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shared_ptr doc

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This commit is contained in:
Baptiste Wicht 2016-09-30 21:36:02 +02:00
parent 2a477e3217
commit 6a897bb3ee
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1 changed files with 48 additions and 2 deletions
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50
tstl/include/shared_ptr.hpp
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@ -27,26 +27,48 @@ struct shared_ptr {
struct control_block_t;
/*!
* \brief Construct an empty shared_ptr
*/
constexpr shared_ptr() : ptr(), control_block() {}
/*!
* \brief Construct an empty shared_ptr
*/
constexpr explicit shared_ptr(decltype(nullptr)) : ptr(), control_block() {}
/*!
* \brief Construct a new shared_ptr around the given pointer.
*
* The pointer will be deleted using the 'delete-expression'
*/
template<typename U>
explicit shared_ptr(U* ptr) : ptr(ptr) {
control_block = new control_block_impl<U, default_delete<U>>(ptr);
control_block->counter = 1;
}
/*!
* \brief Construct a new shared_ptr around the given pointer.
*
* The pointer will be deleted using 'deleter(ptr)'
*/
template<typename U, typename Deleter>
shared_ptr(U* ptr, Deleter deleter) : ptr(ptr) {
control_block = new control_block_impl<U, Deleter>(ptr, deleter);
control_block->counter = 1;
}
/*!
* \brief Construct a new shared_ptr directly with a control block
*/
shared_ptr(T* ptr, control_block_t* control_block, int) : ptr(ptr), control_block(control_block) {
control_block->counter = 1;
}
/*!
* \brief Copy construct a shared_ptr, effectively incrementing the reference counter
*/
shared_ptr(const shared_ptr& rhs) : ptr(rhs.ptr), control_block(rhs.control_block) {
__sync_fetch_and_add(&control_block->counter, 1);
}
@ -62,6 +84,11 @@ struct shared_ptr {
return *this;
}
/*!
* \brief Move construct a shared_ptr.
*
* This does not change the reference counter since the shared pointer moved from does not point to the object anymore
*/
shared_ptr(shared_ptr&& rhs) : ptr(rhs.ptr), control_block(rhs.control_block) {
rhs.ptr = nullptr;
rhs.control_block = nullptr;
@ -79,6 +106,10 @@ struct shared_ptr {
return *this;
}
/*!
* \brief Destroy the shared_ptr. This effectively decrement the counter. If the counter reaches 0,
* the object is deleted.
*/
~shared_ptr(){
if(__sync_fetch_and_sub(&control_block->counter, 1) == 1){
control_block->destroy();
@ -86,14 +117,23 @@ struct shared_ptr {
}
}
/*!
* \brief Returns the managed pointer
*/
pointer_type get() const {
return ptr;
}
/*!
* \brief Returns the managed pointer
*/
pointer_type operator->() const {
return get();
}
/*!
* \brief Returns a reference to the managed object
*/
reference_type operator*() const {
return *get();
}
@ -140,10 +180,16 @@ struct shared_ptr {
};
private:
pointer_type ptr;
control_block_t* control_block;
pointer_type ptr; ///< The managed pointer
control_block_t* control_block; ///< Pointer to the control block
};
/*!
* \brief Creates a new shared_ptr.
*
* This is effectively more efficient than shared_ptr<T>(new T) since it allocates the object directly in the control
* block, saving one allocation.
*/
template <typename T, typename... Args>
std::shared_ptr<T> make_shared(Args&&... args){
auto cb = new typename std::shared_ptr<T>::template inplace_control_block_impl<T>(std::forward<Args>(args)...);