/// <summary>
/// Construct a decoder for a given <see cref="Packed.EliasFanoEncoder"/>.
/// The decoding index is set to just before the first encoded value.
/// </summary>
public EliasFanoDecoder(EliasFanoEncoder efEncoder)
{
this.efEncoder = efEncoder;
this.numEncoded = efEncoder.numEncoded; // not final in EliasFanoEncoder
this.numIndexEntries = efEncoder.currentEntryIndex; // not final in EliasFanoEncoder
this.indexMask = (1L << efEncoder.nIndexEntryBits) - 1;
}
public override bool Equals(object other)
{
if (!(other is EliasFanoEncoder))
{
return(false);
}
EliasFanoEncoder oefs = (EliasFanoEncoder)other;
// no equality needed for upperBound
return((this.numValues == oefs.numValues) &&
(this.numEncoded == oefs.numEncoded) &&
(this.numLowBits == oefs.numLowBits) &&
(this.numIndexEntries == oefs.numIndexEntries) &&
(this.indexInterval == oefs.indexInterval) &&
Arrays.Equals(this.upperLongs, oefs.upperLongs) &&
Arrays.Equals(this.lowerLongs, oefs.lowerLongs)); // no need to check index content
}
/// <summary>
/// Provide an indication that is better to use an <see cref="EliasFanoDocIdSet"/> than a <see cref="FixedBitSet"/>
/// to encode document identifiers. </summary>
/// <param name="numValues"> The number of document identifiers that is to be encoded. Should be non negative. </param>
/// <param name="upperBound"> The maximum possible value for a document identifier. Should be at least <paramref name="numValues"/>. </param>
/// <returns> See <see cref="EliasFanoEncoder.SufficientlySmallerThanBitSet(long, long)"/> </returns>
public static bool SufficientlySmallerThanBitSet(long numValues, long upperBound)
{
return(EliasFanoEncoder.SufficientlySmallerThanBitSet(numValues, upperBound));
}
/// <summary>
/// Construct an EliasFanoDocIdSet. For efficient encoding, the parameters should be chosen as low as possible. </summary>
/// <param name="numValues"> At least the number of document ids that will be encoded. </param>
/// <param name="upperBound"> At least the highest document id that will be encoded. </param>
public EliasFanoDocIdSet(int numValues, int upperBound)
{
efEncoder = new EliasFanoEncoder(numValues, upperBound);
}