godot/core/dvector.h

/*************************************************************************/
/*  dvector.h                                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
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#ifndef DVECTOR_H
#define DVECTOR_H

#include "os/memory.h"

/**
	@author Juan Linietsky <reduzio@gmail.com>
*/

extern Mutex *dvector_lock;

template <class T>
class DVector {

	mutable MID mem;

	void copy_on_write() {

		if (!mem.is_valid())
			return;

		if (dvector_lock)
			dvector_lock->lock();

		MID_Lock lock(mem);

		if (*(int *)lock.data() == 1) {
			// one reference, means no refcount changes
			if (dvector_lock)
				dvector_lock->unlock();
			return;
		}

		MID new_mem = dynalloc(mem.get_size());

		if (!new_mem.is_valid()) {

			if (dvector_lock)
				dvector_lock->unlock();
			ERR_FAIL_COND(new_mem.is_valid()); // out of memory
		}

		MID_Lock dst_lock(new_mem);

		int *rc = (int *)dst_lock.data();

		*rc = 1;

		T *dst = (T *)(rc + 1);

		T *src = (T *)((int *)lock.data() + 1);

		int count = (mem.get_size() - sizeof(int)) / sizeof(T);

		for (int i = 0; i < count; i++) {

			memnew_placement(&dst[i], T(src[i]));
		}

		(*(int *)lock.data())--;

		// unlock all
		dst_lock = MID_Lock();
		lock = MID_Lock();

		mem = new_mem;

		if (dvector_lock)
			dvector_lock->unlock();
	}

	void reference(const DVector &p_dvector) {

		unreference();

		if (dvector_lock)
			dvector_lock->lock();

		if (!p_dvector.mem.is_valid()) {

			if (dvector_lock)
				dvector_lock->unlock();
			return;
		}

		MID_Lock lock(p_dvector.mem);

		int *rc = (int *)lock.data();
		(*rc)++;

		lock = MID_Lock();
		mem = p_dvector.mem;

		if (dvector_lock)
			dvector_lock->unlock();
	}

	void unreference() {

		if (dvector_lock)
			dvector_lock->lock();

		if (!mem.is_valid()) {

			if (dvector_lock)
				dvector_lock->unlock();
			return;
		}

		MID_Lock lock(mem);

		int *rc = (int *)lock.data();
		(*rc)--;

		if (*rc == 0) {
			// no one else using it, destruct

			T *t = (T *)(rc + 1);
			int count = (mem.get_size() - sizeof(int)) / sizeof(T);

			for (int i = 0; i < count; i++) {

				t[i].~T();
			}
		}

		lock = MID_Lock();

		mem = MID();

		if (dvector_lock)
			dvector_lock->unlock();
	}

public:
	class Read {
		friend class DVector;
		MID_Lock lock;
		const T *mem;

	public:
		_FORCE_INLINE_ const T &operator[](int p_index) const { return mem[p_index]; }
		_FORCE_INLINE_ const T *ptr() const { return mem; }

		Read() { mem = NULL; }
	};

	class Write {
		friend class DVector;
		MID_Lock lock;
		T *mem;

	public:
		_FORCE_INLINE_ T &operator[](int p_index) { return mem[p_index]; }
		_FORCE_INLINE_ T *ptr() { return mem; }

		Write() { mem = NULL; }
	};

	Read read() const {

		Read r;
		if (mem.is_valid()) {
			r.lock = MID_Lock(mem);
			r.mem = (const T *)((int *)r.lock.data() + 1);
		}
		return r;
	}
	Write write() {

		Write w;
		if (mem.is_valid()) {
			copy_on_write();
			w.lock = MID_Lock(mem);
			w.mem = (T *)((int *)w.lock.data() + 1);
		}
		return w;
	}

	template <class MC>
	void fill_with(const MC &p_mc) {

		int c = p_mc.size();
		resize(c);
		Write w = write();
		int idx = 0;
		for (const typename MC::Element *E = p_mc.front(); E; E = E->next()) {

			w[idx++] = E->get();
		}
	}

	void remove(int p_index) {

		int s = size();
		ERR_FAIL_INDEX(p_index, s);
		Write w = write();
		for (int i = p_index; i < s - 1; i++) {

			w[i] = w[i + 1];
		};
		w = Write();
		resize(s - 1);
	}

	inline int size() const;
	T get(int p_index) const;
	void set(int p_index, const T &p_val);
	void push_back(const T &p_val);
	void append(const T &p_val) { push_back(p_val); }
	void append_array(const DVector<T> &p_arr) {
		int ds = p_arr.size();
		if (ds == 0)
			return;
		int bs = size();
		resize(bs + ds);
		Write w = write();
		Read r = p_arr.read();
		for (int i = 0; i < ds; i++)
			w[bs + i] = r[i];
	}

