stream-transform/lib/sync.js

Object transformations implementing the Node.js `stream.Transform` API

/*
Stream Transform - sync module

Please look at the [project documentation](https://csv.js.org/transform/) for
additional information.
*/

import { Transformer } from "./index.js";

const transform = function () {
  // Import arguments normalization
  let handler, records;
  let options = {};
  for (const i in arguments) {
    const argument = arguments[i];
    let type = typeof argument;
    if (argument === null) {
      type = "null";
    } else if (type === "object" && Array.isArray(argument)) {
      type = "array";
    }
    if (type === "array") {
      records = argument;
    } else if (type === "object") {
      options = { ...argument };
    } else if (type === "function") {
      handler = argument;
    } else if (type !== "null") {
      throw new Error(
        `Invalid Arguments: got ${JSON.stringify(argument)} at position ${i}`,
      );
    }
  }
  // Validate arguments
  let expected_handler_length = 1;
  if (options.params) {
    expected_handler_length++;
  }
  if (handler.length > expected_handler_length) {
    throw Error("Invalid Handler: only synchonous handlers are supported");
  }
  // Start transformation
  const chunks = [];
  const transformer = new Transformer(options, handler);
  transformer.push = function (chunk) {
    chunks.push(chunk);
  };
  for (const record of records) {
    transformer._transform(record, null, function () {});
  }
  return chunks;
};

// export default transform
export { transform };