preview/buffer_itr.js

/**
 * @license
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

'use strict';

/**
 * Buffers an async iterator until its output is at least min characters
 * @param {Generator} itr async iterator that returns a string to buffer 
 */
module.exports = async function* (itr, min) {
  let buffer = "";
  for await (const chunk of itr) {
    buffer += chunk;
    if (buffer.length > min) {
      yield buffer;
      buffer = "";
    }
  }
  if (buffer !== "") {
    yield buffer;
  }
};