From af6aff6f7db2908992fd8c023d0cb0b127305543 Mon Sep 17 00:00:00 2001 From: Xavier-Do Date: Fri, 23 Jun 2023 14:01:14 +0200 Subject: [PATCH] [IMP] runbot: diffable tracking in chatter The python steps can be long and interresting to track but the change is actually hard to see since a block of code is logged instead of the diff. Also, the whitespaces are not preserverd since we are note in a 
block making it hard to read.

This proposes an alternative to display python code tracking values as
a diff with options to copu the raw content of the old and new version.
(as well as showing unchanged lines or not)
---
 runbot/__manifest__.py                        |    3 +-
 runbot/static/src/js/{ => fields}/fields.js   |    0
 runbot/static/src/js/fields/tracking_value.js |   81 +
 .../static/src/js/fields/tracking_value.scss  |   29 +
 .../static/src/js/fields/tracking_value.xml   |   32 +
 .../static/src/libs/diff_match_patch/LICENSE  |  204 ++
 .../libs/diff_match_patch/diff_match_patch.js | 2236 +++++++++++++++++
 7 files changed, 2584 insertions(+), 1 deletion(-)
 rename runbot/static/src/js/{ => fields}/fields.js (100%)
 create mode 100644 runbot/static/src/js/fields/tracking_value.js
 create mode 100644 runbot/static/src/js/fields/tracking_value.scss
 create mode 100644 runbot/static/src/js/fields/tracking_value.xml
 create mode 100644 runbot/static/src/libs/diff_match_patch/LICENSE
 create mode 100644 runbot/static/src/libs/diff_match_patch/diff_match_patch.js

diff --git a/runbot/__manifest__.py b/runbot/__manifest__.py
index db1fb824..5125a8ca 100644
--- a/runbot/__manifest__.py
+++ b/runbot/__manifest__.py
@@ -62,7 +62,8 @@
 
     'assets': {
         'web.assets_backend': [
-            'runbot/static/src/js/fields.js',
+            'runbot/static/src/libs/diff_match_patch/diff_match_patch.js',
+            'runbot/static/src/js/fields/*',
         ],
         'runbot.assets_frontend': [
             '/web/static/lib/bootstrap/dist/css/bootstrap.css',
diff --git a/runbot/static/src/js/fields.js b/runbot/static/src/js/fields/fields.js
similarity index 100%
rename from runbot/static/src/js/fields.js
rename to runbot/static/src/js/fields/fields.js
diff --git a/runbot/static/src/js/fields/tracking_value.js b/runbot/static/src/js/fields/tracking_value.js
new file mode 100644
index 00000000..0cfcc11b
--- /dev/null
+++ b/runbot/static/src/js/fields/tracking_value.js
@@ -0,0 +1,81 @@
+/** @odoo-module **/
+
+
+import { useState} from "@odoo/owl";
+import { registerMessagingComponent, getMessagingComponent, unregisterMessagingComponent } from '@mail/utils/messaging_component';
+
+const MailTrackingValue = getMessagingComponent('TrackingValue');
+export class TrackingValue extends MailTrackingValue {
+    static template = 'runbot.TrackingValue'
+    
+    setup() {
+        this.display = useState({kept: false});
+        super.setup()
+        this.oldValue = this.props.value.oldValue.formattedValueOrNone;
+        this.newValue = this.props.value.newValue.formattedValueOrNone;
+        this.multiline = (
+            (this.oldValue && this.oldValue.includes('\n'))
+            && 
+            (this.newValue && this.newValue.includes('\n'))
+        )
+        if (this.multiline) {
+            var diff = this.makeDiff(this.oldValue, this.newValue);
+            this.lines = this.prepareForRendering(diff);
+        }
+    }
+    toggleKept() {
+        this.display.kept = !this.display.kept;
+    }
+    makeDiff(text1, text2) {
+        var dmp = new diff_match_patch();
+        var a = dmp.diff_linesToChars_(text1, text2);
+        var lineText1 = a.chars1;
+        var lineText2 = a.chars2;
+        var lineArray = a.lineArray;
+        var diffs = dmp.diff_main(lineText1, lineText2, false);
+        dmp.diff_charsToLines_(diffs, lineArray);
+        dmp.diff_cleanupSemantic(diffs);
+        return diffs;
+    }
+    prepareForRendering(diffs) {
+        var lines = [];
+        var pre_line_counter = 0
+        var post_line_counter = 0
+        for (var x = 0; x < diffs.length; x++) {
+            var diff_type = diffs[x][0];
+            var data = diffs[x][1];
+            var data_lines = data.split('\n');
+            for (var line_index in data_lines) {
+                var line = data_lines[line_index];
+                line = line.replace(/&/g, '&');
+                line = line.replace(//g, '>');
+                //text = text.replace(/\n/g, '
');
+                //text = text.replace(/ /g, '  ');
+                if (diff_type == -1) {
+                    lines.push({type:'removed', pre_line_counter: pre_line_counter, post_line_counter: '-', line: line})
+                    pre_line_counter += 1
+                } else if (diff_type == 0) {
+                    lines.push({type:'kept', pre_line_counter: '', post_line_counter: post_line_counter, line: line})
+                    pre_line_counter += 1
+                    post_line_counter +=1
+                } else if (diff_type == 1) {
+                    lines.push({type:'added', pre_line_counter: '+', post_line_counter: post_line_counter, line: line})
+                    post_line_counter +=1
+                }
+            }
+        }
+        return lines;
+      };
+
+    copyOldToClipboard() {
+        navigator.clipboard.writeText(this.oldValue);
+    }
+
+    copyNewToClipboard() {
+        navigator.clipboard.writeText(this.newValue);
+    }
+}
+
+unregisterMessagingComponent({name:'TrackingValue'});
+registerMessagingComponent(TrackingValue);
diff --git a/runbot/static/src/js/fields/tracking_value.scss b/runbot/static/src/js/fields/tracking_value.scss
new file mode 100644
index 00000000..d548e82f
--- /dev/null
+++ b/runbot/static/src/js/fields/tracking_value.scss
@@ -0,0 +1,29 @@
+.code_diff {
+    white-space: nowrap;
+    overflow-x: auto;
+    font: 12px/normal 'Monaco', 'Menlo', 'Ubuntu Mono', 'Consolas', 'source-code-pro', monospace;
+
+    .col_number {
+        background-color: #EEE;
+    }
+
+    .added {
+        background:#a1f1a1;
+    }
+    
+    .removed {
+        background:#f3a3a3;
+    }
+    
+    .code {
+        white-space: pre-wrap;
+    }
+    .diff_line {
+        background-color: #FFF;
+    }
+
+    .diff_line:hover {
+        filter: brightness(92%);
+    }
+    
+}
diff --git a/runbot/static/src/js/fields/tracking_value.xml b/runbot/static/src/js/fields/tracking_value.xml
new file mode 100644
index 00000000..02c225e2
--- /dev/null
+++ b/runbot/static/src/js/fields/tracking_value.xml
@@ -0,0 +1,32 @@
+
+
+    
+        

+            
+                

+                    
+                    
+                    
+                

+                

+                

+                    
+                        
+                            
+                                
+                        
+                    

+                                
+                                
+                            

+                

+            
+            
+                
+                
+                
+                
+            
+        

+    
+
diff --git a/runbot/static/src/libs/diff_match_patch/LICENSE b/runbot/static/src/libs/diff_match_patch/LICENSE
new file mode 100644
index 00000000..88c3db09
--- /dev/null
+++ b/runbot/static/src/libs/diff_match_patch/LICENSE
@@ -0,0 +1,204 @@
+   Source: https://github.com/google/diff-match-patch/tree/master
+
+
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diff --git a/runbot/static/src/libs/diff_match_patch/diff_match_patch.js b/runbot/static/src/libs/diff_match_patch/diff_match_patch.js
new file mode 100644
index 00000000..e37eac47
--- /dev/null
+++ b/runbot/static/src/libs/diff_match_patch/diff_match_patch.js
@@ -0,0 +1,2236 @@
+/**
+ * Diff Match and Patch
+ * Copyright 2018 The diff-match-patch Authors.
