🚀 go-pugleaf

In Santa Cruz we decided to change the auto_ptr copy semantics to
allow returns of auto_ptr from functions.  Following is a simple
implementation.  It (almost) compiles with the latest Edison Design
Group front end (the template friend declaration choked it).  Note
that on most architectures the owner bit can be overlayed with the
pointer for a smaller footprint, but the following is portable.

template<class X>
   class auto_ptr {
      mutable bool owner;
      X* px;
      template<class Y> friend class auto_ptr;
   public:
      explicit auto_ptr(X* p=0) 
         : owner(p), px(p) {}
      template<class Y>
         auto_ptr(const auto_ptr<Y>& r) 
            : owner(r.owner), px(r.release()) {}
      template<class Y>
         auto_ptr& operator=(const auto_ptr<Y>& r) {
            if ((void*)&r != (void*)this) {
               if (owner) 
                  delete px;
               owner = r.owner; 
               px = r.release();
            }
            return *this;
         }
      ~auto_ptr()           { if (owner) delete px; }
      X& operator*()  const { return *px; }
      X* operator->() const { return px; }
      X* get()        const { return px; }
      X* release()    const { owner = 0; return px; }
   };

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