Introduce TrailingCommaHelper

#KT-34744

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

@@ -0,0 +1,114 @@
+/*
+ * 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.formatter
+
+import com.intellij.openapi.util.registry.Registry
+import com.intellij.psi.PsiComment
+import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiErrorElement
+import com.intellij.psi.PsiWhiteSpace
+import com.intellij.psi.codeStyle.CodeStyleSettings
+import com.intellij.psi.tree.TokenSet
+import com.intellij.psi.util.PsiUtil.getElementType
+import org.jetbrains.kotlin.config.LanguageFeature
+import org.jetbrains.kotlin.idea.project.languageVersionSettings
+import org.jetbrains.kotlin.idea.util.*
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.getPrevSiblingIgnoringWhitespaceAndComments
+import org.jetbrains.kotlin.psi.psiUtil.nextLeaf
+import org.jetbrains.kotlin.psi.psiUtil.prevLeaf
+import org.jetbrains.kotlin.psi.psiUtil.siblings
+import org.jetbrains.kotlin.utils.addToStdlib.cast
+
+object TrailingCommaHelper {
+    fun findInvalidCommas(commaOwner: KtElement): List<PsiElement> = commaOwner.firstChild
+        ?.siblings(withItself = false)
+        ?.filter { it.isComma }
+        ?.filter {
+            it.prevLeaf(true)?.isLineBreak() == true || it.leafIgnoringWhitespace(false) != it.leafIgnoringWhitespaceAndComments(false)
+        }?.toList().orEmpty()
+
+    fun needComma(
+        commaOwner: KtElement,
+        settings: CodeStyleSettings?,
+        checkExistingTrailingComma: Boolean = true,
+    ): Boolean = when {
+        commaOwner is KtWhenEntry ->
+            commaOwner.needTrailingComma(settings, checkExistingTrailingComma)
+
+        commaOwner.parent is KtFunctionLiteral ->
+            commaOwner.parent.cast<KtFunctionLiteral>().needTrailingComma(settings, checkExistingTrailingComma)
+
+        commaOwner is KtDestructuringDeclaration ->
+            commaOwner.needTrailingComma(settings, checkExistingTrailingComma)
+
+        else -> (checkExistingTrailingComma &&
+                trailingCommaOrLastElement(commaOwner)?.isComma == true ||
+                settings?.kotlinCustomSettings?.addTrailingCommaIsAllowedFor(commaOwner) != false) &&
+                commaOwner.isMultiline()
+    }
+
+    fun trailingCommaOrLastElement(commaOwner: KtElement): PsiElement? {
+        val lastChild = commaOwner.lastSignificantChild ?: return null
+        val withSelf = when (getElementType(lastChild)) {
+            KtTokens.COMMA -> return lastChild
+            in RIGHT_BARRIERS -> false
+            else -> true
+        }
+
+        return lastChild.getPrevSiblingIgnoringWhitespaceAndComments(withSelf)?.takeIf {
+            getElementType(it) !in LEFT_BARRIERS
+        }?.takeIfIsNotError()
+    }
+
+    fun trailingCommaAllowedInModule(source: PsiElement): Boolean =
+        Registry.`is`("kotlin.formatter.allowTrailingCommaInAnyProject", false) ||
+                source.module?.languageVersionSettings?.supportsFeature(LanguageFeature.TrailingCommas) == true
+
+    fun elementBeforeFirstElement(commaOwner: KtElement): PsiElement? = when (commaOwner) {
+        is KtParameterList -> {
+            val parent = commaOwner.parent
+            if (parent is KtFunctionLiteral) parent.lBrace else commaOwner.leftParenthesis
+        }
+        is KtWhenEntry -> commaOwner.parent.cast<KtWhenExpression>().openBrace
+        is KtDestructuringDeclaration -> commaOwner.lPar
+        else -> commaOwner.firstChild?.takeIfIsNotError()
+    }
+
+    fun elementAfterLastElement(commaOwner: KtElement): PsiElement? = when (commaOwner) {
+        is KtParameterList -> {
+            val parent = commaOwner.parent
+            if (parent is KtFunctionLiteral) parent.arrow else commaOwner.rightParenthesis
+        }
+        is KtWhenEntry -> commaOwner.arrow
+        is KtDestructuringDeclaration -> commaOwner.rPar
+        else -> commaOwner.lastChild?.takeIfIsNotError()
+    }
+
+    private fun PsiElement.takeIfIsNotError(): PsiElement? = takeIf { it !is PsiErrorElement }
+
+    private val RIGHT_BARRIERS = TokenSet.create(KtTokens.RBRACKET, KtTokens.RPAR, KtTokens.RBRACE, KtTokens.GT, KtTokens.ARROW)
+    private val LEFT_BARRIERS = TokenSet.create(KtTokens.LBRACKET, KtTokens.LPAR, KtTokens.LBRACE, KtTokens.LT)
+    private val PsiElement.lastSignificantChild: PsiElement?
+        get() = when (this) {
+            is KtWhenEntry -> arrow
+            is KtDestructuringDeclaration -> rPar
+            else -> lastChild
+        }
+}
+
+fun PsiElement.leafIgnoringWhitespace(forward: Boolean = true, skipEmptyElements: Boolean = true) =
+    leaf(forward) { (!skipEmptyElements || it.textLength != 0) && it !is PsiWhiteSpace }
+
+fun PsiElement.leafIgnoringWhitespaceAndComments(forward: Boolean = true, skipEmptyElements: Boolean = true) =
+    leaf(forward) { (!skipEmptyElements || it.textLength != 0) && it !is PsiWhiteSpace && it !is PsiComment }
+
+fun PsiElement.leaf(forward: Boolean = true, filter: (PsiElement) -> Boolean): PsiElement? =
+    if (forward) nextLeaf(filter)
+    else prevLeaf(filter)
+
+val PsiElement.isComma: Boolean get() = getElementType(this) == KtTokens.COMMA

