source: trunk/yao/share/antlr-2.7.7/lib/cpp/antlr/ASTRefCount.hpp @ 1

#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: //depot/code/org.antlr/release/antlr-2.7.7/lib/cpp/antlr/ASTRefCount.hpp#2 $
 */

# 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__