49 lines
1.6 KiB
Kotlin
49 lines
1.6 KiB
Kotlin
/* Copyright 2017 Andrew Dawson
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*
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* This file is a part of Tusky.
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*
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* This program is free software; you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation; either version 3 of the
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* License, or (at your option) any later version.
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*
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* Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
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* the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
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* Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along with Tusky; if not,
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* see <http://www.gnu.org/licenses>. */
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package com.keylesspalace.tusky.util
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/**
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* Created by charlag on 05/11/17.
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*
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* Class to represent sum type/tagged union/variant/ADT e.t.c.
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* It is either Left or Right.
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*/
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sealed interface Either<out L, out R> {
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data class Left<out L, out R>(val value: L) : Either<L, R>
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data class Right<out L, out R>(val value: R) : Either<L, R>
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fun isRight(): Boolean = this is Right
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fun isLeft(): Boolean = this is Left
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fun asLeftOrNull(): L? = (this as? Left<L, R>)?.value
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fun asRightOrNull(): R? = (this as? Right<L, R>)?.value
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fun asLeft(): L = (this as Left<L, R>).value
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fun asRight(): R = (this as Right<L, R>).value
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companion object {
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inline fun <L, R, N> Either<L, R>.map(mapper: (R) -> N): Either<L, N> {
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return if (this.isLeft()) {
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Left(this.asLeft())
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} else {
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Right(mapper(this.asRight()))
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}
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}
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}
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}
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