[LL FIR] introduce CompositeKotlinPackageProvider

^KT-57930

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/CompositeKotlinPackageProvider.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2010-2023 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.analysis.low.level.api.fir.project.structure
+
+import org.jetbrains.kotlin.analysis.providers.KotlinPackageProvider
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.platform.TargetPlatform
+
+internal class CompositeKotlinPackageProvider
+private constructor(
+    private val providers: List<KotlinPackageProvider>
+) : KotlinPackageProvider() {
+
+    override fun doesPackageExist(packageFqName: FqName, platform: TargetPlatform): Boolean {
+        return providers.any { it.doesPackageExist(packageFqName, platform) }
+    }
+
+    override fun doesKotlinOnlyPackageExist(packageFqName: FqName): Boolean {
+        return providers.any { it.doesKotlinOnlyPackageExist(packageFqName) }
+    }
+
+    override fun doesPlatformSpecificPackageExist(packageFqName: FqName, platform: TargetPlatform): Boolean {
+        return providers.any { it.doesPlatformSpecificPackageExist(packageFqName, platform) }
+    }
+
+    override fun getSubPackageFqNames(packageFqName: FqName, platform: TargetPlatform, nameFilter: (Name) -> Boolean): Set<Name> {
+        return providers.flatMapTo(mutableSetOf()) { it.getSubPackageFqNames(packageFqName, platform, nameFilter) }
+    }
+
+    override fun getKotlinOnlySubPackagesFqNames(packageFqName: FqName, nameFilter: (Name) -> Boolean): Set<Name> {
+        return providers.flatMapTo(mutableSetOf()) { it.getKotlinOnlySubPackagesFqNames(packageFqName, nameFilter) }
+    }
+
+    override fun getPlatformSpecificSubPackagesFqNames(
+        packageFqName: FqName,
+        platform: TargetPlatform,
+        nameFilter: (Name) -> Boolean
+    ): Set<Name> {
+        return providers.flatMapTo(mutableSetOf()) { it.getPlatformSpecificSubPackagesFqNames(packageFqName, platform, nameFilter) }
+    }
+
+    companion object {
+        fun create(providers: List<KotlinPackageProvider>): KotlinPackageProvider {
+            return when (providers.size) {
+                0 -> EmptyKotlinPackageProvider
+                1 -> providers.single()
+                else -> CompositeKotlinPackageProvider(providers)
+            }
+        }
+    }
+}

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/EmptyKotlinPackageProvider.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2010-2023 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.analysis.low.level.api.fir.project.structure
+
+import org.jetbrains.kotlin.analysis.providers.KotlinPackageProvider
+import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.platform.TargetPlatform
+
+internal object EmptyKotlinPackageProvider : KotlinPackageProvider() {
+    override fun doesPackageExist(packageFqName: FqName, platform: TargetPlatform): Boolean {
+        return false
+    }
+
+    override fun doesKotlinOnlyPackageExist(packageFqName: FqName): Boolean {
+        return false
+    }
+
+    override fun doesPlatformSpecificPackageExist(packageFqName: FqName, platform: TargetPlatform): Boolean {
+        return false
+    }
+
+    override fun getSubPackageFqNames(packageFqName: FqName, platform: TargetPlatform, nameFilter: (Name) -> Boolean): Set<Name> {
+        return emptySet()
+    }
+
+    override fun getKotlinOnlySubPackagesFqNames(packageFqName: FqName, nameFilter: (Name) -> Boolean): Set<Name> {
+        return emptySet()
+    }
+
+    override fun getPlatformSpecificSubPackagesFqNames(
+        packageFqName: FqName,
+        platform: TargetPlatform,
+        nameFilter: (Name) -> Boolean
+    ): Set<Name> {
+        return emptySet()
+    }
+}