com.pinterest.ktlint.ruleset.standard.rules.TrailingCommaOnDeclarationSiteRule.kt Maven / Gradle / Ivy
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An anti-bikeshedding Kotlin linter with built-in formatter.
package com.pinterest.ktlint.ruleset.standard.rules
import com.pinterest.ktlint.rule.engine.core.api.AutocorrectDecision
import com.pinterest.ktlint.rule.engine.core.api.ElementType
import com.pinterest.ktlint.rule.engine.core.api.ElementType.ARROW
import com.pinterest.ktlint.rule.engine.core.api.ElementType.CLASS
import com.pinterest.ktlint.rule.engine.core.api.ElementType.COMMA
import com.pinterest.ktlint.rule.engine.core.api.ElementType.DESTRUCTURING_DECLARATION
import com.pinterest.ktlint.rule.engine.core.api.ElementType.FUNCTION_LITERAL
import com.pinterest.ktlint.rule.engine.core.api.ElementType.FUNCTION_TYPE
import com.pinterest.ktlint.rule.engine.core.api.ElementType.RBRACE
import com.pinterest.ktlint.rule.engine.core.api.ElementType.SEMICOLON
import com.pinterest.ktlint.rule.engine.core.api.ElementType.TYPE_PARAMETER_LIST
import com.pinterest.ktlint.rule.engine.core.api.ElementType.VALUE_PARAMETER_LIST
import com.pinterest.ktlint.rule.engine.core.api.ElementType.WHEN_ENTRY
import com.pinterest.ktlint.rule.engine.core.api.ElementType.WHITE_SPACE
import com.pinterest.ktlint.rule.engine.core.api.Rule.VisitorModifier.RunAfterRule.Mode.ONLY_WHEN_RUN_AFTER_RULE_IS_LOADED_AND_ENABLED
import com.pinterest.ktlint.rule.engine.core.api.RuleId
import com.pinterest.ktlint.rule.engine.core.api.SinceKtlint
import com.pinterest.ktlint.rule.engine.core.api.SinceKtlint.Status.EXPERIMENTAL
import com.pinterest.ktlint.rule.engine.core.api.SinceKtlint.Status.STABLE
import com.pinterest.ktlint.rule.engine.core.api.children
import com.pinterest.ktlint.rule.engine.core.api.editorconfig.EditorConfig
import com.pinterest.ktlint.rule.engine.core.api.editorconfig.EditorConfigProperty
import com.pinterest.ktlint.rule.engine.core.api.ifAutocorrectAllowed
import com.pinterest.ktlint.rule.engine.core.api.indent
import com.pinterest.ktlint.rule.engine.core.api.isCodeLeaf
import com.pinterest.ktlint.rule.engine.core.api.nextLeaf
import com.pinterest.ktlint.rule.engine.core.api.noNewLineInClosedRange
import com.pinterest.ktlint.rule.engine.core.api.prevCodeLeaf
import com.pinterest.ktlint.rule.engine.core.api.prevLeaf
import com.pinterest.ktlint.rule.engine.core.api.remove
import com.pinterest.ktlint.rule.engine.core.api.upsertWhitespaceAfterMe
import com.pinterest.ktlint.rule.engine.core.util.cast
import com.pinterest.ktlint.ruleset.standard.StandardRule
import org.ec4j.core.model.PropertyType
import org.ec4j.core.model.PropertyType.PropertyValueParser
import org.jetbrains.kotlin.KtNodeTypes.WHEN_ENTRY_GUARD
import org.jetbrains.kotlin.com.intellij.lang.ASTNode
import org.jetbrains.kotlin.com.intellij.psi.PsiElement
import org.jetbrains.kotlin.com.intellij.psi.PsiWhiteSpace
import org.jetbrains.kotlin.com.intellij.psi.impl.source.tree.LeafPsiElement
import org.jetbrains.kotlin.com.intellij.psi.impl.source.tree.PsiWhiteSpaceImpl
import org.jetbrains.kotlin.com.intellij.psi.tree.TokenSet
import org.jetbrains.kotlin.psi.KtClass
import org.jetbrains.kotlin.psi.KtCollectionLiteralExpression
import org.jetbrains.kotlin.psi.KtDestructuringDeclaration
import org.jetbrains.kotlin.psi.KtEnumEntry
import org.jetbrains.kotlin.psi.KtFunctionLiteral
import org.jetbrains.kotlin.psi.KtParameterList
import org.jetbrains.kotlin.psi.KtValueArgumentList
import org.jetbrains.kotlin.psi.KtWhenEntry
import org.jetbrains.kotlin.psi.KtWhenExpression
import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
import org.jetbrains.kotlin.psi.psiUtil.collectDescendantsOfType
import org.jetbrains.kotlin.psi.psiUtil.nextLeaf
import org.jetbrains.kotlin.psi.psiUtil.prevLeaf
/**
* Linting trailing comma for declaration site.
