/*
 * Copyright (C) 2008 Apple Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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 APPLE INC. ``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 APPLE INC. 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 WTF_StdLibExtras_h
#define WTF_StdLibExtras_h

#include "wtf/Assertions.h"
#include "wtf/CPU.h"
#include "wtf/CheckedArithmetic.h"
#include "wtf/LeakAnnotations.h"
#include <cstddef>

#if ENABLE(ASSERT)
#include "wtf/Noncopyable.h"
#include "wtf/Threading.h"

class WTF_EXPORT StaticLocalVerifier {
    WTF_MAKE_NONCOPYABLE(StaticLocalVerifier);
public:
    StaticLocalVerifier()
        : m_safelyInitialized(WTF::isBeforeThreadCreated())
        , m_thread(WTF::currentThread())
    {
    }

    bool isNotRacy()
    {
        // Make sure that this 1) is safely initialized, 2) keeps being called
        // on the same thread, or 3) is called within
        // AtomicallyInitializedStatic (i.e. with a lock held).
        return m_safelyInitialized || m_thread == WTF::currentThread() || WTF::isAtomicallyInitializedStaticMutexLockHeld();
    }

private:
    bool m_safelyInitialized;
    ThreadIdentifier m_thread;
};
#endif

// A direct static local to a Blink garbage collected objects isn't allowed;
// must be wrapped up with a persistent reference.
#define STATIC_ASSERT_FOR_LOCAL_WITH_GARBAGE_COLLECTED_TYPE(Name, Type) \
    using Name##NoConstType = std::remove_const<Type>::type; \
    using Name##NoPointerType = std::remove_pointer<Name##NoConstType>::type; \
    using Name##NoReferenceType = std::remove_reference<Name##NoPointerType>::type; \
    static_assert(!WTF::IsGarbageCollectedType<Name##NoReferenceType>::value || WTF::IsPersistentReferenceType<Name##NoReferenceType>::value, "Garbage collected static local needs to be wrapped up with a persistent reference")

// Use DEFINE_STATIC_LOCAL() to declare and define a static local variable (static T;)
// so that it is leaked and its destructors are not called at exit.
//
// To cooperate with leak detection, the objects held onto by these local statics
// will in some cases have to be finalized prior to leak checking. This only applies
// to static references to Oilpan heap objects and what they transitively hold on to.
// LEAK_SANITIZER_REGISTER_STATIC_LOCAL() takes care of the details.
//
#if ENABLE(ASSERT)
#define DEFINE_STATIC_LOCAL(Type, Name, Arguments)        \
    STATIC_ASSERT_FOR_LOCAL_WITH_GARBAGE_COLLECTED_TYPE(Name, Type); \
    static StaticLocalVerifier Name##StaticLocalVerifier; \
    ASSERT(Name##StaticLocalVerifier.isNotRacy());        \
    static Type& Name = *LEAK_SANITIZER_REGISTER_STATIC_LOCAL(Type, new Type Arguments)
#else
#define DEFINE_STATIC_LOCAL(Type, Name, Arguments) \
    STATIC_ASSERT_FOR_LOCAL_WITH_GARBAGE_COLLECTED_TYPE(Name, Type); \
    static Type& Name = *LEAK_SANITIZER_REGISTER_STATIC_LOCAL(Type, new Type Arguments)
#endif

// Use this to declare and define a static local pointer to a ref-counted object so that
// it is leaked so that the object's destructors are not called at exit.
// This macro should be used with ref-counted objects rather than DEFINE_STATIC_LOCAL macro,
// as this macro does not lead to an extra memory allocation.
#define DEFINE_STATIC_REF(type, name, arguments) \
    static type* name = PassRefPtr<type>(arguments).leakRef();

