TrailingComma: Join Lines should remove trailing comma

#KT-34744
#KT-36084 Fixed

idea/idea-core/src/org/jetbrains/kotlin/idea/core/util/PsiLinesUtils.kt

@@ -5,11 +5,13 @@
 
 package org.jetbrains.kotlin.idea.core.util
 
+import com.intellij.openapi.editor.Document
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.*
 import com.intellij.psi.util.PsiTreeUtil
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
+import kotlin.math.abs
 
 fun PsiFile.getLineStartOffset(line: Int): Int? {
     return getLineStartOffset(line, skipWhitespace = true)
@@ -56,4 +58,8 @@ fun PsiElement.getLineCount(): Int {
     return (text ?: "").count { it == '\n' } + 1
 }
 
-fun PsiElement.isMultiLine(): Boolean = getLineCount() > 1
+fun PsiElement.isMultiLine(): Boolean = getLineCount() > 1
+
+fun Document.getLineCountInRange(textRange: TextRange): Int = abs(getLineNumber(textRange.startOffset) - getLineNumber(textRange.endOffset))
+
+fun Document.containsLineBreakInRange(textRange: TextRange): Boolean = getLineCountInRange(textRange) != 0

idea/resources/META-INF/plugin-common.xml

@@ -813,6 +813,7 @@
     <joinLinesHandler implementation="org.jetbrains.kotlin.idea.joinLines.JoinBlockIntoSingleStatementHandler"/>
     <joinLinesHandler implementation="org.jetbrains.kotlin.idea.joinLines.JoinStatementsAddSemicolonHandler"/>
     <joinLinesHandler implementation="org.jetbrains.kotlin.idea.joinLines.JoinToStringTemplateHandler"/>
+    <joinLinesHandler implementation="org.jetbrains.kotlin.idea.joinLines.JoinWithTrailingCommaHandler"/>
 
     <targetElementEvaluator
         language="kotlin"

idea/src/org/jetbrains/kotlin/idea/joinLines/JoinWithTrailingCommaHandler.kt

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.idea.joinLines
+
+import com.intellij.codeInsight.editorActions.JoinLinesHandlerDelegate
+import com.intellij.codeInsight.editorActions.JoinLinesHandlerDelegate.CANNOT_JOIN
+import com.intellij.openapi.editor.Document
+import com.intellij.psi.PsiFile
+import com.intellij.psi.codeStyle.CodeStyleManager
+import org.jetbrains.kotlin.idea.core.util.containsLineBreakInRange
+import org.jetbrains.kotlin.idea.formatter.TrailingCommaHelper
+import org.jetbrains.kotlin.idea.util.addTrailingCommaIsAllowedForThis
+import org.jetbrains.kotlin.psi.KtElement
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.psiUtil.parentsWithSelf
+import org.jetbrains.kotlin.psi.psiUtil.startOffset
+
+class JoinWithTrailingCommaHandler : JoinLinesHandlerDelegate {
+    override fun tryJoinLines(document: Document, file: PsiFile, start: Int, end: Int): Int {
+        if (file !is KtFile) return CANNOT_JOIN
+        val commaOwner = file.findElementAt(start)
+            ?.parentsWithSelf
+            ?.filter { !document.containsLineBreakInRange(it.textRange) }
+            ?.findLast { it.addTrailingCommaIsAllowedForThis() } as? KtElement
+            ?: return CANNOT_JOIN
+
+        if (TrailingCommaHelper.needComma(commaOwner, null, true)) return CANNOT_JOIN
+        val result = CodeStyleManager.getInstance(file.project).reformat(commaOwner) as KtElement
+        return TrailingCommaHelper.elementAfterLastElement(result)?.startOffset ?: end - 1
+    }
+
+}

idea/testData/joinLines/removeTrailingComma/destructionDeclaration.kt

@@ -0,0 +1,4 @@
+fun a() {
+    val (a,<caret>
+    b,) = 1 to 2
+}

idea/testData/joinLines/removeTrailingComma/destructionDeclaration.kt.after

@@ -0,0 +1,3 @@
+fun a() {
+    val (a, b<caret>) = 1 to 2
+}

idea/testData/joinLines/removeTrailingComma/destructionDeclarationInLambda.kt

@@ -0,0 +1,4 @@
+fun a() {
+    val <caret>a = { (a, b // awd
+              ,/**/), c, -> }
+}

idea/testData/joinLines/removeTrailingComma/destructionDeclarationInLambda.kt.after

