Add samples for Comparisons #KT-20357
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/*
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* Copyright 2010-2017 JetBrains s.r.o.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package samples.comparisons
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import samples.*
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import kotlin.test.*
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class Comparisons {
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@Sample
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fun compareValuesByWithSingleSelector() {
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fun compareLength(a: String, b: String): Int =
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compareValuesBy(a, b) { it.length }
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assertTrue(compareLength("a", "b") == 0)
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assertTrue(compareLength("bb", "a") > 0)
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assertTrue(compareLength("a", "bb") < 0)
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}
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@Sample
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fun compareValuesByWithSelectors() {
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fun compareLengthThenString(a: String, b: String): Int =
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compareValuesBy(a, b, { it.length }, { it })
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assertTrue(compareLengthThenString("b", "aa") < 0)
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assertTrue(compareLengthThenString("a", "b") < 0)
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assertTrue(compareLengthThenString("b", "a") > 0)
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assertTrue(compareLengthThenString("a", "a") == 0)
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}
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@Sample
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fun compareValuesByWithComparator() {
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fun compareInsensitiveOrder(a: Char, b: Char): Int =
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compareValuesBy(a, b, String.CASE_INSENSITIVE_ORDER, { c -> c.toString() })
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assertTrue(compareInsensitiveOrder('a', 'a') == 0)
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assertTrue(compareInsensitiveOrder('a', 'A') == 0)
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assertTrue(compareInsensitiveOrder('a', 'b') < 0)
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assertTrue(compareInsensitiveOrder('A', 'b') < 0)
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assertTrue(compareInsensitiveOrder('b', 'a') > 0)
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}
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@Sample
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fun compareValues() {
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assertTrue(compareValues(null, 1) < 0)
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assertTrue(compareValues(1, 2) < 0)
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assertTrue(compareValues(2, 1) > 0)
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assertTrue(compareValues(1, 1) == 0)
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}
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@Sample
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fun compareByWithSingleSelector() {
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val list = listOf("aa", "b", "bb", "a")
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val sorted = list.sortedWith(compareBy { it.length })
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assertPrints(sorted, "[b, a, aa, bb]")
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}
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@Sample
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fun compareByWithSelectors() {
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val list = listOf("aa", "b", "bb", "a")
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val sorted = list.sortedWith(compareBy(
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{ it.length },
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{ it }
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))
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assertPrints(sorted, "[a, b, aa, bb]")
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}
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@Sample
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fun compareByWithComparator() {
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val list = listOf('B', 'a', 'A', 'b')
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val sorted = list.sortedWith(
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compareBy(String.CASE_INSENSITIVE_ORDER) { v -> v.toString() }
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)
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assertPrints(sorted, "[a, A, B, b]")
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}
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@Sample
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fun compareByDescendingWithSingleSelector() {
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val list = listOf("aa", "b", "bb", "a")
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val sorted = list.sortedWith(compareByDescending { it.length })
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assertPrints(sorted, "[aa, bb, b, a]")
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}
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@Sample
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fun compareByDescendingWithComparator() {
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val list = listOf('B', 'a', 'A', 'b')
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val sorted = list.sortedWith(
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compareByDescending(String.CASE_INSENSITIVE_ORDER) { v -> v.toString() }
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)
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assertPrints(sorted, "[B, b, a, A]")
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}
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@Sample
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fun thenBy() {
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val list = listOf("aa", "b", "bb", "a")
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val lengthComparator = compareBy<String> { it.length }
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assertPrints(list.sortedWith(lengthComparator), "[b, a, aa, bb]")
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val lengthThenString = lengthComparator.thenBy { it }
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assertPrints(list.sortedWith(lengthThenString), "[a, b, aa, bb]")
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}
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@Sample
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fun thenByWithComparator() {
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val list = listOf("A", "aa", "b", "bb", "a")
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val lengthComparator = compareBy<String> { it.length }
