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// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package org.jetbrains.kotlin.idea.inspections
import com.intellij.codeHighlighting.HighlightDisplayLevel
import com.intellij.codeInspection.LocalQuickFix
import com.intellij.codeInspection.ProblemDescriptor
import com.intellij.codeInspection.ProblemHighlightType
import com.intellij.codeInspection.ProblemHighlightType.GENERIC_ERROR_OR_WARNING
import com.intellij.codeInspection.ProblemHighlightType.INFORMATION
import com.intellij.codeInspection.ProblemsHolder
import com.intellij.openapi.project.Project
import com.intellij.profile.codeInspection.ProjectInspectionProfileManager
import com.intellij.psi.PsiElement
import org.jetbrains.kotlin.builtins.KotlinBuiltIns
import org.jetbrains.kotlin.builtins.StandardNames
import org.jetbrains.kotlin.idea.KotlinBundle
import org.jetbrains.kotlin.idea.caches.resolve.safeAnalyzeNonSourceRootCode
import org.jetbrains.kotlin.idea.core.canOmitDeclaredType
import org.jetbrains.kotlin.idea.core.replaced
import org.jetbrains.kotlin.idea.core.setType
import org.jetbrains.kotlin.idea.core.util.isOneLiner
import org.jetbrains.kotlin.idea.intentions.hasResultingIfWithoutElse
import org.jetbrains.kotlin.idea.util.CommentSaver
import org.jetbrains.kotlin.idea.util.resultingWhens
import org.jetbrains.kotlin.lexer.KtTokens
import org.jetbrains.kotlin.psi.*
import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
import org.jetbrains.kotlin.psi.psiUtil.endOffset
import org.jetbrains.kotlin.psi.psiUtil.startOffset
import org.jetbrains.kotlin.resolve.BindingContext
class UseExpressionBodyInspection(private val convertEmptyToUnit: Boolean) : AbstractKotlinInspection() {
constructor() : this(convertEmptyToUnit = true)
private data class Status(val toHighlight: PsiElement?, val subject: String, val highlightType: ProblemHighlightType)
fun isActiveFor(declaration: KtDeclarationWithBody) = statusFor(declaration) != null
private fun statusFor(declaration: KtDeclarationWithBody): Status? {
if (declaration is KtConstructor<*>) return null
val valueStatement = declaration.findValueStatement() ?: return null
val value = valueStatement.getValue()
if (value.anyDescendantOfType<KtReturnExpression>(
canGoInside = { it !is KtFunctionLiteral && it !is KtNamedFunction && it !is KtPropertyAccessor }
)
) return null
val toHighlight = valueStatement.toHighlight()
return when {
valueStatement !is KtReturnExpression -> Status(toHighlight, KotlinBundle.message("block.body"), INFORMATION)
valueStatement.returnedExpression is KtWhenExpression -> Status(toHighlight, KotlinBundle.message("return.when"), INFORMATION)
valueStatement.isOneLiner() -> Status(toHighlight, KotlinBundle.message("one.line.return"), GENERIC_ERROR_OR_WARNING)
else -> Status(toHighlight, KotlinBundle.message("text.return"), INFORMATION)
}
}
override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean) =
declarationVisitor(fun(declaration) {
if (declaration !is KtDeclarationWithBody) return
val (toHighlightElement, suffix, highlightType) = statusFor(declaration) ?: return
// Change range to start with left brace
val hasHighlighting = highlightType != INFORMATION
fun defaultLevel(): HighlightDisplayLevel {
val project = declaration.project
val inspectionProfileManager = ProjectInspectionProfileManager.getInstance(project)
val inspectionProfile = inspectionProfileManager.currentProfile
val state = inspectionProfile.getToolDefaultState("UseExpressionBody", project)
return state.level
}
val toHighlightRange = toHighlightElement?.textRange?.let {
if (hasHighlighting && defaultLevel() != HighlightDisplayLevel.DO_NOT_SHOW) {
it
} else {
// Extend range to [left brace..end of highlight element]
val offset = (declaration.blockExpression()?.lBrace?.startOffset ?: it.startOffset) - it.startOffset
it.shiftRight(offset).grown(-offset)
}
}
holder.registerProblemWithoutOfflineInformation(
declaration,
KotlinBundle.message("use.expression.body.instead.of.0", suffix),
isOnTheFly,
highlightType,
toHighlightRange?.shiftRight(-declaration.startOffset),
ConvertToExpressionBodyFix()
)
})
private fun KtDeclarationWithBody.findValueStatement(): KtExpression? {
