bidi.java

linux下建立JAVA虚拟机的源码KAFFE

  }

  /**
   * An internal method to resolve implicit levels.
   * This implements rules I1 and I2.
   */
  private void resolveImplicitLevels()
  {
    // This implements rules I1 and I2.
    for (int i = 0; i < length; ++i)
      {
        if ((levels[i] & 1) == 0)
          {
            if (types[i] == Character.DIRECTIONALITY_RIGHT_TO_LEFT)
              ++levels[i];
            else if (types[i] == Character.DIRECTIONALITY_ARABIC_NUMBER
                     || types[i] == Character.DIRECTIONALITY_EUROPEAN_NUMBER)
              levels[i] += 2;
          }
        else
          {
            if (types[i] == Character.DIRECTIONALITY_LEFT_TO_RIGHT
                || types[i] == Character.DIRECTIONALITY_ARABIC_NUMBER
                || types[i] == Character.DIRECTIONALITY_EUROPEAN_NUMBER)
              ++levels[i];
          }

        // Update the result flags.
        resultFlags |= 1 << (levels[i] & 1);
      }
    // One final update of the result flags, using the base level.
    resultFlags |= 1 << baseEmbedding;
  }

  /**
   * This reinserts the formatting codes that we removed early on.
   * Actually it does not insert formatting codes per se, but rather
   * simply inserts new levels at the appropriate locations in the
   * 'levels' array.
   */
  private void reinsertFormattingCodes()
  {
    if (formatterIndices == null)
      return;
    int input = length;
    int output = levels.length;
    // Process from the end as we are copying the array over itself here.
    for (int index = formatterIndices.size() - 1; index >= 0; --index)
      {
        int nextFmt = ((Integer) formatterIndices.get(index)).intValue();

        // nextFmt points to a location in the original array.  So,
        // nextFmt+1 is the target of our copying.  output is the location
        // to which we last copied, thus we can derive the length of the
        // copy from it.
        int len = output - nextFmt - 1;
        output = nextFmt;
        input -= len;
        // Note that we no longer need 'types' at this point, so we
        // only edit 'levels'.
        if (nextFmt + 1 < levels.length)
          System.arraycopy(levels, input, levels, nextFmt + 1, len);

        // Now set the level at the reinsertion point.
        int rightLevel;
        if (output == levels.length - 1)
          rightLevel = baseEmbedding;
        else
          rightLevel = levels[output + 1];
        int leftLevel;
        if (input == 0)
          leftLevel = baseEmbedding;
        else
          leftLevel = levels[input];
        levels[output] = (byte) Math.max(leftLevel, rightLevel);
      }
    length = levels.length;
  }

  /**
   * This is the main internal entry point.  After a constructor
   * has initialized the appropriate local state, it will call
   * this method to do all the work.
   */
  private void runBidi()
  {
    computeTypes();
    baseEmbedding = computeParagraphEmbeddingLevel();
    computeExplicitLevels();
    computeRuns();
    resolveWeakTypes();
    resolveNeutralTypes();
    resolveImplicitLevels();
    // We're done with the types.  Let the GC clean up.
    types = null;
    reinsertFormattingCodes();
    // After resolving the implicit levels, the number
    // of runs may have changed.
    computeRuns();
  }

  /**
   * Return true if the paragraph base embedding is left-to-right,
   * false otherwise.
   */
  public boolean baseIsLeftToRight()
  {
    return baseEmbedding == DIRECTION_LEFT_TO_RIGHT;
  }

  /**
   * Create a new Bidi object for a single line of text, taken
   * from the text used when creating the current Bidi object.
   * @param start the index of the first character of the line
   * @param end the index of the final character of the line
   * @return a new Bidi object for the indicated line of text
   */
  public Bidi createLineBidi(int start, int end)
  {
    // This isn't the most efficient implementation possible.
    // This probably does not matter, so we choose simplicity instead.
    int level = getLevelAt(start);
    int flag = (((level % 2) == 0)
                ? DIRECTION_LEFT_TO_RIGHT
                : DIRECTION_RIGHT_TO_LEFT);
    return new Bidi(text, textOffset + start,
                    embeddings, embeddingOffset + start,
                    end - start, flag);
  }

  /**
   * Return the base embedding level of the paragraph.
   */
  public int getBaseLevel()
  {
    return baseEmbedding;
  }

  /**
   * Return the length of the paragraph, in characters.
   */
  public int getLength()
  {
    return length;
  }

  /**
   * Return the level at the indicated character.  If the
   * supplied index is less than zero or greater than the length
   * of the text, then the paragraph's base embedding level will
   * be returned.
   * @param offset the character to examine
   * @return the level of that character
   */
  public int getLevelAt(int offset)
  {
    if (offset < 0 || offset >= length)
      return getBaseLevel();
    return levels[offset];
  }

  /**
   * Return the number of runs in the result.  A run is
   * a sequence of characters at the same embedding level.
   */
  public int getRunCount()
  {
    return runs.length;
  }

