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Add Either.flatMapNull

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This commit is contained in:
Him188 2022-03-13 11:29:51 +00:00
parent 351357a8e0
commit 603e29d739
2 changed files with 54 additions and 8 deletions
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20
mirai-core-utils/src/commonMain/kotlin/Either.kt
View File

@ -1,10 +1,10 @@
/*
* Copyright 2019-2021 Mamoe Technologies and contributors.
* Copyright 2019-2022 Mamoe Technologies and contributors.
*
* 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
* Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
* 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
* Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
*
* https://github.com/mamoe/mirai/blob/master/LICENSE
* https://github.com/mamoe/mirai/blob/dev/LICENSE
*/
@file:Suppress("NOTHING_TO_INLINE", "unused")
@ -138,6 +138,18 @@ public value class Either<out L : Any, out R : Any?> private constructor(
onRight = { Result.success(it) }
)
/**
* Invoke and return [block] if the backing value of this [Either] is null. Returns `this` otherwise.
*/
public inline fun <reified L : SuperL, reified R : SuperR, SuperL : Any, SuperR> Either<L, R?>.flatMapNull(
block: () -> Either<SuperL, SuperR?>
): Either<SuperL, SuperR?> {
if (this.leftOrNull == null && this.rightOrNull == null) {
return block()
}
return this
}
@PublishedApi
internal fun getTypeHint(value: Any?): String {
return if (value == null) "null"

42
mirai-core-utils/src/commonTest/kotlin/net/mamoe/mirai/utils/EitherTest.kt
View File

@ -1,16 +1,17 @@
/*
* Copyright 2019-2021 Mamoe Technologies and contributors.
* Copyright 2019-2022 Mamoe Technologies and contributors.
*
* 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
* Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
* 此源代码的使用受 GNU AFFERO GENERAL PUBLIC LICENSE version 3 许可证的约束, 可以在以下链接找到该许可证.
* Use of this source code is governed by the GNU AGPLv3 license that can be found through the following link.
*
* https://github.com/mamoe/mirai/blob/master/LICENSE
* https://github.com/mamoe/mirai/blob/dev/LICENSE
*/
@file:OptIn(ExperimentalStdlibApi::class)
package net.mamoe.mirai.utils
import net.mamoe.mirai.utils.Either.Companion.flatMapNull
import net.mamoe.mirai.utils.Either.Companion.fold
import net.mamoe.mirai.utils.Either.Companion.ifLeft
import net.mamoe.mirai.utils.Either.Companion.ifRight
@ -131,6 +132,39 @@ internal class EitherTest {
)
}
@Test
fun `can flatMapNull`() {
assertTypeIs(typeOf<Either<CharSequence, Int>>(), Either<CharSequence, Int>(1))
// not null types
Either<CharSequence, Int>("left").run {
val result = flatMapNull { throw AssertionError("Fail") }
assertEquals(this, result) // don't assertSame: arguments boxed separately
}
Either<CharSequence, Int>(1).run {
val result = flatMapNull { throw AssertionError("Fail") }
assertEquals(this, result) // don't assertSame: arguments boxed separately
}
// nullable types
Either<CharSequence, Int?>("left").run {
val result = flatMapNull { throw AssertionError("Fail") }
assertEquals(this, result) // don't assertSame: arguments boxed separately
}
Either<CharSequence, Int?>(1).run {
val result = flatMapNull { throw AssertionError("Fail") }
assertEquals(this, result) // don't assertSame: arguments boxed separately
}
// normal case
Either<CharSequence, Int?>(null).run {
val result = flatMapNull { right(true) } // can interlace type
assertEquals(true, result.right)
}
}
@Test
fun `can call onRight`() {
var called = false