diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/library/scala/collection/generic/GenericTraversableTemplate.scala | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/src/library/scala/collection/generic/GenericTraversableTemplate.scala b/src/library/scala/collection/generic/GenericTraversableTemplate.scala index 6a1bff6cec..d6f01718ff 100644 --- a/src/library/scala/collection/generic/GenericTraversableTemplate.scala +++ b/src/library/scala/collection/generic/GenericTraversableTemplate.scala @@ -12,6 +12,7 @@ package scala.collection package generic import mutable.Builder +import annotation.migration import annotation.unchecked.uncheckedVariance /** A template class for companion objects of ``regular`` collection classes @@ -136,18 +137,27 @@ trait GenericTraversableTemplate[+A, +CC[X] <: Traversable[X]] extends HasNewBui * element type of this $coll is a `Traversable`. * @return a two-dimensional $coll of ${coll}s which has as ''n''th row * the ''n''th column of this $coll. + * @throws `IllegalArgumentException` if all collections in this $coll + * are not of the same size. */ + @migration(2, 9, "As of 2.9, transpose throws an exception if collections are not uniformly sized.") def transpose[B](implicit asTraversable: A => /*<:<!!!*/ TraversableOnce[B]): CC[CC[B] @uncheckedVariance] = { if (isEmpty) return genericBuilder[CC[B]].result - val bs: IndexedSeq[Builder[B, CC[B]]] = IndexedSeq.fill(asTraversable(head).size)(genericBuilder[B]) + def fail = throw new IllegalArgumentException("transpose requires all collections have the same size") + + val headSize = asTraversable(head).size + val bs: IndexedSeq[Builder[B, CC[B]]] = IndexedSeq.fill(headSize)(genericBuilder[B]) for (xs <- this) { var i = 0 for (x <- asTraversable(xs)) { + if (i >= headSize) fail bs(i) += x i += 1 } + if (i != headSize) + fail } val bb = genericBuilder[CC[B]] for (b <- bs) bb += b.result |