/addons/web/static/lib/pdfjs/src/core/bidi.js

/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
/* globals PDFJS */
/* Copyright 2012 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.
 */

'use strict';

var bidi = PDFJS.bidi = (function bidiClosure() {
  // Character types for symbols from 0000 to 00FF.
  var baseTypes = [
    'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'S', 'B', 'S', 'WS',
    'B', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN',
    'BN', 'BN', 'B', 'B', 'B', 'S', 'WS', 'ON', 'ON', 'ET', 'ET', 'ET', 'ON',
    'ON', 'ON', 'ON', 'ON', 'ON', 'CS', 'ON', 'CS', 'ON', 'EN', 'EN', 'EN',
    'EN', 'EN', 'EN', 'EN', 'EN', 'EN', 'EN', 'ON', 'ON', 'ON', 'ON', 'ON',
    'ON', 'ON', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L',
    'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'ON', 'ON',
    'ON', 'ON', 'ON', 'ON', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L',
    'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L',
    'L', 'ON', 'ON', 'ON', 'ON', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'B', 'BN',
    'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN',
    'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN', 'BN',
    'BN', 'CS', 'ON', 'ET', 'ET', 'ET', 'ET', 'ON', 'ON', 'ON', 'ON', 'L', 'ON',
    'ON', 'ON', 'ON', 'ON', 'ET', 'ET', 'EN', 'EN', 'ON', 'L', 'ON', 'ON', 'ON',
    'EN', 'L', 'ON', 'ON', 'ON', 'ON', 'ON', 'L', 'L', 'L', 'L', 'L', 'L', 'L',
    'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L',
    'L', 'ON', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L',
    'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L',
    'L', 'L', 'L', 'ON', 'L', 'L', 'L', 'L', 'L', 'L', 'L', 'L'
  ];

  // Character types for symbols from 0600 to 06FF
  var arabicTypes = [
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'CS', 'AL', 'ON', 'ON', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM',
    'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AN', 'AN', 'AN', 'AN', 'AN', 'AN', 'AN', 'AN', 'AN',
    'AN', 'ET', 'AN', 'AN', 'AL', 'AL', 'AL', 'NSM', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM',
    'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'NSM', 'ON', 'NSM',
    'NSM', 'NSM', 'NSM', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL',
    'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL', 'AL'
  ];

  function isOdd(i) {
    return (i & 1) !== 0;
  }

  function isEven(i) {
    return (i & 1) === 0;
  }

  function findUnequal(arr, start, value) {
    for (var j = start, jj = arr.length; j < jj; ++j) {
      if (arr[j] !== value) {
        return j;
      }
    }
    return j;
  }

  function setValues(arr, start, end, value) {
    for (var j = start; j < end; ++j) {
      arr[j] = value;
    }
  }

  function reverseValues(arr, start, end) {
    for (var i = start, j = end - 1; i < j; ++i, --j) {
      var temp = arr[i];
      arr[i] = arr[j];
      arr[j] = temp;
    }
  }

  function createBidiText(str, isLTR, vertical) {
    return {
      str: str,
      dir: (vertical ? 'ttb' : (isLTR ? 'ltr' : 'rtl'))
    };
  }

  // These are used in bidi(), which is called frequently. We re-use them on
  // each call to avoid unnecessary allocations.
  var chars = [];
  var types = [];

  function bidi(str, startLevel, vertical) {
    var isLTR = true;
    var strLength = str.length;
    if (strLength === 0 || vertical) {
      return createBidiText(str, isLTR, vertical);
    }

    // Get types and fill arrays
    chars.length = strLength;
    types.length = strLength;
    var numBidi = 0;

    var i, ii;
    for (i = 0; i < strLength; ++i) {
      chars[i] = str.charAt(i);

      var charCode = str.charCodeAt(i);
      var charType = 'L';
      if (charCode <= 0x00ff) {
        charType = baseTypes[charCode];
      } else if (0x0590 <= charCode && charCode <= 0x05f4) {
        charType = 'R';
      } else if (0x0600 <= charCode && charCode <= 0x06ff) {
        charType = arabicTypes[charCode & 0xff];
      } else if (0x0700 <= charCode && charCode <= 0x08AC) {
        charType = 'AL';
      }
      if (charType === 'R' || charType === 'AL' || charType === 'AN') {
        numBidi++;
      }
      types[i] = charType;
    }