+ * https://github.com/google/diff-match-patch
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @fileoverview Computes the difference between two texts to create a patch.
+ * Applies the patch onto another text, allowing for errors.
+ * @author fraser@google.com (Neil Fraser)
+ */
+
+/**
+ * Class containing the diff, match and patch methods.
+ * @constructor
+ */
+var diff_match_patch = function() {
+
+    // Defaults.
+    // Redefine these in your program to override the defaults.
+  
+    // Number of seconds to map a diff before giving up (0 for infinity).
+    this.Diff_Timeout = 1.0;
+    // Cost of an empty edit operation in terms of edit characters.
+    this.Diff_EditCost = 4;
+    // At what point is no match declared (0.0 = perfection, 1.0 = very loose).
+    this.Match_Threshold = 0.5;
+    // How far to search for a match (0 = exact location, 1000+ = broad match).
+    // A match this many characters away from the expected location will add
+    // 1.0 to the score (0.0 is a perfect match).
+    this.Match_Distance = 1000;
+    // When deleting a large block of text (over ~64 characters), how close do
+    // the contents have to be to match the expected contents. (0.0 = perfection,
+    // 1.0 = very loose).  Note that Match_Threshold controls how closely the
+    // end points of a delete need to match.
+    this.Patch_DeleteThreshold = 0.5;
+    // Chunk size for context length.
+    this.Patch_Margin = 4;
+  
+    // The number of bits in an int.
+    this.Match_MaxBits = 32;
+  };
+  
+  
+  //  DIFF FUNCTIONS
+  
+  
+  /**
+   * The data structure representing a diff is an array of tuples:
+   * [[DIFF_DELETE, 'Hello'], [DIFF_INSERT, 'Goodbye'], [DIFF_EQUAL, ' world.']]
+   * which means: delete 'Hello', add 'Goodbye' and keep ' world.'
+   */
+  var DIFF_DELETE = -1;
+  var DIFF_INSERT = 1;
+  var DIFF_EQUAL = 0;
+  
+  /**
+   * Class representing one diff tuple.
+   * Attempts to look like a two-element array (which is what this used to be).
+   * @param {number} op Operation, one of: DIFF_DELETE, DIFF_INSERT, DIFF_EQUAL.
+   * @param {string} text Text to be deleted, inserted, or retained.
+   * @constructor
+   */
+  diff_match_patch.Diff = function(op, text) {
+    this[0] = op;
+    this[1] = text;
+  };
+  
+  diff_match_patch.Diff.prototype.length = 2;
+  
+  /**
+   * Emulate the output of a two-element array.
+   * @return {string} Diff operation as a string.
+   */
+  diff_match_patch.Diff.prototype.toString = function() {
+    return this[0] + ',' + this[1];
+  };
+  
+  
+  /**
+   * Find the differences between two texts.  Simplifies the problem by stripping
+   * any common prefix or suffix off the texts before diffing.
+   * @param {string} text1 Old string to be diffed.
+   * @param {string} text2 New string to be diffed.
+   * @param {boolean=} opt_checklines Optional speedup flag. If present and false,
+   *     then don't run a line-level diff first to identify the changed areas.
+   *     Defaults to true, which does a faster, slightly less optimal diff.
+   * @param {number=} opt_deadline Optional time when the diff should be complete
+   *     by.  Used internally for recursive calls.  Users should set DiffTimeout
+   *     instead.
+   * @return {!Array.} Array of diff tuples.
+   */
+  diff_match_patch.prototype.diff_main = function(text1, text2, opt_checklines,
+      opt_deadline) {
+    // Set a deadline by which time the diff must be complete.
+    if (typeof opt_deadline == 'undefined') {
+      if (this.Diff_Timeout <= 0) {
+        opt_deadline = Number.MAX_VALUE;
+      } else {
+        opt_deadline = (new Date).getTime() + this.Diff_Timeout * 1000;
+      }
+    }
+    var deadline = opt_deadline;
+  
+    // Check for null inputs.
+    if (text1 == null || text2 == null) {
+      throw new Error('Null input. (diff_main)');
+    }
+  
+    // Check for equality (speedup).
+    if (text1 == text2) {
+      if (text1) {
+        return [new diff_match_patch.Diff(DIFF_EQUAL, text1)];
+      }
+      return [];
+    }
+  
+    if (typeof opt_checklines == 'undefined') {
+      opt_checklines = true;
+    }
+    var checklines = opt_checklines;
+  
+    // Trim off common prefix (speedup).
+    var commonlength = this.diff_commonPrefix(text1, text2);
+    var commonprefix = text1.substring(0, commonlength);
+    text1 = text1.substring(commonlength);
+    text2 = text2.substring(commonlength);
+  
+    // Trim off common suffix (speedup).
+    commonlength = this.diff_commonSuffix(text1, text2);
+    var commonsuffix = text1.substring(text1.length - commonlength);
+    text1 = text1.substring(0, text1.length - commonlength);
+    text2 = text2.substring(0, text2.length - commonlength);
+  
+    // Compute the diff on the middle block.
+    var diffs = this.diff_compute_(text1, text2, checklines, deadline);
+  
+    // Restore the prefix and suffix.
+    if (commonprefix) {
+      diffs.unshift(new diff_match_patch.Diff(DIFF_EQUAL, commonprefix));
+    }
+    if (commonsuffix) {
+      diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, commonsuffix));
+    }
+    this.diff_cleanupMerge(diffs);
+    return diffs;
+  };
+  
+  
+  /**
+   * Find the differences between two texts.  Assumes that the texts do not
+   * have any common prefix or suffix.
+   * @param {string} text1 Old string to be diffed.
+   * @param {string} text2 New string to be diffed.
+   * @param {boolean} checklines Speedup flag.  If false, then don't run a
+   *     line-level diff first to identify the changed areas.
+   *     If true, then run a faster, slightly less optimal diff.
+   * @param {number} deadline Time when the diff should be complete by.
