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Kotlin Full Reflection Library

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/*
 * Copyright 2010-2015 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package kotlin.reflect.jvm

import org.jetbrains.kotlin.load.java.JvmAnnotationNames
import org.jetbrains.kotlin.metadata.deserialization.TypeTable
import org.jetbrains.kotlin.metadata.jvm.deserialization.JvmMetadataVersion
import org.jetbrains.kotlin.metadata.jvm.deserialization.JvmProtoBufUtil
import org.jetbrains.kotlin.serialization.deserialization.MemberDeserializer
import kotlin.reflect.KFunction
import kotlin.reflect.jvm.internal.EmptyContainerForLocal
import kotlin.reflect.jvm.internal.KFunctionImpl
import kotlin.reflect.jvm.internal.deserializeToDescriptor

/**
 * This is an experimental API. Given a class for a compiled Kotlin lambda or a function expression,
 * returns a [KFunction] instance providing introspection capabilities for that lambda or function expression and its parameters.
 * Not all features are currently supported, in particular [KCallable.call] and [KCallable.callBy] will fail at the moment.
 */
fun  Function.reflect(): KFunction? {
    val annotation = javaClass.getAnnotation(Metadata::class.java) ?: return null
    val data = annotation.data1.takeUnless(Array::isEmpty) ?: return null
    val (nameResolver, proto) = JvmProtoBufUtil.readFunctionDataFrom(data, annotation.data2)
    val metadataVersion = JvmMetadataVersion(
        annotation.metadataVersion,
        (annotation.extraInt and JvmAnnotationNames.METADATA_STRICT_VERSION_SEMANTICS_FLAG) != 0
    )

    val descriptor = deserializeToDescriptor(
        javaClass, proto, nameResolver, TypeTable(proto.typeTable), metadataVersion, MemberDeserializer::loadFunction
    ) ?: return null

    @Suppress("UNCHECKED_CAST")
    return KFunctionImpl(EmptyContainerForLocal, descriptor) as KFunction
}