AnnotationMirrorExt.kt

/*
 * Copyright 2023 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 com.google.auto.common.MoreElements
import com.google.auto.common.MoreTypes
import java.lang.annotation.Repeatable
import javax.lang.model.element.AnnotationMirror
import javax.lang.model.type.TypeKind
import javax.lang.model.util.ElementFilter

/** Returns true if the given [AnnotationMirror] represents a repeatable annotation. */
internal fun AnnotationMirror.isRepeatable(): Boolean {
    try {
        val valueType =
            ElementFilter.methodsIn(MoreTypes.asTypeElement(annotationType).enclosedElements)
                .singleOrNull { it.simpleName.toString() == "value" }
                ?.returnType

        // The contract of a repeatable annotation requires that the container annotation have a
        // single "default" method that returns an array typed with the repeatable annotation type.
        if (valueType == null || valueType.kind != TypeKind.ARRAY) {
            return false
        }
        val componentType = MoreTypes.asArray(valueType).componentType
        if (componentType.kind != TypeKind.DECLARED) {
            return false
        }
        val componentElement = MoreTypes.asDeclared(componentType).asElement()

        // Ideally we would read the value of the Repeatable annotation to get the container class
        // type and check that it matches "this" type. However, there seems to be a KSP bug where
        // the value of Repeatable is not present so the best we can do is check that all the nested
        // members are annotated with repeatable.
        // https://github.com/google/ksp/issues/358
        return MoreElements.isAnnotationPresent(componentElement, Repeatable::class.java) ||
            // The java and kotlin versions of Repeatable are not interchangeable.
            // https://github.com/google/ksp/issues/459 asks whether the built in type
            // mapper should convert them, but it may not be possible because there are
            // differences to how they work (eg different parameters).
            MoreElements.isAnnotationPresent(
                componentElement, kotlin.annotation.Repeatable::class.java
            )
    } catch (t: Throwable) {
        // TODO(b/314160063): Turbine can throw when getting enclosed elements. Remove this once
        // we have a better way to work around Turbine exception.
        return false
    }
}