LL API: introduce helper function for throwing invalid FirElement exception

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/api/InvalidFirElementTypeException.kt

@@ -0,0 +1,43 @@
+/*
+ * 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.fir.low.level.api.api
+
+import org.jetbrains.kotlin.fir.FirElement
+import org.jetbrains.kotlin.psi.KtElement
+import java.util.*
+import kotlin.reflect.KClass
+
+class InvalidFirElementTypeException(
+    actualFirClass: KClass<out FirElement>?,
+    ktElement: KtElement?,
+    expectedFirClasses: List<KClass<out FirElement>>,
+) : IllegalStateException() {
+    override val message: String = buildString {
+        if (ktElement != null) {
+            append("For $ktElement with text `${ktElement.text}`, ")
+        }
+        val message = when (expectedFirClasses.size) {
+            0 -> "Unexpected FirElement of type:"
+            1 -> "The FirElement of type ${expectedFirClasses.single()} expected, but"
+            else -> "One of [${expectedFirClasses.joinToString()}] FirElement types expected, but"
+        }
+        append(if (ktElement == null) message else message.replaceFirstChar { it.lowercase(Locale.getDefault()) })
+        if (actualFirClass != null) {
+            append(" ${actualFirClass.simpleName} found")
+        } else {
+            append(" no FirElement found")
+        }
+    }
+}
+
+
+fun throwUnexpectedFirElementError(
+    firElement: FirElement?,
+    ktElement: KtElement? = null,
+    vararg expectedFirClasses: KClass<out FirElement>
+): Nothing {
+    throw InvalidFirElementTypeException(firElement?.let { it::class }, ktElement, expectedFirClasses.toList())
+}

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/api/LowLevelFirApiFacade.kt

@@ -93,7 +93,7 @@ inline fun <reified F : FirDeclaration, R> KtDeclaration.withFirDeclarationOfTyp
     phase: FirResolvePhase = FirResolvePhase.RAW_FIR,
     action: (F) -> R
 ): R = withFirDeclaration(resolveState, phase) { firDeclaration ->
-    if (firDeclaration !is F) throw InvalidFirElementTypeException(this, F::class, firDeclaration::class)
+    if (firDeclaration !is F) throwUnexpectedFirElementError(firDeclaration, this, F::class)
     action(firDeclaration)
 }
 
@@ -111,7 +111,7 @@ inline fun <reified F : FirDeclaration, R> KtLambdaExpression.withFirDeclaration
     action: (F) -> R
 ): R {
     val firDeclaration = resolveState.findSourceFirDeclaration(this)
-    if (firDeclaration !is F) throw InvalidFirElementTypeException(this, F::class, firDeclaration::class)
+    if (firDeclaration !is F) throwUnexpectedFirElementError(firDeclaration, this, F::class)
     return action(firDeclaration)
 }
 
@@ -233,7 +233,7 @@ inline fun <reified E : FirElement> KtElement.getOrBuildFirOfType(
 ): E {
     val fir = this.getOrBuildFir(resolveState)
     if (fir is E) return fir
-    throw InvalidFirElementTypeException(this, E::class, fir::class)
+    throwUnexpectedFirElementError(fir, this, E::class)
 }
 
 /**
@@ -242,9 +242,3 @@ inline fun <reified E : FirElement> KtElement.getOrBuildFirOfType(
  */
 fun KtFile.getOrBuildFirFile(resolveState: FirModuleResolveState): FirFile =
     resolveState.getOrBuildFirFile(this)
-
-class InvalidFirElementTypeException(
-    ktElement: KtElement,
-    expectedFirClass: KClass<out FirElement>,
-    actualFirClass: KClass<out FirElement>
-) : IllegalStateException("For $ktElement with text `${ktElement.text}` the $expectedFirClass expected, but $actualFirClass found")

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/util/declarationUtils.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.fir.psi
 import org.jetbrains.kotlin.fir.realPsi
 import org.jetbrains.kotlin.fir.resolve.providers.FirSymbolProvider
 import org.jetbrains.kotlin.idea.fir.low.level.api.api.InvalidFirElementTypeException
+import org.jetbrains.kotlin.idea.fir.low.level.api.api.throwUnexpectedFirElementError
 import org.jetbrains.kotlin.idea.fir.low.level.api.element.builder.getNonLocalContainingOrThisDeclaration
 import org.jetbrains.kotlin.idea.fir.low.level.api.file.builder.FirFileBuilder
 import org.jetbrains.kotlin.idea.fir.low.level.api.file.builder.ModuleFileCache
@@ -56,7 +57,7 @@ internal inline fun <reified F : FirDeclaration> KtDeclaration.findFirDeclaratio
     moduleFileCache: ModuleFileCache
 ): FirDeclaration {
     val fir = findFirDeclarationForAnyFirSourceDeclaration(firFileBuilder, firSymbolProvider, moduleFileCache)
-    if (fir !is F) throw InvalidFirElementTypeException(this, F::class, fir::class)
+    if (fir !is F) throwUnexpectedFirElementError(fir, this, F::class)
     return fir
 }
 

