Supported forEach

idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/interfaces.kt

@@ -101,7 +101,8 @@ data class MatchingState(
          * Matchers can assume that indexVariable is null if it's not used in the rest of the loop
          */
         val indexVariable: KtCallableDeclaration?,
-        val initializationStatementsToDelete: Collection<KtExpression> = emptyList()
+        val initializationStatementsToDelete: Collection<KtExpression> = emptyList(),
+        val previousTransformations: List<SequenceTransformation>
 )
 
 interface TransformationMatcher {

idea/src/org/jetbrains/kotlin/idea/intentions/loopToCallChain/matchAndConvert.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.result.AddToCollectionTransformation
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.result.CountTransformation
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.result.FindTransformationMatcher
+import org.jetbrains.kotlin.idea.intentions.loopToCallChain.result.ForEachTransformation
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.sequence.FilterTransformation
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.sequence.FlatMapTransformation
 import org.jetbrains.kotlin.idea.intentions.loopToCallChain.sequence.IntroduceIndexMatcher
@@ -52,7 +53,8 @@ object MatcherRegistrar {
             IntroduceIndexMatcher,
             FilterTransformation.Matcher,
             MapTransformation.Matcher,
-            FlatMapTransformation.Matcher
+            FlatMapTransformation.Matcher,
+            ForEachTransformation.Matcher
     )
 }
 
@@ -74,7 +76,8 @@ fun match(loop: KtForExpression): MatchResult? {
             innerLoop = loop,
             statements = listOf(loop.body ?: return null),
             inputVariable = inputVariable,
-            indexVariable = indexVariable
+            indexVariable = indexVariable,
+            previousTransformations = sequenceTransformations
     )
 
     MatchLoop@

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

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.idea.intentions.loopToCallChain.result
+
+import org.jetbrains.kotlin.idea.intentions.loopToCallChain.*
+import org.jetbrains.kotlin.psi.KtCallableDeclaration
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtForExpression
+
+class ForEachTransformation(
+        loop: KtForExpression,
+        private val inputVariable: KtCallableDeclaration,
+        private val statement: KtExpression
+) : ReplaceLoopResultTransformation(loop) {
+
+    override val presentation: String
+        get() = "forEach{}"
+
+    override fun generateCode(chainedCallGenerator: ChainedCallGenerator): KtExpression {
+        val lambda = generateLambda(inputVariable, statement)
+        return chainedCallGenerator.generate("forEach $0:'{}'", lambda)
+    }
+
+    /**
+     * Matches:
+     *     for (...) {
+     *         ...
+     *         <statement>
+     *     }
+     */
+    object Matcher : TransformationMatcher {
+        override val indexVariableAllowed: Boolean
+            get() = false //TODO: support forEachIndexed
+
+        override fun match(state: MatchingState): TransformationMatch.Result? {
+            if (state.previousTransformations.isEmpty()) return null // do not suggest conversion to just ".forEach{}"
+
+            val statement = state.statements.singleOrNull() ?: return null
+            val transformation = ForEachTransformation(state.outerLoop, state.inputVariable, statement)
+            return TransformationMatch.Result(transformation)
+        }
+    }
+}

idea/testData/intentions/loopToCallChain/firstOrNull_returnNotNullIfNone2.kt

@@ -1,5 +1,4 @@
 // WITH_RUNTIME
-// IS_APPLICABLE: false
 fun foo(list: List<String?>): String? {
     <caret>for (s in list) {
         if (s == null || s.isNotEmpty()) {

idea/testData/intentions/loopToCallChain/firstOrNull_returnNotNullIfNone2.kt.after

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+fun foo(list: List<String?>): String? {
+    list
+            .filter { it == null || it.isNotEmpty() }
+            .forEach { return it }
+    return ""
+}

idea/testData/intentions/loopToCallChain/forEach.kt

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filter{}.forEach{}'"
+fun foo(list: List<String>) {
+    <caret>for (s in list) {
+        if (s.isNotBlank()) {
+            println(s)
+        }
+    }
+}

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

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filter{}.forEach{}'"
+fun foo(list: List<String>) {
+    list
+            .filter { it.isNotBlank() }
+            .forEach { println(it) }
+}

idea/testData/intentions/loopToCallChain/forEach_notAvailable.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+// IS_APPLICABLE: false
+fun foo(list: List<String>) {
+    <caret>for (s in list) {
+        println(s)
+    }
+}

idea/testData/intentions/loopToCallChain/resultCollectionUsedInsideLoop.kt

@@ -1,5 +1,4 @@
 // WITH_RUNTIME
-// IS_APPLICABLE: false
 import java.util.ArrayList
 
 fun foo(list: List<String>): List<Int> {

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

@@ -0,0 +1,10 @@
+// WITH_RUNTIME
+import java.util.ArrayList
+
+fun foo(list: List<String>): List<Int> {
+    val result = ArrayList<Int>()
+    list
+            .filter { it.length > result.size }
+            .forEach { result.add(it.hashCode()) }
+    return result
+}