SharedPtr.h

/*
 *  SharedPtr class
 *
 *  This file is part of OTAWA
 *  Copyright (c) 2016, IRIT UPS.
 *
 *  OTAWA is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  OTAWA is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with OTAWA; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#ifndef ELM_UTIL_SHAREDPTR_H_
#define ELM_UTIL_SHAREDPTR_H_
 
#include <elm/io.h>
#include <elm/types.h>
 
namespace elm {
 
template <class T>
class SharedPtr {
    typedef struct cell_t {
        inline cell_t(T *p): cnt(1), ptr(p) { }
        t::uint32 cnt;
        T *ptr;
    } cell_t;
 
public:
    inline SharedPtr(void): c(&null) { lock(); }
    inline SharedPtr(T *p): c(new cell_t(p)) { }
    inline SharedPtr(const SharedPtr<T>& p): c(p.c) { lock(); }
    inline ~SharedPtr(void) { unlock(); }
    inline bool isEmpty(void) const { return c->ptr; }
    inline T *ptr(void) const { return c->ptr; }
    inline T& ref(void) const { return *(c->ptr); }
 
    inline operator bool(void) const { return isEmpty(); }
    inline operator T *(void) const { return ptr(); }
    inline T *operator->(void) const { return ptr(); }
    inline T& operator*(void) const { return ref(); }
    inline T *operator&(void) const { return ptr(); }
    inline SharedPtr<T>& operator=(const SharedPtr<T>& p) { unlock(); c = p.c; lock(); return *this; }
    inline SharedPtr<T>& operator=(T *p) { unlock(); c = new cell_t(p); return *this; }
 
    inline bool operator==(const SharedPtr<T>& p) const { return c->ptr == p.c->ptr; }
    inline bool operator!=(const SharedPtr<T>& p) const { return c->ptr != p.c->ptr; }
    inline bool operator==(T *p) const { return c->ptr == p; }
    inline bool operator!=(T *p) const { return c->ptr != p; }
 
private:
    inline void lock(void) { c->cnt++; }
    inline void unlock(void) { c->cnt--; if(c->cnt == 0) clear(); }
    void clear(void) { if(c->ptr) delete c->ptr; delete c; }
 
    cell_t *c;
    static cell_t null;
};
 
template <class T> typename SharedPtr<T>::cell_t SharedPtr<T>::null(0);
 
}   // elm
 
#endif /* ELM_UTIL_SHAREDPTR_H_ */