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/components/KtFirCompileTimeConstantProvider.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.idea.frontend.api.fir.components
 import org.jetbrains.kotlin.fir.expressions.FirExpression
 import org.jetbrains.kotlin.idea.fir.evaluate.FirCompileTimeConstantEvaluator
 import org.jetbrains.kotlin.idea.fir.low.level.api.api.getOrBuildFir
+import org.jetbrains.kotlin.idea.fir.low.level.api.api.throwUnexpectedFirElementError
 import org.jetbrains.kotlin.idea.frontend.api.components.KtCompileTimeConstantProvider
 import org.jetbrains.kotlin.idea.frontend.api.fir.KtFirAnalysisSession
 import org.jetbrains.kotlin.idea.frontend.api.fir.utils.convertConstantExpression
@@ -24,7 +25,7 @@ internal class KtFirCompileTimeConstantProvider(
     override fun evaluate(expression: KtExpression): KtSimpleConstantValue<*>? = withValidityAssertion {
         when (val fir = expression.getOrBuildFir(firResolveState)) {
             is FirExpression -> FirCompileTimeConstantEvaluator().evaluate(fir)?.convertConstantExpression()
-            else -> error("Unexpected ${fir::class}")
+            else -> throwUnexpectedFirElementError(fir, expression)
         }
     }
 }

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/components/KtFirExpressionTypeProvider.kt

@@ -39,7 +39,7 @@ internal class KtFirExpressionTypeProvider(
             is FirExpression -> fir.typeRef.coneType.asKtType()
             is FirNamedReference -> fir.getReferencedElementType().asKtType()
             is FirStatement -> with(analysisSession) { builtinTypes.UNIT }
-            else -> error("Unexpected ${fir::class}")
+            else -> error("Unexpected ${fir?.let { it::class }}")
         }
     }
 

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/components/KtFirPsiTypeProvider.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.fir.expressions.FirStatement
 import org.jetbrains.kotlin.fir.references.FirNamedReference
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.idea.fir.low.level.api.api.getOrBuildFir
+import org.jetbrains.kotlin.idea.fir.low.level.api.api.throwUnexpectedFirElementError
 import org.jetbrains.kotlin.idea.frontend.api.components.KtPsiTypeProvider
 import org.jetbrains.kotlin.idea.frontend.api.fir.KtFirAnalysisSession
 import org.jetbrains.kotlin.idea.frontend.api.fir.utils.getReferencedElementType
@@ -36,7 +37,7 @@ internal class KtFirPsiTypeProvider(
             is FirExpression -> fir.typeRef.coneType.asPsiType(mode, expression)
             is FirNamedReference -> fir.getReferencedElementType().asPsiType(mode, expression)
             is FirStatement -> PsiType.VOID
-            else -> error("Unexpected ${fir::class}")
+            else -> throwUnexpectedFirElementError(fir, expression)
         }
     }
 
@@ -47,7 +48,7 @@ internal class KtFirPsiTypeProvider(
         when (val fir = ktTypeReference.getOrBuildFir(firResolveState)) {
             // NB: [FirErrorTypeRef] is a subtype of [FirResolvedTypeRef], and the error type in it will be properly handled by [asPsiType].
             is FirResolvedTypeRef -> fir.coneType.asPsiType(mode, ktTypeReference)
-            else -> error("Unexpected ${fir::class}")
+            else -> throwUnexpectedFirElementError(fir, ktTypeReference)
         }
     }
 
@@ -61,7 +62,7 @@ internal class KtFirPsiTypeProvider(
                 fir.typeRef.coneType.getReceiverOfReflectionType()?.asPsiType(mode, receiver)
             is FirCallableReferenceAccess ->
                 fir.typeRef.coneType.getReceiverOfReflectionType()?.asPsiType(mode, receiver)
-            else -> error("Unexpected ${fir::class}")
+            else -> throwUnexpectedFirElementError(fir, ktDoubleColonExpression)
         }
     }