FIR IDE: fix completion of type arguments without closing >

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/FE10CompletionDummyIdentifierProviderService.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2010-2021 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.completion
+
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.ClassKind
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
+import org.jetbrains.kotlin.psi.KtNameReferenceExpression
+import org.jetbrains.kotlin.resolve.bindingContextUtil.getReferenceTargets
+import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
+
+class FE10CompletionDummyIdentifierProviderService: CompletionDummyIdentifierProviderService() {
+    override fun allTargetsAreFunctionsOrClasses(nameReferenceExpression: KtNameReferenceExpression): Boolean {
+        val bindingContext = nameReferenceExpression.getResolutionFacade().analyze(nameReferenceExpression, BodyResolveMode.PARTIAL)
+        val targets = nameReferenceExpression.getReferenceTargets(bindingContext)
+        return targets.isNotEmpty() && targets.all { it is FunctionDescriptor || it is ClassDescriptor && it.kind == ClassKind.CLASS }
+    }
+}

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/KotlinCompletionContributor.kt

@@ -7,22 +7,15 @@ package org.jetbrains.kotlin.idea.completion
 
 import com.intellij.codeInsight.completion.*
 import com.intellij.codeInsight.lookup.LookupElement
-import com.intellij.codeInsight.lookup.LookupElementDecorator
+import com.intellij.openapi.components.service
 import com.intellij.openapi.editor.Document
 import com.intellij.openapi.extensions.ExtensionPointName
 import com.intellij.openapi.util.Key
 import com.intellij.patterns.PlatformPatterns
 import com.intellij.patterns.PsiJavaPatterns.elementType
 import com.intellij.patterns.PsiJavaPatterns.psiElement
-import com.intellij.psi.*
-import com.intellij.psi.search.PsiElementProcessor
-import com.intellij.psi.tree.TokenSet
-import com.intellij.psi.util.PsiTreeUtil
+import com.intellij.psi.PsiComment
 import com.intellij.util.ProcessingContext
-import org.jetbrains.kotlin.descriptors.ClassDescriptor
-import org.jetbrains.kotlin.descriptors.ClassKind
-import org.jetbrains.kotlin.descriptors.FunctionDescriptor
-import org.jetbrains.kotlin.idea.caches.resolve.getResolutionFacade
 import org.jetbrains.kotlin.idea.completion.smart.SmartCompletion
 import org.jetbrains.kotlin.idea.completion.smart.SmartCompletionSession
 import org.jetbrains.kotlin.idea.statistics.CompletionFUSCollector.completionStatsData
@@ -30,10 +23,8 @@ import org.jetbrains.kotlin.idea.statistics.CompletionTypeStats
 import org.jetbrains.kotlin.idea.statistics.FileTypeStats
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
-import org.jetbrains.kotlin.psi.psiUtil.*
-import org.jetbrains.kotlin.resolve.bindingContextUtil.getReferenceTargets
-import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
-import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
+import org.jetbrains.kotlin.psi.psiUtil.endOffset
+import org.jetbrains.kotlin.psi.psiUtil.getNonStrictParentOfType
 import kotlin.math.max
 
 var KtFile.doNotComplete: Boolean? by UserDataProperty(Key.create("DO_NOT_COMPLETE"))
@@ -91,17 +82,7 @@ class KotlinCompletionContributor : CompletionContributor() {
 
             PackageDirectiveCompletion.ACTIVATION_PATTERN.accepts(tokenBefore) -> PackageDirectiveCompletion.DUMMY_IDENTIFIER
 
-            isInClassHeader(tokenBefore) -> CompletionUtilCore.DUMMY_IDENTIFIER // do not add '$' to not interrupt class declaration parsing
-
-            isInUnclosedSuperQualifier(tokenBefore) -> CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED + ">"
-
-            isInSimpleStringTemplate(tokenBefore) -> CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED
-
-            else -> specialLambdaSignatureDummyIdentifier(tokenBefore)
-                ?: specialExtensionReceiverDummyIdentifier(tokenBefore)
-                ?: specialInTypeArgsDummyIdentifier(tokenBefore)
-                ?: specialInArgumentListDummyIdentifier(tokenBefore)
-                ?: DEFAULT_DUMMY_IDENTIFIER
+            else -> service<CompletionDummyIdentifierProviderService>().provideDummyIdentifier(context)
         }
 
         val tokenAt = psiFile.findElementAt(max(0, offset))
@@ -166,76 +147,6 @@ class KotlinCompletionContributor : CompletionContributor() {
         return expression.textRange!!.endOffset
     }
 
