utf.mjs

/**
 * @license
 * UTF.js
 * https://github.com/DesWurstes/utf.js
 * Copyright (c) 2018 DesWurstes MIT License
 *
 * Added exports. Supplies: 
 *   FromString, FromUTF8, FromUTF16, 
 *   ToString, ToUTF8, ToUTF16
 */

export function FromString(str) {
  const len = str.length;
  var ret = new Uint16Array(len);
  for (var i = 0; i < len; i++) {
    ret[i] = str.charCodeAt(i);
  }
  return FromUTF16(ret);
}

export function FromUTF8(str) {
  const len = str.length;
  var ret = new Uint32Array(len);
  var a = 0;
  for (var i = 0; i < len; i++, a++) {
    const c = str[i];
    if ((c & 128) == 0) {
      ret[a] = c;
      continue;
    }
    if ((c & 64) == 0) {
      return [];
    }
    i++;
    const d = str[i];
    if ((c & 32) == 0) {
      ret[a] = ((c & 31) << 6) | (d & 63);
      if ((d & 192) == 128) {
        continue;
      }
      return [];
    }
    i++;
    const e = str[i];
    if ((c & 16) == 0) {
      ret[a] = ((c & 15) << 12) | ((d & 63) << 6) | ((e & 63));
      if (((d & 192) == 128) && ((e & 192) == 128)) {
        continue;
      }
      return [];
    }
    i++;
    const f = str[i];
    if ((c & 8) == 0) {
      ret[a] = ((c & 7) << 18) | ((d & 63) << 12) | ((e & 63) << 6) | ((f & 63));
      if (((d & 192) == 128) && ((e & 192) == 128) && ((f & 192) == 128)) {
        continue;
      }
      return [];
    }
    return [];
  }
  return ret.slice(0, a);
}

export function FromUTF16(str) {
  const len = str.length;
  var ret = new Uint32Array(len);
  var a = 0;
  for (var i = 0; i < len; i++, a++) {
    const c = str[i];
    if ((c < 0xd800) || (c >= 0xe000)) {
      ret[a] = c;
      continue;
    }
    i++;
    const d = str[i];
    if ((c >= 0xdc00) || (d < 0xdc00)) {
      return [];
    }
    // ret[a] = ((c - 0xD800) << 10) + d - 0xDC00 + 0x1000
    ret[a] = ((c - 0xD800) << 10) + d + 0x2400;
  }
  return ret.slice(0, a);
}

export function ToString(str) {
  const a = ToUTF16(str);
  const len = a.length;
  var ret = "";
  for (var i = 0; i < len; i++) {
    ret += String.fromCharCode(a[i]);
  }
  return ret;
}

export function ToUTF8(str) {
  const len = str.length;
  var ret = new Uint8Array(len << 2);
  var a = 0;
  for (var i = 0; i < len; i++, a++) {
    const c = str[i];
    if (c < 0x80) {
      ret[a] = c;
      continue;
    }
    if (c < 0x800) {
      ret[a] = c >>> 6 | 192;
      a++;
      ret[a] = c & 63 | 128;
      continue;
    }
    if (c < 0x10000) {
      ret[a] = c >>> 12 | 224;
      a++;
      ret[a] = c >>> 6 & 63 | 128;
      a++;
      ret[a] = c & 63 | 128;
      continue;
    }
    if (c < 0x110000) {
      ret[a] = c >>> 18 | 240;
      a++;
      ret[a] = c >>> 12 & 63 | 128;
      a++;
      ret[a] = c >>> 6 & 63 | 128;
      a++;
      ret[a] = c & 63 | 128;
      continue;
    }
    return [];
  }
  return ret.slice(0, a);
}

export function ToUTF16(str) {
  const len = str.length;
  var ret = new Uint16Array(len << 1);
  var a = 0;
  for (var i = 0; i < len; i++, a++) {
    let c = str[i];
    if ((c < 0xd800) || ((c >= 0xe000) && (c < 0x10000))) {
      ret[a] = c;
      continue;
    }
    if ((c >= 0xd800) && (c < 0xe000)) {
      // This character can't be encoded using UTF-16!
      return [];
    }
    c -= 0x10000;
    ret[a] = (c >>> 10) + 0xD800;
    a++;
    ret[a] = (c & 1023) + 0xDC00;
  }
  return ret.slice(0, a);
}