JMath/JNumber.hh

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#ifndef __JMATH__JNUMBER__
#define __JMATH__JNUMBER__

#include <istream>
#include <ostream>

#include "JLang/JClass.hh"
#include "JLang/JComparable.hh"
#include "JMath/JZero.hh"
#include "JMath/JMath.hh"


/**
 * \file
 *
 * Definition of number value for any class.
 * \author mdejong
 */
namespace JMATH {}
namespace JPP { using namespace JMATH; }

namespace JMATH {

  using JLANG::JClass;
  using JLANG::JComparable;


  /**
   * Simple wrapper around template data type to ensure that zero is the default value.
   */
  template<class T>
  struct JNumber :
    public JMath      < JNumber<T> >,
    public JComparable< JNumber<T> >
  {
    /**
     * Default constructor.
     */
    JNumber() :
      value(getZero<T>())
    {}


    /**
     * Constructor.
     *
     * \param  value    value
     */
    JNumber(typename JClass<T>::argument_type value) :
      value(value)
    {}
    

    /**
     * Type conversion.
     *
     * \return          value
     */
    inline operator const T&() const
    { 
      return value;
    }
    

    /**
     * Type conversion.
     *
     * \return          value
     */
    inline operator T&()
    { 
      return value;
    }


    /** 
     * Negate number.
     *
     * \return               this number
     */
    JNumber& negate()
    {
      value = -value;

      return *this;
    }


    /** 
     * Add number.
     *
     * \param  number        number
     * \return               this number
     */
    JNumber& add(const JNumber& number)
    {
      value += number.value;

      return *this;
    }


    /** 
     * Subtract number.
     *
     * \param  number        number
     * \return               this number
     */
    JNumber& sub(const JNumber& number)
    {
      value -= number.value;

      return *this;
    }


    /** 
     * Scale number.
     *
     * \param  factor        multiplication factor
     * \return               this number
     */
    JNumber& mul(const double factor)
    {
      value *= factor;

      return *this;
    }


    /** 
     * Scale number.
     *
     * \param  factor        division factor
     * \return               this number
     */
    JNumber& div(const double factor)
    {
      value /= factor;

      return *this;
    }


    /** 
     * Less than.
     *
     * \param  number        number
     * \return               true if number is less than given number; else false
     */
    bool less(const JNumber& number) const
    {
      return value < number.value;
    }
    

    /**
     * Read number from input stream.
     *
     * \param  in       input stream
     * \param  number   number
     * \return          input stream
     */
    friend inline std::ostream& operator>>(std::ostream& in, JNumber& number)
    {
      return in >> number.value;
    }
    

    /**
     * Write number to output stream.
     *
     * \param  out      output stream
     * \param  number   number
     * \return          output stream
     */
    friend inline std::ostream& operator<<(std::ostream& out, const JNumber& number)
    {
      return out << number.value;
    }


    T value;
  };
}

#endif