*
* @see [Kotlin Style Guide](https://kotlinlang.org/docs/coding-conventions.html#trailing-commas)
*/
@SinceKtlint("0.43", EXPERIMENTAL)
@SinceKtlint("0.46", STABLE)
public class TrailingCommaOnDeclarationSiteRule :
StandardRule(
id = "trailing-comma-on-declaration-site",
visitorModifiers =
setOf(
VisitorModifier.RunAfterRule(
ruleId = WRAPPING_RULE_ID,
mode = ONLY_WHEN_RUN_AFTER_RULE_IS_LOADED_AND_ENABLED,
),
VisitorModifier.RunAsLateAsPossible,
),
usesEditorConfigProperties = setOf(TRAILING_COMMA_ON_DECLARATION_SITE_PROPERTY),
) {
private var allowTrailingComma = TRAILING_COMMA_ON_DECLARATION_SITE_PROPERTY.defaultValue
override fun beforeFirstNode(editorConfig: EditorConfig) {
allowTrailingComma = editorConfig[TRAILING_COMMA_ON_DECLARATION_SITE_PROPERTY]
}
override fun beforeVisitChildNodes(
node: ASTNode,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
// Keep processing of element types in sync with Intellij Kotlin formatting settings.
// https://github.com/JetBrains/intellij-kotlin/blob/master/formatter/src/org/jetbrains/kotlin/idea/formatter/trailingComma/util.kt
when (node.elementType) {
CLASS -> visitClass(node, emit)
DESTRUCTURING_DECLARATION -> visitDestructuringDeclaration(node, emit)
FUNCTION_LITERAL -> visitFunctionLiteral(node, emit)
TYPE_PARAMETER_LIST -> visitTypeList(node, emit)
VALUE_PARAMETER_LIST -> visitValueList(node, emit)
WHEN_ENTRY -> visitWhenEntry(node, emit)
else -> Unit
}
}
private fun visitDestructuringDeclaration(
node: ASTNode,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
val inspectNode =
node
.children()
.last { it.elementType == ElementType.RPAR }
node.reportAndCorrectTrailingCommaNodeBefore(
inspectNode = inspectNode,
isTrailingCommaAllowed = node.isTrailingCommaAllowed(),
emit = emit,
)
}
private fun ASTNode.isTrailingCommaAllowed() = elementType in TYPES_ON_DECLARATION_SITE && allowTrailingComma
private fun visitFunctionLiteral(
node: ASTNode,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
val inspectNode =
node
.children()
.lastOrNull { it.elementType == ARROW }
?: // lambda w/o an arrow -> no arguments -> no commas
return
node.reportAndCorrectTrailingCommaNodeBefore(
inspectNode = inspectNode,
isTrailingCommaAllowed = node.isTrailingCommaAllowed(),
emit = emit,
)
}
private fun visitValueList(
node: ASTNode,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
if (node.treeParent.elementType != FUNCTION_LITERAL) {
node
