jars/junit5-r5.10.2/documentation/src/test/kotlin/example/FibonacciCalculator.kt

/*
 * Copyright 2015-2023 the original author or authors.
 *
 * All rights reserved. This program and the accompanying materials are
 * made available under the terms of the Eclipse Public License v2.0 which
 * accompanies this distribution and is available at
 *
 * https://www.eclipse.org/legal/epl-v20.html
 */
package example

class FibonacciCalculator {

    private val fibonacci = sequence {
        yield(0) // 0th Fibonacci number
        yield(1) // first Fibonacci number
        var cur = 1
        var next = 1
        while (true) {
            yield(next) // next Fibonacci number
            val tmp = cur + next
            cur = next
            next = tmp
        }
    }

    fun fib(fibonacciNumber: Int) =
        fibonacci.elementAt(fibonacciNumber)
}