	Error insert(int p_pos, const T &p_val) {

		int s = size();
		ERR_FAIL_INDEX_V(p_pos, s + 1, ERR_INVALID_PARAMETER);
		resize(s + 1);
		{
			Write w = write();
			for (int i = s; i > p_pos; i--)
				w[i] = w[i - 1];
			w[p_pos] = p_val;
		}

		return OK;
	}

	bool is_locked() const { return mem.is_locked(); }

	inline const T operator[](int p_index) const;

	Error resize(int p_size);

	void invert();

	void operator=(const DVector &p_dvector) { reference(p_dvector); }
	DVector() {}
	DVector(const DVector &p_dvector) { reference(p_dvector); }
	~DVector() { unreference(); }
};

template <class T>
int DVector<T>::size() const {

	return mem.is_valid() ? ((mem.get_size() - sizeof(int)) / sizeof(T)) : 0;
}

template <class T>
T DVector<T>::get(int p_index) const {

	return operator[](p_index);
}

template <class T>
void DVector<T>::set(int p_index, const T &p_val) {

	if (p_index < 0 || p_index >= size()) {
		ERR_FAIL_COND(p_index < 0 || p_index >= size());
	}

	Write w = write();
	w[p_index] = p_val;
}

template <class T>
void DVector<T>::push_back(const T &p_val) {

	resize(size() + 1);
	set(size() - 1, p_val);
}

template <class T>
const T DVector<T>::operator[](int p_index) const {

	PRAY_BAD_INDEX(p_index, size(), T);

	Read r = read();
	return r[p_index];
}

template <class T>
Error DVector<T>::resize(int p_size) {

	if (dvector_lock)
		dvector_lock->lock();

	bool same = p_size == size();

	if (dvector_lock)
		dvector_lock->unlock();
	// no further locking is necesary because we are supposed to own the only copy of this (using copy on write)

	if (same)
		return OK;

	if (p_size == 0) {

		unreference();
		return OK;
	}

	copy_on_write(); // make it unique

	ERR_FAIL_COND_V(mem.is_locked(), ERR_LOCKED); // if after copy on write, memory is locked, fail.

	if (p_size > size()) {

		int oldsize = size();

		MID_Lock lock;

		if (oldsize == 0) {

			mem = dynalloc(p_size * sizeof(T) + sizeof(int));
			lock = MID_Lock(mem);
			int *rc = ((int *)lock.data());
			*rc = 1;

		} else {

			if (dynrealloc(mem, p_size * sizeof(T) + sizeof(int)) != OK) {

				ERR_FAIL_V(ERR_OUT_OF_MEMORY); // out of memory
			}

			lock = MID_Lock(mem);
		}

		T *t = (T *)((int *)lock.data() + 1);

		for (int i = oldsize; i < p_size; i++) {

			memnew_placement(&t[i], T);
		}

		lock = MID_Lock(); // clear
	} else {

		int oldsize = size();

		MID_Lock lock(mem);

		T *t = (T *)((int *)lock.data() + 1);

		for (int i = p_size; i < oldsize; i++) {

			t[i].~T();
		}

		lock = MID_Lock(); // clear

		if (dynrealloc(mem, p_size * sizeof(T) + sizeof(int)) != OK) {

			ERR_FAIL_V(ERR_OUT_OF_MEMORY); // wtf error
		}
	}

	return OK;
}

template <class T>
void DVector<T>::invert() {
	T temp;
	Write w = write();
	int s = size();
	int half_s = s / 2;

	for (int i = 0; i < half_s; i++) {
		temp = w[i];
		w[i] = w[s - i - 1];
		w[s - i - 1] = temp;
	}
}

#endif