Function applySingleDataTransform

src/data/helper/transform.ts:392–539

(
    transOption: DataTransformOption,
    upSourceList: Source[],
    infoForPrint: { datasetIndex: number },
    // If `pipeIndex` is null/undefined, no piped transform.
    pipeIndex: number
)

}

function applySingleDataTransform(
    transOption: DataTransformOption,
    upSourceList: Source[],
    infoForPrint: { datasetIndex: number },
    // If `pipeIndex` is null/undefined, no piped transform.
    pipeIndex: number
): Source[] {
    let errMsg = '';
    if (!upSourceList.length) {
        if (__DEV__) {
            errMsg = 'Must have at least one upstream dataset.';
        }
        throwError(errMsg);
    }
    if (!isObject(transOption)) {
        if (__DEV__) {
            errMsg = 'transform declaration must be an object rather than ' + typeof transOption + '.';
        }
        throwError(errMsg);
    }

    const transType = transOption.type;
    const externalTransform = externalTransformMap.get(transType);

    if (!externalTransform) {
        if (__DEV__) {
            errMsg = 'Can not find transform on type "' + transType + '".';
        }
        throwError(errMsg);
    }

    // Prepare source
    const extUpSourceList = map(upSourceList, upSource => createExternalSource(upSource, externalTransform));

    const resultList = normalizeToArray(
        externalTransform.transform({
            upstream: extUpSourceList[0],
            upstreamList: extUpSourceList,
            config: clone(transOption.config)
        })
    );

    if (__DEV__) {
        if (transOption.print) {
            const printStrArr = map(resultList, extSource => {
                const pipeIndexStr = pipeIndex != null ? ' === pipe index: ' + pipeIndex : '';
                return [
                    '=== dataset index: ' + infoForPrint.datasetIndex + pipeIndexStr + ' ===',
                    '- transform result data:',
                    makePrintable(extSource.data),
                    '- transform result dimensions:',
                    makePrintable(extSource.dimensions)
                ].join('\n');
            }).join('\n');
            log(printStrArr);
        }
    }