ScopedObject.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#ifndef META_OCEAN_BASE_SCOPED_OBJECT_H
#define META_OCEAN_BASE_SCOPED_OBJECT_H
 
#include "ocean/base/Base.h"
#include "ocean/base/DataType.h"
 
namespace Ocean
{
 
/**
 * This class wraps an unmanaged object (or reference) which needs to be released after usage.
 * The release function can be defined at runtime.
 * @tparam T The data type of the wrapped object
 * @tparam TReleaseValue The optional explicit data type of the object to be released
 * @tparam TReleaseFunction The data type of the release function
 * @see ScopedObjectCompileTime.
 * @ingroup base
 */
template <typename T, typename TReleaseValue = T, typename TReleaseFunction = void(*)(TReleaseValue)>
class ScopedObjectT
{
    public:
 
        /**
         * Default constructor creating an object with invalid object.
         */
        ScopedObjectT() = default;
 
        /**
         * Move constructor.
         * @param scopedObject The scoped object to be moved
         */
        ScopedObjectT(ScopedObjectT<T, TReleaseValue, TReleaseFunction>&& scopedObject) noexcept;
 
        /**
         * Creates a new scoped object.
         * @param object The object to be wrapped
         * @param releaseFunction The release function
         */
        ScopedObjectT(T&& object, TReleaseFunction&& releaseFunction) noexcept;
 
        /**
         * Creates a new scoped object.
         * This constructor allows to decide at runtime whether the release function will be used or not.
         * @param object The object to be wrapped
         * @param releaseFunction The release function
         * @param useReleaseFunction True, to use the provided release function; False, to ignore the provided release function (so that the wrapped object will never be released)
         */
        ScopedObjectT(T&& object, TReleaseFunction&& releaseFunction, const bool useReleaseFunction) noexcept;
 
        /**
         * Creates a new scoped object.
         * @param object The object to be wrapped
         * @param releaseFunction The release function
         */
        ScopedObjectT(const T& object, TReleaseFunction&& releaseFunction) noexcept;
 
        /**
         * Creates a new scoped object.
         * This constructor allows to decide at runtime whether the release function will be used or not.
         * @param object The object to be wrapped
         * @param releaseFunction The release function
         * @param useReleaseFunction True, to use the provided release function; False, to ignore the provided release function (so that the wrapped object will never be released)
         */
        ScopedObjectT(const T& object, TReleaseFunction&& releaseFunction, const bool useReleaseFunction) noexcept;
 
        /**
         * Destructs this scoped object and releases the internal wrapped object.
         */
        ~ScopedObjectT();
 
        /**
         * Returns whether this scoped object holds a valid release function (which will be invoked once the object is released).
         * @return True, if so
         */
        bool isValid() const;
 
        /**
         * Returns the wrapped object.
         * @return The wrapped object
         */
        const T& object() const;
 
        /**
         * Arrow operator returning the wrapped object.
         * Ensure that the object is valid before calling this operator.
         * @return The wrapped object
         * @see isValid().
         */
        const T& operator->() const;
 
        /**
         * De-reference operator returning the wrapped object.
         * Ensure that the object is valid before calling this operator.
         * @return The wrapped object
         * @see isValid().
         */
        const T& operator*() const;
 
        /**
         * Explicitly releases the wrapped object.
         */
        void release();
 
        /**
         * Move operator.
         * @param scopedObject The scoped object to be moved
         * @return Reference to this object
         */
        ScopedObjectT<T, TReleaseValue, TReleaseFunction>& operator=(ScopedObjectT<T, TReleaseValue, TReleaseFunction>&& scopedObject) noexcept;
 
#ifdef OCEAN_ENABLE_CAST_OPERATOR_FOR_SCOPED_OBJECT
 
        /**
         * Returns the wrapped object.
         * @return The wrapped object
         */
        operator const T&() const;
 
#endif // OCEAN_ENABLE_CAST_OPERATOR_FOR_SCOPED_OBJECT
 
    protected:
 
        /**
         * Disabled copy constructor.
         */
        ScopedObjectT(const ScopedObjectT<T, TReleaseValue, TReleaseFunction>&) = delete;
 
        /**
         * Disabled assign operator.
         * @return Reference to this object
         */
        ScopedObjectT<T, TReleaseValue, TReleaseFunction>& operator=(const ScopedObjectT<T, TReleaseValue, TReleaseFunction>&) = delete;
 
    protected:
 
        /// The wrapped reference.
        T object_ = T();
 
        /// The function used to release the wrapped object.
        TReleaseFunction releaseFunction_ = TReleaseFunction();
};
 
/**
 * This class wraps an unmanaged object (or reference) which needs to be released after usage.
 * The release function needs to be defined at compile time.
 * @tparam T The data type of the wrapped object
 * @tparam TReleaseValue The optional explicit data type of the object to be released
 * @tparam TReleaseReturn The data type of the return value of the release function
 * @tparam tReleaseFunction The data type of the release function
 * @tparam tExpectedReturnValue The expected return value of the release function
 * @tparam tCheckReturnValue True, to check the return value when calling the release function; False, to ignore the return value
 * @tparam tInvalidValue The value of an invalid object
 * @see ScopedObjectT.
 * @ingroup base
 */
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue = NotVoidTyper<TReleaseReturn>::defaultValue(), bool tCheckReturnValue = true, T tInvalidValue = T()>
class ScopedObjectCompileTimeT
{
    public:
 
