Make stream plus operation actually streaming (lazy).

libraries/stdlib/src/generated/_Generators.kt

@@ -420,9 +420,7 @@ public fun <T> Iterable<T>.plus(collection: Iterable<T>) : List<T> {
  * Returns a stream containing all elements of original stream and then all elements of the given *collection*
  */
 public fun <T> Stream<T>.plus(collection: Iterable<T>) : Stream<T> {
-    val answer = toArrayList()
-    answer.addAll(collection)
-    return answer.stream()
+    return Multistream(streamOf(this, collection.stream()))
     
 }
 
@@ -530,9 +528,7 @@ public fun <T> Iterable<T>.plus(element: T) : List<T> {
  * Returns a stream containing all elements of original stream and then the given element
  */
 public fun <T> Stream<T>.plus(element: T) : Stream<T> {
-    val answer = toArrayList()
-    answer.add(element)
-    return answer.stream()
+    return Multistream(streamOf(this, streamOf(element)))
     
 }
 
@@ -540,9 +536,7 @@ public fun <T> Stream<T>.plus(element: T) : Stream<T> {
  * Returns a stream containing all elements of original stream and then all elements of the given *stream*
  */
 public fun <T> Stream<T>.plus(stream: Stream<T>) : Stream<T> {
-    val answer = toArrayList()
-    answer.addAll(stream)
-    return answer.stream()
+    return Multistream(streamOf(this, stream))
     
 }
 

libraries/stdlib/src/generated/_Streams.kt

@@ -0,0 +1,96 @@
+package kotlin
+
+//
+// NOTE THIS FILE IS AUTO-GENERATED by the GenerateStandardLib.kt
+// See: https://github.com/JetBrains/kotlin/tree/master/libraries/stdlib
+//
+
+import java.util.*
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun <T> Array<out T>.stream() : Stream<T> {
+    return object : Stream<T> { override fun iterator() : Iterator<T> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun BooleanArray.stream() : Stream<Boolean> {
+    return object : Stream<Boolean> { override fun iterator() : Iterator<Boolean> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun ByteArray.stream() : Stream<Byte> {
+    return object : Stream<Byte> { override fun iterator() : Iterator<Byte> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun CharArray.stream() : Stream<Char> {
+    return object : Stream<Char> { override fun iterator() : Iterator<Char> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun DoubleArray.stream() : Stream<Double> {
+    return object : Stream<Double> { override fun iterator() : Iterator<Double> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun FloatArray.stream() : Stream<Float> {
+    return object : Stream<Float> { override fun iterator() : Iterator<Float> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun IntArray.stream() : Stream<Int> {
+    return object : Stream<Int> { override fun iterator() : Iterator<Int> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun LongArray.stream() : Stream<Long> {
+    return object : Stream<Long> { override fun iterator() : Iterator<Long> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun ShortArray.stream() : Stream<Short> {
+    return object : Stream<Short> { override fun iterator() : Iterator<Short> { return this@stream.iterator() } }
+    
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun <T> Iterable<T>.stream() : Stream<T> {
+    return object : Stream<T> { override fun iterator() : Iterator<T> { return this@stream.iterator() } }
+}
+
+/**
+ * Returns a stream from the given collection
+ */
+public fun <T> Stream<T>.stream() : Stream<T> {
+    return this
+    
+}
+

libraries/stdlib/src/kotlin/collections/Stream.kt

@@ -6,11 +6,7 @@ public trait Stream<out T> {
     public fun iterator(): Iterator<T>
 }
 
-public fun <T> Iterable<T>.stream(): Stream<T> = object : Stream<T> {
-    override fun iterator(): Iterator<T> {
-        return this@stream.iterator()
-    }
-}
+public fun <T> streamOf(vararg elements : T) : Stream<T> = elements.stream()
 
 public class FilteringStream<T>(val stream: Stream<T>, val sendWhen: Boolean = true, val predicate: (T) -> Boolean) : Stream<T> {
     override fun iterator(): Iterator<T> = object : AbstractIterator<T>() {
@@ -84,6 +80,35 @@ public class FlatteningStream<T, R>(val stream: Stream<T>, val transformer: (T)
     }
 }
 