.children()
.lastOrNull { it.elementType == ElementType.RPAR }
?.let { inspectNode ->
node.reportAndCorrectTrailingCommaNodeBefore(
inspectNode = inspectNode,
isTrailingCommaAllowed = node.isTrailingCommaAllowed(),
emit = emit,
)
}
}
}
private fun visitTypeList(
node: ASTNode,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
val inspectNode =
node
.children()
.first { it.elementType == ElementType.GT }
node.reportAndCorrectTrailingCommaNodeBefore(
inspectNode = inspectNode,
isTrailingCommaAllowed = node.isTrailingCommaAllowed(),
emit = emit,
)
}
private fun visitWhenEntry(
node: ASTNode,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
val psi = node.psi
require(psi is KtWhenEntry)
if (psi.isElse || psi.parent.cast().leftParenthesis == null) {
// no commas for "else" or when there are no opening parenthesis for the when-expression
return
}
val inspectNode =
node
.children()
.first { it.elementType == ARROW }
node.reportAndCorrectTrailingCommaNodeBefore(
inspectNode = inspectNode,
isTrailingCommaAllowed = node.isTrailingCommaAllowed(),
emit = emit,
)
}
private fun visitClass(
node: ASTNode,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
val psi = node.psi
require(psi is KtClass)
node
.takeIf { psi.isEnum() }
?.findChildByType(ElementType.CLASS_BODY)
?.takeUnless { it.noEnumEntries() }
?.let { classBody ->
classBody
.findNodeAfterLastEnumEntry()
?.let { nodeAfterLastEnumEntry ->
when {
!node.isTrailingCommaAllowed() && nodeAfterLastEnumEntry.elementType == RBRACE -> {
node.reportAndCorrectTrailingCommaNodeBefore(
inspectNode = nodeAfterLastEnumEntry,
isTrailingCommaAllowed = false,
emit = emit,
)
}
!classBody.lastTwoEnumEntriesAreOnSameLine() -> {
node.reportAndCorrectTrailingCommaNodeBefore(
inspectNode = nodeAfterLastEnumEntry,
isTrailingCommaAllowed = node.isTrailingCommaAllowed(),
emit = emit,
)
}
}
}
}
}
private fun ASTNode.noEnumEntries() = children().none { it.psi is KtEnumEntry }
private fun ASTNode.lastTwoEnumEntriesAreOnSameLine(): Boolean {
val lastTwoEnumEntries =
children()
.filter { it.psi is KtEnumEntry }
.toList()
.takeLast(2)
return lastTwoEnumEntries.count() == 2 && noNewLineInClosedRange(lastTwoEnumEntries[0], lastTwoEnumEntries[1])
}
/**
* Determines the [ASTNode] before which the trailing comma is allowed.
*
* If the list of enumeration entries is terminated by a semicolon, that semicolon will be returned. Otherwise, the
* last element of the class.
