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author | Aleksandar Prokopec <axel22@gmail.com> | 2012-06-28 19:48:31 +0200 |
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committer | Aleksandar Prokopec <axel22@gmail.com> | 2012-06-28 19:48:31 +0200 |
commit | b379ff4f59c139ff7d2b77e7e808f0b74aa9f268 (patch) | |
tree | d531663cc08c71cc2631c119403af3032c71b543 /test/files/run/t3326.scala | |
parent | 2f0d94c02ab328a3f8da25b5ab8f402a68143af3 (diff) | |
parent | 6f08c06a35a0b70c49e23a296b13ac391a460584 (diff) | |
download | scala-b379ff4f59c139ff7d2b77e7e808f0b74aa9f268.tar.gz scala-b379ff4f59c139ff7d2b77e7e808f0b74aa9f268.tar.bz2 scala-b379ff4f59c139ff7d2b77e7e808f0b74aa9f268.zip |
Merge branch 'master' into issue/5846,4597,4027,4112
Conflicts:
src/library/scala/collection/MapLike.scala
src/library/scala/collection/SortedMapLike.scala
Diffstat (limited to 'test/files/run/t3326.scala')
-rw-r--r-- | test/files/run/t3326.scala | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/test/files/run/t3326.scala b/test/files/run/t3326.scala new file mode 100644 index 0000000000..f70cb01504 --- /dev/null +++ b/test/files/run/t3326.scala @@ -0,0 +1,74 @@ + + + +import scala.math.Ordering + + + +/** The heart of the problem - we want to retain the ordering when + * using `++` on sorted maps. + * + * There are 2 `++` overloads - a generic one in traversables and + * a map-specific one in `MapLike` - which knows about the ordering. + * + * The problem here is that the expected return type for the expression + * in which `++` appears drives the decision of the overload that needs + * to be taken. + * The `collection.SortedMap` does not have `++` overridden to return + * `SortedMap`, but `immutable.Map` instead. + * This is why `collection.SortedMap` used to resort to the generic + * `TraversableLike.++` which knows nothing about the ordering. + * + * To avoid `collection.SortedMap`s resort to the more generic `TraverableLike.++`, + * we override the `MapLike.++` overload in `collection.SortedMap` to return + * the proper type `SortedMap`. + */ +object Test { + + def main(args: Array[String]) { + testCollectionSorted() + testImmutableSorted() + } + + def testCollectionSorted() { + import collection._ + val order = implicitly[Ordering[Int]].reverse + var m1: SortedMap[Int, String] = SortedMap.empty[Int, String](order) + var m2: SortedMap[Int, String] = SortedMap.empty[Int, String](order) + + m1 += (1 -> "World") + m1 += (2 -> "Hello") + + m2 += (4 -> "Bar") + m2 += (5 -> "Foo") + + val m3: SortedMap[Int, String] = m1 ++ m2 + + println(m1) + println(m2) + println(m3) + + println(m1 + (3 -> "?")) + } + + def testImmutableSorted() { + import collection.immutable._ + val order = implicitly[Ordering[Int]].reverse + var m1: SortedMap[Int, String] = SortedMap.empty[Int, String](order) + var m2: SortedMap[Int, String] = SortedMap.empty[Int, String](order) + + m1 += (1 -> "World") + m1 += (2 -> "Hello") + + m2 += (4 -> "Bar") + m2 += (5 -> "Foo") + + val m3: SortedMap[Int, String] = m1 ++ m2 + + println(m1) + println(m2) + println(m3) + + println(m1 + (3 -> "?")) + } +} |