+   * @return {!Array.} Array of diff tuples.
+   * @private
+   */
+  diff_match_patch.prototype.diff_compute_ = function(text1, text2, checklines,
+      deadline) {
+    var diffs;
+  
+    if (!text1) {
+      // Just add some text (speedup).
+      return [new diff_match_patch.Diff(DIFF_INSERT, text2)];
+    }
+  
+    if (!text2) {
+      // Just delete some text (speedup).
+      return [new diff_match_patch.Diff(DIFF_DELETE, text1)];
+    }
+  
+    var longtext = text1.length > text2.length ? text1 : text2;
+    var shorttext = text1.length > text2.length ? text2 : text1;
+    var i = longtext.indexOf(shorttext);
+    if (i != -1) {
+      // Shorter text is inside the longer text (speedup).
+      diffs = [new diff_match_patch.Diff(DIFF_INSERT, longtext.substring(0, i)),
+               new diff_match_patch.Diff(DIFF_EQUAL, shorttext),
+               new diff_match_patch.Diff(DIFF_INSERT,
+                   longtext.substring(i + shorttext.length))];
+      // Swap insertions for deletions if diff is reversed.
+      if (text1.length > text2.length) {
+        diffs[0][0] = diffs[2][0] = DIFF_DELETE;
+      }
+      return diffs;
+    }
+  
+    if (shorttext.length == 1) {
+      // Single character string.
+      // After the previous speedup, the character can't be an equality.
+      return [new diff_match_patch.Diff(DIFF_DELETE, text1),
+              new diff_match_patch.Diff(DIFF_INSERT, text2)];
+    }
+  
+    // Check to see if the problem can be split in two.
+    var hm = this.diff_halfMatch_(text1, text2);
+    if (hm) {
+      // A half-match was found, sort out the return data.
+      var text1_a = hm[0];
+      var text1_b = hm[1];
+      var text2_a = hm[2];
+      var text2_b = hm[3];
+      var mid_common = hm[4];
+      // Send both pairs off for separate processing.
+      var diffs_a = this.diff_main(text1_a, text2_a, checklines, deadline);
+      var diffs_b = this.diff_main(text1_b, text2_b, checklines, deadline);
+      // Merge the results.
+      return diffs_a.concat([new diff_match_patch.Diff(DIFF_EQUAL, mid_common)],
+                            diffs_b);
+    }
+  
+    if (checklines && text1.length > 100 && text2.length > 100) {
+      return this.diff_lineMode_(text1, text2, deadline);
+    }
+  
+    return this.diff_bisect_(text1, text2, deadline);
+  };
+  
+  
+  /**
+   * Do a quick line-level diff on both strings, then rediff the parts for
+   * greater accuracy.
+   * This speedup can produce non-minimal diffs.
+   * @param {string} text1 Old string to be diffed.
+   * @param {string} text2 New string to be diffed.
+   * @param {number} deadline Time when the diff should be complete by.
+   * @return {!Array.} Array of diff tuples.
+   * @private
+   */
+  diff_match_patch.prototype.diff_lineMode_ = function(text1, text2, deadline) {
+    // Scan the text on a line-by-line basis first.
+    var a = this.diff_linesToChars_(text1, text2);
+    text1 = a.chars1;
+    text2 = a.chars2;
+    var linearray = a.lineArray;
+  
+    var diffs = this.diff_main(text1, text2, false, deadline);
+  
+    // Convert the diff back to original text.
+    this.diff_charsToLines_(diffs, linearray);
+    // Eliminate freak matches (e.g. blank lines)
+    this.diff_cleanupSemantic(diffs);
+  
+    // Rediff any replacement blocks, this time character-by-character.
+    // Add a dummy entry at the end.
+    diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, ''));
+    var pointer = 0;
+    var count_delete = 0;
+    var count_insert = 0;
+    var text_delete = '';
+    var text_insert = '';
+    while (pointer < diffs.length) {
+      switch (diffs[pointer][0]) {
+        case DIFF_INSERT:
+          count_insert++;
+          text_insert += diffs[pointer][1];
+          break;
+        case DIFF_DELETE:
+          count_delete++;
+          text_delete += diffs[pointer][1];
+          break;
+        case DIFF_EQUAL:
+          // Upon reaching an equality, check for prior redundancies.
+          if (count_delete >= 1 && count_insert >= 1) {
+            // Delete the offending records and add the merged ones.
+            diffs.splice(pointer - count_delete - count_insert,
+                         count_delete + count_insert);
+            pointer = pointer - count_delete - count_insert;
+            var subDiff =
+                this.diff_main(text_delete, text_insert, false, deadline);
+            for (var j = subDiff.length - 1; j >= 0; j--) {
+              diffs.splice(pointer, 0, subDiff[j]);
+            }
+            pointer = pointer + subDiff.length;
+          }
+          count_insert = 0;
+          count_delete = 0;
+          text_delete = '';
+          text_insert = '';
+          break;
+      }
+      pointer++;
+    }
+    diffs.pop();  // Remove the dummy entry at the end.
+  
+    return diffs;
+  };
+  
+  
+  /**
+   * Find the 'middle snake' of a diff, split the problem in two
+   * and return the recursively constructed diff.
+   * See Myers 1986 paper: An O(ND) Difference Algorithm and Its Variations.
+   * @param {string} text1 Old string to be diffed.
+   * @param {string} text2 New string to be diffed.
+   * @param {number} deadline Time at which to bail if not yet complete.
+   * @return {!Array.} Array of diff tuples.
+   * @private
+   */
+  diff_match_patch.prototype.diff_bisect_ = function(text1, text2, deadline) {
+    // Cache the text lengths to prevent multiple calls.
+    var text1_length = text1.length;
+    var text2_length = text2.length;
+    var max_d = Math.ceil((text1_length + text2_length) / 2);
+    var v_offset = max_d;
+    var v_length = 2 * max_d;
+    var v1 = new Array(v_length);
+    var v2 = new Array(v_length);
+    // Setting all elements to -1 is faster in Chrome & Firefox than mixing
+    // integers and undefined.
+    for (var x = 0; x < v_length; x++) {
+      v1[x] = -1;
+      v2[x] = -1;
+    }
+    v1[v_offset + 1] = 0;
+    v2[v_offset + 1] = 0;
+    var delta = text1_length - text2_length;
+    // If the total number of characters is odd, then the front path will collide
+    // with the reverse path.
+    var front = (delta % 2 != 0);
+    // Offsets for start and end of k loop.
+    // Prevents mapping of space beyond the grid.
+    var k1start = 0;
+    var k1end = 0;
+    var k2start = 0;
+    var k2end = 0;
+    for (var d = 0; d < max_d; d++) {
+      // Bail out if deadline is reached.
+      if ((new Date()).getTime() > deadline) {
+        break;
+      }
+  
+      // Walk the front path one step.
