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Fix ZStream#intersperse #3730

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Merged
merged 3 commits into from
May 30, 2020
Merged

Fix ZStream#intersperse #3730

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939b53a
Fix ZStream#intersperse
iravid May 30, 2020
a420009
Prop check for the other variant
iravid May 30, 2020
d72011b
Simplify
iravid May 30, 2020
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46 changes: 46 additions & 0 deletions streams-tests/shared/src/test/scala/zio/stream/ZStreamSpec.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1625,6 +1625,52 @@ object ZStreamSpec extends ZIOBaseSpec {
.intersperse("[", "@", "]")
.runCollect
.map(result => assert(result)(equalTo(Chunk("[", "1", "]"))))
},
testM("mkString(Sep) equivalence") {
checkM(
Gen
.int(0, 10)
.flatMap(Gen.listOfN(_)(Gen.small(Gen.chunkOfN(_)(Gen.anyInt))))
) { chunks =>
val stream = ZStream.fromChunks(chunks: _*)

for {
interspersed <- stream.map(_.toString).intersperse("@").runCollect.map(_.mkString)
regular <- stream.map(_.toString).runCollect.map(_.mkString("@"))
} yield assert(interspersed)(equalTo(regular))
}
},
testM("mkString(Before, Sep, After) equivalence") {
checkM(
Gen
.int(0, 10)
.flatMap(Gen.listOfN(_)(Gen.small(Gen.chunkOfN(_)(Gen.anyInt))))
) { chunks =>
val stream = ZStream.fromChunks(chunks: _*)

for {
interspersed <- stream.map(_.toString).intersperse("[", "@", "]").runCollect.map(_.mkString)
regular <- stream.map(_.toString).runCollect.map(_.mkString("[", "@", "]"))
} yield assert(interspersed)(equalTo(regular))
}
},
testM("intersperse several from repeat effect (#3729)") {
Stream
.repeatEffect(ZIO.succeed(42))
.map(_.toString)
.take(4)
.intersperse("@")
.runCollect
.map(result => assert(result)(equalTo(Chunk("42", "@", "42", "@", "42", "@", "42"))))
},
testM("intersperse several from repeat effect chunk single element (#3729)") {
Stream
.repeatEffectChunk(ZIO.succeed(Chunk(42)))
.map(_.toString)
.intersperse("@")
.take(4)
.runCollect
.map(result => assert(result)(equalTo(Chunk("42", "@", "42", "@"))))
}
),
suite("interruptWhen")(
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22 changes: 16 additions & 6 deletions streams/shared/src/main/scala/zio/stream/ZStream.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -1688,15 +1688,25 @@ abstract class ZStream[-R, +E, +O](val process: ZManaged[R, Nothing, ZIO[R, Opti
final def intersperse[O1 >: O](middle: O1): ZStream[R, E, O1] =
ZStream {
for {
state <- ZRef.makeManaged(false)
state <- ZRef.makeManaged(true)
chunks <- self.process
pull = chunks.flatMap { os =>
state.modify { flag =>
os.foldRight(List.empty[O1] -> flag) {
case (o, (Nil, curr)) => List(o) -> !curr
case (o, (out, curr)) => (o :: middle :: out) -> !curr
state.modify { first =>
val builder = ChunkBuilder.make[O1]()
var flagResult = first

os.foreach { o =>
if (flagResult) {
flagResult = false
builder += o
} else {
builder += middle
builder += o
}
}
}.map(e => Chunk.fromIterable(e))

(builder.result(), flagResult)
}
}
} yield pull
}
Expand Down