exprproxy.h

精确的函数表达模板,里面包含了许多C和C++的函数表达模板

/****************************************************************************
 * Copyright (C) 2001        Piece Wise Functions
 *                           Carlo Galotto
 *                           Italy
 *                           Email: [e-mail]
 *                                  [e-mail]
 *
 *
 * This framework is free  software; you can  redistribute it and/or modify
 * it. This framework 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.
 * The proposed framework is based upon the paper "Expression Templates" by
 * Todd Veldhuizen.
 ****************************************************************************/

// Class: ExprProxy

#ifndef __EXPRPRXY_H             //Required for current class
  #define __EXPRPRXY_H

#ifndef __EXPRINTR_H           //Required for base classes
  #include "ExprInterface.h"
#endif

   // Expression Proxy (PROXY pattern)
   template <class argT, class resT>
   class ExprProxy : public ExprInterface< argT, resT >
   {
      public:
         typedef typename argT argument_type;
         typedef typename resT result_type;

      private:
         ExprInterface<argT, resT>* expr;

      public:
         // Conversion and Default constructor
         ExprProxy(ExprInterface<argT, resT>* e = 0) : expr(e) { }

         // Copy constructor
         ExprProxy(const ExprProxy& aProxy) : expr(aProxy.expr->clone())
         {
            ;
         }

         // Destructor
         virtual ~ExprProxy() { delete expr; }

         // Assignement operator
         void operator = (const ExprProxy& aProxy) {
            if(this != &aProxy) {
               if(expr != 0) {
                  expr = 0;
                  delete expr;
               }
               if(aProxy.expr != 0) expr = aProxy.expr->clone();
            }
         }

         // Evaluator
         result_type operator() (const argument_type& x) const
         { return expr ? (*expr)(x) : result_type(); }

         // Clone
         ExprInterface<argT, resT>* clone() const { return new ExprProxy(*this); }
   };
#endif