+      for (var k1 = -d + k1start; k1 <= d - k1end; k1 += 2) {
+        var k1_offset = v_offset + k1;
+        var x1;
+        if (k1 == -d || (k1 != d && v1[k1_offset - 1] < v1[k1_offset + 1])) {
+          x1 = v1[k1_offset + 1];
+        } else {
+          x1 = v1[k1_offset - 1] + 1;
+        }
+        var y1 = x1 - k1;
+        while (x1 < text1_length && y1 < text2_length &&
+               text1.charAt(x1) == text2.charAt(y1)) {
+          x1++;
+          y1++;
+        }
+        v1[k1_offset] = x1;
+        if (x1 > text1_length) {
+          // Ran off the right of the graph.
+          k1end += 2;
+        } else if (y1 > text2_length) {
+          // Ran off the bottom of the graph.
+          k1start += 2;
+        } else if (front) {
+          var k2_offset = v_offset + delta - k1;
+          if (k2_offset >= 0 && k2_offset < v_length && v2[k2_offset] != -1) {
+            // Mirror x2 onto top-left coordinate system.
+            var x2 = text1_length - v2[k2_offset];
+            if (x1 >= x2) {
+              // Overlap detected.
+              return this.diff_bisectSplit_(text1, text2, x1, y1, deadline);
+            }
+          }
+        }
+      }
+  
+      // Walk the reverse path one step.
+      for (var k2 = -d + k2start; k2 <= d - k2end; k2 += 2) {
+        var k2_offset = v_offset + k2;
+        var x2;
+        if (k2 == -d || (k2 != d && v2[k2_offset - 1] < v2[k2_offset + 1])) {
+          x2 = v2[k2_offset + 1];
+        } else {
+          x2 = v2[k2_offset - 1] + 1;
+        }
+        var y2 = x2 - k2;
+        while (x2 < text1_length && y2 < text2_length &&
+               text1.charAt(text1_length - x2 - 1) ==
+               text2.charAt(text2_length - y2 - 1)) {
+          x2++;
+          y2++;
+        }
+        v2[k2_offset] = x2;
+        if (x2 > text1_length) {
+          // Ran off the left of the graph.
+          k2end += 2;
+        } else if (y2 > text2_length) {
+          // Ran off the top of the graph.
+          k2start += 2;
+        } else if (!front) {
+          var k1_offset = v_offset + delta - k2;
+          if (k1_offset >= 0 && k1_offset < v_length && v1[k1_offset] != -1) {
+            var x1 = v1[k1_offset];
+            var y1 = v_offset + x1 - k1_offset;
+            // Mirror x2 onto top-left coordinate system.
+            x2 = text1_length - x2;
+            if (x1 >= x2) {
+              // Overlap detected.
+              return this.diff_bisectSplit_(text1, text2, x1, y1, deadline);
+            }
+          }
+        }
+      }
+    }
+    // Diff took too long and hit the deadline or
+    // number of diffs equals number of characters, no commonality at all.
+    return [new diff_match_patch.Diff(DIFF_DELETE, text1),
+            new diff_match_patch.Diff(DIFF_INSERT, text2)];
+  };
+  
+  
+  /**
+   * Given the location of the 'middle snake', split the diff in two parts
+   * and recurse.
+   * @param {string} text1 Old string to be diffed.
+   * @param {string} text2 New string to be diffed.
+   * @param {number} x Index of split point in text1.
+   * @param {number} y Index of split point in text2.
+   * @param {number} deadline Time at which to bail if not yet complete.
+   * @return {!Array.} Array of diff tuples.
+   * @private
+   */
+  diff_match_patch.prototype.diff_bisectSplit_ = function(text1, text2, x, y,
+      deadline) {
+    var text1a = text1.substring(0, x);
+    var text2a = text2.substring(0, y);
+    var text1b = text1.substring(x);
+    var text2b = text2.substring(y);
+  
+    // Compute both diffs serially.
+    var diffs = this.diff_main(text1a, text2a, false, deadline);
+    var diffsb = this.diff_main(text1b, text2b, false, deadline);
+  
+    return diffs.concat(diffsb);
+  };
+  
+  
+  /**
+   * Split two texts into an array of strings.  Reduce the texts to a string of
+   * hashes where each Unicode character represents one line.
+   * @param {string} text1 First string.
+   * @param {string} text2 Second string.
+   * @return {{chars1: string, chars2: string, lineArray: !Array.}}
+   *     An object containing the encoded text1, the encoded text2 and
+   *     the array of unique strings.
+   *     The zeroth element of the array of unique strings is intentionally blank.
+   * @private
+   */
+  diff_match_patch.prototype.diff_linesToChars_ = function(text1, text2) {
+    var lineArray = [];  // e.g. lineArray[4] == 'Hello\n'
+    var lineHash = {};   // e.g. lineHash['Hello\n'] == 4
+  
+    // '\x00' is a valid character, but various debuggers don't like it.
+    // So we'll insert a junk entry to avoid generating a null character.
+    lineArray[0] = '';
+  
+    /**
+     * Split a text into an array of strings.  Reduce the texts to a string of
+     * hashes where each Unicode character represents one line.
+     * Modifies linearray and linehash through being a closure.
+     * @param {string} text String to encode.
+     * @return {string} Encoded string.
+     * @private
+     */
+    function diff_linesToCharsMunge_(text) {
+      var chars = '';
+      // Walk the text, pulling out a substring for each line.
+      // text.split('\n') would would temporarily double our memory footprint.
+      // Modifying text would create many large strings to garbage collect.
+      var lineStart = 0;
+      var lineEnd = -1;
+      // Keeping our own length variable is faster than looking it up.
+      var lineArrayLength = lineArray.length;
+      while (lineEnd < text.length - 1) {
+        lineEnd = text.indexOf('\n', lineStart);
+        if (lineEnd == -1) {
+          lineEnd = text.length - 1;
+        }
+        var line = text.substring(lineStart, lineEnd + 1);
+  
+        if (lineHash.hasOwnProperty ? lineHash.hasOwnProperty(line) :
+            (lineHash[line] !== undefined)) {
+          chars += String.fromCharCode(lineHash[line]);
+        } else {
+          if (lineArrayLength == maxLines) {
+            // 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;
+    }
+    // Allocate 2/3rds of the space for text1, the rest for text2.
+    var maxLines = 40000;
+    var chars1 = diff_linesToCharsMunge_(text1);
+    maxLines = 65535;
+    var chars2 = diff_linesToCharsMunge_(text2);
+    return {chars1: chars1, chars2: chars2, lineArray: lineArray};
+  };
+  
+  
+  /**
+   * Rehydrate the text in a diff from a string of line hashes to real lines of
+   * text.
+   * @param {!Array.} diffs Array of diff tuples.
+   * @param {!Array.} lineArray Array of unique strings.
+   * @private
+   */
+  diff_match_patch.prototype.diff_charsToLines_ = function(diffs, lineArray) {
+    for (var i = 0; i < diffs.length; i++) {
+      var chars = diffs[i][1];
+      var text = [];
+      for (var j = 0; j < chars.length; j++) {
+        text[j] = lineArray[chars.charCodeAt(j)];
+      }
+      diffs[i][1] = text.join('');
+    }
+  };
+  
+  
+  /**
+   * Determine the common prefix of two strings.