/*
 * The reinterpret_cast<Type1*>([pointer to Type2]) expressions - where
 * sizeof(Type1) > sizeof(Type2) - cause the following warning on ARM with GCC:
 * increases required alignment of target type.
 *
 * An implicit or an extra static_cast<void*> bypasses the warning.
 * For more info see the following bugzilla entries:
 * - https://bugs.webkit.org/show_bug.cgi?id=38045
 * - http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43976
 */
#if CPU(ARM) && COMPILER(GCC)
template<typename Type>
bool isPointerTypeAlignmentOkay(Type* ptr)
{
    return !(reinterpret_cast<intptr_t>(ptr) % __alignof__(Type));
}

template<typename TypePtr>
TypePtr reinterpret_cast_ptr(void* ptr)
{
    ASSERT(isPointerTypeAlignmentOkay(reinterpret_cast<TypePtr>(ptr)));
    return reinterpret_cast<TypePtr>(ptr);
}

template<typename TypePtr>
TypePtr reinterpret_cast_ptr(const void* ptr)
{
    ASSERT(isPointerTypeAlignmentOkay(reinterpret_cast<TypePtr>(ptr)));
    return reinterpret_cast<TypePtr>(ptr);
}
#else
template<typename Type>
bool isPointerTypeAlignmentOkay(Type*)
{
    return true;
}
#define reinterpret_cast_ptr reinterpret_cast
#endif

namespace WTF {

/*
 * C++'s idea of a reinterpret_cast lacks sufficient cojones.
 */
template<typename TO, typename FROM>
inline TO bitwise_cast(FROM from)
{
    static_assert(sizeof(TO) == sizeof(FROM), "WTF::bitwise_cast sizeof casted types should be equal");
    union {
        FROM from;
        TO to;
    } u;
    u.from = from;
    return u.to;
}

template<typename To, typename From>
inline To safeCast(From value)
{
    RELEASE_ASSERT(isInBounds<To>(value));
    return static_cast<To>(value);
}

// Use the following macros to prevent errors caused by accidental
// implicit casting of function arguments.  For example, this can
// be used to prevent overflows from non-promoting conversions.
//
// Example:
//
// HAS_STRICTLY_TYPED_ARG
// void sendData(void* data, STRICTLY_TYPED_ARG(size))
// {
//    ALLOW_NUMERIC_ARG_TYPES_PROMOTABLE_TO(size_t);
//    ...
// }
//
// The previous example will prevent callers from passing, for example, an
// 'int'. On a 32-bit build, it will prevent use of an 'unsigned long long'.
#define HAS_STRICTLY_TYPED_ARG template<typename ActualArgType>
#define STRICTLY_TYPED_ARG(argName) ActualArgType argName
#define STRICT_ARG_TYPE(ExpectedArgType) \
    static_assert(std::is_same<ActualArgType, ExpectedArgType>::value, \
        "Strictly typed argument must be of type '" #ExpectedArgType "'." )
#define ALLOW_NUMERIC_ARG_TYPES_PROMOTABLE_TO(ExpectedArgType) \
    static_assert(std::numeric_limits<ExpectedArgType>::is_integer == std::numeric_limits<ActualArgType>::is_integer, \
        "Conversion between integer and non-integer types not allowed."); \
    static_assert(sizeof(ExpectedArgType) >= sizeof(ActualArgType), \
        "Truncating conversions not allowed."); \
    static_assert(!std::numeric_limits<ActualArgType>::is_signed || std::numeric_limits<ExpectedArgType>::is_signed, \
        "Signed to unsigned conversion not allowed."); \
    static_assert((sizeof(ExpectedArgType) != sizeof(ActualArgType)) || (std::numeric_limits<ActualArgType>::is_signed == std::numeric_limits<ExpectedArgType>::is_signed), \
        "Unsigned to signed conversion not allowed for types with identical size (could overflow).");

// Macro that returns a compile time constant with the length of an array, but gives an error if passed a non-array.
template<typename T, size_t Size> char (&ArrayLengthHelperFunction(T (&)[Size]))[Size];
// GCC needs some help to deduce a 0 length array.
#if COMPILER(GCC)
template<typename T> char (&ArrayLengthHelperFunction(T (&)[0]))[0];
#endif
#define WTF_ARRAY_LENGTH(array) sizeof(::WTF::ArrayLengthHelperFunction(array))

} // namespace WTF

// This version of placement new omits a 0 check.
enum NotNullTag { NotNull };
inline void* operator new(size_t, NotNullTag, void* location)
{
    ASSERT(location);
    return location;
}

using WTF::bitwise_cast;
using WTF::safeCast;

#endif // WTF_StdLibExtras_h