-    private fun isInClassHeader(tokenBefore: PsiElement?): Boolean {
-        val classOrObject = tokenBefore?.parents?.firstIsInstanceOrNull<KtClassOrObject>() ?: return false
-        val name = classOrObject.nameIdentifier ?: return false
-        val headerEnd = classOrObject.body?.startOffset ?: classOrObject.endOffset
-        val offset = tokenBefore.startOffset
-        return name.endOffset <= offset && offset <= headerEnd
-    }
-
-    private fun specialLambdaSignatureDummyIdentifier(tokenBefore: PsiElement?): String? {
-        var leaf = tokenBefore
-        while (leaf is PsiWhiteSpace || leaf is PsiComment) {
-            leaf = leaf.prevLeaf(true)
-        }
-
-        val lambda = leaf?.parents?.firstOrNull { it is KtFunctionLiteral } ?: return null
-
-        val lambdaChild = leaf.parents.takeWhile { it != lambda }.lastOrNull()
-
-        return if (lambdaChild is KtParameterList)
-            CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED
-        else
-            null
-
-    }
-
-    private val declarationKeywords = TokenSet.create(KtTokens.FUN_KEYWORD, KtTokens.VAL_KEYWORD, KtTokens.VAR_KEYWORD)
-    private val declarationTokens = TokenSet.orSet(
-        TokenSet.create(
-            KtTokens.IDENTIFIER, KtTokens.LT, KtTokens.GT,
-            KtTokens.COMMA, KtTokens.DOT, KtTokens.QUEST, KtTokens.COLON,
-            KtTokens.IN_KEYWORD, KtTokens.OUT_KEYWORD,
-            KtTokens.LPAR, KtTokens.RPAR, KtTokens.ARROW,
-            TokenType.ERROR_ELEMENT
-        ),
-        KtTokens.WHITE_SPACE_OR_COMMENT_BIT_SET
-    )
-
-    private fun specialExtensionReceiverDummyIdentifier(tokenBefore: PsiElement?): String? {
-        var token = tokenBefore ?: return null
-        var ltCount = 0
-        var gtCount = 0
-        val builder = StringBuilder()
-        while (true) {
-            val tokenType = token.node!!.elementType
-            if (tokenType in declarationKeywords) {
-                val balance = ltCount - gtCount
-                if (balance < 0) return null
-                builder.append(token.text!!.reversed())
-                builder.reverse()
-
-                var tail = "X" + ">".repeat(balance) + ".f"
-                if (tokenType == KtTokens.FUN_KEYWORD) {
-                    tail += "()"
-                }
-                builder.append(tail)
-
-                val text = builder.toString()
-                val file = KtPsiFactory(tokenBefore.project).createFile(text)
-                val declaration = file.declarations.singleOrNull() ?: return null
-                if (declaration.textLength != text.length) return null
-                val containsErrorElement = !PsiTreeUtil.processElements(file, PsiElementProcessor<PsiElement> { it !is PsiErrorElement })
-                return if (containsErrorElement) null else "$tail$"
-            }
-            if (tokenType !in declarationTokens) return null
-            if (tokenType == KtTokens.LT) ltCount++
-            if (tokenType == KtTokens.GT) gtCount++
-            builder.append(token.text!!.reversed())
-            token = PsiTreeUtil.prevLeaf(token) ?: return null
-        }
-    }
 