+   * @param {string} text1 First string.
+   * @param {string} text2 Second string.
+   * @return {number} The number of characters common to the start of each
+   *     string.
+   */
+  diff_match_patch.prototype.diff_commonPrefix = function(text1, text2) {
+    // Quick check for common null cases.
+    if (!text1 || !text2 || text1.charAt(0) != text2.charAt(0)) {
+      return 0;
+    }
+    // Binary search.
+    // Performance analysis: https://neil.fraser.name/news/2007/10/09/
+    var pointermin = 0;
+    var pointermax = Math.min(text1.length, text2.length);
+    var pointermid = pointermax;
+    var pointerstart = 0;
+    while (pointermin < pointermid) {
+      if (text1.substring(pointerstart, pointermid) ==
+          text2.substring(pointerstart, pointermid)) {
+        pointermin = pointermid;
+        pointerstart = pointermin;
+      } else {
+        pointermax = pointermid;
+      }
+      pointermid = Math.floor((pointermax - pointermin) / 2 + pointermin);
+    }
+    return pointermid;
+  };
+  
+  
+  /**
+   * Determine the common suffix of two strings.
+   * @param {string} text1 First string.
+   * @param {string} text2 Second string.
+   * @return {number} The number of characters common to the end of each string.
+   */
+  diff_match_patch.prototype.diff_commonSuffix = function(text1, text2) {
+    // Quick check for common null cases.
+    if (!text1 || !text2 ||
+        text1.charAt(text1.length - 1) != text2.charAt(text2.length - 1)) {
+      return 0;
+    }
+    // Binary search.
+    // Performance analysis: https://neil.fraser.name/news/2007/10/09/
+    var pointermin = 0;
+    var pointermax = Math.min(text1.length, text2.length);
+    var pointermid = pointermax;
+    var pointerend = 0;
+    while (pointermin < pointermid) {
+      if (text1.substring(text1.length - pointermid, text1.length - pointerend) ==
+          text2.substring(text2.length - pointermid, text2.length - pointerend)) {
+        pointermin = pointermid;
+        pointerend = pointermin;
+      } else {
+        pointermax = pointermid;
+      }
+      pointermid = Math.floor((pointermax - pointermin) / 2 + pointermin);
+    }
+    return pointermid;
+  };
+  
+  
+  /**
+   * Determine if the suffix of one string is the prefix of another.
+   * @param {string} text1 First string.
+   * @param {string} text2 Second string.
+   * @return {number} The number of characters common to the end of the first
+   *     string and the start of the second string.
+   * @private
+   */
+  diff_match_patch.prototype.diff_commonOverlap_ = function(text1, text2) {
+    // Cache the text lengths to prevent multiple calls.
+    var text1_length = text1.length;
+    var text2_length = text2.length;
+    // Eliminate the null case.
+    if (text1_length == 0 || text2_length == 0) {
+      return 0;
+    }
+    // Truncate the longer string.
+    if (text1_length > text2_length) {
+      text1 = text1.substring(text1_length - text2_length);
+    } else if (text1_length < text2_length) {
+      text2 = text2.substring(0, text1_length);
+    }
+    var text_length = Math.min(text1_length, text2_length);
+    // Quick check for the worst case.
+    if (text1 == text2) {
+      return text_length;
+    }
+  
+    // Start by looking for a single character match
+    // and increase length until no match is found.
+    // Performance analysis: https://neil.fraser.name/news/2010/11/04/
+    var best = 0;
+    var length = 1;
+    while (true) {
+      var pattern = text1.substring(text_length - length);
+      var found = text2.indexOf(pattern);
+      if (found == -1) {
+        return best;
+      }
+      length += found;
+      if (found == 0 || text1.substring(text_length - length) ==
+          text2.substring(0, length)) {
+        best = length;
+        length++;
+      }
+    }
+  };
+  
+  
+  /**
+   * Do the two texts share a substring which is at least half the length of the
+   * longer text?
+   * This speedup can produce non-minimal diffs.
+   * @param {string} text1 First string.
+   * @param {string} text2 Second string.
+   * @return {Array.} Five element Array, containing the prefix of
+   *     text1, the suffix of text1, the prefix of text2, the suffix of
+   *     text2 and the common middle.  Or null if there was no match.
+   * @private
+   */
+  diff_match_patch.prototype.diff_halfMatch_ = function(text1, text2) {
+    if (this.Diff_Timeout <= 0) {
+      // Don't risk returning a non-optimal diff if we have unlimited time.
+      return null;
+    }
+    var longtext = text1.length > text2.length ? text1 : text2;
+    var shorttext = text1.length > text2.length ? text2 : text1;
+    if (longtext.length < 4 || shorttext.length * 2 < longtext.length) {
+      return null;  // Pointless.
+    }
+    var dmp = this;  // 'this' becomes 'window' in a closure.
+  
+    /**
+     * Does a substring of shorttext exist within longtext such that the substring
+     * is at least half the length of longtext?
+     * Closure, but does not reference any external variables.
+     * @param {string} longtext Longer string.
+     * @param {string} shorttext Shorter string.
+     * @param {number} i Start index of quarter length substring within longtext.
+     * @return {Array.} Five element Array, containing the prefix of
+     *     longtext, the suffix of longtext, the prefix of shorttext, the suffix
+     *     of shorttext and the common middle.  Or null if there was no match.
+     * @private
+     */
+    function diff_halfMatchI_(longtext, shorttext, i) {
+      // Start with a 1/4 length substring at position i as a seed.
+      var seed = longtext.substring(i, i + Math.floor(longtext.length / 4));
+      var j = -1;
+      var best_common = '';
+      var best_longtext_a, best_longtext_b, best_shorttext_a, best_shorttext_b;
+      while ((j = shorttext.indexOf(seed, j + 1)) != -1) {
+        var prefixLength = dmp.diff_commonPrefix(longtext.substring(i),
+                                                 shorttext.substring(j));
+        var suffixLength = dmp.diff_commonSuffix(longtext.substring(0, i),
+                                                 shorttext.substring(0, j));
+        if (best_common.length < suffixLength + prefixLength) {
+          best_common = shorttext.substring(j - suffixLength, j) +
+              shorttext.substring(j, j + prefixLength);
+          best_longtext_a = longtext.substring(0, i - suffixLength);
+          best_longtext_b = longtext.substring(i + prefixLength);
+          best_shorttext_a = shorttext.substring(0, j - suffixLength);
+          best_shorttext_b = shorttext.substring(j + prefixLength);
+        }
+      }
+      if (best_common.length * 2 >= longtext.length) {
+        return [best_longtext_a, best_longtext_b,
+                best_shorttext_a, best_shorttext_b, best_common];
+      } else {
+        return null;
+      }
+    }
+  
+    // First check if the second quarter is the seed for a half-match.
+    var hm1 = diff_halfMatchI_(longtext, shorttext,
+                               Math.ceil(longtext.length / 4));
+    // Check again based on the third quarter.
