[GitHub] [commons-lang] XenoAmess commented on a change in pull request #534: [LANG-1548] split regionMatches for better performance

[GitBox <gi...@apache.org>]

XenoAmess commented on a change in pull request #534:
URL: https://github.com/apache/commons-lang/pull/534#discussion_r435717449



##########
File path: src/main/java/org/apache/commons/lang3/CharSequenceUtils.java
##########
@@ -252,17 +252,58 @@ static int lastIndexOf(final CharSequence cs, final CharSequence searchChar, fin
      * Green implementation of regionMatches.
      *
      * @param cs the {@code CharSequence} to be processed
-     * @param ignoreCase whether or not to be case insensitive
      * @param thisStart the index to start on the {@code cs} CharSequence
      * @param substring the {@code CharSequence} to be looked for
      * @param start the index to start on the {@code substring} CharSequence
      * @param length character length of the region
      * @return whether the region matched
      */
-    static boolean regionMatches(final CharSequence cs, final boolean ignoreCase, final int thisStart,
-            final CharSequence substring, final int start, final int length)    {
+    static boolean regionMatches(final CharSequence cs, final int thisStart,
+                                 final CharSequence substring, final int start, final int length)    {
+        if (cs instanceof String && substring instanceof String) {
+            return ((String) cs).regionMatches(thisStart, (String) substring, start, length);
+        }
+        int index1 = thisStart;
+        int index2 = start;
+        int tmpLen = length;
+
+        // Extract these first so we detect NPEs the same as the java.lang.String version
+        final int srcLen = cs.length() - thisStart;
+        final int otherLen = substring.length() - start;
+
+        // Check for invalid parameters
+        if (thisStart < 0 || start < 0 || length < 0) {
+            return false;
+        }
+
+        // Check that the regions are long enough
+        if (srcLen < length || otherLen < length) {
+            return false;
+        }
+
+        while (tmpLen-- > 0) {

Review comment:
       the `while (tmpLen-- > 0) {` is same as it in original codes.
   I just want to make as less changes as possible.
   If you think we should reformat the codes I feel like agreed, but lets' do that after this pr, or at least, when merging this pr.




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