Function detectSourceFormat

src/data/Source.ts:256–294

(data: DatasetOption['source'])

 * Note: An empty array will be detected as `SOURCE_FORMAT_ARRAY_ROWS`.
 */
export function detectSourceFormat(data: DatasetOption['source']): SourceFormat {
    let sourceFormat: SourceFormat = SOURCE_FORMAT_UNKNOWN;

    if (isTypedArray(data)) {
        sourceFormat = SOURCE_FORMAT_TYPED_ARRAY;
    }
    else if (isArray(data)) {
        // FIXME Whether tolerate null in top level array?
        if (data.length === 0) {
            sourceFormat = SOURCE_FORMAT_ARRAY_ROWS;
        }

        for (let i = 0, len = data.length; i < len; i++) {
            const item = data[i];

            if (item == null) {
                continue;
            }
            else if (isArray(item) || isTypedArray(item)) {
                sourceFormat = SOURCE_FORMAT_ARRAY_ROWS;
                break;
            }
            else if (isObject(item)) {
                sourceFormat = SOURCE_FORMAT_OBJECT_ROWS;
                break;
            }
        }
    }
    else if (isObject(data)) {
        for (const key in data) {
            if (hasOwn(data, key) && isArrayLike((data as Dictionary<unknown>)[key])) {
                sourceFormat = SOURCE_FORMAT_KEYED_COLUMNS;
                break;
            }
        }
    }

    return sourceFormat;
}

/**
 * Determine the source definitions from data standalone dimensions definitions