ref_ptr.h

#pragma once
 
#include "ref_counted.h"
 
#include <cgv/defines/assert.h>
#include <cgv/type/cond/is_base_of.h>
#include <cgv/type/cond/has_virtual_destructor.h>
#include <assert.h>
 
#include "lib_begin.h"
 
namespace cgv {
    namespace data {
 
// extern CGV_API bool validate_delete(const void* ptr);
 
template <class T, bool is_ref_counted>
class ref_ptr;
 
class ref_ptr_tag
{
protected:
    void inc_ref_count(const ref_counted* ptr) const
    {
        ptr->set_ref_count(ptr->get_ref_count()+1);
    }
    bool dec_ref_count(const ref_counted* ptr) const
    {
        int count = ptr->get_ref_count();
        if (count > 0) {
            ptr->set_ref_count(count-1);
            return count == 1;
        }
        // ERROR: zero ref count decremented
        assert(0);
        return false;
    }
};
 
template <typename T, bool is_ref_counted = false>
class ref_ptr_impl
{
protected:
    friend class ref_ptr_impl<const T, is_ref_counted>;
    struct counter_type 
    {
        counter_type(T* p, int c) : ptr(p), count(c) {}
        T*  ptr;
        int count;
    };
    mutable counter_type* counter;
    void release()
    {
        if (counter) {
            if (--counter->count == 0) {
                delete counter->ptr;
                counter->ptr = 0;
                delete counter;
            }
            counter = 0;
        }
    }
    T*  ref () const        { return counter ? counter->ptr : 0; }
    explicit ref_ptr_impl(T* p = 0) : counter(0) {
        if (p) 
            counter = new counter_type(p, 1);
    }
    ref_ptr_impl(const ref_ptr_impl<T,false>& r) : counter(r.counter)
    {
        if (counter)
            ++counter->count;
    }
    template <typename S>
    ref_ptr_impl(const ref_ptr_impl<S,false>& s)
    {
        // ref_ptr conversion only valid if T is base of S
        CGV_DEFINES_ASSERT(type::cond::is_base_of<T,S>::value);
        // and T has a virtual destructor
        CGV_DEFINES_ASSERT(type::cond::has_virtual_destructor<T>::value);
        // after validity checks, set pointer 
        counter = reinterpret_cast<counter_type*>(s.counter);
        // and increment reference count
        if (counter)
            ++counter->count;
    }
public:
    int get_count() const  { return counter ? counter->count : 0; }
};
 
template <typename T>
class ref_ptr_impl<T,true> : public ref_ptr_tag
{
    T* ptr;
protected:
    void release() {
        if (ptr) { 
            if (dec_ref_count(ptr)) {
//              if (validate_delete(ptr))
                    delete ptr;
            }
            ptr = 0; 
        }
    }
    T*  ref () const         { 
        return ptr; 
    }
    explicit ref_ptr_impl(T* p) : ptr(p) {
        if (ptr)
            inc_ref_count(ptr);
    }
    ref_ptr_impl(const ref_ptr_impl<T,true>& r) : ptr(r.ref())
    {
        if (ptr)
            inc_ref_count(ptr);
    }
    template <typename S>
    ref_ptr_impl(const ref_ptr_impl<S,true>& s)
    {
        // ref_ptr conversion only valid if T is base of S
        CGV_DEFINES_ASSERT(type::cond::is_base_of<T,S>::value);
        // and T has a virtual destructor
        CGV_DEFINES_ASSERT(type::cond::has_virtual_destructor<T>::value);
        // after validity checks, set pointer with a very bad hack!!
        ptr = static_cast<const ref_ptr<S,true>&>(s).operator->();
        // and increment reference count
        if (ptr)
            inc_ref_count(ptr);
    }
public:
    // void kill() { ptr = 0; }
    int get_count() const   { 
        return ptr ? ptr->get_ref_count() : 0; 
    }
};
 
template <class T, bool is_ref_counted = type::cond::is_base_of<ref_counted,T>::value>
class ref_ptr : public ref_ptr_impl<T,is_ref_counted>
{
public:
    typedef ref_ptr<T,is_ref_counted> this_type;
    typedef ref_ptr_impl<T,is_ref_counted> base_type;
public:
    ref_ptr(T* p = 0) : base_type(p) {}
    ref_ptr(const this_type& r) : base_type(r) {}
   ~ref_ptr() { 
        this->release();
    }
    template <typename S>
    ref_ptr(const ref_ptr<S,is_ref_counted>& s) : base_type(s) {}
    template <typename S>
    ref_ptr<S,is_ref_counted> down_cast() const {
        // ref_ptr conversion only valid if T is base of S
        CGV_DEFINES_ASSERT(type::cond::is_base_of<T,S>::value);
        // and S has a virtual destructor
        CGV_DEFINES_ASSERT(type::cond::has_virtual_destructor<T>::value);
        // after validity checks, return converted pointer
        return ref_ptr<S,is_ref_counted>(
                    *reinterpret_cast<const ref_ptr<S,is_ref_counted>*>(this)
                 );
    }
    this_type& operator = (const this_type& r) {
        if (this == &r)
            return *this;
        this->release();
        new (this) this_type(r);
        return *this;
    }
    template <typename S>
    this_type& operator = (const ref_ptr<S,is_ref_counted>& r) {
        if (this == (const this_type*)&r)
            return *this;
        return *this = this_type(r);
    }
    T& operator*() const { 
        return *this->ref();
    }
   T* operator->() const {
        return this->ref();
    }
    bool operator == (const this_type& r) const { 
        return this->ref() == r.ref(); 
    }
    bool operator < (const this_type& r) const { 
        return this->ref() < r.ref(); 
    }
    bool operator != (const this_type& r) const { 
        return this->ref() != r.ref(); 
    }
    bool unique() const {
        return this->get_count() <= 1; 
    }
    bool empty() const { 
        return this->get_count() == 0; 
    }
    operator bool () const {
        return !empty();
    }
    void clear() { 
        this->release();
    }
};
 
    }
}
 
#include <cgv/config/lib_end.h>