Class IterableComparator

  • All Implemented Interfaces:

    public class IterableComparator
    extends java.lang.Object
    implements java.util.Comparator<java.lang.Iterable<?>>
    A Tuple-compatible Comparator that will sort Iterables in a manner that is consistent with the byte-representation of Tuples. In particular, if one has two Tuples, tuple1 and tuple2, it is the case that:
          == new IterableComparator().compare(tuple1, tuple2)
          == new IterableComparator().compare(tuple1.getItems(), tuple2.getItems()),
          == ByteArrayUtil.compareUnsigned(tuple1.pack(), tuple2.pack())

    The individual elements of the Iterable must be of a type that can be serialized by a Tuple. For items of identical types, they will be sorted in a way that is consistent with their natural ordering with a few caveats:

    • For floating point types, negative NaN values are sorted before all regular values, and positive NaN values are sorted after all regular values.
    • Single-precision floating point numbers are sorted before all double-precision floating point numbers.
    • UUIDs are sorted by their unsigned Big-Endian byte representation rather than their signed byte representation (which is the behavior of UUID.compareTo()).
    • Strings are sorted explicitly by their UTF-8 byte representation
    • Nested Tuples and Lists are sorted element-wise.
    • Constructor Summary

      Constructor Description
      Creates a new IterableComparator.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int compare​(java.lang.Iterable<?> iterable1, java.lang.Iterable<?> iterable2)
      Compare two Iterables in a way consistent with their byte representation.
      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
      • Methods inherited from interface java.util.Comparator

        equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong
    • Constructor Detail

      • IterableComparator

        public IterableComparator()
        Creates a new IterableComparator. This Comparator has no internal state.
    • Method Detail

      • compare

        public int compare​(java.lang.Iterable<?> iterable1,
                           java.lang.Iterable<?> iterable2)
        Compare two Iterables in a way consistent with their byte representation. This is done element-wise and is consistent with a number of other ways of sorting Tuples. This will raise an IllegalArgumentException if any of the items of either Iterable cannot be serialized by a Tuple.
        Specified by:
        compare in interface java.util.Comparator<java.lang.Iterable<?>>
        iterable1 - the first Iterable of items
        iterable2 - the second Iterable of items
        a negative number if the first iterable would sort before the second when serialized, a positive number if the opposite is true, and zero if the two are equal