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

@@ -7,26 +7,25 @@ package org.jetbrains.kotlin.idea.formatter
 
 import com.intellij.openapi.diagnostic.Logger
 import com.intellij.openapi.util.TextRange
-import com.intellij.openapi.util.registry.Registry
-import com.intellij.psi.*
+import com.intellij.psi.PsiComment
+import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiFile
+import com.intellij.psi.PsiWhiteSpace
 import com.intellij.psi.codeStyle.CodeStyleManager
 import com.intellij.psi.codeStyle.CodeStyleSettings
 import com.intellij.psi.impl.source.PostprocessReformattingAspect
 import com.intellij.psi.impl.source.codeStyle.PostFormatProcessor
 import com.intellij.psi.impl.source.codeStyle.PostFormatProcessorHelper
-import com.intellij.psi.tree.TokenSet
 import com.intellij.psi.util.PsiUtil.getElementType
-import org.jetbrains.kotlin.config.LanguageFeature
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.findInvalidCommas
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.needComma
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.trailingCommaAllowedInModule
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.trailingCommaOrLastElement
-import org.jetbrains.kotlin.idea.project.languageVersionSettings
-import org.jetbrains.kotlin.idea.util.*
+import org.jetbrains.kotlin.idea.formatter.TrailingCommaHelper.findInvalidCommas
+import org.jetbrains.kotlin.idea.formatter.TrailingCommaHelper.needComma
+import org.jetbrains.kotlin.idea.formatter.TrailingCommaHelper.trailingCommaAllowedInModule
+import org.jetbrains.kotlin.idea.formatter.TrailingCommaHelper.trailingCommaOrLastElement
 import org.jetbrains.kotlin.lexer.KtTokens
-import org.jetbrains.kotlin.psi.*
-import org.jetbrains.kotlin.psi.psiUtil.*
-import org.jetbrains.kotlin.utils.addToStdlib.cast
+import org.jetbrains.kotlin.psi.KtElement
+import org.jetbrains.kotlin.psi.KtPsiFactory
+import org.jetbrains.kotlin.psi.psiUtil.createSmartPointer
+import org.jetbrains.kotlin.psi.psiUtil.siblings
 
 class TrailingCommaPostFormatProcessor : PostFormatProcessor {
     override fun processElement(source: PsiElement, settings: CodeStyleSettings): PsiElement =
@@ -34,76 +33,8 @@ class TrailingCommaPostFormatProcessor : PostFormatProcessor {
 
