text: /* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
  
  /*
   Copyright (C) 2003, 2006 Ferdinando Ametrano
   Copyright (C) 2006 StatPro Italia srl
  
   This file is part of QuantLib, a free-software/open-source library
   for financial quantitative analysts and developers - http://quantlib.org/
  
   QuantLib is free software: you can redistribute it and/or modify it
   under the terms of the QuantLib license.  You should have received a
   copy of the license along with this program; if not, please email
   <quantlib-dev@lists.sf.net>. The license is also available online at
   <http://quantlib.org/license.shtml>.
  
   This program 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.  See the license for more details.
  */
  
  /*! \file payoff.hpp
      \brief Option payoff classes
  */
  
  #ifndef quantlib_payoff_hpp
  #define quantlib_payoff_hpp
  
  #include <ql/types.hpp>
  #include <ql/patterns/visitor.hpp>
  #include <ql/errors.hpp>
  #include <functional>
  
  namespace QuantLib {
  
      //! Abstract base class for option payoffs
      class Payoff : std::unary_function<Real,Real> {
        public:
          virtual ~Payoff() {}
          //! \name Payoff interface
          //@{
          /*! \warning This method is used for output and comparison between
                  payoffs. It is <b>not</b> meant to be used for writing
                  switch-on-type code.
          */
          virtual std::string name() const = 0;
          virtual std::string description() const = 0;
          virtual Real operator()(Real price) const = 0;
          //@}
          //! \name Visitability
          //@{
          virtual void accept(AcyclicVisitor&);
          //@}
      };
  
  
      // inline definitions
  
      inline void Payoff::accept(AcyclicVisitor& v) {
          Visitor<Payoff>* v1 = dynamic_cast<Visitor<Payoff>*>(&v);
          if (v1 != 0)
              v1->visit(*this);
          else
              QL_FAIL("not a payoff visitor");
      }
  
  }
  
  
  #endif
  