     private fun performCompletion(parameters: CompletionParameters, result: CompletionResultSet) {
         val position = parameters.position
@@ -402,94 +313,6 @@ class KotlinCompletionContributor : CompletionContributor() {
         }
         return true
     }
-
-    private fun specialInTypeArgsDummyIdentifier(tokenBefore: PsiElement?): String? {
-        if (tokenBefore == null) return null
-
-        if (tokenBefore.getParentOfType<KtTypeArgumentList>(true) != null) { // already parsed inside type argument list
-            return CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED // do not insert '$' to not break type argument list parsing
-        }
-
-        val pair = unclosedTypeArgListNameAndBalance(tokenBefore) ?: return null
-        val (nameToken, balance) = pair
-        assert(balance > 0)
-
-        val nameRef = nameToken.parent as? KtNameReferenceExpression ?: return null
-        val bindingContext = nameRef.getResolutionFacade().analyze(nameRef, BodyResolveMode.PARTIAL)
-        val targets = nameRef.getReferenceTargets(bindingContext)
-        return if (targets.isNotEmpty() && targets.all { it is FunctionDescriptor || it is ClassDescriptor && it.kind == ClassKind.CLASS }) {
-            CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED + ">".repeat(balance) + "$"
-        } else {
-            null
-        }
-    }
-
-    private fun unclosedTypeArgListNameAndBalance(tokenBefore: PsiElement): Pair<PsiElement, Int>? {
-        val nameToken = findCallNameTokenIfInTypeArgs(tokenBefore) ?: return null
-        val pair = unclosedTypeArgListNameAndBalance(nameToken)
-        return if (pair == null) {
-            Pair(nameToken, 1)
-        } else {
-            Pair(pair.first, pair.second + 1)
-        }
-    }
-
-    private val callTypeArgsTokens = TokenSet.orSet(
-        TokenSet.create(
-            KtTokens.IDENTIFIER, KtTokens.LT, KtTokens.GT,
-            KtTokens.COMMA, KtTokens.DOT, KtTokens.QUEST, KtTokens.COLON,
-            KtTokens.LPAR, KtTokens.RPAR, KtTokens.ARROW
-        ),
-        KtTokens.WHITE_SPACE_OR_COMMENT_BIT_SET
-    )
-
-    // if the leaf could be located inside type argument list of a call (if parsed properly)
-    // then it returns the call name reference this type argument list would belong to
-    private fun findCallNameTokenIfInTypeArgs(leaf: PsiElement): PsiElement? {
-        var current = leaf
-        while (true) {
-            val tokenType = current.node!!.elementType
-            if (tokenType !in callTypeArgsTokens) return null
-
-            if (tokenType == KtTokens.LT) {
-                val nameToken = current.prevLeaf(skipEmptyElements = true) ?: return null
-                if (nameToken.node!!.elementType != KtTokens.IDENTIFIER) return null
-                return nameToken
-            }
-
-            if (tokenType == KtTokens.GT) { // pass nested type argument list
-                val prev = current.prevLeaf(skipEmptyElements = true) ?: return null
-                val typeRef = findCallNameTokenIfInTypeArgs(prev) ?: return null
-                current = typeRef
-                continue
-            }
-
-            current = current.prevLeaf(skipEmptyElements = true) ?: return null
-        }
-    }
-
-    private fun specialInArgumentListDummyIdentifier(tokenBefore: PsiElement?): String? {
-        // If we insert $ in the argument list of a delegation specifier, this will break parsing
-        // and the following block will not be attached as a body to the constructor. Therefore
-        // we need to use a regular identifier.
-        val argumentList = tokenBefore?.getNonStrictParentOfType<KtValueArgumentList>() ?: return null
-        if (argumentList.parent is KtConstructorDelegationCall) return CompletionUtil.DUMMY_IDENTIFIER_TRIMMED
-        return null
-    }
-
-    private fun isInUnclosedSuperQualifier(tokenBefore: PsiElement?): Boolean {
-        if (tokenBefore == null) return false
-        val tokensToSkip = TokenSet.orSet(TokenSet.create(KtTokens.IDENTIFIER, KtTokens.DOT), KtTokens.WHITE_SPACE_OR_COMMENT_BIT_SET)
-        val tokens = generateSequence(tokenBefore) { it.prevLeaf() }
-        val ltToken = tokens.firstOrNull { it.node.elementType !in tokensToSkip } ?: return false
-        if (ltToken.node.elementType != KtTokens.LT) return false
-        val superToken = ltToken.prevLeaf { it !is PsiWhiteSpace && it !is PsiComment }
-        return superToken?.node?.elementType == KtTokens.SUPER_KEYWORD
-    }
-
-    private fun isInSimpleStringTemplate(tokenBefore: PsiElement?): Boolean {
-        return tokenBefore?.parents?.firstIsInstanceOrNull<KtStringTemplateExpression>()?.isPlain() ?: false
-    }
 }
 