@@ -0,0 +1,3 @@
+fun a() {
+    val a = { (a, b /* awd*//**/), c -> <caret>}
+}

idea/testData/joinLines/removeTrailingComma/inner.kt

@@ -0,0 +1,4 @@
+fun a(<caret>
+    a: Int, b: Any = fun(a: Int,),) {
+
+}

idea/testData/joinLines/removeTrailingComma/inner.kt.after

@@ -0,0 +1,3 @@
+fun a(a: Int, b: Any = fun(a: Int)<caret>) {
+
+}

idea/testData/joinLines/removeTrailingComma/lambda.kt

@@ -0,0 +1,6 @@
+fun a() {
+    <caret>val a = { a: Int,
+    b: Int, ->
+
+    }
+}

idea/testData/joinLines/removeTrailingComma/lambda.kt.after

@@ -0,0 +1,5 @@
+fun a() {
+    val a = { a: Int, b: Int <caret>->
+
+    }
+}

idea/testData/joinLines/removeTrailingComma/simple.kt

@@ -0,0 +1,4 @@
+fun a(<caret>
+    a: Int,) {
+
+}

idea/testData/joinLines/removeTrailingComma/simple.kt.after

@@ -0,0 +1,3 @@
+fun a(a: Int<caret>) {
+
+}

idea/testData/joinLines/removeTrailingComma/typeParameters.kt

@@ -0,0 +1,2 @@
+fun <T,<caret>
+        B,> a() = Unit

idea/testData/joinLines/removeTrailingComma/typeParameters.kt.after

@@ -0,0 +1 @@
+fun <T, B<caret>> a() = Unit

idea/testData/joinLines/removeTrailingComma/whenEntry.kt

@@ -0,0 +1,7 @@
+fun a() {
+    when (val b = 5) {
+        1, 2,
+        <caret>3,
+        ->
+    }
+}

idea/testData/joinLines/removeTrailingComma/whenEntry.kt.after

@@ -0,0 +1,6 @@
+fun a() {
+    when (val b = 5) {
+        1, 2,
+        3, ->
+    }
+}

idea/testData/joinLines/removeTrailingComma/whenEntry2.kt

@@ -0,0 +1,6 @@
+fun a() {
+    when (val b = 5) {
+        <caret>1, 2,
+        3, ->
+    }
+}

idea/testData/joinLines/removeTrailingComma/whenEntry2.kt.after

@@ -0,0 +1,5 @@
+fun a() {
+    when (val b = 5) {
+        1, 2, 3 <caret>->
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/intentions/declarations/JoinLinesTestGenerated.java

@@ -393,6 +393,59 @@ public class JoinLinesTestGenerated extends AbstractJoinLinesTest {
         }
     }
 
+    @TestMetadata("idea/testData/joinLines/removeTrailingComma")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class RemoveTrailingComma extends AbstractJoinLinesTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInRemoveTrailingComma() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("idea/testData/joinLines/removeTrailingComma"), Pattern.compile("^(.+)\\.kt$"), null, true);
+        }
+
+        @TestMetadata("destructionDeclaration.kt")
+        public void testDestructionDeclaration() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/destructionDeclaration.kt");
+        }
+
+        @TestMetadata("destructionDeclarationInLambda.kt")
+        public void testDestructionDeclarationInLambda() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/destructionDeclarationInLambda.kt");
+        }
+
+        @TestMetadata("inner.kt")
+        public void testInner() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/inner.kt");
+        }
+
+        @TestMetadata("lambda.kt")
+        public void testLambda() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/lambda.kt");
+        }
+
+        @TestMetadata("simple.kt")
+        public void testSimple() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/simple.kt");
+        }
+
+        @TestMetadata("typeParameters.kt")
+        public void testTypeParameters() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/typeParameters.kt");
+        }
+
+        @TestMetadata("whenEntry.kt")
+        public void testWhenEntry() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/whenEntry.kt");
+        }
+
+        @TestMetadata("whenEntry2.kt")
+        public void testWhenEntry2() throws Exception {
+            runTest("idea/testData/joinLines/removeTrailingComma/whenEntry2.kt");
+        }
+    }
+
     @TestMetadata("idea/testData/joinLines/stringTemplate")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)