Improve performance in CharOperation

Signed-off-by: Rob Stryker <stryker@redhat.com>

Author: Rob Stryker

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/core/compiler/CharOperation.java

@@ -3750,7 +3750,7 @@ public static final char[] replace(
 		next : for (int i = 0; i < max;) {
 			int index = indexOf(toBeReplaced, array, true, i);
 			if (index == -1) {
-				i++;
+				i = max; // end
 				continue next;
 			}
 			if (occurrenceCount == starts.length) {

org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/CharOperationTest.java

@@ -170,4 +170,26 @@ public void test012() {
 			4,
 			true));
 }
+
+public void testReplacePerformance001() {
+	// This is the test that takes an excessively long time
+	// The improvement here is drastic, 99% reduction in time
+	testReplaceImpl("This is one line with no matches\n", 9, 0.01);
+}
+
+private void testReplaceImpl(String oneLine, int power, double multiplier) {
+	String total = oneLine;
+	for( int i = 0; i < power; i++ ) {
+		total = total + total; // Double the length
+	}
+	total = oneLine + total;
+
+	// Now replace
+	long start = System.currentTimeMillis();
+	char[] found = CharOperation.replace(total.toCharArray(), new char[]{'/'}, new char[] {'z'});
+	assertNotNull(found);
+	long end = System.currentTimeMillis();
+	long spent = end - start;
+	assertTrue(spent < 10);
+}
 }