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assertPrints(list.sortedWith(lengthComparator), "[A, b, a, aa, bb]")
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val lengthThenCaseInsensitive = lengthComparator
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.thenBy(String.CASE_INSENSITIVE_ORDER) { it }
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assertPrints(list.sortedWith(lengthThenCaseInsensitive), "[A, a, b, aa, bb]")
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}
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@Sample
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fun thenByDescending() {
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val list = listOf("aa", "b", "bb", "a")
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val lengthComparator = compareBy<String> { it.length }
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assertPrints(list.sortedWith(lengthComparator), "[b, a, aa, bb]")
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val lengthThenStringDesc = lengthComparator.thenByDescending { it }
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assertPrints(list.sortedWith(lengthThenStringDesc), "[b, a, bb, aa]")
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}
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@Sample
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fun thenByDescendingWithComparator() {
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val list = listOf("A", "aa", "b", "bb", "a")
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val lengthComparator = compareBy<String> { it.length }
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assertPrints(list.sortedWith(lengthComparator), "[A, b, a, aa, bb]")
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val lengthThenCaseInsensitive = lengthComparator
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.thenByDescending(String.CASE_INSENSITIVE_ORDER) { it }
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assertPrints(list.sortedWith(lengthThenCaseInsensitive), "[b, A, a, bb, aa]")
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}
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@Sample
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fun thenComparator() {
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val array = arrayOf("c" to 1, "b" to 2, "a" to 1, "d" to 0, null to 0)
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val valueComparator = compareBy<Pair<String?, Int>> { it.second }
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val map1 = listOf(*array).sortedWith(valueComparator).toMap()
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assertPrints(map1, "{d=0, null=0, c=1, a=1, b=2}")
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val valueThenKeyComparator = valueComparator
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.thenComparator({ a, b -> compareValues(a.first, b.first) })
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val map2 = listOf(*array).sortedWith(valueThenKeyComparator).toMap()
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assertPrints(map2, "{null=0, d=0, a=1, c=1, b=2}")
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}
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@Sample
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fun then() {
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val list = listOf("A", "aa", "b", "bb", "a")
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val lengthThenCaseInsensitive = compareBy<String> { it.length }
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.then(String.CASE_INSENSITIVE_ORDER)
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val sorted = list.sortedWith(lengthThenCaseInsensitive)
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assertPrints(sorted, "[A, a, b, aa, bb]")
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}
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@Sample
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fun thenDescending() {
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val list = listOf("A", "aa", "b", "bb", "a")
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val lengthThenCaseInsensitive = compareBy<String> { it.length }
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.thenDescending(String.CASE_INSENSITIVE_ORDER)
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val sorted = list.sortedWith(lengthThenCaseInsensitive)
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assertPrints(sorted, "[b, A, a, bb, aa]")
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}
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@Sample
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fun nullsFirstLastComparator() {
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val list = listOf(4, null, -1, 1)
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val nullsFirstList = list.sortedWith(nullsFirst())
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assertPrints(nullsFirstList, "[null, -1, 1, 4]")
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val nullsLastList = list.sortedWith(nullsLast())
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assertPrints(nullsLastList, "[-1, 1, 4, null]")
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}
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@Sample
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fun nullsFirstLastWithComparator() {
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val list = listOf(4, null, 1, -2, 3)
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val nullsFirstList = list.sortedWith(nullsFirst(reverseOrder()))
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assertPrints(nullsFirstList, "[null, 4, 3, 1, -2]")
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val nullsLastList = list.sortedWith(nullsLast(reverseOrder()))
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assertPrints(nullsLastList, "[4, 3, 1, -2, null]")
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}
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@Sample
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fun naturalOrderComparator() {
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val list = listOf("aa", "b", "bb", "a")
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val lengthThenNatural = compareBy<String> { it.length }
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.then(naturalOrder())
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val sorted = list.sortedWith(lengthThenNatural)
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assertPrints(sorted, "[a, b, aa, bb]")
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}
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@Sample
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fun reversed() {
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val list = listOf("aa", "b", "bb", "a")
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val lengthThenString = compareBy<String> { it.length }.thenBy { it }
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val sorted = list.sortedWith(lengthThenString)
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assertPrints(sorted, "[a, b, aa, bb]")
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val sortedReversed = list.sortedWith(lengthThenString.reversed())
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assertPrints(sortedReversed, "[bb, aa, b, a]")
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}
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}
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