Make more clear representation of placeholder in notifications

app/src/main/java/com/keylesspalace/tusky/util/CollectionUtil.java

@@ -0,0 +1,38 @@
+/* Copyright 2017 Andrew Dawson
+ *
+ * This file is a part of Tusky.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky; if not,
+ * see <http://www.gnu.org/licenses>. */
+package com.keylesspalace.tusky.util;
+
+import android.arch.core.util.Function;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Created by charlag on 05/11/17.
+ */
+
+public final class CollectionUtil {
+    private CollectionUtil() {
+        throw new AssertionError();
+    }
+
+    public static <E, R> List<R> map(List<E> list, Function<E, R> mapper) {
+        final List<R> newList = new ArrayList<>(list.size());
+        for (E el : list) {
+            newList.add(mapper.apply(el));
+        }
+        return newList;
+    }
+}

app/src/main/java/com/keylesspalace/tusky/util/Either.java

@@ -0,0 +1,125 @@
+/* Copyright 2017 Andrew Dawson
+ *
+ * This file is a part of Tusky.
+ *
+ * This program is free software; you can redistribute it and/or modify it under the terms of the
+ * GNU General Public License as published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
+ * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+ * Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with Tusky; if not,
+ * see <http://www.gnu.org/licenses>. */
+package com.keylesspalace.tusky.util;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+/**
+ * Created by charlag on 05/11/17.
+ *
+ * Class to represent sum type/tagged union/variant/ADT e.t.c.
+ * It is either Left or Right.
+ */
+public final class Either<L, R> {
+
+    /**
+     * Constructs Left instance of either
+     * @param left Object to be considered Left
+     * @param <L> Left type
+     * @param <R> Right type
+     * @return new instance of Either which contains left.
+     */
+    public static <L, R> Either<L, R> left(L left) {
+        return new Either<>(left, false);
+    }
+
+    /**
+     * Constructs Right instance of either
+     * @param right Object to be considered Right
+     * @param <L> Left type
+     * @param <R> Right type
+     * @return new instance of Either which contains right.
+     */
+    public static <L, R> Either<L, R> right(R right) {
+        return new Either<>(right, true);
+    }
+
+    private final Object value;
+    // we need it because of the types erasure
+    private boolean isRight;
+
+    private Either(Object value, boolean isRight) {
+        this.value = value;
+        this.isRight = isRight;
+    }
+
+    public boolean isRight() {
+        return isRight;
+    }
+
+    /**
+     * Try to get contained object as a Left or throw an exception.
+     * @throws AssertionError If contained value is Right
+     * @return contained value as Right
+     */
+    public @NonNull L getAsLeft() {
+        if (isRight) {
+            throw new AssertionError("Tried to get the Either as Left while it is Right");
+        }
+        //noinspection unchecked
+        return (L) value;
+    }
+
+    /**
+     * Try to get contained object as a Right or throw an exception.
+     * @throws AssertionError If contained value is Left
+     * @return contained value as Right
+     */
+    public @NonNull R getAsRight() {
+        if (!isRight) {
+            throw new AssertionError("Tried to get the Either as Right while it is Left");
+        }
+        //noinspection unchecked
+        return (R) value;
+    }
+
+    /**
+     * Same as {@link #getAsLeft()} but returns {@code null} is the value if Right instead of
+     * throwing an exception.
+     * @return contained value as Left or null
+     */
+    public @Nullable L getAsLeftOrNull() {
+        if (isRight) {
+            return null;
+        }
+        //noinspection unchecked
+        return (L) value;
+    }
+
+    /**
+     * Same as {@link #getAsRightOrNull()} but returns {@code null} is the value if Left instead of
+     * throwing an exception.
+     * @return contained value as Right or null
+     */
+    public @Nullable R getAsRightOrNull() {
+        if (!isRight) {
+            return null;
+        }
+        //noinspection unchecked
+        return (R) value;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null) return false;
+        if (!(obj instanceof Either)) return false;
+        Either that = (Either) obj;
+        return this.isRight == that.isRight &&
+                (this.value == that.value ||
+                        this.value != null && this.value.equals(that.value));
+    }
+}

app/src/main/java/com/keylesspalace/tusky/util/ViewDataUtils.java

@@ -34,7 +34,7 @@ public final class ViewDataUtils {
     @Nullable
     public static StatusViewData statusToViewData(@Nullable Status status) {
         if (status == null) return null;
-        if(status.placeholder) {
+        if (status.placeholder) {
             return new StatusViewData.Builder().setId(status.id)
                     .setPlaceholder(true)
                     .createStatusViewData();
@@ -80,8 +80,8 @@ public final class ViewDataUtils {
     }
 
     public static NotificationViewData notificationToViewData(Notification notification) {
-        return new NotificationViewData(notification.type, notification.id, notification.account,
-                statusToViewData(notification.status), false);
+        return new NotificationViewData.Concrete(notification.type, notification.id, notification.account,
+                statusToViewData(notification.status));
     }
 
     public static List<NotificationViewData> notificationListToViewDataList(