Package org.apache.lucene.util.fst

Class BitTableUtil

  • class BitTableUtil
extends java.lang.Object
    Static helper methods for FST.Arc.BitTable.

    • Constructor Summary

      Constructors 
      Constructor Description
      BitTableUtil()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) static int countBits​(int bitTableBytes, FST.BytesReader reader)
      Counts all bits set in the bit-table.
      (package private) static int countBitsUpTo​(int bitIndex, FST.BytesReader reader)
      Counts the bits set up to the given bit zero-based index, exclusive.
      (package private) static boolean isBitSet​(int bitIndex, FST.BytesReader reader)
      Returns whether the bit at given zero-based index is set.
      (package private) static int nextBitSet​(int bitIndex, int bitTableBytes, FST.BytesReader reader)
      Returns the index of the next bit set following the given bit zero-based index.
      (package private) static int previousBitSet​(int bitIndex, FST.BytesReader reader)
      Returns the index of the previous bit set preceding the given bit zero-based index.
      private static long read8Bytes​(FST.BytesReader reader)  
      private static long readByte​(FST.BytesReader reader)  
      private static long readUpTo8Bytes​(int numBytes, FST.BytesReader reader)  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • BitTableUtil

        BitTableUtil()

    • Method Detail

      • isBitSet

        static boolean isBitSet​(int bitIndex,
                        FST.BytesReader reader)
                 throws java.io.IOException
        Returns whether the bit at given zero-based index is set.
        Example: bitIndex 10 means the third bit on the right of the second byte.
        Parameters:
        bitIndex - The bit zero-based index. It must be greater than or equal to 0, and strictly less than number of bit-table bytes * Byte.SIZE.
        reader - The FST.BytesReader to read. It must be positioned at the beginning of the bit-table.
        Throws:
        java.io.IOException

      • countBits

        static int countBits​(int bitTableBytes,
                     FST.BytesReader reader)
              throws java.io.IOException
        Counts all bits set in the bit-table.
        Parameters:
        bitTableBytes - The number of bytes in the bit-table.
        reader - The FST.BytesReader to read. It must be positioned at the beginning of the bit-table.
        Throws:
        java.io.IOException

      • countBitsUpTo

        static int countBitsUpTo​(int bitIndex,
                         FST.BytesReader reader)
                  throws java.io.IOException
        Counts the bits set up to the given bit zero-based index, exclusive.
        In other words, how many 1s there are up to the bit at the given index excluded.
        Example: bitIndex 10 means the third bit on the right of the second byte.
        Parameters:
        bitIndex - The bit zero-based index, exclusive. It must be greater than or equal to 0, and less than or equal to number of bit-table bytes * Byte.SIZE.
        reader - The FST.BytesReader to read. It must be positioned at the beginning of the bit-table.
        Throws:
        java.io.IOException

      • nextBitSet

        static int nextBitSet​(int bitIndex,
                      int bitTableBytes,
                      FST.BytesReader reader)
               throws java.io.IOException
        Returns the index of the next bit set following the given bit zero-based index.
        For example with bits 100011: the next bit set after index=-1 is at index=0; the next bit set after index=0 is at index=1; the next bit set after index=1 is at index=5; there is no next bit set after index=5.
        Parameters:
        bitIndex - The bit zero-based index. It must be greater than or equal to -1, and strictly less than number of bit-table bytes * Byte.SIZE.
        bitTableBytes - The number of bytes in the bit-table.
        reader - The FST.BytesReader to read. It must be positioned at the beginning of the bit-table.
        Returns:
        The zero-based index of the next bit set after the provided bitIndex; or -1 if none.
        Throws:
        java.io.IOException

      • previousBitSet

        static int previousBitSet​(int bitIndex,
                          FST.BytesReader reader)
                   throws java.io.IOException
        Returns the index of the previous bit set preceding the given bit zero-based index.
        For example with bits 100011: there is no previous bit set before index=0. the previous bit set before index=1 is at index=0; the previous bit set before index=5 is at index=1; the previous bit set before index=64 is at index=5;
        Parameters:
        bitIndex - The bit zero-based index. It must be greater than or equal to 0, and less than or equal to number of bit-table bytes * Byte.SIZE.
        reader - The FST.BytesReader to read. It must be positioned at the beginning of the bit-table.
        Returns:
        The zero-based index of the previous bit set before the provided bitIndex; or -1 if none.
        Throws:
        java.io.IOException

      • readByte

        private static long readByte​(FST.BytesReader reader)
                      throws java.io.IOException
        Throws:
        java.io.IOException

      • readUpTo8Bytes

        private static long readUpTo8Bytes​(int numBytes,
                                   FST.BytesReader reader)
                            throws java.io.IOException
        Throws:
        java.io.IOException

      • read8Bytes

        private static long read8Bytes​(FST.BytesReader reader)
                        throws java.io.IOException
        Throws:
        java.io.IOException