+    var hm2 = diff_halfMatchI_(longtext, shorttext,
+                               Math.ceil(longtext.length / 2));
+    var hm;
+    if (!hm1 && !hm2) {
+      return null;
+    } else if (!hm2) {
+      hm = hm1;
+    } else if (!hm1) {
+      hm = hm2;
+    } else {
+      // Both matched.  Select the longest.
+      hm = hm1[4].length > hm2[4].length ? hm1 : hm2;
+    }
+  
+    // A half-match was found, sort out the return data.
+    var text1_a, text1_b, text2_a, text2_b;
+    if (text1.length > text2.length) {
+      text1_a = hm[0];
+      text1_b = hm[1];
+      text2_a = hm[2];
+      text2_b = hm[3];
+    } else {
+      text2_a = hm[0];
+      text2_b = hm[1];
+      text1_a = hm[2];
+      text1_b = hm[3];
+    }
+    var mid_common = hm[4];
+    return [text1_a, text1_b, text2_a, text2_b, mid_common];
+  };
+  
+  
+  /**
+   * Reduce the number of edits by eliminating semantically trivial equalities.
+   * @param {!Array.} diffs Array of diff tuples.
+   */
+  diff_match_patch.prototype.diff_cleanupSemantic = function(diffs) {
+    var changes = false;
+    var equalities = [];  // Stack of indices where equalities are found.
+    var equalitiesLength = 0;  // Keeping our own length var is faster in JS.
+    /** @type {?string} */
+    var lastEquality = null;
+    // Always equal to diffs[equalities[equalitiesLength - 1]][1]
+    var pointer = 0;  // Index of current position.
+    // Number of characters that changed prior to the equality.
+    var length_insertions1 = 0;
+    var length_deletions1 = 0;
+    // Number of characters that changed after the equality.
+    var length_insertions2 = 0;
+    var length_deletions2 = 0;
+    while (pointer < diffs.length) {
+      if (diffs[pointer][0] == DIFF_EQUAL) {  // Equality found.
+        equalities[equalitiesLength++] = pointer;
+        length_insertions1 = length_insertions2;
+        length_deletions1 = length_deletions2;
+        length_insertions2 = 0;
+        length_deletions2 = 0;
+        lastEquality = diffs[pointer][1];
+      } else {  // An insertion or deletion.
+        if (diffs[pointer][0] == DIFF_INSERT) {
+          length_insertions2 += diffs[pointer][1].length;
+        } else {
+          length_deletions2 += diffs[pointer][1].length;
+        }
+        // Eliminate an equality that is smaller or equal to the edits on both
+        // sides of it.
+        if (lastEquality && (lastEquality.length <=
+            Math.max(length_insertions1, length_deletions1)) &&
+            (lastEquality.length <= Math.max(length_insertions2,
+                                             length_deletions2))) {
+          // Duplicate record.
+          diffs.splice(equalities[equalitiesLength - 1], 0,
+                       new diff_match_patch.Diff(DIFF_DELETE, lastEquality));
+          // Change second copy to insert.
+          diffs[equalities[equalitiesLength - 1] + 1][0] = DIFF_INSERT;
+          // Throw away the equality we just deleted.
+          equalitiesLength--;
+          // Throw away the previous equality (it needs to be reevaluated).
+          equalitiesLength--;
+          pointer = equalitiesLength > 0 ? equalities[equalitiesLength - 1] : -1;
+          length_insertions1 = 0;  // Reset the counters.
+          length_deletions1 = 0;
+          length_insertions2 = 0;
+          length_deletions2 = 0;
+          lastEquality = null;
+          changes = true;
+        }
+      }
+      pointer++;
+    }
+  
+    // Normalize the diff.
+    if (changes) {
+      this.diff_cleanupMerge(diffs);
+    }
+    this.diff_cleanupSemanticLossless(diffs);
+  
+    // Find any overlaps between deletions and insertions.
+    // e.g: abcxxxxxxdef
+    //   -> abcxxxdef
+    // e.g: xxxabcdefxxx
+    //   -> defxxxabc
+    // Only extract an overlap if it is as big as the edit ahead or behind it.
+    pointer = 1;
+    while (pointer < diffs.length) {
+      if (diffs[pointer - 1][0] == DIFF_DELETE &&
+          diffs[pointer][0] == DIFF_INSERT) {
+        var deletion = diffs[pointer - 1][1];
+        var insertion = diffs[pointer][1];
+        var overlap_length1 = this.diff_commonOverlap_(deletion, insertion);
+        var overlap_length2 = this.diff_commonOverlap_(insertion, deletion);
+        if (overlap_length1 >= overlap_length2) {
+          if (overlap_length1 >= deletion.length / 2 ||
+              overlap_length1 >= insertion.length / 2) {
+            // Overlap found.  Insert an equality and trim the surrounding edits.
+            diffs.splice(pointer, 0, new diff_match_patch.Diff(DIFF_EQUAL,
+                insertion.substring(0, overlap_length1)));
+            diffs[pointer - 1][1] =
+                deletion.substring(0, deletion.length - overlap_length1);
+            diffs[pointer + 1][1] = insertion.substring(overlap_length1);
+            pointer++;
+          }
+        } else {
+          if (overlap_length2 >= deletion.length / 2 ||
+              overlap_length2 >= insertion.length / 2) {
+            // Reverse overlap found.
+            // Insert an equality and swap and trim the surrounding edits.
+            diffs.splice(pointer, 0, new diff_match_patch.Diff(DIFF_EQUAL,
+                deletion.substring(0, overlap_length2)));
+            diffs[pointer - 1][0] = DIFF_INSERT;
+            diffs[pointer - 1][1] =
+                insertion.substring(0, insertion.length - overlap_length2);
+            diffs[pointer + 1][0] = DIFF_DELETE;
+            diffs[pointer + 1][1] =
+                deletion.substring(overlap_length2);
+            pointer++;
+          }
+        }
+        pointer++;
+      }
+      pointer++;
+    }
+  };
+  
+  
+  /**
+   * Look for single edits surrounded on both sides by equalities
+   * which can be shifted sideways to align the edit to a word boundary.
+   * e.g: The cat came. -> The cat came.
+   * @param {!Array.} diffs Array of diff tuples.
+   */
+  diff_match_patch.prototype.diff_cleanupSemanticLossless = function(diffs) {
+    /**
+     * Given two strings, compute a score representing whether the internal
+     * boundary falls on logical boundaries.
+     * Scores range from 6 (best) to 0 (worst).
+     * Closure, but does not reference any external variables.
+     * @param {string} one First string.
+     * @param {string} two Second string.
+     * @return {number} The score.
+     * @private
+     */
+    function diff_cleanupSemanticScore_(one, two) {
+      if (!one || !two) {
+        // Edges are the best.
+        return 6;
+      }
+  
+      // Each port of this function behaves slightly differently due to
+      // subtle differences in each language's definition of things like
+      // 'whitespace'.  Since this function's purpose is largely cosmetic,
+      // the choice has been made to use each language's native features
+      // rather than force total conformity.