*/
private fun ASTNode.findNodeAfterLastEnumEntry() =
children()
.lastOrNull { it.psi is KtEnumEntry }
?.children()
?.singleOrNull { it.elementType == SEMICOLON }
?: lastChildNode
private fun ASTNode.reportAndCorrectTrailingCommaNodeBefore(
inspectNode: ASTNode,
isTrailingCommaAllowed: Boolean,
emit: (offset: Int, errorMessage: String, canBeAutoCorrected: Boolean) -> AutocorrectDecision,
) {
val prevLeaf = inspectNode.prevLeaf()
val trailingCommaNode = prevLeaf?.findPreviousTrailingCommaNodeOrNull()
val trailingCommaState =
when {
hasWhenEntryGuard() -> {
// The compiler won't allow any comma in the when-entry in case it contains a guard clause
TrailingCommaState.NOT_EXISTS
}
isMultiline(psi) -> {
if (trailingCommaNode != null) TrailingCommaState.EXISTS else TrailingCommaState.MISSING
}
else -> {
if (trailingCommaNode != null) TrailingCommaState.REDUNDANT else TrailingCommaState.NOT_EXISTS
}
}
when (trailingCommaState) {
TrailingCommaState.EXISTS -> {
if (isTrailingCommaAllowed) {
inspectNode
.treeParent
.takeIf { it.elementType == WHEN_ENTRY }
?.findChildByType(ARROW)
?.prevLeaf()
?.let { lastNodeBeforeArrow ->
if (lastNodeBeforeArrow.elementType != WHITE_SPACE || !lastNodeBeforeArrow.textContains('\n')) {
emit(
trailingCommaNode!!.startOffset,
"Expected a newline between the trailing comma and \"${inspectNode.text}\"",
true,
).ifAutocorrectAllowed {
lastNodeBeforeArrow.upsertWhitespaceAfterMe(inspectNode.treeParent.indent())
}
}
}
} else {
emit(
trailingCommaNode!!.startOffset,
"Unnecessary trailing comma before \"${inspectNode.text}\"",
true,
).ifAutocorrectAllowed {
this.removeChild(trailingCommaNode)
}
}
}
TrailingCommaState.MISSING -> {
if (isTrailingCommaAllowed) {
val leafBeforeArrowOrNull = leafBeforeArrowOrNull()
val addNewLine =
leafBeforeArrowOrNull
?.let { !(leafBeforeArrowOrNull is PsiWhiteSpace && leafBeforeArrowOrNull.textContains('\n')) }
?: false
val prevNode = inspectNode.prevCodeLeaf()!!
if (addNewLine) {
emit(
prevNode.startOffset + prevNode.textLength,
"Missing trailing comma and newline before \"${inspectNode.text}\"",
true,
)
} else {
emit(
prevNode.startOffset + prevNode.textLength,
"Missing trailing comma before \"${inspectNode.text}\"",
true,
)
}.ifAutocorrectAllowed {
if (addNewLine) {
val indent =
prevNode
.treeParent
.indent()
if (leafBeforeArrowOrNull is PsiWhiteSpace) {
(leafBeforeArrowOrNull as LeafPsiElement).rawReplaceWithText(indent)
} else {
inspectNode
.prevCodeLeaf()
?.nextLeaf()
?.let { before ->
before.treeParent.addChild(PsiWhiteSpaceImpl(indent), before)
}
}
}
if (inspectNode.treeParent.elementType == ElementType.ENUM_ENTRY) {
val parentIndent =
(prevNode.psi.parent.prevLeaf() as? PsiWhiteSpace)?.text
?: prevNode.indent()
(inspectNode as LeafPsiElement).apply {
this.treeParent.addChild(LeafPsiElement(COMMA, ","), this)
this.treeParent.addChild(PsiWhiteSpaceImpl(parentIndent), null)
this.treeParent.addChild(LeafPsiElement(SEMICOLON, ";"), null)
}
inspectNode.remove()
} else {
inspectNode
.prevCodeLeaf()
?.nextLeaf()
?.let { before ->
before.treeParent.addChild(LeafPsiElement(COMMA, ","), before)
}
}
}
}
}
TrailingCommaState.REDUNDANT -> {
emit(
trailingCommaNode!!.startOffset,
"Unnecessary trailing comma before \"${inspectNode.text}\"",
true,
).ifAutocorrectAllowed {
this.removeChild(trailingCommaNode)
}
}
TrailingCommaState.NOT_EXISTS -> {
Unit
}
}
}
private fun isMultiline(element: PsiElement): Boolean =
when {
element.parent is KtFunctionLiteral -> {
isMultiline(element.parent)
}
element is KtFunctionLiteral -> {
containsLineBreakInLeavesRange(element.valueParameterList!!, element.arrow!!)
}
element is KtWhenEntry -> {
containsLineBreakInLeavesRange(element.firstChild, element.arrow!!)
