FIR IDE: Add API to get implicit receiver types at a position

This will be used in completion contribution.

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/components/KtFirTypeProvider.kt

@@ -5,18 +5,6 @@
 
 package org.jetbrains.kotlin.analysis.api.fir.components
 
-import org.jetbrains.kotlin.fir.analysis.checkers.ConeTypeCompatibilityChecker
-import org.jetbrains.kotlin.fir.analysis.checkers.ConeTypeCompatibilityChecker.isCompatible
-import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
-import org.jetbrains.kotlin.fir.expressions.FirCallableReferenceAccess
-import org.jetbrains.kotlin.fir.expressions.FirDelegatedConstructorCall
-import org.jetbrains.kotlin.fir.expressions.FirGetClassCall
-import org.jetbrains.kotlin.fir.typeContext
-import org.jetbrains.kotlin.fir.types.*
-import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
-import org.jetbrains.kotlin.fir.types.impl.ConeTypeParameterTypeImpl
-import org.jetbrains.kotlin.analysis.low.level.api.fir.api.getOrBuildFir
-import org.jetbrains.kotlin.analysis.low.level.api.fir.api.throwUnexpectedFirElementError
 import org.jetbrains.kotlin.analysis.api.components.KtBuiltinTypes
 import org.jetbrains.kotlin.analysis.api.components.KtTypeProvider
 import org.jetbrains.kotlin.analysis.api.fir.KtFirAnalysisSession
@@ -29,8 +17,22 @@ import org.jetbrains.kotlin.analysis.api.tokens.ValidityToken
 import org.jetbrains.kotlin.analysis.api.types.KtType
 import org.jetbrains.kotlin.analysis.api.types.KtTypeNullability
 import org.jetbrains.kotlin.analysis.api.withValidityAssertion
+import org.jetbrains.kotlin.analysis.low.level.api.fir.api.LowLevelFirApiFacadeForResolveOnAir.getTowerContextProvider
+import org.jetbrains.kotlin.analysis.low.level.api.fir.api.getOrBuildFir
+import org.jetbrains.kotlin.analysis.low.level.api.fir.api.throwUnexpectedFirElementError
+import org.jetbrains.kotlin.fir.analysis.checkers.ConeTypeCompatibilityChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.ConeTypeCompatibilityChecker.isCompatible
+import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
+import org.jetbrains.kotlin.fir.expressions.FirCallableReferenceAccess
+import org.jetbrains.kotlin.fir.expressions.FirDelegatedConstructorCall
+import org.jetbrains.kotlin.fir.expressions.FirGetClassCall
+import org.jetbrains.kotlin.fir.typeContext
+import org.jetbrains.kotlin.fir.types.*
+import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
+import org.jetbrains.kotlin.fir.types.impl.ConeTypeParameterTypeImpl
 import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.psi.KtDoubleColonExpression
+import org.jetbrains.kotlin.psi.KtElement
 import org.jetbrains.kotlin.psi.KtTypeReference
 
 internal class KtFirTypeProvider(
@@ -103,5 +105,10 @@ internal class KtFirTypeProvider(
             b.coneType
         ) == ConeTypeCompatibilityChecker.Compatibility.COMPATIBLE
     }
+
+    override fun getImplicitReceiverTypesAtPosition(position: KtElement): List<KtType> {
+        return analysisSession.firResolveState.getTowerContextProvider()
+            .getClosestAvailableParentContext(position)?.implicitReceiverStack?.map { it.type.asKtType() } ?: emptyList()
+    }
 }
 

analysis/analysis-api/src/org/jetbrains/kotlin/analysis/api/components/KtTypeProvider.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.analysis.api.types.KtFlexibleType
 import org.jetbrains.kotlin.analysis.api.types.KtType
 import org.jetbrains.kotlin.analysis.api.types.KtTypeNullability
 import org.jetbrains.kotlin.psi.KtDoubleColonExpression
+import org.jetbrains.kotlin.psi.KtElement
 import org.jetbrains.kotlin.psi.KtTypeReference
 
 public abstract class KtTypeProvider : KtAnalysisSessionComponent() {
@@ -29,6 +30,8 @@ public abstract class KtTypeProvider : KtAnalysisSessionComponent() {
     public abstract fun withNullability(type: KtType, newNullability: KtTypeNullability): KtType
 
     public abstract fun haveCommonSubtype(a: KtType, b: KtType): Boolean
+
+    public abstract fun getImplicitReceiverTypesAtPosition(position: KtElement): List<KtType>
 }
 
 public interface KtTypeProviderMixIn : KtAnalysisSessionMixIn {
@@ -81,6 +84,13 @@ public interface KtTypeProviderMixIn : KtAnalysisSessionMixIn {
 
     /** Check whether this type is compatible with that type. If they are compatible, it means they can have a common subtype. */
     public fun KtType.hasCommonSubTypeWith(that: KtType): Boolean = analysisSession.typeProvider.haveCommonSubtype(this, that)
+
+    /**
+     * Gets all the implicit receiver types available at the given position. The type of the outermost receiver appears at the beginning
+     * of the returned list.
+     */
+    public fun getImplicitReceiverTypesAtPosition(position: KtElement): List<KtType> =
+        analysisSession.typeProvider.getImplicitReceiverTypesAtPosition(position)
 }
 
 @Suppress("PropertyName")