qv4alloca_p.h

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#ifndef QV4_ALLOCA_H
#define QV4_ALLOCA_H
 
//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//
 
#include <QtCore/private/qglobal_p.h>
 
#include <stdlib.h>
#if __has_include(<alloca.h>)
#  include <alloca.h>
#endif
#if __has_include(<malloc.h>)
#  include <malloc.h>
#endif
 
#ifdef Q_CC_MSVC
// This does not matter unless compiling in strict standard mode.
#  define alloca _alloca
#endif
 
// Define Q_ALLOCA_VAR macro to be used instead of #ifdeffing
// the occurrences of alloca() in case it's not supported.
// Q_ALLOCA_DECLARE and Q_ALLOCA_ASSIGN macros separate
// memory allocation from the declaration and RAII.
#define Q_ALLOCA_VAR(type, name, size)
    Q_ALLOCA_DECLARE(type, name);
    Q_ALLOCA_ASSIGN(type, name, size)
 
#ifdef alloca
 
#define Q_ALLOCA_DECLARE(type, name)
    type *name = 0
 
#define Q_ALLOCA_ASSIGN(type, name, size)
    name = static_cast<type*>(alloca(size))
 
#else
#  include <memory>
 
#define Q_ALLOCA_DECLARE(type, name)
    std::unique_ptr<char[]> _qt_alloca_##name;
    type *name = nullptr
 
#define Q_ALLOCA_ASSIGN(type, name, size)
    do {
        _qt_alloca_##name.reset(new char[size]);
        name = reinterpret_cast<type*>(_qt_alloca_##name.get());
    } while (false)
 
#endif
 
#endif