FIR JS: Refactor Klib serialization for FIR support

compiler/ir/serialization.js/build.gradle.kts

@@ -9,6 +9,7 @@ dependencies {
     api(project(":js:js.frontend"))
 
     implementation(project(":compiler:ir.backend.common"))
+    implementation(project(":compiler:fir:fir-serialization"))
 
     compileOnly(intellijCore())
 }

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/firKlibSerialization.kt

@@ -0,0 +1,67 @@
+/*
+ * Copyright 2010-2022 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.ir.backend.js
+
+import org.jetbrains.kotlin.backend.common.serialization.metadata.buildKlibPackageFragment
+import org.jetbrains.kotlin.config.CommonConfigurationKeys
+import org.jetbrains.kotlin.config.CompilerConfiguration
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.declarations.utils.classId
+import org.jetbrains.kotlin.fir.packageFqName
+import org.jetbrains.kotlin.fir.resolve.ScopeSession
+import org.jetbrains.kotlin.fir.serialization.FirElementAwareStringTable
+import org.jetbrains.kotlin.fir.serialization.FirElementSerializer
+import org.jetbrains.kotlin.fir.serialization.FirSerializerExtension
+import org.jetbrains.kotlin.fir.serialization.TypeApproximatorForMetadataSerializer
+import org.jetbrains.kotlin.metadata.ProtoBuf
+import org.jetbrains.kotlin.metadata.deserialization.BinaryVersion
+import org.jetbrains.kotlin.serialization.SerializableStringTable
+
+fun serializeSingleFirFile(file: FirFile, session: FirSession, scopeSession: ScopeSession, configuration: CompilerConfiguration): ProtoBuf.PackageFragment {
+    val serializerExtension = FirKLibSerializerExtension(
+        session,
+        configuration.get(CommonConfigurationKeys.METADATA_VERSION)!!,
+        FirElementAwareSerializableStringTable()
+    )
+    val approximator = TypeApproximatorForMetadataSerializer(session)
+    val packageSerializer = FirElementSerializer.createTopLevel(session, scopeSession, serializerExtension, approximator)
+
+    // TODO: typealiases (see klib serializer)
+    // TODO: split package fragment (see klib serializer)
+    // TODO: handle incremental/monolothic (see klib serializer) - maybe externally
+
+    val packageProto = packageSerializer.packagePartProto(file.packageFqName, file).build()
+
+    // TODO: filter out expects
+    val classifiers = file.declarations.filterIsInstance<FirClass>().sortedBy { it.classId.asFqNameString() }
+
+    val classesProto = classifiers.map {
+        val classSerializer = FirElementSerializer.create(session, scopeSession, it, serializerExtension, null, approximator)
+        val index = classSerializer.stringTable.getFqNameIndex(it)
+        classSerializer.classProto(it).build() to index
+    }
+
+    val hasTopLevelDeclarations = file.declarations.any {
+        it is FirProperty || it is FirSimpleFunction || it is FirTypeAlias
+    }
+
+    return buildKlibPackageFragment(
+        packageProto,
+        classesProto,
+        file.packageFqName,
+        hasTopLevelDeclarations && classesProto.isEmpty(),
+        serializerExtension.stringTable as SerializableStringTable
+    )
+}
+
+class FirKLibSerializerExtension(
+    override val session: FirSession,
+    override val metadataVersion: BinaryVersion,
+    override val stringTable: FirElementAwareSerializableStringTable
+) : FirSerializerExtension()
+
+class FirElementAwareSerializableStringTable() : FirElementAwareStringTable, SerializableStringTable()