examples_from_lect3: shared_ptr.cpp

#include "shared_ptr.h"

// Storage class definitions

Storage::Storage(GaussNumber *p_obj) {
        this->p_obj = p_obj;
        count = 1;
}

Storage::~Storage() {
        if (p_obj != NULL)
                delete p_obj;
}

void Storage::increaseCount() {
        count++;
}

void Storage::decreaseCount() {
        count--;

        if (count == 0)
                delete this;
}

GaussNumber *Storage::ptr() const {
        return p_obj;
}

bool Storage::isNull() const {
        if (p_obj == NULL)
                return true;
        else
                return false;
}

// shared_ptr class definitions

shared_ptr::shared_ptr() {
        storage = new Storage(NULL);
}

shared_ptr::shared_ptr(GaussNumber *p_obj) {
        storage = new Storage(p_obj);
}

shared_ptr::shared_ptr(const shared_ptr &sptr) {
        storage = sptr.storage;
        storage->increaseCount();
}

shared_ptr::~shared_ptr() {
        storage->decreaseCount();
}

const shared_ptr &shared_ptr::operator=(const shared_ptr &sptr) {
        sptr.storage->increaseCount();
        storage->decreaseCount();
        
        storage = sptr.storage;
        return *this;
}

GaussNumber &shared_ptr::operator*() const {
        return *storage->ptr();
}

GaussNumber *shared_ptr::operator->() const {
        return storage->ptr();
}

GaussNumber *shared_ptr::ptr() const {
        return storage->ptr();
}

bool shared_ptr::isNull() const {
        return storage->isNull();
}