csv-generate/lib/index.js

CSV and object generation implementing the Node.js `stream.Readable` API

/*
CSV Generate - main module

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

import stream from "stream";
import util from "util";
import { normalize_options, init_state, read } from "./api/index.js";

const Generator = function (options = {}) {
  this.options = normalize_options(options);
  // Call parent constructor
  stream.Readable.call(this, this.options);
  this.state = init_state(this.options);
  return this;
};
util.inherits(Generator, stream.Readable);

// Stop the generation.
Generator.prototype.end = function () {
  this.push(null);
};
// Put new data into the read queue.
Generator.prototype._read = function (size) {
  setImmediate(() => {
    this.__read(size);
  });
};
Generator.prototype.__read = function (size) {
  read(
    this.options,
    this.state,
    size,
    (chunk) => {
      this.__push(chunk);
    },
    (err) => {
      if (err) {
        this.destroy(err);
      } else {
        this.push(null);
      }
    },
  );
};
// Put new data into the read queue.
Generator.prototype.__push = function (record) {
  const push = () => {
    this.state.count_written++;
    this.push(record);
    if (this.state.end === true) {
      return this.push(null);
    }
  };
  this.options.sleep > 0 ? setTimeout(push, this.options.sleep) : push();
};

const generate = function () {
  let options;
  let callback;
  if (arguments.length === 2) {
    options = arguments[0];
    callback = arguments[1];
  } else if (arguments.length === 1) {
    if (typeof arguments[0] === "function") {
      options = {};
      callback = arguments[0];
    } else {
      options = arguments[0];
    }
  } else if (arguments.length === 0) {
    options = {};
  }
  const generator = new Generator(options);
  if (callback) {
    const data = [];
    generator.on("readable", function () {
      let d;
      while ((d = generator.read()) !== null) {
        data.push(d);
      }
    });
    generator.on("error", callback);
    generator.on("end", function () {
      if (generator.options.objectMode) {
        callback(null, data);
      } else {
        if (generator.options.encoding) {
          callback(null, data.join(""));
        } else {
          callback(null, Buffer.concat(data));
        }
      }
    });
  }
  return generator;
};

// export default generate
export { generate, Generator };