}
element is KtDestructuringDeclaration -> {
containsLineBreakInLeavesRange(element.lPar!!, element.rPar!!)
}
element is KtValueArgumentList &&
element.children.size == 1 &&
element.anyDescendantOfType() -> {
// special handling for collection literal
// @Annotation([
// "something",
// ])
val lastChild = element.collectDescendantsOfType().last()
containsLineBreakInLeavesRange(lastChild.rightBracket!!, element.rightParenthesis!!)
}
element is KtParameterList && element.parameters.isEmpty() -> {
false
}
else -> {
element.textContains('\n')
}
}
private fun ASTNode.leafBeforeArrowOrNull() =
when (psi) {
is KtWhenEntry -> {
(psi as KtWhenEntry)
.arrow
?.prevLeaf()
}
is KtFunctionLiteral -> {
(psi as KtFunctionLiteral)
.arrow
?.prevLeaf()
}
else -> {
null
}
}
private fun ASTNode.findPreviousTrailingCommaNodeOrNull(): ASTNode? {
val codeLeaf =
if (isCodeLeaf()) {
this
} else {
prevCodeLeaf()
}
return codeLeaf?.takeIf { it.elementType == COMMA }
}
private fun ASTNode.hasWhenEntryGuard() = elementType == WHEN_ENTRY && hasWhenEntryGuardKotlin21()
private fun ASTNode.hasWhenEntryGuardKotlin21(): Boolean =
// TODO: Remove try-catch wrapping once kotlin version is upgraded to 2.1 or above
try {
children().any { it.elementType == WHEN_ENTRY_GUARD }
} catch (e: NoSuchFieldError) {
// Prior to Kotlin 2.1 the WHEN_ENTRY_GUARD can not be retrieved successfully.
false
}
private fun containsLineBreakInLeavesRange(
from: PsiElement,
to: PsiElement,
): Boolean {
var leaf: PsiElement? = from
while (leaf != null && !leaf.isEquivalentTo(to)) {
if (leaf.textContains('\n')) {
return true
}
leaf = leaf.nextLeaf(skipEmptyElements = false)
}
return leaf?.textContains('\n') ?: false
}
private enum class TrailingCommaState {
/**
* The trailing comma is needed and exists
*/
EXISTS,
/**
* The trailing comma is needed and doesn't exist
*/
MISSING,
/**
* The trailing comma isn't needed and doesn't exist
*/
NOT_EXISTS,
/**
* The trailing comma isn't needed, but exists
*/
REDUNDANT,
}
public companion object {
private val BOOLEAN_VALUES_SET = setOf("true", "false")
public val TRAILING_COMMA_ON_DECLARATION_SITE_PROPERTY: EditorConfigProperty =
EditorConfigProperty(
type =
PropertyType.LowerCasingPropertyType(
"ij_kotlin_allow_trailing_comma",
"Defines whether a trailing comma (or no trailing comma) should be enforced on the defining " +
"side, e.g. parameter-list, type-argument-list, lambda-value-parameters, enum-entries, etc." +
"When set, IntelliJ IDEA uses this property to allow usage of a trailing comma by discretion " +
"of the developer. KtLint however uses this setting to enforce consistent usage of the " +
"trailing comma when set.",
PropertyValueParser.BOOLEAN_VALUE_PARSER,
BOOLEAN_VALUES_SET,
),
defaultValue = true,
androidStudioCodeStyleDefaultValue = false,
)
private val TYPES_ON_DECLARATION_SITE =
TokenSet.create(
CLASS,
DESTRUCTURING_DECLARATION,
FUNCTION_LITERAL,
FUNCTION_TYPE,
TYPE_PARAMETER_LIST,
VALUE_PARAMETER_LIST,
WHEN_ENTRY,
)
}
}
public val TRAILING_COMMA_ON_DECLARATION_SITE_RULE_ID: RuleId = TrailingCommaOnDeclarationSiteRule().ruleId
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