Method pairs

core/src/main/java/org/apache/calcite/util/Util.java:2118–2121

Given a list with N elements [e 0 , e 1 , ..., e N-1 ] (where N is even), returns a list of the N / 2 elements [ (e 0 , e 1 ), (e 2 , e 3 ), ... ].

(final List<E> list)

   * [ (e<sub>0</sub>, e<sub>1</sub>),
   * (e<sub>2</sub>, e<sub>3</sub>), ... ]. */
  public static <E> List<Pair<E, E>> pairs(final List<E> list) {
    return Pair.zip(quotientList(list, 2, 0),
        quotientList(list, 2, 1));
  }

  /** Returns the first value if it is not null,
   * otherwise the second value.