    // Detect the bidi method
    // - If there are no rtl characters then no bidi needed
    // - If less than 30% chars are rtl then string is primarily ltr
    // - If more than 30% chars are rtl then string is primarily rtl
    if (numBidi === 0) {
      isLTR = true;
      return createBidiText(str, isLTR);
    }

    if (startLevel === -1) {
      if ((strLength / numBidi) < 0.3) {
        isLTR = true;
        startLevel = 0;
      } else {
        isLTR = false;
        startLevel = 1;
      }
    }

    var levels = [];
    for (i = 0; i < strLength; ++i) {
      levels[i] = startLevel;
    }

    /*
     X1-X10: skip most of this, since we are NOT doing the embeddings.
     */
    var e = (isOdd(startLevel) ? 'R' : 'L');
    var sor = e;
    var eor = sor;

    /*
     W1. Examine each non-spacing mark (NSM) in the level run, and change the
     type of the NSM to the type of the previous character. If the NSM is at the
     start of the level run, it will get the type of sor.
     */
    var lastType = sor;
    for (i = 0; i < strLength; ++i) {
      if (types[i] === 'NSM') {
        types[i] = lastType;
      } else {
        lastType = types[i];
      }
    }

    /*
     W2. Search backwards from each instance of a European number until the
     first strong type (R, L, AL, or sor) is found.  If an AL is found, change
     the type of the European number to Arabic number.
     */
    lastType = sor;
    var t;
    for (i = 0; i < strLength; ++i) {
      t = types[i];
      if (t === 'EN') {
        types[i] = (lastType === 'AL') ? 'AN' : 'EN';
      } else if (t === 'R' || t === 'L' || t === 'AL') {
        lastType = t;
      }
    }

    /*
     W3. Change all ALs to R.
     */
    for (i = 0; i < strLength; ++i) {
      t = types[i];
      if (t === 'AL') {
        types[i] = 'R';
      }
    }

    /*
     W4. A single European separator between two European numbers changes to a
     European number. A single common separator between two numbers of the same
     type changes to that type:
     */
    for (i = 1; i < strLength - 1; ++i) {
      if (types[i] === 'ES' && types[i - 1] === 'EN' && types[i + 1] === 'EN') {
        types[i] = 'EN';
      }
      if (types[i] === 'CS' &&
          (types[i - 1] === 'EN' || types[i - 1] === 'AN') &&
          types[i + 1] === types[i - 1]) {
        types[i] = types[i - 1];
      }
    }

    /*
     W5. A sequence of European terminators adjacent to European numbers changes
     to all European numbers:
     */
    for (i = 0; i < strLength; ++i) {
      if (types[i] === 'EN') {
        // do before
        var j;
        for (j = i - 1; j >= 0; --j) {
          if (types[j] !== 'ET') {
            break;
          }
          types[j] = 'EN';
        }
        // do after
        for (j = i + 1; j < strLength; --j) {
          if (types[j] !== 'ET') {
            break;
          }
          types[j] = 'EN';
        }
      }
    }

    /*
     W6. Otherwise, separators and terminators change to Other Neutral:
     */
    for (i = 0; i < strLength; ++i) {
      t = types[i];
      if (t === 'WS' || t === 'ES' || t === 'ET' || t === 'CS') {
        types[i] = 'ON';
      }
    }

    /*
     W7. Search backwards from each instance of a European number until the
     first strong type (R, L, or sor) is found. If an L is found,  then change
     the type of the European number to L.
     */
    lastType = sor;
    for (i = 0; i < strLength; ++i) {
      t = types[i];
      if (t === 'EN') {
        types[i] = ((lastType === 'L') ? 'L' : 'EN');
      } else if (t === 'R' || t === 'L') {
        lastType = t;
      }
    }

