charlag
7 years ago
committed by
Konrad Pozniak
parent
cbf6062bce
commit
33ece0410d
@ -0,0 +1,38 @@ |
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/* 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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import android.arch.core.util.Function; |
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import java.util.ArrayList; |
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import java.util.List; |
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/** |
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* Created by charlag on 05/11/17. |
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*/ |
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public final class CollectionUtil { |
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private CollectionUtil() { |
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throw new AssertionError(); |
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} |
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public static <E, R> List<R> map(List<E> list, Function<E, R> mapper) { |
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final List<R> newList = new ArrayList<>(list.size()); |
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for (E el : list) { |
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newList.add(mapper.apply(el)); |
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} |
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return newList; |
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} |
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} |
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@ -0,0 +1,125 @@ |
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/* 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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import android.support.annotation.NonNull; |
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import android.support.annotation.Nullable; |
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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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public final class Either<L, R> { |
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/** |
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* Constructs Left instance of either |
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* @param left Object to be considered Left |
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* @param <L> Left type |
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* @param <R> Right type |
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* @return new instance of Either which contains left. |
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*/ |
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public static <L, R> Either<L, R> left(L left) { |
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return new Either<>(left, false); |
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} |
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/** |
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* Constructs Right instance of either |
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* @param right Object to be considered Right |
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* @param <L> Left type |
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* @param <R> Right type |
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* @return new instance of Either which contains right. |
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*/ |
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public static <L, R> Either<L, R> right(R right) { |
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return new Either<>(right, true); |
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} |
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private final Object value; |
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// we need it because of the types erasure
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private boolean isRight; |
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private Either(Object value, boolean isRight) { |
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this.value = value; |
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this.isRight = isRight; |
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} |
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public boolean isRight() { |
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return isRight; |
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} |
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/** |
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* Try to get contained object as a Left or throw an exception. |
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* @throws AssertionError If contained value is Right |
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* @return contained value as Right |
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*/ |
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public @NonNull L getAsLeft() { |
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if (isRight) { |
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throw new AssertionError("Tried to get the Either as Left while it is Right"); |
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} |
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//noinspection unchecked
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return (L) value; |
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} |
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/** |
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* Try to get contained object as a Right or throw an exception. |
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* @throws AssertionError If contained value is Left |
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* @return contained value as Right |
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*/ |
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public @NonNull R getAsRight() { |
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if (!isRight) { |
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throw new AssertionError("Tried to get the Either as Right while it is Left"); |
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} |
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//noinspection unchecked
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return (R) value; |
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} |
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/** |
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* Same as {@link #getAsLeft()} but returns {@code null} is the value if Right instead of |
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* throwing an exception. |
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* @return contained value as Left or null |
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*/ |
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public @Nullable L getAsLeftOrNull() { |
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if (isRight) { |
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return null; |
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} |
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//noinspection unchecked
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return (L) value; |
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} |
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/** |
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* Same as {@link #getAsRightOrNull()} but returns {@code null} is the value if Left instead of |
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* throwing an exception. |
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* @return contained value as Right or null |
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*/ |
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public @Nullable R getAsRightOrNull() { |
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if (!isRight) { |
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return null; |
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} |
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//noinspection unchecked
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return (R) value; |
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} |
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@Override |
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public boolean equals(Object obj) { |
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if (this == obj) return true; |
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if (obj == null) return false; |
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if (!(obj instanceof Either)) return false; |
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Either that = (Either) obj; |
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return this.isRight == that.isRight && |
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(this.value == that.value || |
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this.value != null && this.value.equals(that.value)); |
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} |
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} |
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