     override fun processText(source: PsiFile, rangeToReformat: TextRange, settings: CodeStyleSettings): TextRange =
         TrailingCommaPostFormatVisitor(settings).processText(source, rangeToReformat)
-
-    companion object {
-        fun findInvalidCommas(commaOwner: KtElement): List<PsiElement> = commaOwner.firstChild
-            ?.siblings(withItself = false)
-            ?.filter { it.isComma }
-            ?.filter {
-                it.prevLeaf(true)?.isLineBreak() == true || it.leafIgnoringWhitespace(false) != it.leafIgnoringWhitespaceAndComments(false)
-            }?.toList().orEmpty()
-
-        fun needComma(
-            commaOwner: KtElement,
-            settings: CodeStyleSettings?,
-            checkExistingTrailingComma: Boolean = true,
-        ): Boolean = when {
-            commaOwner is KtWhenEntry ->
-                commaOwner.needTrailingComma(settings, checkExistingTrailingComma)
-
-            commaOwner.parent is KtFunctionLiteral ->
-                commaOwner.parent.cast<KtFunctionLiteral>().needTrailingComma(settings, checkExistingTrailingComma)
-
-            commaOwner is KtDestructuringDeclaration ->
-                commaOwner.needTrailingComma(settings, checkExistingTrailingComma)
-
-            else -> (checkExistingTrailingComma &&
-                    trailingCommaOrLastElement(commaOwner)?.isComma == true ||
-                    settings?.kotlinCustomSettings?.addTrailingCommaIsAllowedFor(commaOwner) != false) &&
-                    commaOwner.isMultiline()
-        }
-
-        fun trailingCommaOrLastElement(commaOwner: KtElement): PsiElement? {
-            val lastChild = commaOwner.lastSignificantChild ?: return null
-            val withSelf = when (getElementType(lastChild)) {
-                KtTokens.COMMA -> return lastChild
-                in RIGHT_BARRIERS -> false
-                else -> true
-            }
-
-            return lastChild.getPrevSiblingIgnoringWhitespaceAndComments(withSelf)?.takeIf {
-                getElementType(it) !in LEFT_BARRIERS
-            }?.takeIfIsNotError()
-        }
-
-        fun trailingCommaAllowedInModule(source: PsiElement): Boolean =
-            Registry.`is`("kotlin.formatter.allowTrailingCommaInAnyProject", false) ||
-                    source.module?.languageVersionSettings?.supportsFeature(LanguageFeature.TrailingCommas) == true
-
-        fun elementBeforeFirstElement(commaOwner: KtElement): PsiElement? = when (commaOwner) {
-            is KtParameterList -> {
-                val parent = commaOwner.parent
-                if (parent is KtFunctionLiteral) parent.lBrace else commaOwner.leftParenthesis
-            }
-            is KtWhenEntry -> commaOwner.parent.cast<KtWhenExpression>().openBrace
-            is KtDestructuringDeclaration -> commaOwner.lPar
-            else -> commaOwner.firstChild?.takeIfIsNotError()
-        }
-
-        fun elementAfterLastElement(commaOwner: KtElement): PsiElement? = when (commaOwner) {
-            is KtParameterList -> {
-                val parent = commaOwner.parent
-                if (parent is KtFunctionLiteral) parent.arrow else commaOwner.rightParenthesis
-            }
-            is KtWhenEntry -> commaOwner.arrow
-            is KtDestructuringDeclaration -> commaOwner.rPar
-            else -> commaOwner.lastChild?.takeIfIsNotError()
-        }
-    }
 }
 
-private fun PsiElement.takeIfIsNotError(): PsiElement? = takeIf { it !is PsiErrorElement }
-
 private class TrailingCommaPostFormatVisitor(val settings: CodeStyleSettings) : TrailingCommaVisitor() {
     private val myPostProcessor = PostFormatProcessorHelper(settings.kotlinCommonSettings)
 
@@ -199,24 +130,3 @@ private fun correctComma(comma: PsiElement) {
         commentOwner.deleteChildRange(firstElement, prevWithComment)
     }
 }
-
-private val RIGHT_BARRIERS = TokenSet.create(KtTokens.RBRACKET, KtTokens.RPAR, KtTokens.RBRACE, KtTokens.GT, KtTokens.ARROW)
-private val LEFT_BARRIERS = TokenSet.create(KtTokens.LBRACKET, KtTokens.LPAR, KtTokens.LBRACE, KtTokens.LT)
-private val PsiElement.lastSignificantChild: PsiElement?
-    get() = when (this) {
-        is KtWhenEntry -> arrow
-        is KtDestructuringDeclaration -> rPar
-        else -> lastChild
-    }
-
-fun PsiElement.leafIgnoringWhitespace(forward: Boolean = true, skipEmptyElements: Boolean = true) =
-    leaf(forward) { (!skipEmptyElements || it.textLength != 0) && it !is PsiWhiteSpace }
-
-fun PsiElement.leafIgnoringWhitespaceAndComments(forward: Boolean = true, skipEmptyElements: Boolean = true) =
-    leaf(forward) { (!skipEmptyElements || it.textLength != 0) && it !is PsiWhiteSpace && it !is PsiComment }
-
-fun PsiElement.leaf(forward: Boolean = true, filter: (PsiElement) -> Boolean): PsiElement? =
-    if (forward) nextLeaf(filter)
-    else prevLeaf(filter)
-
-val PsiElement.isComma: Boolean get() = getElementType(this) == KtTokens.COMMA

