src/share/classes/java/util/stream/LongStream.java

rev 7532 : 8015315: Stream.concat methods
Contributed-by: brian.goetz@oracle.com, henry.jen@oracle.com

*** 763,776 ****
          } else if (endExclusive - startInclusive < 0) {
              // Size of range > Long.MAX_VALUE
              // Split the range in two and concatenate
              // Note: if the range is [Long.MIN_VALUE, Long.MAX_VALUE) then
              // the lower range, [Long.MIN_VALUE, 0) will be further split in two
! //            long m = startInclusive + Long.divideUnsigned(endExclusive - startInclusive, 2) + 1;
! //            return Streams.concat(range(startInclusive, m), range(m, endExclusive));
!             // This is temporary until Streams.concat is supported
!             throw new UnsupportedOperationException();
          } else {
              return StreamSupport.longStream(
                      new Streams.RangeLongSpliterator(startInclusive, endExclusive, false));
          }
      }
--- 763,774 ----
          } else if (endExclusive - startInclusive < 0) {
              // Size of range > Long.MAX_VALUE
              // Split the range in two and concatenate
              // Note: if the range is [Long.MIN_VALUE, Long.MAX_VALUE) then
              // the lower range, [Long.MIN_VALUE, 0) will be further split in two
!             long m = startInclusive + Long.divideUnsigned(endExclusive - startInclusive, 2) + 1;
!             return concat(range(startInclusive, m), range(m, endExclusive));
          } else {
              return StreamSupport.longStream(
                      new Streams.RangeLongSpliterator(startInclusive, endExclusive, false));
          }
      }
*** 799,813 ****
              // Size of range > Long.MAX_VALUE
              // Split the range in two and concatenate
              // Note: if the range is [Long.MIN_VALUE, Long.MAX_VALUE] then
              // the lower range, [Long.MIN_VALUE, 0), and upper range,
              // [0, Long.MAX_VALUE], will both be further split in two
! //            long m = startInclusive + Long.divideUnsigned(endInclusive - startInclusive, 2) + 1;
! //            return Streams.concat(range(startInclusive, m), rangeClosed(m, endInclusive));
!             // This is temporary until Streams.concat is supported
!             throw new UnsupportedOperationException();
          } else {
              return StreamSupport.longStream(
                      new Streams.RangeLongSpliterator(startInclusive, endInclusive, true));
          }
      }
  }
--- 797,831 ----
              // Size of range > Long.MAX_VALUE
              // Split the range in two and concatenate
              // Note: if the range is [Long.MIN_VALUE, Long.MAX_VALUE] then
              // the lower range, [Long.MIN_VALUE, 0), and upper range,
              // [0, Long.MAX_VALUE], will both be further split in two
!             long m = startInclusive + Long.divideUnsigned(endInclusive - startInclusive, 2) + 1;
!             return concat(range(startInclusive, m), rangeClosed(m, endInclusive));
          } else {
              return StreamSupport.longStream(
                      new Streams.RangeLongSpliterator(startInclusive, endInclusive, true));
          }
      }
+ 
+     /**
+      * Creates a lazy concatenated {@code LongStream} whose elements are all the
+      * elements of a first {@code LongStream} succeeded by all the elements of the
+      * second {@code LongStream}. The resulting stream is ordered if both
+      * of the input streams are ordered, and parallel if either of the input
+      * streams is parallel.
+      *
+      * @param a the first stream
+      * @param b the second stream to concatenate on to end of the first stream
+      * @return the concatenation of the two streams
+      */
+     public static LongStream concat(LongStream a, LongStream b) {
+         Objects.requireNonNull(a);
+         Objects.requireNonNull(b);
+ 
+         Spliterator.OfLong split = new Streams.ConcatSpliterator.OfLong(
+                 a.spliterator(), b.spliterator());
+         return (a.isParallel() || b.isParallel())
+                ? StreamSupport.longParallelStream(split)
+                : StreamSupport.longStream(split);
+     }
  }