1 files changed, 98 insertions, 0 deletions
diff --git a/java/com/android/dialer/common/FragmentUtils.java b/java/com/android/dialer/common/FragmentUtils.java
new file mode 100644
index 000000000..cb036959d
--- /dev/null
+++ b/java/com/android/dialer/common/FragmentUtils.java
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package com.android.dialer.common;
+
+import android.support.annotation.CheckResult;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.annotation.VisibleForTesting;
+import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentActivity;
+
+/** Utility methods for working with Fragments */
+public class FragmentUtils {
+
+  private static Object parentForTesting;
+
+  @VisibleForTesting(otherwise = VisibleForTesting.NONE)
+  public static void setParentForTesting(Object parentForTesting) {
+    FragmentUtils.parentForTesting = parentForTesting;
+  }
+
+  /**
+   * @return The parent of frag that implements the callbackInterface or null if no such parent can
+   *     be found
+   */
+  @CheckResult(suggest = "#checkParent(Fragment, Class)}")
+  @Nullable
+  public static <T> T getParent(@NonNull Fragment fragment, @NonNull Class<T> callbackInterface) {
+    if (callbackInterface.isInstance(parentForTesting)) {
+      @SuppressWarnings("unchecked") // Casts are checked using runtime methods
+      T parent = (T) parentForTesting;
+      return parent;
+    }
+
+    Fragment parentFragment = fragment.getParentFragment();
+    if (callbackInterface.isInstance(parentFragment)) {
+      @SuppressWarnings("unchecked") // Casts are checked using runtime methods
+      T parent = (T) parentFragment;
+      return parent;
+    } else {
+      FragmentActivity activity = fragment.getActivity();
+      if (callbackInterface.isInstance(activity)) {
+        @SuppressWarnings("unchecked") // Casts are checked using runtime methods
+        T parent = (T) activity;
+        return parent;
+      }
+    }
+    return null;
+  }
+
+  /** Returns the parent or throws. Should perform check elsewhere(e.g. onAttach, newInstance). */
+  @NonNull
+  public static <T> T getParentUnsafe(
+      @NonNull Fragment fragment, @NonNull Class<T> callbackInterface) {
+    return Assert.isNotNull(getParent(fragment, callbackInterface));
+  }
+
+  /**
+   * Ensures fragment has a parent that implements the corresponding interface
+   *
+   * @param frag The Fragment whose parents are to be checked
+   * @param callbackInterface The interface class that a parent should implement
+   * @throws IllegalStateException if no parents are found that implement callbackInterface
+   */
+  public static void checkParent(@NonNull Fragment frag, @NonNull Class<?> callbackInterface)
+      throws IllegalStateException {
+    if (parentForTesting != null) {
+      return;
+    }
+    if (FragmentUtils.getParent(frag, callbackInterface) == null) {
+      String parent =
+          frag.getParentFragment() == null
+              ? frag.getActivity().getClass().getName()
+              : frag.getParentFragment().getClass().getName();
+      throw new IllegalStateException(
+          frag.getClass().getName()
+              + " must be added to a parent"
+              + " that implements "
+              + callbackInterface.getName()
+              + ". Instead found "
+              + parent);
+    }
+  }
+}