 abstract class KotlinCompletionExtension {

idea/idea-completion/testData/basic/common/GenericExtensionFunReceiver1.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun foo() {}
 
 fun <T> S<caret>

idea/idea-completion/testData/basic/common/GenericExtensionFunReceiver2.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Foo{}
 
 fun foo() {}

idea/idea-completion/testData/basic/common/NestedClassNameForExtension.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Test {
     public class Nested
 }

idea/idea-completion/testData/basic/common/NestedClassNameForExtension2.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Test {
     public class Nested
 }

idea/idea-completion/testData/basic/common/annotations/AnnotationTarget.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 @<caret> annotation class Annotated
 
 // EXIST: Target

idea/idea-completion/testData/basic/common/autoPopup/AutopopupInFunExtensionReceiver.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Xyz
 
 fun X<caret>

idea/idea-completion/testData/basic/common/autoPopup/GenericExtensionFunTypeArgument.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun Strange(){}
 
 fun Annotations<S<caret>

idea/idea-completion/testData/basic/common/autoPopup/GenericExtensionFunTypeArgument2.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun Strange(){}
 
 fun Map<() -> Unit, Str<caret>

idea/idea-completion/testData/basic/common/autoPopup/InExtFunName.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Outer {
     class Nested
 }

idea/idea-completion/testData/basic/common/autoPopup/InGenericExtFunName.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Outer {
     class Nested
 }

idea/idea-completion/testData/basic/common/autoPopup/InValExtType.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 class Some
 
 val S<caret>

idea/idea-completion/testData/basic/common/typeArgsOrNot/ConstructorTypeArg.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 import java.util.HashMap
 
 fun foo() {

idea/idea-completion/testData/basic/common/typeArgsOrNot/FunctionTypeArg.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun foo() {
     val v = listOf<<caret>
 }

idea/idea-completion/testData/basic/common/typeArgsOrNot/FunctionTypeArg2.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun <T> genericFoo(p: Int){}
 fun <T> genericFoo(c: Char){}
 

idea/idea-completion/testData/basic/common/typeArgsOrNot/LessThan.kt

@@ -1,4 +1,3 @@
-// FIR_COMPARISON
 val v = 1
 fun f() = 2
 

idea/idea-completion/testData/basic/common/typeArgsOrNot/NestedTypeArg.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun foo() {
     val v = HashMap<List<(s: String?) -> Unit>, Set<<caret>
 }

idea/idea-completion/testData/basic/common/typeArgsOrNot/SecondTypeArg.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 fun foo() {
     val v = HashMap<String, <caret>
 }

idea/idea-completion/testData/basic/common/typeArgsOrNot/SecondTypeArg3.kt

@@ -1,3 +1,4 @@
+// FIR_COMPARISON
 import java.util.HashMap
 
 fun foo() {

idea/idea-fir/src/org/jetbrains/kotlin/idea/completion/FirCompletionDummyIdentifierProviderService.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2021 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.completion
+
+import org.jetbrains.kotlin.idea.frontend.api.analyse
+import org.jetbrains.kotlin.idea.frontend.api.symbols.KtClassKind
+import org.jetbrains.kotlin.idea.frontend.api.symbols.KtClassOrObjectSymbol
+import org.jetbrains.kotlin.idea.frontend.api.symbols.KtFunctionSymbol
+import org.jetbrains.kotlin.idea.references.mainReference
+import org.jetbrains.kotlin.psi.KtNameReferenceExpression
+
+class FirCompletionDummyIdentifierProviderService : CompletionDummyIdentifierProviderService() {
+    override fun allTargetsAreFunctionsOrClasses(nameReferenceExpression: KtNameReferenceExpression): Boolean {
+        return true
+        // TODO fir cannot handle invalid code and handles listOf< as binary expression
+//        return analyse(nameReferenceExpression) {
+//            val reference = nameReferenceExpression.mainReference
+//            val targets = reference.resolveToSymbols()
+//            targets.isNotEmpty() && targets.all { target ->
+//                target is KtFunctionSymbol || target is KtClassOrObjectSymbol && target.classKind == KtClassKind.CLASS
+//            }
+//        }
+    }
+}

idea/idea-fir/src/org/jetbrains/kotlin/idea/completion/KotlinFirCompletionContributor.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.idea.completion
 