+public class Multistream<T>(val streams: Stream<Stream<T>>) : Stream<T> {
+    override fun iterator(): Iterator<T> = object : AbstractIterator<T>() {
+        val iterator = streams.iterator()
+        var streamIterator: Iterator<T>? = null
+        override fun computeNext() {
+            while (streamIterator == null) {
+                if (!iterator.hasNext()) {
+                    done()
+                    break;
+                } else {
+                    val stream = iterator.next()
+                    val nextStreamIterator = stream.iterator()
+                    if (nextStreamIterator.hasNext())
+                        streamIterator = nextStreamIterator
+                }
+            }
+
+            val currentStreamIterator = streamIterator
+            if (currentStreamIterator == null) {
+                done()
+            } else {
+                setNext(currentStreamIterator.next())
+                if (!currentStreamIterator.hasNext())
+                    streamIterator = null
+            }
+        }
+    }
+}
+
 public class LimitedStream<T>(val stream: Stream<T>, val stopWhen: Boolean = true, val predicate: (T) -> Boolean) : Stream<T> {
     override fun iterator(): Iterator<T> = object : AbstractIterator<T>() {
         val iterator = stream.iterator()

libraries/stdlib/src/kotlin/dom/Dom.kt

@@ -1,6 +1,5 @@
 package kotlin.dom
 
-import kotlin.*
 import kotlin.support.*
 import java.util.*
 import org.w3c.dom.*

libraries/tools/kotlin-stdlib-gen/src/generators/GenerateCollections.kt

@@ -16,6 +16,7 @@ fun generateCollectionsAPI(outDir : File) {
     guards().writeTo(File(outDir, "_Guards.kt")) { build() }
     generators().writeTo(File(outDir, "_Generators.kt")) { build() }
     strings().writeTo(File(outDir, "_Strings.kt")) { build() }
+    streams().writeTo(File(outDir, "_Streams.kt")) { build() }
     specialJVM().writeTo(File(outDir, "_SpecialJVM.kt")) { build() }
 
     numeric().writeTo(File(outDir, "_Numeric.kt")) {

libraries/tools/kotlin-stdlib-gen/src/templates/Generators.kt

@@ -18,12 +18,9 @@ fun generators(): List<GenericFunction> {
 
         doc(Streams) { "Returns a stream containing all elements of original stream and then the given element" }
         returns(Streams) { "Stream<T>" }
-        // TODO: Implement lazy behavior
         body(Streams) {
             """
-                val answer = toArrayList()
-                answer.add(element)
-                return answer.stream()
+            return Multistream(streamOf(this, streamOf(element)))
             """
         }
     }
@@ -32,7 +29,6 @@ fun generators(): List<GenericFunction> {
         exclude(Streams)
         doc { "Returns a list containing all elements of original collection and then all elements of the given *collection*" }
         returns("List<T>")
-
         body {
             """
                 val answer = toArrayList()
@@ -46,7 +42,6 @@ fun generators(): List<GenericFunction> {
         exclude(Streams)
         doc { "Returns a list containing all elements of original collection and then all elements of the given *collection*" }
         returns("List<T>")
-
         body {
             """
                 val answer = toArrayList()
@@ -60,13 +55,9 @@ fun generators(): List<GenericFunction> {
         only(Streams)
         doc { "Returns a stream containing all elements of original stream and then all elements of the given *collection*" }
         returns("Stream<T>")
-
-        // TODO: Implement lazy behavior
         body {
             """
-                val answer = toArrayList()
-                answer.addAll(collection)
-                return answer.stream()
+            return Multistream(streamOf(this, collection.stream()))
             """
         }
     }
@@ -76,11 +67,8 @@ fun generators(): List<GenericFunction> {
         doc { "Returns a stream containing all elements of original stream and then all elements of the given *stream*" }
         returns("Stream<T>")
         body {
-            // TODO: Implement lazy behavior
             """
-                val answer = toArrayList()
-                answer.addAll(stream)
-                return answer.stream()
+            return Multistream(streamOf(this, stream))
             """
         }
     }

libraries/tools/kotlin-stdlib-gen/src/templates/Stream.kt

@@ -0,0 +1,25 @@
+package templates
+
+import templates.Family.*
+
+fun streams(): List<GenericFunction> {
+    val templates = arrayListOf<GenericFunction>()
+
+    templates add f("stream()") {
+        doc { "Returns a stream from the given collection" }
+        returns("Stream<T>")
+        body {
+            """
+            return object : Stream<T> { override fun iterator() : Iterator<T> { return this@stream.iterator() } }
+            """
+        }
+
+        body(Streams) {
+            """
+            return this
+            """
+        }
+    }
+
+    return templates
+}