Class BidiOrder


  • public final class BidiOrder
    extends java.lang.Object
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static byte AL
      Right-to-Left Arabic
      static byte AN
      Arabic Number
      static byte B
      Paragraph Separator
      private static char[] baseTypes  
      static byte BN
      Boundary Neutral
      static byte CS
      Common Number Separator
      private byte[] embeddings  
      static byte EN
      European Number
      static byte ES
      European Number Separator
      static byte ET
      European Number Terminator
      private byte[] initialTypes  
      static byte L
      Left-to-right
      static byte LRE
      Left-to-Right Embedding
      static byte LRO
      Left-to-Right Override
      static byte NSM
      Non-Spacing Mark
      static byte ON
      Other Neutrals
      private byte paragraphEmbeddingLevel  
      static byte PDF
      Pop Directional Format
      static byte R
      Right-to-Left
      private byte[] resultLevels  
      private byte[] resultTypes  
      static byte RLE
      Right-to-Left Embedding
      static byte RLO
      Right-to-Left Override
      private static byte[] rtypes  
      static byte S
      Segment Separator
      private int textLength  
      static byte TYPE_MAX
      Maximum bidi type value.
      static byte TYPE_MIN
      Minimum bidi type value.
      static byte WS
      Whitespace
    • Constructor Summary

      Constructors 
      Constructor Description
      BidiOrder​(byte[] types)
      Initialize using an array of direction types.
      BidiOrder​(byte[] types, byte paragraphEmbeddingLevel)
      Initialize using an array of direction types and an externally supplied paragraph embedding level.
      BidiOrder​(char[] text, int offset, int length, byte paragraphEmbeddingLevel)  
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private static int[] computeMultilineReordering​(byte[] levels, int[] linebreaks)
      Return multiline reordering array for a given level array.
      private static int[] computeReordering​(byte[] levels)
      Return reordering array for a given level array.
      private void determineExplicitEmbeddingLevels()
      Process embedding format codes.
      private void determineParagraphEmbeddingLevel()
      1) determining the paragraph level.
      private int findRunLimit​(int index, int limit, byte[] validSet)
      Return the limit of the run starting at index that includes only resultTypes in validSet.
      private int findRunStart​(int index, byte[] validSet)
      Return the start of the run including index that includes only resultTypes in validSet.
      byte getBaseLevel()
      Return the base level of the paragraph.
      static byte getDirection​(char c)  
      byte[] getLevels()  
      byte[] getLevels​(int[] linebreaks)
      Return levels array breaking lines at offsets in linebreaks.
      int[] getReordering​(int[] linebreaks)
      Return reordering array breaking lines at offsets in linebreaks.
      private static boolean isWhitespace​(byte biditype)
      Return true if the type is considered a whitespace type for the line break rules.
      private static byte[] processEmbeddings​(byte[] resultTypes, byte paragraphEmbeddingLevel)
      2) determining explicit levels Rules X1 - X8 The interaction of these rules makes handling them a bit complex.
      private int reinsertExplicitCodes​(int textLength)
      Reinsert levels information for explicit codes.
      private int removeExplicitCodes()
      Rules X9.
      private void resolveImplicitLevels​(int start, int limit, byte level, byte sor, byte eor)
      7) resolving implicit embedding levels Rules I1, I2.
      private void resolveNeutralTypes​(int start, int limit, byte level, byte sor, byte eor)
      6) resolving neutral types Rules N1-N2.
      private void resolveWeakTypes​(int start, int limit, byte level, byte sor, byte eor)
      3) resolving weak types Rules W1-W7.
      private void runAlgorithm()
      The algorithm.
      private void setLevels​(int start, int limit, byte newLevel)
      Set resultLevels from start up to (but not including) limit to newLevel.
      private void setTypes​(int start, int limit, byte newType)
      Set resultTypes from start up to (but not including) limit to newType.
      private static byte typeForLevel​(int level)
      Return the strong type (L or R) corresponding to the level.
      private static void validateLineBreaks​(int[] linebreaks, int textLength)
      Throw exception if line breaks array is invalid.
      private static void validateParagraphEmbeddingLevel​(byte paragraphEmbeddingLevel)
      Throw exception if paragraph embedding level is invalid.
      private static void validateTypes​(byte[] types)
      Throw exception if type array is invalid.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • BidiOrder

        public BidiOrder​(byte[] types)
        Initialize using an array of direction types. Types range from TYPE_MIN to TYPE_MAX inclusive and represent the direction codes of the characters in the text.
        Parameters:
        types - the types array
      • BidiOrder

        public BidiOrder​(byte[] types,
                         byte paragraphEmbeddingLevel)
        Initialize using an array of direction types and an externally supplied paragraph embedding level. The embedding level may be -1, 0, or 1. -1 means to apply the default algorithm (rules P2 and P3), 0 is for LTR paragraphs, and 1 is for RTL paragraphs.
        Parameters:
        types - the types array
        paragraphEmbeddingLevel - the externally supplied paragraph embedding level.
      • BidiOrder

        public BidiOrder​(char[] text,
                         int offset,
                         int length,
                         byte paragraphEmbeddingLevel)
    • Method Detail

      • getDirection

        public static final byte getDirection​(char c)
      • runAlgorithm

        private void runAlgorithm()
        The algorithm. Does not include line-based processing (Rules L1, L2). These are applied later in the line-based phase of the algorithm.
      • determineParagraphEmbeddingLevel

        private void determineParagraphEmbeddingLevel()
        1) determining the paragraph level.