 import com.intellij.codeInsight.completion.*
+import com.intellij.openapi.components.service
 import com.intellij.patterns.PlatformPatterns
 import com.intellij.patterns.PsiJavaPatterns
 import com.intellij.util.ProcessingContext
@@ -28,11 +29,19 @@ import org.jetbrains.kotlin.idea.fir.low.level.api.IndexHelper
 import org.jetbrains.kotlin.idea.fir.low.level.api.util.originalKtFile
 import org.jetbrains.kotlin.idea.frontend.api.KtAnalysisSession
 import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.KtFile
 
 class KotlinFirCompletionContributor : CompletionContributor() {
     init {
         extend(CompletionType.BASIC, PlatformPatterns.psiElement(), KotlinFirCompletionProvider)
     }
+
+    override fun beforeCompletion(context: CompletionInitializationContext) {
+        val psiFile = context.file
+        if (psiFile !is KtFile) return
+
+        context.dummyIdentifier = service<CompletionDummyIdentifierProviderService>().provideDummyIdentifier(context)
+    }
 }
 
 private object KotlinFirCompletionProvider : CompletionProvider<CompletionParameters>() {

idea/idea-frontend-independent/src/org/jetbrains/kotlin/idea/completion/CompletionDummyIdentifierProviderService.kt

