1 files changed, 36 insertions, 0 deletions
diff --git a/src/main/java/com/android/tools/r8/utils/ArrayUtils.java b/src/main/java/com/android/tools/r8/utils/ArrayUtils.java
new file mode 100644
index 000000000..976768bd8
--- /dev/null
+++ b/src/main/java/com/android/tools/r8/utils/ArrayUtils.java
@@ -0,0 +1,36 @@
+// Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+package com.android.tools.r8.utils;
+
+import java.lang.reflect.Array;
+import java.util.Map;
+
+public class ArrayUtils {
+
+  /**
+   * Copies the input array and then applies specified sparse changes.
+   *
+   * @param clazz target type's Class to cast
+   * @param original an array of original elements
+   * @param changedElements sparse changes to apply
+   * @param <T> target type
+   * @return a copy of original arrays while sparse changes are applied
+   */
+  public static <T> T[] copyWithSparseChanges(
+      Class<T[]> clazz, T[] original, Map<Integer, T> changedElements) {
+    T[] results = clazz.cast(Array.newInstance(clazz.getComponentType(), original.length));
+    int pos = 0;
+    for (Map.Entry<Integer, T> entry : changedElements.entrySet()) {
+      int i = entry.getKey();
+      System.arraycopy(original, pos, results, pos, i - pos);
+      results[i] = entry.getValue();
+      pos = i + 1;
+    }
+    if (pos < original.length) {
+      System.arraycopy(original, pos, results, pos, original.length - pos);
+    }
+    return results;
+  }
+
+}