  /**
   * Return the level of the indicated run.
   * @param which the run to examine
   * @return the level of that run
   */
  public int getRunLevel(int which)
  {
    return levels[runs[which]];
  }

  /**
   * Return the index of the character just following the end
   * of the indicated run.
   * @param which the run to examine
   * @return the index of the character after the final character
   * of the run
   */
  public int getRunLimit(int which)
  {
    if (which == runs.length - 1)
      return length;
    return runs[which + 1];
  }

  /**
   * Return the index of the first character in the indicated run.
   * @param which the run to examine
   * @return the index of the first character of the run
   */
  public int getRunStart(int which)
  {
    return runs[which];
  }

  /**
   * Return true if the text is entirely left-to-right, and the
   * base embedding is also left-to-right.
   */
  public boolean isLeftToRight()
  {
    return resultFlags == LTOR;
  }

  /**
   * Return true if the text consists of mixed left-to-right and
   * right-to-left runs, or if the text consists of one kind of run
   * which differs from the base embedding direction.
   */
  public boolean isMixed()
  {
    return resultFlags == (LTOR | RTOL);
  }

  /**
   * Return true if the text is entirely right-to-left, and the
   * base embedding is also right-to-left.
   */
  public boolean isRightToLeft()
  {
    return resultFlags == RTOL;
  }

  /**
   * Return a String describing the internal state of this object.
   * This is only useful for debugging.
   */
  public String toString()
  {
    return "Bidi Bidi Bidi I like you, Buck!";
  }

  /**
   * Reorder objects according to the levels passed in.  This implements
   * reordering as defined by the Unicode bidirectional layout specification.
   * The levels are integers from 0 to 62; even numbers represent left-to-right
   * runs, and odd numbers represent right-to-left runs.
   *
   * @param levels the levels associated with each object
   * @param levelOffset the index of the first level to use
   * @param objs the objects to reorder according to the levels
   * @param objOffset the index of the first object to use
   * @param count the number of objects (and levels) to manipulate
   */
  public static void reorderVisually(byte[] levels, int levelOffset,
                                     Object[] objs, int objOffset, int count)
  {
    // We need a copy of the 'levels' array, as we are going to modify it.
    // This is unfortunate but difficult to avoid.
    byte[] levelCopy = new byte[count];
    // Do this explicitly so we can also find the maximum depth at the
    // same time.
    int max = 0;
    int lowestOdd = 63;
    for (int i = 0; i < count; ++i)
      {
        levelCopy[i] = levels[levelOffset + i];
        max = Math.max(levelCopy[i], max);
        if (levelCopy[i] % 2 != 0)
          lowestOdd = Math.min(lowestOdd, levelCopy[i]);
      }

    // Reverse the runs starting with the deepest.
    for (int depth = max; depth >= lowestOdd; --depth)
      {
        int start = 0;
        while (start < count)
          {
            // Find the start of a run >= DEPTH.
            while (start < count && levelCopy[start] < depth)
              ++start;
            if (start == count)
              break;
            // Find the end of the run.
            int end = start + 1;
            while (end < count && levelCopy[end] >= depth)
              ++end;

            // Reverse this run.
            for (int i = 0; i < (end - start) / 2; ++i)
              {
                byte tmpb = levelCopy[end - i - 1];
                levelCopy[end - i - 1] = levelCopy[start + i];
                levelCopy[start + i] = tmpb;
                Object tmpo = objs[objOffset + end - i - 1];
                objs[objOffset + end - i - 1] = objs[objOffset + start + i];
                objs[objOffset + start + i] = tmpo;
              }

            // Handle the next run.
            start = end + 1;
          }
      }
  }

  /**
   * Returns false if all characters in the text between start and end
   * are all left-to-right text. This implementation is just calls
   * <code>Character.getDirectionality(char)</code> on all characters
   * and makes sure all characters are either explicitly left-to-right
   * or neutral in directionality (character types L, EN, ES, ET, AN,
   * CS, S and WS).
   */
  public static boolean requiresBidi(char[] text, int start, int end)
  {
    for (int i = start; i < end; i++)
      {
	byte dir = Character.getDirectionality(text[i]);
	if (dir != Character.DIRECTIONALITY_LEFT_TO_RIGHT
	    && dir != Character.DIRECTIONALITY_EUROPEAN_NUMBER
	    && dir != Character.DIRECTIONALITY_EUROPEAN_NUMBER_SEPARATOR
	    && dir != Character.DIRECTIONALITY_EUROPEAN_NUMBER_TERMINATOR
	    && dir != Character.DIRECTIONALITY_ARABIC_NUMBER
	    && dir != Character.DIRECTIONALITY_COMMON_NUMBER_SEPARATOR
	    && dir != Character.DIRECTIONALITY_SEGMENT_SEPARATOR
	    && dir != Character.DIRECTIONALITY_WHITESPACE)
	  return true;
      }

    return false;
  }
}