From 7483a0e0d63835e148f0db9f4a055e5bec64dea6 Mon Sep 17 00:00:00 2001
From: Philip Helger <philip@helger.com>
Date: Tue, 9 Jul 2024 17:18:36 +0200
Subject: [PATCH] Extended ByteArarySearcher API

---
 .../validator/ByteArraySearcher.java          | 45 +++++++++++--------
 .../validator/ByteArraySearcherTest.java      | 24 ++++++++++
 2 files changed, 51 insertions(+), 18 deletions(-)
 create mode 100644 validator/src/test/java/org/mustangproject/validator/ByteArraySearcherTest.java

diff --git a/validator/src/main/java/org/mustangproject/validator/ByteArraySearcher.java b/validator/src/main/java/org/mustangproject/validator/ByteArraySearcher.java
index 169d0dd4..ac1417c3 100644
--- a/validator/src/main/java/org/mustangproject/validator/ByteArraySearcher.java
+++ b/validator/src/main/java/org/mustangproject/validator/ByteArraySearcher.java
@@ -5,24 +5,33 @@ public final class ByteArraySearcher {
 	private ByteArraySearcher() {
 	}
 
+  public static int indexOf(byte[] haystack, byte[] needle) {
+    if (needle.length > haystack.length) {
+      return -1;
+    }
+    
+    // Any needle to search?
+    if (needle.length == 0) {
+      return -1;
+    }
+
+    for (int i = 0; i <= haystack.length - needle.length; 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;
+  }
+
 	public static boolean contains(byte[] haystack, byte[] needle) {
-		if (needle.length > haystack.length) {
-			return false;
-		}
-
-		for (int i = 0; i <= haystack.length - needle.length; i++) {
-			boolean found = true;
-			for (int j = 0; j < needle.length; j++) {
-				if (haystack[i + j] != needle[j]) {
-					found = false;
-					break;
-				}
-			}
-			if (found) {
-				return true;
-			}
-		}
-
-		return false;
+	  return indexOf (haystack, needle) >= 0;
 	}
 }
diff --git a/validator/src/test/java/org/mustangproject/validator/ByteArraySearcherTest.java b/validator/src/test/java/org/mustangproject/validator/ByteArraySearcherTest.java
new file mode 100644
index 00000000..fda28aaa
--- /dev/null
+++ b/validator/src/test/java/org/mustangproject/validator/ByteArraySearcherTest.java
@@ -0,0 +1,24 @@
+package org.mustangproject.validator;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.nio.charset.StandardCharsets;
+
+import org.junit.Test;
+
+public class ByteArraySearcherTest {
+  @Test
+  public void testIndexOf () {
+    byte[] haystack = "Hello World".getBytes (StandardCharsets.ISO_8859_1);
+    assertEquals (0, ByteArraySearcher.indexOf (haystack, new byte[] {'H'}));
+    assertEquals (1, ByteArraySearcher.indexOf (haystack, new byte[] {'e'}));
+    assertEquals (0, ByteArraySearcher.indexOf (haystack, new byte[] {'H', 'e'}));
+    assertEquals (0, ByteArraySearcher.indexOf (haystack, new byte[] {'H', 'e'}));
+    assertEquals (0, ByteArraySearcher.indexOf (haystack, new byte[] {'H', 'e', 'l', 'l'}));
+    assertEquals (0, ByteArraySearcher.indexOf (haystack, haystack));
+    assertEquals (0, ByteArraySearcher.indexOf (haystack, new byte[0]));
+    assertEquals (-1, ByteArraySearcher.indexOf (haystack, new byte[] {'a'}));
+    assertEquals (-1, ByteArraySearcher.indexOf (haystack, new byte[] {'h'}));
+    assertEquals (-1, ByteArraySearcher.indexOf (haystack, new byte[] {'r', 'o'}));
+  }
+}