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/*
 * MIT License
 *
 * Copyright (c) 2023 Telereso
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package io.telereso.kmp.core

import kotlinx.coroutines.sync.Mutex
import kotlinx.coroutines.sync.withLock

/**
 * https://github.com/Kotlin/kotlinx.coroutines/issues/706
 */
class LazySuspend(initializer: suspend () -> T) {
    private var initializer: (suspend () -> T)? = initializer
    private var mutex: Mutex? = Mutex()
    private var _value: T? = null

    suspend fun value(): T {
        val m = mutex ?: return _value as T // Warning: unchecked cast.
        m.withLock {
            val i = initializer ?: return _value as T // Warning: unchecked cast.
            val v = i()
            _value = v
            initializer = null
            mutex = null
            return v
        }
    }
}