godot-cpp/include/godot_cpp/core/memory.hpp

/*************************************************************************/
/*  memory.hpp                                                           */
/*************************************************************************/
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#ifndef GODOT_CPP_MEMORY_HPP
#define GODOT_CPP_MEMORY_HPP

#include <cstddef>
#include <cstdint>

#include <godot_cpp/core/defs.hpp>
#include <godot_cpp/core/error_macros.hpp>
#include <godot_cpp/godot.hpp>

#include <type_traits>

void *operator new(size_t p_size, const char *p_description); ///< operator new that takes a description and uses MemoryStaticPool
void *operator new(size_t p_size, void *p_pointer, size_t check, const char *p_description); ///< operator new that takes a description and uses a pointer to the preallocated memory

_ALWAYS_INLINE_ void *operator new(size_t p_size, void *p_pointer, size_t check, const char *p_description) {
	return p_pointer;
}

#ifdef _MSC_VER
// When compiling with VC++ 2017, the above declarations of placement new generate many irrelevant warnings (C4291).
// The purpose of the following definitions is to muffle these warnings, not to provide a usable implementation of placement delete.
void operator delete(void *p_mem, const char *p_description);
void operator delete(void *p_mem, void *(*p_allocfunc)(size_t p_size));
void operator delete(void *p_mem, void *p_pointer, size_t check, const char *p_description);
#endif

namespace godot {

class Wrapped;

class Memory {
	Memory();

public:
	static void *alloc_static(size_t p_bytes);
	static void *realloc_static(void *p_memory, size_t p_bytes);
	static void free_static(void *p_ptr);
};

_ALWAYS_INLINE_ void postinitialize_handler(void *) {}

template <class T>
_ALWAYS_INLINE_ T *_post_initialize(T *p_obj) {
	postinitialize_handler(p_obj);
	return p_obj;
}

#define memnew(m_class) _post_initialize(new ("") m_class)

#define memnew_placement(m_placement, m_class) _post_initialize(new (m_placement, sizeof(m_class), "") m_class)

template <class T>
void memdelete(T *p_class, typename std::enable_if<!std::is_base_of_v<godot::Wrapped, T>>::type * = 0) {
	if (!__has_trivial_destructor(T)) {
		p_class->~T();
	}

	Memory::free_static(p_class);
}

template <class T, std::enable_if_t<std::is_base_of_v<godot::Wrapped, T>, bool> = true>
void memdelete(T *p_class) {
	godot::internal::gdn_interface->object_destroy(p_class->_owner);
}

#define memnew_arr(m_class, m_count) memnew_arr_template<m_class>(m_count)

template <typename T>
T *memnew_arr_template(size_t p_elements, const char *p_descr = "") {
	if (p_elements == 0) {
		return nullptr;
	}
	/** overloading operator new[] cannot be done , because it may not return the real allocated address (it may pad the 'element count' before the actual array). Because of that, it must be done by hand. This is the
	same strategy used by std::vector, and the Vector class, so it should be safe.*/

	size_t len = sizeof(T) * p_elements;
	uint64_t *mem = (uint64_t *)Memory::alloc_static(len);
	T *failptr = nullptr; // Get rid of a warning.
	ERR_FAIL_COND_V(!mem, failptr);
	*(mem - 1) = p_elements;

	if (!__has_trivial_constructor(T)) {
		T *elems = (T *)mem;

		/* call operator new */
		for (size_t i = 0; i < p_elements; i++) {
			new (&elems[i], sizeof(T), p_descr) T;
		}
	}

	return (T *)mem;
}

template <typename T>
void memdelete_arr(T *p_class) {
	uint64_t *ptr = (uint64_t *)p_class;

	if (!__has_trivial_destructor(T)) {
		uint64_t elem_count = *(ptr - 1);

		for (uint64_t i = 0; i < elem_count; i++) {
			p_class[i].~T();
		}
	}

	Memory::free_static(ptr);
}

} // namespace godot

#endif // ! GODOT_CPP_MEMORY_HPP