From f9acb40b9996a848056f51dc8ea9e786ef80a135 Mon Sep 17 00:00:00 2001
From: Henri Yandell <bayard@apache.org>
Date: Thu, 18 Apr 2013 08:15:47 +0000
Subject: [PATCH] Adding Dmitry Katsubo's patch from LANG-846, providing
 CharSequenceUtils.regionMatches with a proper green implementation instead of
 inefficiently converting to Strings

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1469220 13f79535-47bb-0310-9956-ffa450edef68
---
 .../commons/lang3/CharSequenceUtils.java      | 27 ++++++++++++++++---
 .../lang3/StringUtilsStartsEndsWithTest.java  | 14 ++++++++++
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java b/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
index 0b096c974..b69e12f52 100644
--- a/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
+++ b/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
@@ -189,9 +189,30 @@ static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, fi
         if (cs instanceof String && substring instanceof String) {
             return ((String) cs).regionMatches(ignoreCase, thisStart, (String) substring, start, length);
         } else {
-            // TODO: Implement rather than convert to String
-            return cs.toString().regionMatches(ignoreCase, thisStart, substring.toString(), start, length);
+            int index1 = thisStart;
+            int index2 = start;
+            int tmpLen = length;
+
+            while (tmpLen-- > 0) {
+                char c1 = cs.charAt(index1++);
+                char c2 = substring.charAt(index2++);
+
+                if (c1 == c2) {
+                    continue;
+                }
+
+                if (!ignoreCase) {
+                    return false;
+                }
+
+                // The same check as in String.regionMatches():
+                if (Character.toUpperCase(c1) != Character.toUpperCase(c2)
+                        && Character.toLowerCase(c1) != Character.toLowerCase(c2)) {
+                    return false;
+                }
+            }
+
+            return true;
         }
     }
-
 }
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsStartsEndsWithTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsStartsEndsWithTest.java
index d994e8f5c..440793dba 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsStartsEndsWithTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsStartsEndsWithTest.java
@@ -120,6 +120,13 @@ public void testEndsWith() {
         assertTrue("endsWith(FOOBAR, BAR)",  StringUtils.endsWith(FOOBAR, BAR));
         assertFalse("endsWith(foobar, BAR)", StringUtils.endsWith(foobar, BAR));
         assertFalse("endsWith(FOOBAR, bar)", StringUtils.endsWith(FOOBAR, bar));
+
+        // "alpha,beta,gamma,delta".endsWith("delta")
+        assertTrue("endsWith(\u03B1\u03B2\u03B3\u03B4, \u03B4)",
+                StringUtils.endsWith("\u03B1\u03B2\u03B3\u03B4", "\u03B4"));
+        // "alpha,beta,gamma,delta".endsWith("gamma,DELTA")
+        assertFalse("endsWith(\u03B1\u03B2\u03B3\u03B4, \u03B3\u0394)",
+                StringUtils.endsWith("\u03B1\u03B2\u03B3\u03B4", "\u03B3\u0394"));
     }
 
     /**
@@ -149,6 +156,13 @@ public void testEndsWithIgnoreCase() {
         assertTrue(StringUtils.endsWithIgnoreCase("abcdef", "def"));
         assertTrue(StringUtils.endsWithIgnoreCase("ABCDEF", "def"));
         assertFalse(StringUtils.endsWithIgnoreCase("ABCDEF", "cde"));
+
+        // "alpha,beta,gamma,delta".endsWith("DELTA")
+        assertTrue("endsWith(\u03B1\u03B2\u03B3\u03B4, \u0394)",
+                StringUtils.endsWithIgnoreCase("\u03B1\u03B2\u03B3\u03B4", "\u0394"));
+        // "alpha,beta,gamma,delta".endsWith("GAMMA")
+        assertFalse("endsWith(\u03B1\u03B2\u03B3\u03B4, \u0393)",
+                StringUtils.endsWithIgnoreCase("\u03B1\u03B2\u03B3\u03B4", "\u0393"));
     }
 
     @Test