nats.js/core/src/encoders.ts

/*
 * Copyright 2020 The NATS Authors
 * Licensed 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.
 */
export const Empty: Uint8Array = new Uint8Array(0);

export const TE: InstanceType<typeof TextEncoder> = new TextEncoder();
export const TD: InstanceType<typeof TextDecoder> = new TextDecoder();

function concat(...bufs: Uint8Array[]): Uint8Array {
  let max = 0;
  for (let i = 0; i < bufs.length; i++) {
    max += bufs[i].length;
  }
  const out = new Uint8Array(max);
  let index = 0;
  for (let i = 0; i < bufs.length; i++) {
    out.set(bufs[i], index);
    index += bufs[i].length;
  }
  return out;
}

export function encode(...a: string[]): Uint8Array {
  const bufs = [];
  for (let i = 0; i < a.length; i++) {
    bufs.push(TE.encode(a[i]));
  }
  if (bufs.length === 0) {
    return Empty;
  }
  if (bufs.length === 1) {
    return bufs[0];
  }
  return concat(...bufs);
}

export function decode(a: Uint8Array): string {
  if (!a || a.length === 0) {
    return "";
  }
  return TD.decode(a);
}