+      var char1 = one.charAt(one.length - 1);
+      var char2 = two.charAt(0);
+      var nonAlphaNumeric1 = char1.match(diff_match_patch.nonAlphaNumericRegex_);
+      var nonAlphaNumeric2 = char2.match(diff_match_patch.nonAlphaNumericRegex_);
+      var whitespace1 = nonAlphaNumeric1 &&
+          char1.match(diff_match_patch.whitespaceRegex_);
+      var whitespace2 = nonAlphaNumeric2 &&
+          char2.match(diff_match_patch.whitespaceRegex_);
+      var lineBreak1 = whitespace1 &&
+          char1.match(diff_match_patch.linebreakRegex_);
+      var lineBreak2 = whitespace2 &&
+          char2.match(diff_match_patch.linebreakRegex_);
+      var blankLine1 = lineBreak1 &&
+          one.match(diff_match_patch.blanklineEndRegex_);
+      var blankLine2 = lineBreak2 &&
+          two.match(diff_match_patch.blanklineStartRegex_);
+  
+      if (blankLine1 || blankLine2) {
+        // Five points for blank lines.
+        return 5;
+      } else if (lineBreak1 || lineBreak2) {
+        // Four points for line breaks.
+        return 4;
+      } else if (nonAlphaNumeric1 && !whitespace1 && whitespace2) {
+        // Three points for end of sentences.
+        return 3;
+      } else if (whitespace1 || whitespace2) {
+        // Two points for whitespace.
+        return 2;
+      } else if (nonAlphaNumeric1 || nonAlphaNumeric2) {
+        // One point for non-alphanumeric.
+        return 1;
+      }
+      return 0;
+    }
+  
+    var pointer = 1;
+    // Intentionally ignore the first and last element (don't need checking).
+    while (pointer < diffs.length - 1) {
+      if (diffs[pointer - 1][0] == DIFF_EQUAL &&
+          diffs[pointer + 1][0] == DIFF_EQUAL) {
+        // This is a single edit surrounded by equalities.
+        var equality1 = diffs[pointer - 1][1];
+        var edit = diffs[pointer][1];
+        var equality2 = diffs[pointer + 1][1];
+  
+        // First, shift the edit as far left as possible.
+        var commonOffset = this.diff_commonSuffix(equality1, edit);
+        if (commonOffset) {
+          var commonString = edit.substring(edit.length - commonOffset);
+          equality1 = equality1.substring(0, equality1.length - commonOffset);
+          edit = commonString + edit.substring(0, edit.length - commonOffset);
+          equality2 = commonString + equality2;
+        }
+  
+        // Second, step character by character right, looking for the best fit.
+        var bestEquality1 = equality1;
+        var bestEdit = edit;
+        var bestEquality2 = equality2;
+        var bestScore = diff_cleanupSemanticScore_(equality1, edit) +
+            diff_cleanupSemanticScore_(edit, equality2);
+        while (edit.charAt(0) === equality2.charAt(0)) {
+          equality1 += edit.charAt(0);
+          edit = edit.substring(1) + equality2.charAt(0);
+          equality2 = equality2.substring(1);
+          var score = diff_cleanupSemanticScore_(equality1, edit) +
+              diff_cleanupSemanticScore_(edit, equality2);
+          // The >= encourages trailing rather than leading whitespace on edits.
+          if (score >= bestScore) {
+            bestScore = score;
+            bestEquality1 = equality1;
+            bestEdit = edit;
+            bestEquality2 = equality2;
+          }
+        }
+  
+        if (diffs[pointer - 1][1] != bestEquality1) {
+          // We have an improvement, save it back to the diff.
+          if (bestEquality1) {
+            diffs[pointer - 1][1] = bestEquality1;
+          } else {
+            diffs.splice(pointer - 1, 1);
+            pointer--;
+          }
+          diffs[pointer][1] = bestEdit;
+          if (bestEquality2) {
+            diffs[pointer + 1][1] = bestEquality2;
+          } else {
+            diffs.splice(pointer + 1, 1);
+            pointer--;
+          }
+        }
+      }
+      pointer++;
+    }
+  };
+  
+  // Define some regex patterns for matching boundaries.
+  diff_match_patch.nonAlphaNumericRegex_ = /[^a-zA-Z0-9]/;
+  diff_match_patch.whitespaceRegex_ = /\s/;
+  diff_match_patch.linebreakRegex_ = /[\r\n]/;
+  diff_match_patch.blanklineEndRegex_ = /\n\r?\n$/;
+  diff_match_patch.blanklineStartRegex_ = /^\r?\n\r?\n/;
+  
+  /**
+   * Reduce the number of edits by eliminating operationally trivial equalities.
+   * @param {!Array.} diffs Array of diff tuples.
+   */
+  diff_match_patch.prototype.diff_cleanupEfficiency = function(diffs) {
+    var changes = false;
+    var equalities = [];  // Stack of indices where equalities are found.
+    var equalitiesLength = 0;  // Keeping our own length var is faster in JS.
+    /** @type {?string} */
+    var lastEquality = null;
+    // Always equal to diffs[equalities[equalitiesLength - 1]][1]
+    var pointer = 0;  // Index of current position.
+    // Is there an insertion operation before the last equality.
+    var pre_ins = false;
+    // Is there a deletion operation before the last equality.
+    var pre_del = false;
+    // Is there an insertion operation after the last equality.
+    var post_ins = false;
+    // Is there a deletion operation after the last equality.
+    var post_del = false;
+    while (pointer < diffs.length) {
+      if (diffs[pointer][0] == DIFF_EQUAL) {  // Equality found.
+        if (diffs[pointer][1].length < this.Diff_EditCost &&
+            (post_ins || post_del)) {
+          // Candidate found.
+          equalities[equalitiesLength++] = pointer;
+          pre_ins = post_ins;
+          pre_del = post_del;
+          lastEquality = diffs[pointer][1];
+        } else {
+          // Not a candidate, and can never become one.
+          equalitiesLength = 0;
+          lastEquality = null;
+        }
+        post_ins = post_del = false;
+      } else {  // An insertion or deletion.
+        if (diffs[pointer][0] == DIFF_DELETE) {
+          post_del = true;
+        } else {
+          post_ins = true;
+        }
+        /*
+         * Five types to be split:
+         * ABXYCD
+         * AXCD
+         * ABXC
+         * AXCD
+         * ABXC
+         */
+        if (lastEquality && ((pre_ins && pre_del && post_ins && post_del) ||
+                             ((lastEquality.length < this.Diff_EditCost / 2) &&
+                              (pre_ins + pre_del + post_ins + post_del) == 3))) {
+          // Duplicate record.
+          diffs.splice(equalities[equalitiesLength - 1], 0,
+                       new diff_match_patch.Diff(DIFF_DELETE, lastEquality));
+          // Change second copy to insert.
+          diffs[equalities[equalitiesLength - 1] + 1][0] = DIFF_INSERT;
+          equalitiesLength--;  // Throw away the equality we just deleted;
+          lastEquality = null;
+          if (pre_ins && pre_del) {
+            // No changes made which could affect previous entry, keep going.
