filterNotNullTo supported

idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/result/AddToCollectionTransformation.kt

@@ -44,6 +44,10 @@ class AddToCollectionTransformation(
                 FilterIndexedToTransformation.create(loop, previousTransformation.inputVariable, previousTransformation.indexVariable, targetCollection, previousTransformation.condition)
             }
 
+            is FilterNotNullTransformation -> {
+                FilterNotNullToTransformation.create(loop, targetCollection)
+            }
+
             is MapTransformation -> {
                 MapToTransformation.create(loop, previousTransformation.inputVariable, targetCollection, previousTransformation.mapping)
             }
@@ -253,6 +257,35 @@ class FilterIndexedToTransformation private constructor(
     }
 }
 
+class FilterNotNullToTransformation private constructor(
+        loop: KtForExpression,
+        private val targetCollection: KtExpression
+) : ReplaceLoopResultTransformation(loop) {
+
+    override val presentation: String
+        get() = "filterNotNullTo()"
+
+    override fun generateCode(chainedCallGenerator: ChainedCallGenerator): KtExpression {
+        return chainedCallGenerator.generate("filterNotNullTo($0)", targetCollection)
+    }
+
+    companion object {
+        fun create(
+                loop: KtForExpression,
+                targetCollection: KtExpression
+        ): ResultTransformation {
+            val initialization = targetCollection.detectInitializationBeforeLoop(loop, checkNoOtherUsagesInLoop = true)
+            if (initialization != null && initialization.initializer.hasNoSideEffect()) {
+                val transformation = FilterNotNullToTransformation(loop, initialization.initializer)
+                return AssignToVariableResultTransformation.createDelegated(transformation, initialization)
+            }
+            else {
+                return FilterNotNullToTransformation(loop, targetCollection)
+            }
+        }
+    }
+}
+
 class MapToTransformation private constructor(
         loop: KtForExpression,
         private val inputVariable: KtCallableDeclaration,

idea/testData/intentions/loopToCallChain/filterNotNullTo.kt

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterNotNullTo()'"
+fun foo(list: List<String?>, target: MutableCollection<String>) {
+    <caret>for (s in list) {
+        if (s != null) {
+            target.add(s)
+        }
+    }
+}

idea/testData/intentions/loopToCallChain/filterNotNullTo.kt.after

@@ -0,0 +1,5 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterNotNullTo()'"
+fun foo(list: List<String?>, target: MutableCollection<String>) {
+    <caret>list.filterNotNullTo(target)
+}

idea/testData/intentions/loopToCallChain/filterNotNullTo2.kt

@@ -0,0 +1,12 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterNotNullTo()'"
+import java.util.ArrayList
+
+fun foo(list: List<String?>) {
+    val target = ArrayList<String>(1000)
+    <caret>for (s in list) {
+        if (s != null) {
+            target.add(s)
+        }
+    }
+}

idea/testData/intentions/loopToCallChain/filterNotNullTo2.kt.after

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterNotNullTo()'"
+import java.util.ArrayList
+
+fun foo(list: List<String?>) {
+    val <caret>target = list.filterNotNullTo(ArrayList<String>(1000))
+}