unaryexpr.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: UnaryExpr

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

#include <functional> // required for base classes

/****************************************************************************
 * UnaryExpr represents an unary operation on an expressions.
 * E is the expression and Op is an applicative template representing
 * the operation.
 */
   template <class E, class Op>
   class UnaryExpr : public std::unary_function < typename E::argument_type,
                                                  typename Op::result_type >

   {
      public:
         typedef typename E::argument_type argument_type;
         typedef typename Op::result_type result_type;

      private:
         E expr;

      public:
			//Default constructor
         UnaryExpr () : expr() { }

			//Constructor with arguments
         explicit UnaryExpr(const E & e) : expr(e) {;}

	      //Copy constructor
         UnaryExpr(const UnaryExpr& aUnaryExpr ) : expr(aUnaryExpr.expr) {;}

  	      //Assignment Operator
         UnaryExpr& operator= (const UnaryExpr& aUnaryExpr)
         {
            if(&aUnaryExpr != this)
               expr = aUnaryExpr.expr;
            return *this;
         }

         // Evaluator operator: Op::apply() will be invoked
         result_type operator ()(const argument_type& x) const
         { return Op::apply(expr(x)); }

         // Destructor
         ~UnaryExpr() {}
   };

#endif