constant.h

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// -*- C++ -*-

#if !defined(__ads_Constant_h__)
#define __ads_Constant_h__

#include "../defs.h"

#include <functional>

BEGIN_NAMESPACE_ADS

//-----------------------------------------------------------------------------
// @{

template<typename _Result>
class GeneratorConstant {
  //
  // Public types.
  //
public:

  typedef _Result result_type;

  //
  // Member data.
  //
private:

  result_type _value;

  //--------------------------------------------------------------------------

public:

  GeneratorConstant() :
    _value()
  {}

  GeneratorConstant(const result_type& x) :
    _value(x)
  {}

  //--------------------------------------------------------------------------

public:

  void
  set(const result_type& x) {
    _value = x;
  }

  //--------------------------------------------------------------------------

public:

  const result_type&
  operator()() const {
    return _value;
  }

};


template<>
class GeneratorConstant<void> {
  //
  // Public types.
  //
public:

  typedef void result_type;

  //--------------------------------------------------------------------------

public:

  void
  set() {
  }

  //--------------------------------------------------------------------------

public:

  void
  operator()() const {
  }

};



template<typename _Result>
inline
GeneratorConstant<_Result>
constructGeneratorConstant(const _Result& x) {
  return GeneratorConstant<_Result>(x);
}



template<typename _Result>
inline
GeneratorConstant<_Result>
constructGeneratorConstant() {
  return GeneratorConstant<_Result>();
}







template<typename _Argument, typename _Result>
class UnaryConstant : 
  public std::unary_function<_Argument,_Result> {
  //
  // Private types.
  //
private:

  typedef std::unary_function<_Argument,_Result> Base;

  //
  // Public types.
  //
public:

  typedef typename Base::argument_type argument_type;
  typedef typename Base::result_type result_type;

  //
  // Member data.
  //
private:

  result_type _value;

  //--------------------------------------------------------------------------

public:

  UnaryConstant() :
    _value()
  {}

  UnaryConstant(const result_type& x) :
    _value(x)
  {}

  //--------------------------------------------------------------------------

public:

  void
  set(const result_type& x) {
    _value = x;
  }

  //--------------------------------------------------------------------------

public:

  const result_type&
  operator()(const argument_type& x) const {
    return _value;
  }

};



template<typename _Argument, typename _Result>
inline
UnaryConstant<_Argument, _Result>
constructUnaryConstant(const _Result& x) {
  return UnaryConstant<_Argument, _Result>(x);
}


template<typename _Argument, typename _Result>
inline
UnaryConstant<_Argument, _Result>
constructUnaryConstant() {
  return UnaryConstant<_Argument, _Result>();
}







template<typename _FirstArgument, typename _SecondArgument, typename _Result>
class BinaryConstant : 
  public std::binary_function<_FirstArgument,_SecondArgument,_Result> {
  //
  // Private types.
  //
private:

  typedef std::binary_function<_FirstArgument,_SecondArgument,_Result> Base;

  //
  // Public types.
  //
public:

  typedef typename Base::first_argument_type first_argument_type;
  typedef typename Base::second_argument_type second_argument_type;
  typedef typename Base::result_type result_type;

  //
  // Member data.
  //
private:

  result_type _value;

  //--------------------------------------------------------------------------

public:

  BinaryConstant() :
    _value()
  {}

  BinaryConstant(const result_type& x) :
    _value(x)
  {}

  //--------------------------------------------------------------------------

public:

  void
  set(const result_type& x) {
    _value = x;
  }

  //--------------------------------------------------------------------------

public:

  const result_type&
  operator()(const first_argument_type& x, 
             const second_argument_type& y) const {
    return _value;
  }

};



template<typename _FirstArgument, typename _SecondArgument, typename _Result>
inline
BinaryConstant<_FirstArgument, _SecondArgument, _Result>
constructBinaryConstant(const _Result& x) {
  return BinaryConstant<_FirstArgument, _SecondArgument, _Result>(x);
}



template<typename _FirstArgument, typename _SecondArgument, typename _Result>
inline
BinaryConstant<_FirstArgument, _SecondArgument, _Result>
constructBinaryConstant() {
  return BinaryConstant<_FirstArgument, _SecondArgument, _Result>();
}

// @}

END_NAMESPACE_ADS

#endif

---