Do not generate redundant .toList()

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

@@ -378,7 +378,7 @@ class AssignToListTransformation(
         get() = "toList()"
 
     override fun mergeWithPrevious(previousTransformation: SequenceTransformation): ResultTransformation? {
-        if (previousTransformation !is FilterTransformation) return null
+        //TODO: can be any SequenceTransformation's that return not List<T>? Also this code needs to be changed when .asSequence() used
         return AssignSequenceTransformationResultTransformation(previousTransformation, initialization)
     }
 

idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/sequence/FilterTransformation.kt

@@ -76,6 +76,22 @@ class FilterTransformation(
      */
     object Matcher : SequenceTransformationMatcher {
         override fun match(state: MatchingState): SequenceTransformationMatch? {
+            var (transformation, currentState) = matchOneTransformation(state, takeWhileAllowed = true) ?: return null
+
+/*
+            if (transformation is FilterTransformation || transformation is FilterIndexedTransformation) {
+                while (true) {
+                    val (nextTransformation, nextState) = matchOneTransformation(currentState, takeWhileAllowed = false) ?: break
+                    if (nextTransformation !is FilterTransformation && nextTransformation !is FilterIndexedTransformation) break
+
+                }
+            }
+*/
+
+            return SequenceTransformationMatch(transformation, currentState)
+        }
+
+        private fun matchOneTransformation(state: MatchingState, takeWhileAllowed: Boolean): Pair<SequenceTransformation, MatchingState>? {
             val ifStatement = state.statements.firstOrNull() as? KtIfExpression ?: return null
             if (ifStatement.`else` != null) return null
             val condition = ifStatement.condition ?: return null
@@ -84,7 +100,7 @@ class FilterTransformation(
             if (state.statements.size == 1) {
                 val transformation = createFilterTransformation(state.outerLoop, state.inputVariable, state.indexVariable, condition, isInverse = false)
                 val newState = state.copy(statements = listOf(then))
-                return SequenceTransformationMatch(transformation, newState)
+                return transformation to newState
             }
             else {
                 val statement = then.blockExpressionsOrSingle().singleOrNull() ?: return null
@@ -93,14 +109,15 @@ class FilterTransformation(
                         if (statement.targetLoop() != state.innerLoop) return null
                         val transformation = createFilterTransformation(state.outerLoop, state.inputVariable, state.indexVariable, condition, isInverse = true)
                         val newState = state.copy(statements = state.statements.drop(1))
-                        return SequenceTransformationMatch(transformation, newState)
+                        return transformation to newState
                     }
 
                     is KtBreakExpression -> {
+                        if (!takeWhileAllowed) return null
                         if (statement.targetLoop() != state.outerLoop) return null
                         val transformation = TakeWhileTransformation(state.outerLoop, state.inputVariable, condition.negate())
                         val newState = state.copy(statements = state.statements.drop(1))
-                        return SequenceTransformationMatch(transformation, newState)
+                        return transformation to newState
                     }
 
                     else -> return null
@@ -108,6 +125,8 @@ class FilterTransformation(
             }
         }
 
+//        private fun mergeFilterTransformations(transformation1: )
+
         //TODO: choose filter or filterNot depending on condition
         private fun createFilterTransformation(
                 loop: KtForExpression,

idea/testData/intentions/loopToCallChain/assignFilterIndexed.kt

@@ -0,0 +1,13 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterIndexed{}'"
+import java.util.*
+
+fun foo(list: List<String>): List<String> {
+    val result = ArrayList<String>()
+    <caret>for ((index, s) in list.withIndex()) {
+        if (s.length > index) {
+            result.add(s)
+        }
+    }
+    return result
+}

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

@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterIndexed{}'"
+import java.util.*
+
+fun foo(list: List<String>): List<String> {
+    val <caret>result = list.filterIndexed { index, s -> s.length > index }
+    return result
+}

idea/testData/intentions/loopToCallChain/assignFilterNotNull.kt

@@ -0,0 +1,13 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterNotNull()'"
+import java.util.ArrayList
+
+fun foo(list: List<String?>): List<String> {
+    val result = ArrayList<String>()
+    <caret>for (s in list) {
+        if (s != null) {
+            result.add(s)
+        }
+    }
+    return result
+}

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

@@ -0,0 +1,8 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterNotNull()'"
+import java.util.ArrayList
+
+fun foo(list: List<String?>): List<String> {
+    val <caret>result = list.filterNotNull()
+    return result
+}

idea/testData/intentions/loopToCallChain/assignMap2.kt

@@ -0,0 +1,14 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filter{}.map{}'"
+import java.util.ArrayList
+
+fun foo(list: List<String>): List<Int> {
+    val result = ArrayList<Int>()
+    <caret>for (s in list) {
+        if (s.length > 0) {
+            val h = s.hashCode()
+            result.add(h)
+        }
+    }
+    return result
+}

idea/testData/intentions/loopToCallChain/assignMap2.kt.after

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filter{}.map{}'"
+import java.util.ArrayList
+
+fun foo(list: List<String>): List<Int> {
+    val <caret>result = list
+            .filter { it.length > 0 }
+            .map { it.hashCode() }
+    return result
+}