pdf.js.mirror/src/core/string_utils.js

/* Copyright 2019 Mozilla Foundation
 *
 * 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.
 */

import { stringToBytes, Util, warn } from "../shared/util.js";

function isAscii(str) {
  // eslint-disable-next-line no-control-regex
  return typeof str === "string" && (!str || /^[\x00-\x7F]*$/.test(str));
}

// If the string is null or undefined then it is returned as is.
function stringToAsciiOrUTF16BE(str) {
  return str === null || str === undefined || isAscii(str)
    ? str
    : stringToUTF16String(str, /* bigEndian = */ true);
}

function stringToUTF16HexString(str) {
  const buf = [];
  for (let i = 0, ii = str.length; i < ii; i++) {
    const char = str.charCodeAt(i);
    buf.push(Util.hexNums[(char >> 8) & 0xff], Util.hexNums[char & 0xff]);
  }
  return buf.join("");
}

function stringToUTF16String(str, bigEndian = false) {
  const buf = [];
  if (bigEndian) {
    buf.push("\xFE\xFF");
  }
  for (let i = 0, ii = str.length; i < ii; i++) {
    const char = str.charCodeAt(i);
    buf.push(
      String.fromCharCode((char >> 8) & 0xff),
      String.fromCharCode(char & 0xff)
    );
  }
  return buf.join("");
}

const PDFStringTranslateTable = [
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x2d8,
  0x2c7, 0x2c6, 0x2d9, 0x2dd, 0x2db, 0x2da, 0x2dc, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0x2022, 0x2020, 0x2021, 0x2026, 0x2014, 0x2013, 0x192,
  0x2044, 0x2039, 0x203a, 0x2212, 0x2030, 0x201e, 0x201c, 0x201d, 0x2018,
  0x2019, 0x201a, 0x2122, 0xfb01, 0xfb02, 0x141, 0x152, 0x160, 0x178, 0x17d,
  0x131, 0x142, 0x153, 0x161, 0x17e, 0, 0x20ac,
];

function stringToPDFString(str, keepEscapeSequence = false) {
  // See section 7.9.2.2 Text String Type.
  // The string can contain some language codes bracketed with 0x1b,
  // so we must remove them.
  if (str[0] >= "\xEF") {
    let encoding;
    if (str[0] === "\xFE" && str[1] === "\xFF") {
      encoding = "utf-16be";
      if (str.length % 2 === 1) {
        str = str.slice(0, -1);
      }
    } else if (str[0] === "\xFF" && str[1] === "\xFE") {
      encoding = "utf-16le";
      if (str.length % 2 === 1) {
        str = str.slice(0, -1);
      }
    } else if (str[0] === "\xEF" && str[1] === "\xBB" && str[2] === "\xBF") {
      encoding = "utf-8";
    }

    if (encoding) {
      try {
        const decoder = new TextDecoder(encoding, { fatal: true });
        const buffer = stringToBytes(str);
        const decoded = decoder.decode(buffer);
        if (keepEscapeSequence || !decoded.includes("\x1b")) {
          return decoded;
        }
        // eslint-disable-next-line no-control-regex
        return decoded.replaceAll(/\x1b[^\x1b]*(?:\x1b|$)/g, "");
      } catch (ex) {
        warn(`stringToPDFString: "${ex}".`);
      }
    }
  }
  // ISO Latin 1
  const strBuf = [];
  for (let i = 0, ii = str.length; i < ii; i++) {
    const charCode = str.charCodeAt(i);
    if (!keepEscapeSequence && charCode === 0x1b) {
      // eslint-disable-next-line no-empty
      while (++i < ii && str.charCodeAt(i) !== 0x1b) {}
      continue;
    }
    const code = PDFStringTranslateTable[charCode];
    strBuf.push(code ? String.fromCharCode(code) : str.charAt(i));
  }
  return strBuf.join("");
}

export {
  isAscii,
  stringToAsciiOrUTF16BE,
  stringToPDFString,
  stringToUTF16HexString,
  stringToUTF16String,
};