@@ -0,0 +1,215 @@
+/*
+ * Copyright 2010-2021 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.completion
+
+import com.intellij.codeInsight.completion.CompletionInitializationContext
+import com.intellij.codeInsight.completion.CompletionType
+import com.intellij.codeInsight.completion.CompletionUtil
+import com.intellij.codeInsight.completion.CompletionUtilCore
+import com.intellij.psi.*
+import com.intellij.psi.tree.TokenSet
+import com.intellij.psi.util.PsiTreeUtil
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.*
+import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
+import kotlin.math.max
+
+abstract class CompletionDummyIdentifierProviderService {
+    fun provideDummyIdentifier(context: CompletionInitializationContext): String {
+        val psiFile = context.file
+        if (psiFile !is KtFile) {
+            error("CompletionDummyIdentifierProviderService.providerDummyIdentifier should not be called for non KtFile")
+        }
+
+        val offset = context.startOffset
+        val tokenBefore = psiFile.findElementAt(max(0, offset - 1))
+
+        return when {
+            context.completionType == CompletionType.SMART -> DEFAULT_DUMMY_IDENTIFIER
+
+            // TODO package completion
+
+            isInClassHeader(tokenBefore) -> CompletionUtilCore.DUMMY_IDENTIFIER // do not add '$' to not interrupt class declaration parsing
+
+            isInUnclosedSuperQualifier(tokenBefore) -> CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED + ">"
+
+            isInSimpleStringTemplate(tokenBefore) -> CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED
+
+            else -> specialLambdaSignatureDummyIdentifier(tokenBefore)
+                ?: specialExtensionReceiverDummyIdentifier(tokenBefore)
+                ?: specialInTypeArgsDummyIdentifier(tokenBefore)
+                ?: specialInArgumentListDummyIdentifier(tokenBefore)
+                ?: DEFAULT_DUMMY_IDENTIFIER
+        }
+    }
+
+    private fun specialLambdaSignatureDummyIdentifier(tokenBefore: PsiElement?): String? {
+        var leaf = tokenBefore
+        while (leaf is PsiWhiteSpace || leaf is PsiComment) {
+            leaf = leaf.prevLeaf(true)
+        }
+
+        val lambda = leaf?.parents?.firstOrNull { it is KtFunctionLiteral } ?: return null
+
+        val lambdaChild = leaf.parents.takeWhile { it != lambda }.lastOrNull()
+
+        return if (lambdaChild is KtParameterList)
+            CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED
+        else
+            null
+
+    }
+
+    private fun isInClassHeader(tokenBefore: PsiElement?): Boolean {
+        val classOrObject = tokenBefore?.parents?.firstIsInstanceOrNull<KtClassOrObject>() ?: return false
+        val name = classOrObject.nameIdentifier ?: return false
+        val headerEnd = classOrObject.body?.startOffset ?: classOrObject.endOffset
+        val offset = tokenBefore.startOffset
+        return name.endOffset <= offset && offset <= headerEnd
+    }
+
+    private fun isInUnclosedSuperQualifier(tokenBefore: PsiElement?): Boolean {
+        if (tokenBefore == null) return false
+        val tokensToSkip = TokenSet.orSet(TokenSet.create(KtTokens.IDENTIFIER, KtTokens.DOT), KtTokens.WHITE_SPACE_OR_COMMENT_BIT_SET)
+        val tokens = generateSequence(tokenBefore) { it.prevLeaf() }
+        val ltToken = tokens.firstOrNull { it.node.elementType !in tokensToSkip } ?: return false
+        if (ltToken.node.elementType != KtTokens.LT) return false
+        val superToken = ltToken.prevLeaf { it !is PsiWhiteSpace && it !is PsiComment }
+        return superToken?.node?.elementType == KtTokens.SUPER_KEYWORD
+    }
+
+    private fun isInSimpleStringTemplate(tokenBefore: PsiElement?): Boolean {
+        return tokenBefore?.parents?.firstIsInstanceOrNull<KtStringTemplateExpression>()?.isPlain() ?: false
+    }
+
+
+    private fun specialExtensionReceiverDummyIdentifier(tokenBefore: PsiElement?): String? {
+        var token = tokenBefore ?: return null
+        var ltCount = 0
+        var gtCount = 0
+        val builder = StringBuilder()
+        while (true) {
+            val tokenType = token.node!!.elementType
+            if (tokenType in declarationKeywords) {
+                val balance = ltCount - gtCount
+                if (balance < 0) return null
+                builder.append(token.text!!.reversed())
+                builder.reverse()
+
+                var tail = "X" + ">".repeat(balance) + ".f"
+                if (tokenType == KtTokens.FUN_KEYWORD) {
+                    tail += "()"
+                }
+                builder.append(tail)
+
+                val text = builder.toString()
+                val file = KtPsiFactory(tokenBefore.project).createFile(text)
+                val declaration = file.declarations.singleOrNull() ?: return null
+                if (declaration.textLength != text.length) return null
+                val containsErrorElement = !PsiTreeUtil.processElements(file) { it !is PsiErrorElement }
+                return if (containsErrorElement) null else "$tail$"
+            }
+            if (tokenType !in declarationTokens) return null
+            if (tokenType == KtTokens.LT) ltCount++
+            if (tokenType == KtTokens.GT) gtCount++
+            builder.append(token.text!!.reversed())
+            token = PsiTreeUtil.prevLeaf(token) ?: return null
+        }
+    }
+
+    private fun specialInTypeArgsDummyIdentifier(tokenBefore: PsiElement?): String? {
+        if (tokenBefore == null) return null
+
+        if (tokenBefore.getParentOfType<KtTypeArgumentList>(true) != null) { // already parsed inside type argument list
+            return CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED // do not insert '$' to not break type argument list parsing
+        }
+
+        val pair = unclosedTypeArgListNameAndBalance(tokenBefore) ?: return null
+        val (nameToken, balance) = pair
+        assert(balance > 0)
+
+        val nameRef = nameToken.parent as? KtNameReferenceExpression ?: return null
+        return if (allTargetsAreFunctionsOrClasses(nameRef)) {
+            CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED + ">".repeat(balance) + "$"
+        } else {
+            null
+        }
+    }
+
+    protected abstract fun allTargetsAreFunctionsOrClasses(nameReferenceExpression: KtNameReferenceExpression): Boolean
+
+    private fun unclosedTypeArgListNameAndBalance(tokenBefore: PsiElement): Pair<PsiElement, Int>? {
+        val nameToken = findCallNameTokenIfInTypeArgs(tokenBefore) ?: return null
+        val pair = unclosedTypeArgListNameAndBalance(nameToken)
+        return if (pair == null) {
+            Pair(nameToken, 1)
+        } else {
+            Pair(pair.first, pair.second + 1)
+        }
+    }
+
+    private val callTypeArgsTokens = TokenSet.orSet(
+        TokenSet.create(
+            KtTokens.IDENTIFIER, KtTokens.LT, KtTokens.GT,
+            KtTokens.COMMA, KtTokens.DOT, KtTokens.QUEST, KtTokens.COLON,
+            KtTokens.LPAR, KtTokens.RPAR, KtTokens.ARROW
+        ),
+        KtTokens.WHITE_SPACE_OR_COMMENT_BIT_SET
+    )
+
+    // if the leaf could be located inside type argument list of a call (if parsed properly)
+    // then it returns the call name reference this type argument list would belong to
+    private fun findCallNameTokenIfInTypeArgs(leaf: PsiElement): PsiElement? {
+        var current = leaf
+        while (true) {
+            val tokenType = current.node!!.elementType
+            if (tokenType !in callTypeArgsTokens) return null
+
+            if (tokenType == KtTokens.LT) {
+                val nameToken = current.prevLeaf(skipEmptyElements = true) ?: return null
+                if (nameToken.node!!.elementType != KtTokens.IDENTIFIER) return null
+                return nameToken
+            }
+
+            if (tokenType == KtTokens.GT) { // pass nested type argument list
+                val prev = current.prevLeaf(skipEmptyElements = true) ?: return null
+                val typeRef = findCallNameTokenIfInTypeArgs(prev) ?: return null
+                current = typeRef
+                continue
+            }
+
+            current = current.prevLeaf(skipEmptyElements = true) ?: return null
+        }
+    }
+
+
+    private fun specialInArgumentListDummyIdentifier(tokenBefore: PsiElement?): String? {
+        // If we insert $ in the argument list of a delegation specifier, this will break parsing
+        // and the following block will not be attached as a body to the constructor. Therefore
+        // we need to use a regular identifier.
+        val argumentList = tokenBefore?.getNonStrictParentOfType<KtValueArgumentList>() ?: return null
+        if (argumentList.parent is KtConstructorDelegationCall) return CompletionUtil.DUMMY_IDENTIFIER_TRIMMED
+        return null
+    }
+
+    companion object {
+        val DEFAULT_DUMMY_IDENTIFIER: String =
+            CompletionUtilCore.DUMMY_IDENTIFIER_TRIMMED + "$" // add '$' to ignore context after the caret
+
+        private val declarationKeywords = TokenSet.create(KtTokens.FUN_KEYWORD, KtTokens.VAL_KEYWORD, KtTokens.VAR_KEYWORD)
+        private val declarationTokens = TokenSet.orSet(
+            TokenSet.create(
+                KtTokens.IDENTIFIER, KtTokens.LT, KtTokens.GT,
+                KtTokens.COMMA, KtTokens.DOT, KtTokens.QUEST, KtTokens.COLON,
+                KtTokens.IN_KEYWORD, KtTokens.OUT_KEYWORD,
+                KtTokens.LPAR, KtTokens.RPAR, KtTokens.ARROW,
+                TokenType.ERROR_ELEMENT
+            ),
+            KtTokens.WHITE_SPACE_OR_COMMENT_BIT_SET
+        )
+    }
+}

