ASTRefCount.hpp

#ifndef INC_ASTRefCount_hpp__
# define INC_ASTRefCount_hpp__
 
/* ANTLR Translator Generator
 * Project led by Terence Parr at http://www.jGuru.com
 * Software rights: http://www.antlr.org/license.html
 *
 * $Id$
 */
 
# include <antlr/config.hpp>
 
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
namespace antlr {
#endif
 
        class AST;
 
struct ANTLR_API ASTRef
{
        AST* const ptr;
        unsigned int count;
 
        ASTRef(AST* p);
        ~ASTRef();
        ASTRef* increment()
        {
                ++count;
                return this;
        }
        bool decrement()
        {
                return (--count==0);
        }
 
        static ASTRef* getRef(const AST* p);
private:
        ASTRef( const ASTRef& );
        ASTRef& operator=( const ASTRef& );
};
 
template<class T>
        class ANTLR_API ASTRefCount
{
private:
        ASTRef* ref;
 
public:
        ASTRefCount(const AST* p=0)
        : ref(p ? ASTRef::getRef(p) : 0)
        {
        }
        ASTRefCount(const ASTRefCount<T>& other)
        : ref(other.ref ? other.ref->increment() : 0)
        {
        }
        ~ASTRefCount()
        {
                if (ref && ref->decrement())
                        delete ref;
        }
        ASTRefCount<T>& operator=(AST* other)
        {
                ASTRef* tmp = ASTRef::getRef(other);
 
                if (ref && ref->decrement())
                        delete ref;
 
                ref=tmp;
 
                return *this;
        }
        ASTRefCount<T>& operator=(const ASTRefCount<T>& other)
        {
                if( other.ref != ref )
                {
                        ASTRef* tmp = other.ref ? other.ref->increment() : 0;
 
                        if (ref && ref->decrement())
                                delete ref;
 
                        ref=tmp;
                }
                return *this;
        }
 
        operator T* ()  const { return ref ? static_cast<T*>(ref->ptr) : 0; }
        T* operator->() const { return ref ? static_cast<T*>(ref->ptr) : 0; }
        T* get()        const { return ref ? static_cast<T*>(ref->ptr) : 0; }
};
 
typedef ASTRefCount<AST> RefAST;
 
#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
}
#endif
 
#endif //INC_ASTRefCount_hpp__