CoolProp/include/CachedElement.h

/*
 * CachedElement.h
 *
 *  Created on: 21 Dec 2013
 *      Author: jowr
 */

#ifndef CACHEDELEMENT_H_
#define CACHEDELEMENT_H_

#include "CoolPropTools.h"
#include "DataStructures.h"

namespace CoolProp {

/*!
A class that contains the magic to cache a value.

Includes an "=" assignment operator and casting to boolean
so you can do something like::

double CoolPropStateClassSI::d3phir_dTau3(double tau, double delta){
    if (cache.d3phir_dTau3)    {
        return cache.d3phir_dTau3;
    } else {
        cache.d3phir_dTau3 = pFluid->d3phir_dTau3(tau,delta);
        return cache.d3phir_dTau3;
    }
};
*/

class CachedElement {

private:
    bool is_cached;
    long double value;
public:
    /// Default constructor
    CachedElement() {
        this->clear();
    };

    /// Function to carry out the caching
    void _do_cache(double value)
    {
        this->value = value;
        this->is_cached = true;
    }

    /// Assignment operator - sets the value and sets the flag
    void operator=(const double& value) {
        _do_cache(value);
    };

    /// Cast to boolean, for checking if cached
    operator bool() {return is_cached;};

    /// Cast to double, for returning value
    operator double() {
        if (is_cached) {return static_cast<double>(value); }
        else {
            throw std::exception();
        }
    }
    operator long double() {
        if (is_cached) {return value; }
        else {
            throw std::exception();
        }
    }
    /// Clear the flag and the value
    void clear() {
        is_cached = false;
        this->value = _HUGE;
    };
    long double &pt(){
        return this->value;
    }
};

} /* namespace CoolProp */
#endif /* CACHEDELEMENT_H_ */