Alexey Tsvetkov
84 lines
2.2 KiB
Kotlin
84 lines
2.2 KiB
Kotlin
package foo
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import java.util.ArrayList
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data class Holder<T>(val v: T)
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data class Dat(val start: String, val end: String)
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class Obj(val start: String, val end: String)
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fun assertSomeNotEqual<T>(c: Iterable<T>) {
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val it = c.iterator()
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val first = it.next()
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while (it.hasNext()) {
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val item: T = it.next()
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if (item != first) {
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return;
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}
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}
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throw Exception("All elements are the same: $first")
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}
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fun assertAllEqual<T>(c: Iterable<out T>) {
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val it = c.iterator()
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val first = it.next()
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while (it.hasNext()) {
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val item: T = it.next()
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assertEquals(first, item)
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}
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}
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val hashCoder: (o: Any) -> Int = { o -> o.hashCode() }
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val <T> wrapInH = { (t: T) -> Holder(t) }
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fun box(): String {
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// Check that same Dat's have the same hashcode.
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val sameDs = listOf(Dat("a", "b"), Dat("a", "b"))
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assertAllEqual(map(sameDs, hashCoder))
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// Check that different Dat's have different hashcodes (at least some of them).
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val differentDs = listOf(Dat("a", "b"), Dat("a", "c"), Dat("a", "d"))
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assertSomeNotEqual(map(differentDs, hashCoder))
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// Check the same on Obj's, which should be always different and with different hashcodes.
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val sameOs = listOf(Obj("a", "b"), Obj("a", "b"), Obj("a", "b"))
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val differentOs = listOf(Obj("a", "b"), Obj("a", "b"), Obj("a", "b"))
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// Obj's are always different.
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assertSomeNotEqual(map(sameOs, hashCoder))
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assertSomeNotEqual(map(differentOs, hashCoder))
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// Both Dat's and Obj's wrapped as Holder should retain their hashcode relations.
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val sameHDs = map(sameDs, wrapInH)
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assertAllEqual(map(sameHDs, hashCoder))
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val differentHDs = map(differentDs, wrapInH)
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assertSomeNotEqual(map(differentHDs, hashCoder))
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val sameHOs = map(sameOs, wrapInH)
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assertSomeNotEqual(map(sameHOs, hashCoder))
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val differentHOs = map(differentOs, wrapInH)
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assertSomeNotEqual(map(differentHOs, hashCoder))
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return "OK"
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}
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fun listOf<T>(vararg a: T): List<T> {
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val list = ArrayList<T>()
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for (e in a) {
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list.add(e)
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}
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return list
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}
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fun map<T, S>(c : Iterable<T>, transform : (T) -> S) : List<S> {
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val list = ArrayList<S>()
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for (t in c) {
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list.add(transform(t))
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}
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return list
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}
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