    /*
     N1. A sequence of neutrals takes the direction of the surrounding strong
     text if the text on both sides has the same direction. European and Arabic
     numbers are treated as though they were R. Start-of-level-run (sor) and
     end-of-level-run (eor) are used at level run boundaries.
     */
    for (i = 0; i < strLength; ++i) {
      if (types[i] === 'ON') {
        var end = findUnequal(types, i + 1, 'ON');
        var before = sor;
        if (i > 0) {
          before = types[i - 1];
        }

        var after = eor;
        if (end + 1 < strLength) {
          after = types[end + 1];
        }
        if (before !== 'L') {
          before = 'R';
        }
        if (after !== 'L') {
          after = 'R';
        }
        if (before === after) {
          setValues(types, i, end, before);
        }
        i = end - 1; // reset to end (-1 so next iteration is ok)
      }
    }

    /*
     N2. Any remaining neutrals take the embedding direction.
     */
    for (i = 0; i < strLength; ++i) {
      if (types[i] === 'ON') {
        types[i] = e;
      }
    }

    /*
     I1. For all characters with an even (left-to-right) embedding direction,
     those of type R go up one level and those of type AN or EN go up two
     levels.
     I2. For all characters with an odd (right-to-left) embedding direction,
     those of type L, EN or AN go up one level.
     */
    for (i = 0; i < strLength; ++i) {
      t = types[i];
      if (isEven(levels[i])) {
        if (t === 'R') {
          levels[i] += 1;
        } else if (t === 'AN' || t === 'EN') {
          levels[i] += 2;
        }
      } else { // isOdd
        if (t === 'L' || t === 'AN' || t === 'EN') {
          levels[i] += 1;
        }
      }
    }

    /*
     L1. On each line, reset the embedding level of the following characters to
     the paragraph embedding level:

     segment separators,
     paragraph separators,
     any sequence of whitespace characters preceding a segment separator or
     paragraph separator, and any sequence of white space characters at the end
     of the line.
     */

    // don't bother as text is only single line

    /*
     L2. From the highest level found in the text to the lowest odd level on
     each line, reverse any contiguous sequence of characters that are at that
     level or higher.
     */

    // find highest level & lowest odd level
    var highestLevel = -1;
    var lowestOddLevel = 99;
    var level;
    for (i = 0, ii = levels.length; i < ii; ++i) {
      level = levels[i];
      if (highestLevel < level) {
        highestLevel = level;
      }
      if (lowestOddLevel > level && isOdd(level)) {
        lowestOddLevel = level;
      }
    }

    // now reverse between those limits
    for (level = highestLevel; level >= lowestOddLevel; --level) {
      // find segments to reverse
      var start = -1;
      for (i = 0, ii = levels.length; i < ii; ++i) {
        if (levels[i] < level) {
          if (start >= 0) {
            reverseValues(chars, start, i);
            start = -1;
          }
        } else if (start < 0) {
          start = i;
        }
      }
      if (start >= 0) {
        reverseValues(chars, start, levels.length);
      }
    }

    /*
     L3. Combining marks applied to a right-to-left base character will at this
     point precede their base character. If the rendering engine expects them to
     follow the base characters in the final display process, then the ordering
     of the marks and the base character must be reversed.
     */

    // don't bother for now

    /*
     L4. A character that possesses the mirrored property as specified by
     Section 4.7, Mirrored, must be depicted by a mirrored glyph if the resolved
     directionality of that character is R.
     */

    // don't mirror as characters are already mirrored in the pdf

    // Finally, return string
    var result = '';
    for (i = 0, ii = chars.length; i < ii; ++i) {
      var ch = chars[i];
      if (ch !== '<' && ch !== '>') {
        result += ch;
      }
    }
    return createBidiText(result, isLTR);
  }

  return bidi;
})();