From 7ab3b3d335b3fb9d70e8e5b7fb9683c08f8a91fe Mon Sep 17 00:00:00 2001
From: Graham <gpe@openrs2.dev>
Date: Tue, 18 Aug 2020 20:42:39 +0100
Subject: [PATCH] Add method for calculating the K&R hash code of a
 CP-1252-encoded string

Signed-off-by: Graham <gpe@openrs2.dev>
---
 util/src/main/java/dev/openrs2/util/StringUtils.kt     | 10 ++++++++++
 util/src/test/java/dev/openrs2/util/StringUtilsTest.kt |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/util/src/main/java/dev/openrs2/util/StringUtils.kt b/util/src/main/java/dev/openrs2/util/StringUtils.kt
index e48c10d5..d48ac8d4 100644
--- a/util/src/main/java/dev/openrs2/util/StringUtils.kt
+++ b/util/src/main/java/dev/openrs2/util/StringUtils.kt
@@ -1,5 +1,7 @@
 package dev.openrs2.util
 
+import dev.openrs2.util.charset.Cp1252Charset
+
 fun CharSequence.indefiniteArticle(): String {
     require(isNotEmpty())
 
@@ -8,3 +10,11 @@ fun CharSequence.indefiniteArticle(): String {
         else -> "a"
     }
 }
+
+fun CharSequence.krHashCode(): Int {
+    var hash = 0
+    for (c in this) {
+        hash = ((hash shl 5) - hash) + Cp1252Charset.encode(c)
+    }
+    return hash
+}
diff --git a/util/src/test/java/dev/openrs2/util/StringUtilsTest.kt b/util/src/test/java/dev/openrs2/util/StringUtilsTest.kt
index c780e20d..1dfacf5c 100644
--- a/util/src/test/java/dev/openrs2/util/StringUtilsTest.kt
+++ b/util/src/test/java/dev/openrs2/util/StringUtilsTest.kt
@@ -13,4 +13,11 @@ object StringUtilsTest {
             "".indefiniteArticle()
         }
     }
+
+    @Test
+    fun testKrHashCode() {
+        assertEquals(0, "".krHashCode())
+        assertEquals(99162322, "hello".krHashCode())
+        assertEquals(92340183, "h€llo".krHashCode())
+    }
 }