val body = blockExpression() ?: return null
return body.findValueStatement()
}
private fun KtDeclarationWithBody.blockExpression() = when (this) {
is KtFunctionLiteral -> null
else -> if (!hasBlockBody()) null else bodyBlockExpression
}
private fun KtBlockExpression.findValueStatement(): KtExpression? {
val bodyStatements = statements
if (bodyStatements.isEmpty()) {
return if (convertEmptyToUnit) KtPsiFactory(this).createExpression("Unit") else null
}
val statement = bodyStatements.singleOrNull() ?: return null
when (statement) {
is KtReturnExpression -> {
return statement
}
//TODO: IMO this is not good code, there should be a way to detect that KtExpression does not have value
is KtDeclaration, is KtLoopExpression -> return null
else -> {
// assignment does not have value
if (statement is KtBinaryExpression && statement.operationToken in KtTokens.ALL_ASSIGNMENTS) return null
val context = statement.safeAnalyzeNonSourceRootCode()
val expressionType = context.getType(statement) ?: return null
val isUnit = KotlinBuiltIns.isUnit(expressionType)
if (!isUnit && !KotlinBuiltIns.isNothing(expressionType)) return null
if (isUnit) {
if (statement.hasResultingIfWithoutElse()) {
return null
}
val resultingWhens = statement.resultingWhens()
if (resultingWhens.any { it.elseExpression == null && context.get(BindingContext.EXHAUSTIVE_WHEN, it) != true }) {
return null
}
}
return statement
}
}
}
private fun KtExpression.getValue() = when (this) {
is KtReturnExpression -> returnedExpression
else -> null
} ?: this
private fun KtExpression.toHighlight(): PsiElement? = when (this) {
is KtReturnExpression -> returnKeyword
is KtCallExpression -> calleeExpression
is KtQualifiedExpression -> selectorExpression?.toHighlight()
is KtObjectLiteralExpression -> objectDeclaration.getObjectKeyword()
else -> null
}
fun simplify(declaration: KtDeclarationWithBody, canDeleteTypeRef: Boolean) {
val deleteTypeHandler: (KtCallableDeclaration) -> Unit = {
it.deleteChildRange(it.colon!!, it.typeReference!!)
}
simplify(declaration, deleteTypeHandler.takeIf { canDeleteTypeRef })
}
private fun simplify(declaration: KtDeclarationWithBody, deleteTypeHandler: ((KtCallableDeclaration) -> Unit)?) {
val block = declaration.blockExpression() ?: return
val valueStatement = block.findValueStatement() ?: return
val value = valueStatement.getValue()
if (!declaration.hasDeclaredReturnType() && declaration is KtNamedFunction && block.statements.isNotEmpty()) {
val valueType = value.safeAnalyzeNonSourceRootCode().getType(value)
if (valueType == null || !KotlinBuiltIns.isUnit(valueType)) {
declaration.setType(StandardNames.FqNames.unit.asString(), shortenReferences = true)
}
}
val body = declaration.bodyExpression!!
val commentSaver = CommentSaver(body)
val factory = KtPsiFactory(declaration)
val eq = declaration.addBefore(factory.createEQ(), body)
declaration.addAfter(factory.createWhiteSpace(), eq)
val newBody = body.replaced(value)
commentSaver.restore(newBody)
if (deleteTypeHandler != null && declaration is KtCallableDeclaration) {
if (declaration.hasDeclaredReturnType() && declaration.canOmitDeclaredType(newBody, canChangeTypeToSubtype = true)) {
deleteTypeHandler(declaration)
}
}
val editor = declaration.findExistingEditor()
if (editor != null) {
val startOffset = newBody.startOffset
val document = editor.document
val startLine = document.getLineNumber(startOffset)
val rightMargin = editor.settings.getRightMargin(editor.project)
if (document.getLineEndOffset(startLine) - document.getLineStartOffset(startLine) >= rightMargin) {
declaration.addBefore(factory.createNewLine(), newBody)
}
}
}
inner class ConvertToExpressionBodyFix : LocalQuickFix {
override fun getFamilyName() = name
override fun getName() = KotlinBundle.message("convert.to.expression.body.fix.text")
override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
val declaration = descriptor.psiElement as? KtDeclarationWithBody ?: return
simplify(declaration) {
val typeRef = it.typeReference!!
val colon = it.colon!!
it.findExistingEditor()?.apply {
selectionModel.setSelection(colon.startOffset, typeRef.endOffset)
caretModel.moveToOffset(typeRef.endOffset)
}
}
}
}
}
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