Class AvgVectorState

src/modules/linalg/average.cpp:31–95

 */
template <class Handle>
class AvgVectorState {
    template <class OtherHandle>
    friend class AvgVectorState;

public:
    AvgVectorState(const AnyType &inArray)
        : mStorage(inArray.getAs<Handle>()) {

        rebind(static_cast<uint32_t>(mStorage[1]));
    }

    inline operator AnyType() const {
        return mStorage;
    }

    inline void initialize(const Allocator &inAllocator,
        uint32_t inNumDimensions) {

        mStorage = inAllocator.allocateArray<double, dbal::AggregateContext,
            dbal::DoZero, dbal::ThrowBadAlloc>(arraySize(inNumDimensions));
        rebind(inNumDimensions);
        numDimensions = inNumDimensions;
    }

    template <class OtherHandle>
    AvgVectorState &operator+=(
        const AvgVectorState<OtherHandle> &inOtherState) {

        numRows += inOtherState.numRows;
        sumOfVectors += inOtherState.sumOfVectors;
        return *this;
    }

private:
    static inline size_t arraySize(uint32_t inNumDimensions) {
        return static_cast<size_t>(2 + inNumDimensions);
    }

    /**
     * @brief Rebind to a new storage array
     *
     * @param inNumDimensions The number of dimensions
     *
     * Array layout (iteration refers to one aggregate-function call):
     * Inter-iteration components (updated in final function):
     * - 0: numRows (number of rows already processed in this iteration)
     * - 1: numDimensions (dimension of space that points are from)
     * - 2: sumOfPoints (vector with \c numDimensions rows)
     */
    void rebind(uint32_t inNumDimensions) {
        numRows.rebind(&mStorage[0]);
        numDimensions.rebind(&mStorage[1]);
        sumOfVectors.rebind(&mStorage[2], inNumDimensions);
        madlib_assert(mStorage.size() >= arraySize(inNumDimensions),
            std::runtime_error("Out-of-bounds array access detected."));
    }

    Handle mStorage;