JavacAnnotationValue.kt

/*
 * Copyright 2021 The Android Open Source Project
 *
 * 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 androidx.room.compiler.processing.javac

import androidx.room.compiler.processing.XEnumTypeElement
import androidx.room.compiler.processing.XNullability
import androidx.room.compiler.processing.XAnnotationValue
import com.google.auto.common.MoreTypes
import javax.lang.model.element.AnnotationMirror
import javax.lang.model.element.AnnotationValue
import javax.lang.model.element.ElementKind
import javax.lang.model.element.ExecutableElement
import javax.lang.model.element.VariableElement
import javax.lang.model.type.TypeMirror

internal class JavacAnnotationValue(
    val env: JavacProcessingEnv,
    val element: ExecutableElement,
    val annotationValue: AnnotationValue
) : XAnnotationValue {
    override val name: String
        get() = element.simpleName.toString()

    override val value: Any? by lazy { annotationValue.unwrap() }

    private fun AnnotationValue.unwrap(): Any? {
        val value = this.value
        fun Any?.unwrapIfNeeded(): Any? {
            return if (this is AnnotationValue) this.unwrap() else this
        }
        return when {
            // The List implementation further wraps each value as a AnnotationValue.
            // We don't expose arrays because we don't have a reified type to instantiate the array
            // with, and using "Any" prevents the array from being cast to the correct
            // type later on.
            value is List<*> -> value.map { it.unwrapIfNeeded() }
            value is TypeMirror -> env.wrap(value, kotlinType = null, XNullability.NONNULL)
            value is AnnotationMirror -> JavacAnnotation(env, value)
            // Enums are wrapped in a variable element with kind ENUM_CONSTANT
            value is VariableElement -> {
                when {
                    value.kind == ElementKind.ENUM_CONSTANT -> {
                        val enumTypeElement = MoreTypes.asTypeElement(value.asType())
                        JavacEnumEntry(
                            env,
                            value,
                            JavacTypeElement.create(env, enumTypeElement) as XEnumTypeElement
                        )
                    }
                    else -> error("Unexpected annotation value $value for argument $name")
                }
            }
            else -> value
        }
    }
}