        /**
         * Default constructor creating an object with invalid object.
         */
        ScopedObjectCompileTimeT() = default;
 
        /**
         * Move constructor.
         * @param scopedObject The scoped object to be moved
         */
        ScopedObjectCompileTimeT(ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>&& scopedObject) noexcept;
 
        /**
         * Creates a new scoped object.
         * If 'object == tInvalidValue' the object will not be released once this scoped object is disposed.
         * @param object The object to be wrapped
         */
        explicit ScopedObjectCompileTimeT(T&& object) noexcept;
 
        /**
         * Creates a new scoped object.
         * @param object The object to be wrapped
         * @param needsRelease True, if the given object needs to be released once the scoped object is disposed; False, if the given object does not need to be released
         */
        ScopedObjectCompileTimeT(T&& object, const bool needsRelease) noexcept;
 
        /**
         * Creates a new scoped object.
         * If 'object == tInvalidValue' the object will not be released once this scoped object is disposed.
         * @param object The object to be wrapped
         */
        explicit ScopedObjectCompileTimeT(const T& object);
 
        /**
         * Creates a new scoped object.
         * @param object The object to be wrapped
         * @param needsRelease True, if the given object needs to be released once the scoped object is disposed; False, if the given object does not need to be released
         */
        ScopedObjectCompileTimeT(const T& object, const bool needsRelease);
 
        /**
         * Destructs this scoped object and releases the internal wrapped object.
         */
        ~ScopedObjectCompileTimeT();
 
        /**
         * Returns whether this scoped object holds a valid object.
         * @return True, if so
         */
        bool isValid() const;
 
        /**
         * Returns the wrapped object.
         * @return The wrapped object
         */
        const T& object() const;
 
        /**
         * Returns the wrapped object.
         * Ensure that the object is valid before calling this operator.
         * @return The wrapped object
         * @see isValid().
         */
        const T& operator->() const;
 
        /**
         * De-reference operator returning the wrapped object.
         * Ensure that the object is valid before calling this operator.
         * @return The wrapped object
         * @see isValid().
         */
        const T& operator*() const;
 
        /**
         * Releases the current wrapped object and returns a new wrapped object.
         * @param needsRelease True, if the new object needs to be released once the scoped object is disposed; False, if the new object does not need to be released
         * @return The new wrapped object
         */
        T& resetObject(const bool needsRelease = true);
 
        /**
         * Explicitly releases the wrapped object.
         */
        void release();
 
        /**
         * Move operator.
         * @param scopedObject The scoped object to be moved
         * @return Reference to this object
         */
        ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>& operator=(ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>&& scopedObject) noexcept;
 
#ifdef OCEAN_ENABLE_CAST_OPERATOR_FOR_SCOPED_OBJECT
 
        /**
         * Returns the wrapped object.
         * @return The wrapped object
         */
        operator const T&() const;
 
#endif // OCEAN_ENABLE_CAST_OPERATOR_FOR_SCOPED_OBJECT
 
    protected:
 
        /**
         * Disabled copy constructor.
         */
        ScopedObjectCompileTimeT(const ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>&) = delete;
 
        /**
         * Disabled assign operator.
         * @return Reference to this object
         */
        ScopedObjectCompileTimeT& operator=(const ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>&) = delete;
 
    protected:
 
        /// The wrapped reference.
        T object_ = tInvalidValue;
 
        /// True, if the wrapped object needs to be released.
        bool needsRelease_ = false;
};
 
/**
 * Template specialization for ScopedObjectCompileTimeT with void return value.
 * @tparam T The data type of the wrapped object
 * @tparam tReleaseFunction The data type of the release function
 * @see ScopedObjectCompileTimeT.
 * @ingroup base
 */
template <typename T, void (*tReleaseFunction)(T)>
using ScopedObjectCompileTimeVoidT = ScopedObjectCompileTimeT<T, T, void, tReleaseFunction>;
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>::ScopedObjectT(ScopedObjectT<T, TReleaseValue, TReleaseFunction>&& scopedObject) noexcept
{
    *this = std::move(scopedObject);
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>::ScopedObjectT(T&& object, TReleaseFunction&& releaseFunction) noexcept :
    object_(std::move(object)),
    releaseFunction_(std::move(releaseFunction))
{
    // nothing to do here
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>::ScopedObjectT(T&& object, TReleaseFunction&& releaseFunction, const bool useReleaseFunction) noexcept :
    object_(std::move(object))
{
    if (useReleaseFunction)
    {
        releaseFunction_ = std::move(releaseFunction);
    }
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>::ScopedObjectT(const T& object, TReleaseFunction&& releaseFunction) noexcept :
    object_(object),
    releaseFunction_(std::move(releaseFunction))
{
    // nothing to do here
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>::ScopedObjectT(const T& object, TReleaseFunction&& releaseFunction, const bool useReleaseFunction) noexcept :
    object_(object)
{
    if (useReleaseFunction)
    {
        releaseFunction_ = std::move(releaseFunction);
    }
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>::~ScopedObjectT()
{
    release();
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
bool ScopedObjectT<T, TReleaseValue, TReleaseFunction>::isValid() const
{
    return bool(releaseFunction_);
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
const T& ScopedObjectT<T, TReleaseValue, TReleaseFunction>::object() const
{
    return object_;
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
const T& ScopedObjectT<T, TReleaseValue, TReleaseFunction>::operator->() const
{
    ocean_assert(isValid());
 