        Rules P2, P3.

        At the end of this function, the member variable paragraphEmbeddingLevel is set to either 0 or 1.

      • determineExplicitEmbeddingLevels

        private void determineExplicitEmbeddingLevels()
        Process embedding format codes.

        Calls processEmbeddings to generate an embedding array from the explicit format codes. The embedding overrides in the array are then applied to the result types, and the result levels are initialized.

        See Also:
        processEmbeddings(byte[], byte)
      • removeExplicitCodes

        private int removeExplicitCodes()
        Rules X9. Remove explicit codes so that they may be ignored during the remainder of the main portion of the algorithm. The length of the resulting text is returned.
        Returns:
        the length of the data excluding explicit codes and BN.
      • reinsertExplicitCodes

        private int reinsertExplicitCodes​(int textLength)
        Reinsert levels information for explicit codes. This is for ease of relating the level information to the original input data. Note that the levels assigned to these codes are arbitrary, they're chosen so as to avoid breaking level runs.
        Parameters:
        textLength - the length of the data after compression
        Returns:
        the length of the data (original length of types array supplied to constructor)
      • processEmbeddings

        private static byte[] processEmbeddings​(byte[] resultTypes,
                                                byte paragraphEmbeddingLevel)
        2) determining explicit levels Rules X1 - X8 The interaction of these rules makes handling them a bit complex. This examines resultTypes but does not modify it. It returns embedding and override information in the result array. The low 7 bits are the level, the high bit is set if the level is an override, and clear if it is an embedding.
      • resolveWeakTypes

        private void resolveWeakTypes​(int start,
                                      int limit,
                                      byte level,
                                      byte sor,
                                      byte eor)
        3) resolving weak types Rules W1-W7. Note that some weak types (EN, AN) remain after this processing is complete.
      • resolveNeutralTypes

        private void resolveNeutralTypes​(int start,
                                         int limit,
                                         byte level,
                                         byte sor,
                                         byte eor)
        6) resolving neutral types Rules N1-N2.
      • resolveImplicitLevels

        private void resolveImplicitLevels​(int start,
                                           int limit,
                                           byte level,
                                           byte sor,
                                           byte eor)
        7) resolving implicit embedding levels Rules I1, I2.
      • getLevels

        public byte[] getLevels()
      • getLevels

        public byte[] getLevels​(int[] linebreaks)
        Return levels array breaking lines at offsets in linebreaks.
        Rule L1.

        The returned levels array contains the resolved level for each bidi code passed to the constructor.

        The linebreaks array must include at least one value. The values must be in strictly increasing order (no duplicates) between 1 and the length of the text, inclusive. The last value must be the length of the text.

        Parameters:
        linebreaks - the offsets at which to break the paragraph
        Returns:
        the resolved levels of the text
      • getReordering

        public int[] getReordering​(int[] linebreaks)
        Return reordering array breaking lines at offsets in linebreaks.

        The reordering array maps from a visual index to a logical index. Lines are concatenated from left to right. So for example, the fifth character from the left on the third line is

         getReordering(linebreaks)[linebreaks[1] + 4]
        (linebreaks[1] is the position after the last character of the second line, which is also the index of the first character on the third line, and adding four gets the fifth character from the left).

        The linebreaks array must include at least one value. The values must be in strictly increasing order (no duplicates) between 1 and the length of the text, inclusive. The last value must be the length of the text.

        Parameters:
        linebreaks - the offsets at which to break the paragraph.
      • computeMultilineReordering

        private static int[] computeMultilineReordering​(byte[] levels,
                                                        int[] linebreaks)
        Return multiline reordering array for a given level array. Reordering does not occur across a line break.
      • computeReordering

        private static int[] computeReordering​(byte[] levels)
        Return reordering array for a given level array. This reorders a single line. The reordering is a visual to logical map. For example, the leftmost char is string.charAt(order[0]). Rule L2.
      • getBaseLevel

        public byte getBaseLevel()
        Return the base level of the paragraph.
      • isWhitespace

        private static boolean isWhitespace​(byte biditype)
        Return true if the type is considered a whitespace type for the line break rules.
      • typeForLevel

        private static byte typeForLevel​(int level)
        Return the strong type (L or R) corresponding to the level.
      • findRunLimit

        private int findRunLimit​(int index,
                                 int limit,
                                 byte[] validSet)
        Return the limit of the run starting at index that includes only resultTypes in validSet. This checks the value at index, and will return index if that value is not in validSet.
      • findRunStart

        private int findRunStart​(int index,
                                 byte[] validSet)
        Return the start of the run including index that includes only resultTypes in validSet. This assumes the value at index is valid, and does not check it.
      • setTypes

        private void setTypes​(int start,
                              int limit,
                              byte newType)
        Set resultTypes from start up to (but not including) limit to newType.
      • setLevels

        private void setLevels​(int start,
                               int limit,
                               byte newLevel)
        Set resultLevels from start up to (but not including) limit to newLevel.
      • validateTypes

        private static void validateTypes​(byte[] types)
        Throw exception if type array is invalid.
      • validateParagraphEmbeddingLevel

        private static void validateParagraphEmbeddingLevel​(byte paragraphEmbeddingLevel)
        Throw exception if paragraph embedding level is invalid. Special allowance for -1 so that default processing can still be performed when using this API.
      • validateLineBreaks

        private static void validateLineBreaks​(int[] linebreaks,
                                               int textLength)
        Throw exception if line breaks array is invalid.