From 217da1e6aa2b2c9f626ed2efa42e3e3996175571 Mon Sep 17 00:00:00 2001
From: XenoAmess <xenoamess@gmail.com>
Date: Mon, 1 Jun 2020 02:26:14 +0800
Subject: [PATCH] implement lastIndexOf

---
 .../commons/lang3/CharSequenceUtils.java      | 31 +++++++++++++------
 .../commons/lang3/CharSequenceUtilsTest.java  | 23 +++-----------
 2 files changed, 25 insertions(+), 29 deletions(-)

diff --git a/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java b/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
index 4dab0637e..01de17c2b 100644
--- a/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
+++ b/src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
@@ -266,22 +266,33 @@ public class CharSequenceUtils {
             start = len1 - len2;
         }
 
-        if (check(cs, searchChar, len2, start)) {
-            return start;
-        }
+        char char0 = searchChar.charAt(0);
 
-        for (int i = start - 1; i >= 0; i--) {
-            if (check(cs, searchChar, len2, i)) {
+        int i = start;
+        while (true) {
+            while (cs.charAt(i) != char0) {
+                i--;
+                if (i < 0) {
+                    return -1;
+                }
+            }
+            if (checkLaterThan1(cs, searchChar, len2, i)) {
                 return i;
+            } else {
+                i--;
+                if (i < 0) {
+                    return -1;
+                }
             }
         }
-
-        return -1;
     }
 
-    private static boolean check(final CharSequence cs, final CharSequence searchChar, int len2, int start1) {
-        for (int i = 0; i < len2; i++) {
-            if (cs.charAt(start1 + i) != searchChar.charAt(i)) {
+    private static boolean checkLaterThan1(final CharSequence cs, final CharSequence searchChar, int len2, int start1) {
+        for (int i = 1, j = len2 - 1; i <= j; i++, j--) {
+            if (cs.charAt(start1 + i) != searchChar.charAt(i)
+                    ||
+                    cs.charAt(start1 + j) != searchChar.charAt(j)
+            ) {
                 return false;
             }
         }
diff --git a/src/test/java/org/apache/commons/lang3/CharSequenceUtilsTest.java b/src/test/java/org/apache/commons/lang3/CharSequenceUtilsTest.java
index c230c4507..796e8f24e 100644
--- a/src/test/java/org/apache/commons/lang3/CharSequenceUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/CharSequenceUtilsTest.java
@@ -16,23 +16,14 @@
  */
 package org.apache.commons.lang3;
 
-import static java.nio.CharBuffer.wrap;
-import static org.junit.jupiter.api.Assertions.assertArrayEquals;
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertFalse;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
-import static org.junit.jupiter.api.Assertions.assertNull;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
+import org.junit.jupiter.api.Test;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Modifier;
-import java.nio.CharBuffer;
 import java.util.Random;
 import java.util.stream.IntStream;
 
-import org.apache.commons.lang3.text.StrBuilder;
-import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
 
 /**
  * Tests CharSequenceUtils
@@ -258,7 +249,7 @@ public class CharSequenceUtilsTest {
 
     private void testNewLastIndexOfSingle(CharSequence a, CharSequence b) {
         int maxa = Math.max(a.length(), b.length());
-        for (int i = -maxa-10; i <= maxa+10; i++) {
+        for (int i = -maxa - 10; i <= maxa + 10; i++) {
             testNewLastIndexOfSingle(a, b, i);
         }
     }
@@ -269,14 +260,8 @@ public class CharSequenceUtilsTest {
     }
 
     private void testNewLastIndexOfSingleSingle(CharSequence a, CharSequence b, int start) {
-        int expected = a.toString().lastIndexOf(b.toString(), start);
-//        assertEquals(
-//                expected,
-//                lastIndexOf(new WrapperString(a), b, start),
-//                "testNewLastIndexOf fails! original : " + a + " seg : " + b + " start : " + start
-//        );
         assertEquals(
-                expected,
+                a.toString().lastIndexOf(b.toString(), start),
                 CharSequenceUtils.lastIndexOf(new WrapperString(a.toString()), b.toString(), start),
                 "testNewLastIndexOf fails! original : " + a + " seg : " + b + " start : " + start
         );