subtotal.hxx

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#ifndef INCLUDED_SC_INC_SUBTOTAL_HXX
#define INCLUDED_SC_INC_SUBTOTAL_HXX

#include "global.hxx"

class SubTotal
{
public:
    static bool SafePlus( double& fVal1, double fVal2);
    static bool SafeMult( double& fVal1, double fVal2);
    static bool SafeDiv( double& fVal1, double fVal2);
};

class ScFunctionData;

class WelfordRunner
{
public:
    WelfordRunner() : mfMean(0.0), mfM2(0.0), mnCount(0) {}
    void        update( double fVal );
    sal_uInt64  getCount() const                { return mnCount; }
    double      getVarianceSample() const       { return mnCount > 1 ? mfM2 / (mnCount-1) : 0.0; }
    double      getVariancePopulation() const   { return mnCount > 0 ? mfM2 / mnCount : 0.0; }

    // The private variables can be abused by ScFunctionData as general
    // sum/min/max/ave/count/... variables to reduce memory footprint for that
    // ScFunctionData may be a mass object during consolidation.
    // ScFunctionData::update() and getResult() take care that purposes are not
    // mixed.
    friend class ScFunctionData;
private:
    double      mfMean;
    double      mfM2;
    sal_uInt64  mnCount;
};

class ScFunctionData
{
public:
    ScFunctionData() : meFunc(SUBTOTAL_FUNC_NONE), mbError(false) {}
    ScFunctionData( ScSubTotalFunc eFn ) : meFunc(eFn), mbError(false) {}

    void            update( double fNewVal );
    double          getResult();
    bool            getError() const    { return mbError; }
    ScSubTotalFunc  getFunc() const     { return meFunc; }
    void            setError()          { mbError = true; }

private:
    WelfordRunner   maWelford;
    ScSubTotalFunc  meFunc;
    bool            mbError;

    double&         getValueRef()   { return maWelford.mfMean; }
    sal_uInt64&     getCountRef()   { return maWelford.mnCount; }
};

#endif

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