    return object();
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
const T& ScopedObjectT<T, TReleaseValue, TReleaseFunction>::operator*() const
{
    ocean_assert(isValid());
 
    return object();
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
void ScopedObjectT<T, TReleaseValue, TReleaseFunction>::release()
{
    if (releaseFunction_)
    {
        releaseFunction_(TReleaseValue(object_));
 
        object_ = T();
        releaseFunction_ = TReleaseFunction();
    }
}
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>& ScopedObjectT<T, TReleaseValue, TReleaseFunction>::operator=(ScopedObjectT<T, TReleaseValue, TReleaseFunction>&& scopedObject) noexcept
{
    if (this != &scopedObject)
    {
        release();
 
        object_ = std::move(scopedObject.object_);
        scopedObject.object_ = T();
 
        releaseFunction_ = std::move(scopedObject.releaseFunction_);
        scopedObject.releaseFunction_ = TReleaseFunction();
    }
 
    return *this;
}
 
#ifdef OCEAN_ENABLE_CAST_OPERATOR_FOR_SCOPED_OBJECT
 
template <typename T, typename TReleaseValue, typename TReleaseFunction>
ScopedObjectT<T, TReleaseValue, TReleaseFunction>::operator const T&() const
{
    return object_;
}
 
#endif
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::ScopedObjectCompileTimeT(ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>&& scopedObject) noexcept
{
    *this = std::move(scopedObject);
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::ScopedObjectCompileTimeT(T&& object) noexcept :
    object_(std::move(object))
{
    needsRelease_ = object_ != tInvalidValue;
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::ScopedObjectCompileTimeT(T&& object, const bool needsRelease) noexcept :
    object_(std::move(object)),
    needsRelease_(needsRelease)
{
    // nothing to do here
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::ScopedObjectCompileTimeT(const T& object) :
    object_(object)
{
    needsRelease_ = object_ != tInvalidValue;
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::ScopedObjectCompileTimeT(const T& object, const bool needsRelease) :
    object_(object),
    needsRelease_(needsRelease)
{
    // nothing to do here
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::~ScopedObjectCompileTimeT()
{
    release();
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
bool ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::isValid() const
{
    return object_ != tInvalidValue;
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
const T& ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::object() const
{
    return object_;
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
const T& ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::operator->() const
{
    ocean_assert(isValid());
 
    return object();
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
const T& ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::operator*() const
{
    ocean_assert(isValid());
 
    return object();
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
T& ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::resetObject(const bool needsRelease)
{
    release();
    object_ = tInvalidValue;
 
    needsRelease_ = needsRelease;
 
    return object_;
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
void ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::release()
{
    if (needsRelease_)
    {
        if constexpr (std::is_same<TReleaseReturn, void>::value)
        {
            tReleaseFunction(TReleaseValue(object_));
        }
        else
        {
            if constexpr (tCheckReturnValue)
            {
                const TReleaseReturn returnValue = tReleaseFunction(TReleaseValue(object_));
                ocean_assert_and_suppress_unused(returnValue == tExpectedReturnValue, returnValue);
            }
            else
            {
                const TReleaseReturn returnValue = tReleaseFunction(TReleaseValue(object_));
                OCEAN_SUPPRESS_UNUSED_WARNING(returnValue);
            }
        }
 
        object_ = tInvalidValue;
        needsRelease_ = false;
    }
}
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>& ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::operator=(ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>&& scopedObject) noexcept
{
    if (this != &scopedObject)
    {
        release();
 
        object_ = std::move(scopedObject.object_);
        scopedObject.object_ = tInvalidValue;
 
        needsRelease_ = scopedObject.needsRelease_;
        scopedObject.needsRelease_ = false;
    }
 
    return *this;
}
 
#ifdef OCEAN_ENABLE_CAST_OPERATOR_FOR_SCOPED_OBJECT
 
template <typename T, typename TReleaseValue, typename TReleaseReturn, TReleaseReturn (*tReleaseFunction)(TReleaseValue), typename NotVoidTyper<TReleaseReturn>::Type tExpectedReturnValue, bool tCheckReturnValue, T tInvalidValue>
ScopedObjectCompileTimeT<T, TReleaseValue, TReleaseReturn, tReleaseFunction, tExpectedReturnValue, tCheckReturnValue, tInvalidValue>::operator const T&() const
{
    return object_;
}
 
#endif
 
}
 
#endif // META_OCEAN_BASE_SCOPED_OBJECT_H