commit acb83d2339e3fb091fcfb844da1852fcb5d4e0d1
author Cole Faust <colefaust@google.com> Mon Aug 22 22:42:59 2022 +0000
committer Gerrit Code Review <noreply-gerritcodereview@google.com> Mon Aug 22 22:42:59 2022 +0000
tree 47343e27edeb2df35dab90c1f189dce5f448899f
parent ad9456d322aae66aa3beef64f70005e4bf9741c4
parent 0d8bd9005ddbec351ef5a4bd79fe8cf6fba3b0de

Merge "Add CollectionUtils.indexOfSubArray()"

staticlibs/framework/com/android/net/module/util/CollectionUtils.java

diff --git a/staticlibs/framework/com/android/net/module/util/CollectionUtils.java b/staticlibs/framework/com/android/net/module/util/CollectionUtils.java
index a16ef33..58689fb 100644
--- a/staticlibs/framework/com/android/net/module/util/CollectionUtils.java
+++ b/staticlibs/framework/com/android/net/module/util/CollectionUtils.java
@@ -165,6 +165,26 @@
     }
 
     /**
+     * Returns the index of the needle array in the haystack array, or -1 if it can't be found.
+     * This is a byte array equivalent of Collections.indexOfSubList().
+     */
+    public static int indexOfSubArray(@NonNull byte[] haystack, @NonNull byte[] needle) {
+        for (int i = 0; i < haystack.length - needle.length + 1; i++) {
+            boolean found = true;
+            for (int j = 0; j < needle.length; j++) {
+                if (haystack[i + j] != needle[j]) {
+                    found = false;
+                    break;
+                }
+            }
+            if (found) {
+                return i;
+            }
+        }
+        return -1;
+    }
+
+    /**
      * Returns a new collection of elements that match the passed predicate.
      * @param source the elements to filter.
      * @param test the predicate to test for.

staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt

diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt b/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt
index 911483a..c925a0c 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/CollectionUtilsTest.kt
@@ -18,6 +18,7 @@
 
 import androidx.test.filters.SmallTest
 import androidx.test.runner.AndroidJUnit4
+import com.android.testutils.assertThrows
 import org.junit.Test
 import org.junit.runner.RunWith
 import kotlin.test.assertEquals
@@ -50,6 +51,21 @@
     }
 
     @Test
+    fun testIndexOfSubArray() {
+        val haystack = byteArrayOf(1, 2, 3, 4, 5)
+        assertEquals(2, CollectionUtils.indexOfSubArray(haystack, byteArrayOf(3, 4)))
+        assertEquals(3, CollectionUtils.indexOfSubArray(haystack, byteArrayOf(4, 5)))
+        assertEquals(4, CollectionUtils.indexOfSubArray(haystack, byteArrayOf(5)))
+        assertEquals(-1, CollectionUtils.indexOfSubArray(haystack, byteArrayOf(3, 2)))
+        assertEquals(0, CollectionUtils.indexOfSubArray(haystack, byteArrayOf()))
+        assertEquals(-1, CollectionUtils.indexOfSubArray(byteArrayOf(), byteArrayOf(3, 2)))
+        assertEquals(0, CollectionUtils.indexOfSubArray(byteArrayOf(), byteArrayOf()))
+        assertThrows(NullPointerException::class.java) {
+            CollectionUtils.indexOfSubArray(haystack, null)
+        }
+    }
+
+    @Test
     fun testAll() {
         assertFalse(CollectionUtils.all(listOf("A", "B", "C", "D", "E")) { it != "E" })
         assertTrue(CollectionUtils.all(listOf("A", "B", "C", "D", "E")) { it != "F" })