Fix issue with line-mode speedup (all language).

Lua not affected.  Python 3 unique in having a larger bailout.

Author: Neil Fraser

objectivec/DiffMatchPatchCFUtilities.c

@@ -480,14 +480,18 @@ CFStringRef diff_linesToCharsMungeCFStringCreate(CFStringRef text, CFMutableArra
     }*/
 
     line = diff_CFStringCreateJavaSubstring(text, lineStart, lineEnd + 1);
-    lineStart = lineEnd + 1;
 
     if (CFDictionaryContainsKey(lineHash, line)) {
       CFDictionaryGetValueIfPresent(lineHash, line, (const void **)&hashNumber);
       CFNumberGetValue(hashNumber, kCFNumberCFIndexType, &hash);
       const UniChar hashChar = (UniChar)hash;
       CFStringAppendCharacters(chars, &hashChar, 1);
     } else {
+      if (CFArrayGetCount(lineArray) == 65535) {
+        // Bail out at 65535 because char 65536 == char 0.
+        line = diff_CFStringCreateJavaSubstring(text, lineStart, textLength);
+        lineEnd = textLength;
+      }
       CFArrayAppendValue(lineArray, line);
       hash = CFArrayGetCount(lineArray) - 1;
       hashNumber = CFNumberCreate(kCFAllocatorDefault, kCFNumberCFIndexType, &hash);
@@ -497,6 +501,7 @@ CFStringRef diff_linesToCharsMungeCFStringCreate(CFStringRef text, CFMutableArra
       const UniChar hashChar = (UniChar)hash;
       CFStringAppendCharacters(chars, &hashChar, 1);
     }
+    lineStart = lineEnd + 1;
 
     CFRelease(line);
   }

objectivec/Tests/DiffMatchPatchTest.m

@@ -172,11 +172,11 @@ - (void)test_diff_linesToCharsTest {
   NSMutableString *lines = [NSMutableString string];
   NSMutableString *chars = [NSMutableString string];
   NSString *currentLine;
-  for (unichar x = 1; x < n + 1; x++) {
-    currentLine = [NSString stringWithFormat:@"%d\n", (int)x];
+  for (unichar i = 1; i < n + 1; i++) {
+    currentLine = [NSString stringWithFormat:@"%d\n", (int)i];
     [tmpVector addObject:currentLine];
     [lines appendString:currentLine];
-    [chars appendString:[NSString stringWithFormat:@"%C", x]];
+    [chars appendString:[NSString stringWithFormat:@"%C", i]];
   }
   XCTAssertEqual((NSUInteger)n, tmpVector.count, @"More than 256 #1.");
   XCTAssertEqual((NSUInteger)n, chars.length, @"More than 256 #2.");
@@ -212,11 +212,11 @@ - (void)test_diff_charsToLinesTest {
   NSMutableString *lines = [NSMutableString string];
   NSMutableString *chars = [NSMutableString string];
   NSString *currentLine;
-  for (unichar x = 1; x < n + 1; x++) {
-    currentLine = [NSString stringWithFormat:@"%d\n", (int)x];
+  for (unichar i = 1; i < n + 1; i++) {
+    currentLine = [NSString stringWithFormat:@"%d\n", (int)i];
     [tmpVector addObject:currentLine];
     [lines appendString:currentLine];
-    [chars appendString:[NSString stringWithFormat:@"%C", x]];
+    [chars appendString:[NSString stringWithFormat:@"%C", i]];
   }
   XCTAssertEqual((NSUInteger)n, tmpVector.count, @"More than 256 #1.");
   XCTAssertEqual((NSUInteger)n, chars.length, @"More than 256 #2.");
@@ -225,6 +225,19 @@ - (void)test_diff_charsToLinesTest {
   [dmp diff_chars:diffs toLines:tmpVector];
   XCTAssertEqualObjects([NSArray arrayWithObject:[Diff diffWithOperation:DIFF_DELETE andText:lines]], diffs, @"More than 256 #3.");
 
+  // More than 65536 to verify any 16-bit limitation.
+  lines = [NSMutableString string];
+  for (int i = 1; i < 66000; i++) {
+    currentLine = [NSString stringWithFormat:@"%d\n", i];
+    [lines appendString:currentLine];
+  }
+  NSArray *result;
+  result = [dmp diff_linesToCharsForFirstString:lines andSecondString:@""];
+  diffs = [NSArray arrayWithObject:[Diff diffWithOperation:DIFF_INSERT andText:result[0]]];
+  [dmp diff_chars:diffs toLines:result[2]];
+  Diff *myDiff = diffs.firstObject;
+  XCTAssertEqualObjects(lines, myDiff.text, @"More than 65536.");
+
   [dmp release];
 }
 
@@ -859,7 +872,7 @@ - (void)test_diff_mainTest {
   NSMutableString *aMutable = [NSMutableString stringWithString:a];
   NSMutableString *bMutable = [NSMutableString stringWithString:b];
   // Increase the text lengths by 1024 times to ensure a timeout.
-  for (int x = 0; x < 10; x++) {
+  for (int i = 0; i < 10; i++) {
     [aMutable appendString:aMutable];
     [bMutable appendString:bMutable];
   }