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

@@ -156,6 +156,9 @@ The Kotlin plugin provides language support in IntelliJ IDEA and Android Studio.
   </extensions>
 
   <extensions defaultExtensionNs="com.intellij">
+    <applicationService serviceImplementation="org.jetbrains.kotlin.idea.completion.FE10CompletionDummyIdentifierProviderService"
+                        serviceInterface="org.jetbrains.kotlin.idea.completion.CompletionDummyIdentifierProviderService"/>
+
     <pathMacroContributor implementation="org.jetbrains.kotlin.idea.KotlinPluginMacros"/>
     <applicationService serviceImplementation="org.jetbrains.kotlin.idea.PluginStartupApplicationService" />
     <applicationService serviceInterface="org.jetbrains.kotlin.idea.completion.handlers.SmartCompletionTailOffsetProvider"

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

@@ -218,6 +218,8 @@ The Kotlin FIR plugin provides language support in IntelliJ IDEA and Android Stu
 
 
   <extensions defaultExtensionNs="com.intellij">
+    <applicationService serviceImplementation="org.jetbrains.kotlin.idea.completion.FirCompletionDummyIdentifierProviderService"
+                        serviceInterface="org.jetbrains.kotlin.idea.completion.CompletionDummyIdentifierProviderService"/>
 
     <postStartupActivity implementation="org.jetbrains.kotlin.idea.PluginStartupActivity"/>
     <projectService serviceImplementation="org.jetbrains.kotlin.idea.PluginStartupService"/>