StatInstCalculator.hpp

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// <StatInstCalculator> -*- C++ -*-
 
#pragma once
 
#include "sparta/kernel/SpartaHandler.hpp"
#include "sparta/utils/SpartaAssert.hpp"
 
namespace sparta {
 
class TreeNode;
 
/*
 * \brief This class is a wrapper around user-implemented
 * code (SpartaHandler's) that calculate the value of a SPARTA
 * statistic on demand. There are cases where expressing
 * a statistic equation in a single std::string is not
 * very easy to do - if it were easily written out in
 * a single string, you could use StatisticDef's to get
 * the statistic values in reports as usual.
 *
 * StatisticInstance's have a constructor overload which
 * takes one of these StatInstCalculator objects, and
 * when the reporting infrastructure calls 'SI::getValue()'
 * it will invoke the user's SpartaHandler to retrieve the
 * value.
 */
class StatInstCalculator {
public:
    StatInstCalculator(const SpartaHandler & handler,
                       const double & aggregated_value) :
        handler_(handler),
        aggregated_value_(aggregated_value)
    {}
 
    double getCurrentValue() const {
        handler_();
        return aggregated_value_;
    }
 
    void setNode(const TreeNode * node) {
        sparta_assert(node_ == nullptr || node_ == node);
        sparta_assert(node != nullptr);
        node_ = node;
    }
 
    const TreeNode * getNode() const {
        return node_;
    }
 
private:
    SpartaHandler handler_;
    const double & aggregated_value_;
    const TreeNode * node_ = nullptr;
};
 
}