idea/src/org/jetbrains/kotlin/idea/inspections/TrailingCommaInspection.kt

@@ -18,10 +18,6 @@ import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiElementVisitor
 import com.intellij.psi.codeStyle.CodeStyleManager
 import org.jetbrains.kotlin.idea.formatter.*
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.findInvalidCommas
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.needComma
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.trailingCommaAllowedInModule
-import org.jetbrains.kotlin.idea.formatter.TrailingCommaPostFormatProcessor.Companion.trailingCommaOrLastElement
 import org.jetbrains.kotlin.idea.util.isLineBreak
 import org.jetbrains.kotlin.psi.KtElement
 import org.jetbrains.kotlin.psi.psiUtil.*
@@ -44,7 +40,7 @@ class TrailingCommaInspection(
         }
 
         private fun checkLineBreaks(commaOwner: KtElement) {
-            val first = TrailingCommaPostFormatProcessor.elementBeforeFirstElement(commaOwner)
+            val first = TrailingCommaHelper.elementBeforeFirstElement(commaOwner)
             if (first?.nextLeaf(true)?.isLineBreak() == false) {
                 first.nextSibling?.let {
                     registerProblemForLineBreak(
@@ -59,7 +55,7 @@ class TrailingCommaInspection(
 
             }
 
-            val last = TrailingCommaPostFormatProcessor.elementAfterLastElement(commaOwner)
+            val last = TrailingCommaHelper.elementAfterLastElement(commaOwner)
             if (last?.prevLeaf(true)?.isLineBreak() == false) {
                 registerProblemForLineBreak(
                     commaOwner,
@@ -70,15 +66,15 @@ class TrailingCommaInspection(
         }
 
         private fun checkCommaPosition(commaOwner: KtElement) {
-            for (invalidComma in findInvalidCommas(commaOwner)) {
+            for (invalidComma in TrailingCommaHelper.findInvalidCommas(commaOwner)) {
                 reportProblem(invalidComma, "Comma loses the advantages in this position", "Fix comma position")
             }
         }
 
         private fun checkTrailingComma(commaOwner: KtElement, action: TrailingCommaAction) {
-            val trailingCommaOrLastElement = trailingCommaOrLastElement(commaOwner) ?: return
+            val trailingCommaOrLastElement = TrailingCommaHelper.trailingCommaOrLastElement(commaOwner) ?: return
             if (action == TrailingCommaAction.ADD) {
-                if (!trailingCommaAllowedInModule(commaOwner) || trailingCommaOrLastElement.isComma) return
+                if (!TrailingCommaHelper.trailingCommaAllowedInModule(commaOwner) || trailingCommaOrLastElement.isComma) return
                 reportProblem(
                     trailingCommaOrLastElement,
                     "Missing trailing comma",
@@ -147,8 +143,8 @@ class TrailingCommaInspection(
         }
 
         private fun createFormatterTextRange(commaOwner: KtElement): TextRange {
-            val startElement = TrailingCommaPostFormatProcessor.elementBeforeFirstElement(commaOwner) ?: commaOwner
-            val endElement = TrailingCommaPostFormatProcessor.elementAfterLastElement(commaOwner) ?: commaOwner
+            val startElement = TrailingCommaHelper.elementBeforeFirstElement(commaOwner) ?: commaOwner
+            val endElement = TrailingCommaHelper.elementAfterLastElement(commaOwner) ?: commaOwner
             return TextRange.create(startElement.startOffset, endElement.endOffset)
         }
 
@@ -175,8 +171,8 @@ private enum class TrailingCommaAction {
 
     companion object {
         fun create(commaOwner: KtElement): TrailingCommaAction = when {
-            needComma(commaOwner, null, checkExistingTrailingComma = false) -> ADD
-            needComma(commaOwner, null, checkExistingTrailingComma = true) -> REFORMAT
+            TrailingCommaHelper.needComma(commaOwner, null, checkExistingTrailingComma = false) -> ADD
+            TrailingCommaHelper.needComma(commaOwner, null, checkExistingTrailingComma = true) -> REFORMAT
             else -> REMOVE
         }
     }