Class SemiExternalGammaList

  • All Implemented Interfaces:
    LongCollection, LongIterable, LongList, LongStack, Stack<Long>, Comparable<List<? extends Long>>, Iterable<Long>, Collection<Long>, List<Long>

    public class SemiExternalGammaList
    extends AbstractLongList
    Provides semi-external random access to a list of γ-encoded integers.

    This class is a semi-external LongList that MG4J uses to access files containing frequencies.

    Instead, this class accesses frequencies in their compressed forms, and provides entry points for random access to each long. At construction time, entry points are computed with a certain step, which is the number of longs accessible from each entry point, or, equivalently, the maximum number of longs that will be necessary to read to access a given long.

    Warning: This class is not thread safe, and needs to be synchronised to be used in a multithreaded environment.

    Author:
    Fabien Campagne, Sebastiano Vigna
    • Constructor Detail

      • SemiExternalGammaList

        public SemiExternalGammaList​(InputBitStream longs,
                                     int step,
                                     int numLongs)
                              throws IOException
        Creates a new semi-external list.
        Parameters:
        longs - a bit stream containing γ-encoded longs.
        step - the step used to build random-access entry points, or -1 to get DEFAULT_STEP.
        numLongs - the overall number of offsets (i.e., the number of terms).
        Throws:
        IOException
      • SemiExternalGammaList

        public SemiExternalGammaList​(InputBitStream longs)
                              throws IOException
        Creates a new semi-external list.

        This quick-and-dirty constructor estimates the number of longs by checking for an EOFException.

        Parameters:
        longs - a bit stream containing γ-encoded longs.
        Throws:
        IOException