(std::forward<Args>(args)...);
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#ifndef NDEBUG
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initialized = true;
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#endif
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}
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void Destruct() {
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assert(initialized);
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T *t = (T *)data;
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t->T::~T();
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#ifndef NDEBUG
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initialized = false;
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#endif
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}
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operator T &() {
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return *(T *)data;
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}
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operator const T &() const {
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return *(const T *)data;
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}
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T *operator->() {
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return (T *)data;
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}
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const T *operator->() const {
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return (T *)data;
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}
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};
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#if defined(__clang__) || GCC_VERSION >= 40700
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#pragma GCC diagnostic pop
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#endif
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#endif
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