Formatter: support trailing comma in value parameters

#KT-34744

idea/formatter/src/org/jetbrains/kotlin/idea/core/formatter/KotlinCodeStyleSettings.java

@@ -11,7 +11,10 @@ import com.intellij.openapi.components.ServiceManager;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.InvalidDataException;
 import com.intellij.openapi.util.WriteExternalException;
-import com.intellij.psi.codeStyle.*;
+import com.intellij.psi.codeStyle.CodeStyleSettings;
+import com.intellij.psi.codeStyle.CustomCodeStyleSettings;
+import com.intellij.psi.codeStyle.PackageEntry;
+import com.intellij.psi.codeStyle.PackageEntryTable;
 import org.jdom.Element;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -50,6 +53,7 @@ public class KotlinCodeStyleSettings extends CustomCodeStyleSettings {
     public int WRAP_EXPRESSION_BODY_FUNCTIONS = 0;
     public int WRAP_ELVIS_EXPRESSIONS = 1;
     public boolean IF_RPAREN_ON_NEW_LINE = false;
+    public boolean ALLOW_TRAILING_COMMA = true;
 
     @ReflectionUtil.SkipInEquals
     public String CODE_STYLE_DEFAULTS = null;

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/KotlinCommonBlock.kt

@@ -19,6 +19,7 @@ import com.intellij.psi.tree.TokenSet
 import org.jetbrains.kotlin.KtNodeTypes.*
 import org.jetbrains.kotlin.idea.core.formatter.KotlinCodeStyleSettings
 import org.jetbrains.kotlin.idea.formatter.NodeIndentStrategy.Companion.strategy
+import org.jetbrains.kotlin.idea.util.getLineCount
 import org.jetbrains.kotlin.idea.util.requireNode
 import org.jetbrains.kotlin.kdoc.lexer.KDocTokens
 import org.jetbrains.kotlin.kdoc.parser.KDocElementTypes
@@ -598,7 +599,14 @@ abstract class KotlinCommonBlock(
                     parentElementType === SECONDARY_CONSTRUCTOR
                 ) {
                     val wrap = Wrap.createWrap(commonSettings.METHOD_PARAMETERS_WRAP, false)
-                    return { childElement -> wrap.takeIf { childElement.elementType === VALUE_PARAMETER } }
+                    val withTrailingComma = node.withTrailingComma
+                    return { childElement ->
+                        val childElementType = childElement.elementType
+                        if (withTrailingComma && (childElementType === RPAR || getPrevWithoutWhitespaceAndComments(childElement)?.elementType === LPAR))
+                            Wrap.createWrap(WrapType.ALWAYS, true)
+                        else
+                            wrap.takeIf { childElementType === VALUE_PARAMETER }
+                    }
                 }
             }
 
@@ -698,6 +706,13 @@ abstract class KotlinCommonBlock(
 
         return ::noWrapping
     }
+
+    private val ASTNode.withTrailingComma: Boolean
+        get() = when {
+            lastChildNode?.let { getPrevWithoutWhitespaceAndComments(it) }?.elementType === COMMA -> true
+            settings.kotlinCustomSettings.ALLOW_TRAILING_COMMA -> psi?.getLineCount()?.let { it > 1 } == true
+            else -> false
+        }
 }
 
 private fun ASTNode.isFirstParameter(): Boolean = treePrev?.elementType == LPAR

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt

@@ -271,10 +271,9 @@ fun createSpacingBuilder(settings: CodeStyleSettings, builderUtil: KotlinSpacing
             after(DOC_COMMENT).lineBreakInCode()
 
             // =============== Spacing ================
-            before(COMMA).spaceIf(kotlinCommonSettings.SPACE_BEFORE_COMMA)
+            before(COMMA).spacesNoLineBreak(if (kotlinCommonSettings.SPACE_BEFORE_COMMA) 1 else 0)
             after(COMMA).spaceIf(kotlinCommonSettings.SPACE_AFTER_COMMA)
 
-
             val spacesAroundAssignment = if (kotlinCommonSettings.SPACE_AROUND_ASSIGNMENT_OPERATORS) 1 else 0
             beforeInside(EQ, PROPERTY).spacesNoLineBreak(spacesAroundAssignment)
             beforeInside(EQ, FUN).spacing(spacesAroundAssignment, spacesAroundAssignment, 0, false, 0)

idea/formatter/src/org/jetbrains/kotlin/idea/util/FormatterUtil.kt

@@ -1,11 +1,15 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2019 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.util
 
 import com.intellij.formatting.ASTBlock
+import com.intellij.openapi.util.TextRange
+import com.intellij.openapi.util.text.StringUtil
+import com.intellij.psi.PsiDocumentManager
+import com.intellij.psi.PsiElement
 import org.jetbrains.kotlin.idea.core.formatter.KotlinCodeStyleSettings
 
 /*
@@ -16,4 +20,20 @@ fun ASTBlock.requireNode() = node ?: error("ASTBlock.getNode() returned null")
 /**
  * Can be removed with all usages after moving master to 1.3 with new default code style settings.
  */
-val isDefaultOfficialCodeStyle by lazy { !KotlinCodeStyleSettings.defaultSettings().CONTINUATION_INDENT_FOR_CHAINED_CALLS }
+val isDefaultOfficialCodeStyle by lazy { !KotlinCodeStyleSettings.defaultSettings().CONTINUATION_INDENT_FOR_CHAINED_CALLS }
+
+fun PsiElement.getLineCount(): Int {
+    val doc = containingFile?.let { file -> file.viewProvider.document ?: PsiDocumentManager.getInstance(project).getDocument(file) }
+    if (doc != null) {
+        val spaceRange = textRange ?: TextRange.EMPTY_RANGE
+
+        if (spaceRange.endOffset <= doc.textLength) {
+            val startLine = doc.getLineNumber(spaceRange.startOffset)
+            val endLine = doc.getLineNumber(spaceRange.endOffset)
+
+            return endLine - startLine + 1
+        }
+    }
+
+    return StringUtil.getLineBreakCount(text ?: "") + 1
+}