compose/compiler/compiler-hosted/src/main/java/androidx/compose/compiler/plugins/kotlin/WeakBindingTrace.kt

/*
 * Copyright 2019 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.compose.compiler.plugins.kotlin

import com.intellij.util.keyFMap.KeyFMap
import java.util.WeakHashMap
import org.jetbrains.kotlin.backend.common.extensions.IrPluginContext
import org.jetbrains.kotlin.ir.declarations.IrAttributeContainer
import org.jetbrains.kotlin.util.slicedMap.ReadOnlySlice
import org.jetbrains.kotlin.util.slicedMap.WritableSlice

/**
 * This class is meant to have the shape of a BindingTrace object that could exist and flow
 * through the Psi2Ir -> Ir phase, but doesn't currently exist. Ideally, this gets replaced in
 * the future by a trace that handles this use case in upstream. For now, we are okay with this
 * because the combination of IrAttributeContainer and WeakHashMap makes this relatively safe.
 */
class WeakBindingTrace {
    private val map = WeakHashMap<Any, KeyFMap>()

    fun <K : IrAttributeContainer, V> record(slice: WritableSlice<K, V>, key: K, value: V) {
        var holder = map[key.attributeOwnerId] ?: KeyFMap.EMPTY_MAP
        val prev = holder.get(slice.key)
        if (prev != null) {
            holder = holder.minus(slice.key)
        }
        holder = holder.plus(slice.key, value!!)
        map[key.attributeOwnerId] = holder
    }

    operator fun <K : IrAttributeContainer, V> get(slice: ReadOnlySlice<K, V>, key: K): V? {
        return map[key.attributeOwnerId]?.get(slice.key)
    }
}

private val ComposeTemporaryGlobalBindingTrace = WeakBindingTrace()

@Suppress("unused")
val IrPluginContext.irTrace: WeakBindingTrace get() = ComposeTemporaryGlobalBindingTrace