1 files changed, 109 insertions, 0 deletions
diff --git a/ui/src/main/java/com/wireguard/android/util/ObservableKeyedArrayList.java b/ui/src/main/java/com/wireguard/android/util/ObservableKeyedArrayList.java
new file mode 100644
index 00000000..0ba02184
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/util/ObservableKeyedArrayList.java
@@ -0,0 +1,109 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.android.util;
+
+import androidx.databinding.ObservableArrayList;
+import androidx.annotation.Nullable;
+
+import com.wireguard.util.Keyed;
+
+import java.util.Collection;
+import java.util.ListIterator;
+import java.util.Objects;
+
+/**
+ * ArrayList that allows looking up elements by some key property. As the key property must always
+ * be retrievable, this list cannot hold {@code null} elements. Because this class places no
+ * restrictions on the order or duplication of keys, lookup by key, as well as all list modification
+ * operations, require O(n) time.
+ */
+
+public class ObservableKeyedArrayList<K, E extends Keyed<? extends K>>
+        extends ObservableArrayList<E> implements ObservableKeyedList<K, E> {
+    @Override
+    public boolean add(@Nullable final E e) {
+        if (e == null)
+            throw new NullPointerException("Trying to add a null element");
+        return super.add(e);
+    }
+
+    @Override
+    public void add(final int index, @Nullable final E e) {
+        if (e == null)
+            throw new NullPointerException("Trying to add a null element");
+        super.add(index, e);
+    }
+
+    @Override
+    public boolean addAll(final Collection<? extends E> c) {
+        if (c.contains(null))
+            throw new NullPointerException("Trying to add a collection with null element(s)");
+        return super.addAll(c);
+    }
+
+    @Override
+    public boolean addAll(final int index, final Collection<? extends E> c) {
+        if (c.contains(null))
+            throw new NullPointerException("Trying to add a collection with null element(s)");
+        return super.addAll(index, c);
+    }
+
+    @Override
+    public boolean containsAllKeys(final Collection<K> keys) {
+        for (final K key : keys)
+            if (!containsKey(key))
+                return false;
+        return true;
+    }
+
+    @Override
+    public boolean containsKey(final K key) {
+        return indexOfKey(key) >= 0;
+    }
+
+    @Nullable
+    @Override
+    public E get(final K key) {
+        final int index = indexOfKey(key);
+        return index >= 0 ? get(index) : null;
+    }
+
+    @Nullable
+    @Override
+    public E getLast(final K key) {
+        final int index = lastIndexOfKey(key);
+        return index >= 0 ? get(index) : null;
+    }
+
+    @Override
+    public int indexOfKey(final K key) {
+        final ListIterator<E> iterator = listIterator();
+        while (iterator.hasNext()) {
+            final int index = iterator.nextIndex();
+            if (Objects.equals(iterator.next().getKey(), key))
+                return index;
+        }
+        return -1;
+    }
+
+    @Override
+    public int lastIndexOfKey(final K key) {
+        final ListIterator<E> iterator = listIterator(size());
+        while (iterator.hasPrevious()) {
+            final int index = iterator.previousIndex();
+            if (Objects.equals(iterator.previous().getKey(), key))
+                return index;
+        }
+        return -1;
+    }
+
+    @Override
+    public E set(final int index, @Nullable final E e) {
+        if (e == null)
+            throw new NullPointerException("Trying to set a null key");
+        return super.set(index, e);
+    }
+}