Fix issue with line-mode speedup.

Fixes issue google#11 for JavaScript. Other languages to follow.

Author: Neil Fraser

javascript/diff_match_patch.js

@@ -470,16 +470,22 @@ diff_match_patch.prototype.diff_linesToChars_ = function(text1, text2) {
  lineEnd = text.length - 1;
  }
  var line = text.substring(lineStart, lineEnd + 1);
- lineStart = lineEnd + 1;
 
  if (lineHash.hasOwnProperty ? lineHash.hasOwnProperty(line) :
  (lineHash[line] !== undefined)) {
  chars += String.fromCharCode(lineHash[line]);
  } else {
+ if (lineArrayLength == 65535) {
+ // Bail out at 65535 because
+ // String.fromCharCode(65536) == String.fromCharCode(0)
+ line = text.substring(lineStart);
+ lineEnd = text.length;
+ }
  chars += String.fromCharCode(lineArrayLength);
  lineHash[line] = lineArrayLength;
  lineArray[lineArrayLength++] = line;
  }
+ lineStart = lineEnd + 1;
  }
  return chars;
  }

javascript/diff_match_patch_uncompressed.js

@@ -174,9 +174,9 @@ function testDiffLinesToChars() {
  var n = 300;
  var lineList = [];
  var charList = [];
- for (var x = 1; x < n + 1; x++) {
- lineList[x - 1] = x + '\n';
- charList[x - 1] = String.fromCharCode(x);
+ for (var i = 1; i < n + 1; i++) {
+ lineList[i - 1] = i + '\n';
+ charList[i - 1] = String.fromCharCode(i);
  }
  assertEquals(n, lineList.length);
  var lines = lineList.join('');
@@ -196,9 +196,9 @@ function testDiffCharsToLines() {
  var n = 300;
  var lineList = [];
  var charList = [];
- for (var x = 1; x < n + 1; x++) {
- lineList[x - 1] = x + '\n';
- charList[x - 1] = String.fromCharCode(x);
+ for (var i = 1; i < n + 1; i++) {
+ lineList[i - 1] = i + '\n';
+ charList[i - 1] = String.fromCharCode(i);
  }
  assertEquals(n, lineList.length);
  var lines = lineList.join('');
@@ -208,6 +208,17 @@ function testDiffCharsToLines() {
  var diffs = [[DIFF_DELETE, chars]];
  dmp.diff_charsToLines_(diffs, lineList);
  assertEquivalent([[DIFF_DELETE, lines]], diffs);
+
+ // More than 65536 to verify any 16-bit limitation.
+ lineList = [];
+ for (var i = 0; i < 66000; i++) {
+ lineList[i] = i + '\n';
+ }
+ chars = lineList.join('');
+ var results = dmp.diff_linesToChars_(chars, '');
+ diffs = [[DIFF_INSERT, results.chars1]];
+ dmp.diff_charsToLines_(diffs, results.lineArray);
+ assertEquals(chars, diffs[0][1]);
 }
 
 function testDiffCleanupMerge() {
@@ -560,8 +571,8 @@ function testDiffMain() {
  var b = 'I am the very model of a modern major general,\nI\'ve information vegetable, animal, and mineral,\nI know the kings of England, and I quote the fights historical,\nFrom Marathon to Waterloo, in order categorical.\n';
  // Increase the text lengths by 1024 times to ensure a timeout.
  for (var x = 0; x < 10; x++) {
- a = a + a;
- b = b + b;
+ a += a;
+ b += b;
  }
  var startTime = (new Date()).getTime();
  dmp.diff_main(a, b);
@@ -571,11 +582,7 @@ function testDiffMain() {
  // Test that we didn't take forever (be forgiving).
  // Theoretically this test could fail very occasionally if the
  // OS task swaps or locks up for a second at the wrong moment.
- // ****
- // TODO(fraser): For unknown reasons this is taking 500 ms on Google's
- // internal test system. Whereas browsers take 140 ms.
- //assertTrue(dmp.Diff_Timeout * 1000 * 2 > endTime - startTime);
- // ****
+ assertTrue(dmp.Diff_Timeout * 1000 * 2 > endTime - startTime);
  dmp.Diff_Timeout = 0;
 
  // Test the linemode speedup.
@@ -596,7 +603,7 @@ function testDiffMain() {
  var texts_linemode = diff_rebuildtexts(dmp.diff_main(a, b, true));
  var texts_textmode = diff_rebuildtexts(dmp.diff_main(a, b, false));
  assertEquivalent(texts_textmode, texts_linemode);
-
+ 
  // Test null inputs.
  try {
  dmp.diff_main(null, null);