+            post_ins = post_del = true;
+            equalitiesLength = 0;
+          } else {
+            equalitiesLength--;  // Throw away the previous equality.
+            pointer = equalitiesLength > 0 ?
+                equalities[equalitiesLength - 1] : -1;
+            post_ins = post_del = false;
+          }
+          changes = true;
+        }
+      }
+      pointer++;
+    }
+  
+    if (changes) {
+      this.diff_cleanupMerge(diffs);
+    }
+  };
+  
+  
+  /**
+   * Reorder and merge like edit sections.  Merge equalities.
+   * Any edit section can move as long as it doesn't cross an equality.
+   * @param {!Array.} diffs Array of diff tuples.
+   */
+  diff_match_patch.prototype.diff_cleanupMerge = function(diffs) {
+    // Add a dummy entry at the end.
+    diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, ''));
+    var pointer = 0;
+    var count_delete = 0;
+    var count_insert = 0;
+    var text_delete = '';
+    var text_insert = '';
+    var commonlength;
+    while (pointer < diffs.length) {
+      switch (diffs[pointer][0]) {
+        case DIFF_INSERT:
+          count_insert++;
+          text_insert += diffs[pointer][1];
+          pointer++;
+          break;
+        case DIFF_DELETE:
+          count_delete++;
+          text_delete += diffs[pointer][1];
+          pointer++;
+          break;
+        case DIFF_EQUAL:
+          // Upon reaching an equality, check for prior redundancies.
+          if (count_delete + count_insert > 1) {
+            if (count_delete !== 0 && count_insert !== 0) {
+              // Factor out any common prefixies.
+              commonlength = this.diff_commonPrefix(text_insert, text_delete);
+              if (commonlength !== 0) {
+                if ((pointer - count_delete - count_insert) > 0 &&
+                    diffs[pointer - count_delete - count_insert - 1][0] ==
+                    DIFF_EQUAL) {
+                  diffs[pointer - count_delete - count_insert - 1][1] +=
+                      text_insert.substring(0, commonlength);
+                } else {
+                  diffs.splice(0, 0, new diff_match_patch.Diff(DIFF_EQUAL,
+                      text_insert.substring(0, commonlength)));
+                  pointer++;
+                }
+                text_insert = text_insert.substring(commonlength);
+                text_delete = text_delete.substring(commonlength);
+              }
+              // Factor out any common suffixies.
+              commonlength = this.diff_commonSuffix(text_insert, text_delete);
+              if (commonlength !== 0) {
+                diffs[pointer][1] = text_insert.substring(text_insert.length -
+                    commonlength) + diffs[pointer][1];
+                text_insert = text_insert.substring(0, text_insert.length -
+                    commonlength);
+                text_delete = text_delete.substring(0, text_delete.length -
+                    commonlength);
+              }
+            }
+            // Delete the offending records and add the merged ones.
+            pointer -= count_delete + count_insert;
+            diffs.splice(pointer, count_delete + count_insert);
+            if (text_delete.length) {
+              diffs.splice(pointer, 0,
+                  new diff_match_patch.Diff(DIFF_DELETE, text_delete));
+              pointer++;
+            }
+            if (text_insert.length) {
+              diffs.splice(pointer, 0,
+                  new diff_match_patch.Diff(DIFF_INSERT, text_insert));
+              pointer++;
+            }
+            pointer++;
+          } else if (pointer !== 0 && diffs[pointer - 1][0] == DIFF_EQUAL) {
+            // Merge this equality with the previous one.
+            diffs[pointer - 1][1] += diffs[pointer][1];
+            diffs.splice(pointer, 1);
+          } else {
+            pointer++;
+          }
+          count_insert = 0;
+          count_delete = 0;
+          text_delete = '';
+          text_insert = '';
+          break;
+      }
+    }
+    if (diffs[diffs.length - 1][1] === '') {
+      diffs.pop();  // Remove the dummy entry at the end.
+    }
+  
+    // Second pass: look for single edits surrounded on both sides by equalities
+    // which can be shifted sideways to eliminate an equality.
+    // e.g: ABAC -> ABAC
+    var changes = false;
+    pointer = 1;
+    // Intentionally ignore the first and last element (don't need checking).
+    while (pointer < diffs.length - 1) {
+      if (diffs[pointer - 1][0] == DIFF_EQUAL &&
+          diffs[pointer + 1][0] == DIFF_EQUAL) {
+        // This is a single edit surrounded by equalities.
+        if (diffs[pointer][1].substring(diffs[pointer][1].length -
+            diffs[pointer - 1][1].length) == diffs[pointer - 1][1]) {
+          // Shift the edit over the previous equality.
+          diffs[pointer][1] = diffs[pointer - 1][1] +
+              diffs[pointer][1].substring(0, diffs[pointer][1].length -
+                                          diffs[pointer - 1][1].length);
+          diffs[pointer + 1][1] = diffs[pointer - 1][1] + diffs[pointer + 1][1];
+          diffs.splice(pointer - 1, 1);
+          changes = true;
+        } else if (diffs[pointer][1].substring(0, diffs[pointer + 1][1].length) ==
+            diffs[pointer + 1][1]) {
+          // Shift the edit over the next equality.
+          diffs[pointer - 1][1] += diffs[pointer + 1][1];
+          diffs[pointer][1] =
+              diffs[pointer][1].substring(diffs[pointer + 1][1].length) +
+              diffs[pointer + 1][1];
+          diffs.splice(pointer + 1, 1);
+          changes = true;
+        }
+      }
+      pointer++;
+    }
+    // If shifts were made, the diff needs reordering and another shift sweep.
+    if (changes) {
+      this.diff_cleanupMerge(diffs);
+    }
+  };
+  
+  
+  /**
+   * loc is a location in text1, compute and return the equivalent location in
+   * text2.
+   * e.g. 'The cat' vs 'The big cat', 1->1, 5->8
+   * @param {!Array.} diffs Array of diff tuples.
+   * @param {number} loc Location within text1.
+   * @return {number} Location within text2.
+   */
+  diff_match_patch.prototype.diff_xIndex = function(diffs, loc) {
+    var chars1 = 0;
+    var chars2 = 0;
+    var last_chars1 = 0;
+    var last_chars2 = 0;
+    var x;
+    for (x = 0; x < diffs.length; x++) {
+      if (diffs[x][0] !== DIFF_INSERT) {  // Equality or deletion.
+        chars1 += diffs[x][1].length;
+      }
+      if (diffs[x][0] !== DIFF_DELETE) {  // Equality or insertion.
+        chars2 += diffs[x][1].length;
+      }
+      if (chars1 > loc) {  // Overshot the location.
+        break;
+      }
+      last_chars1 = chars1;
+      last_chars2 = chars2;
+    }
+    // Was the location was deleted?
+    if (diffs.length != x && diffs[x][0] === DIFF_DELETE) {
+      return last_chars2;
+    }
+    // Add the remaining character length.
+    return last_chars2 + (loc - last_chars1);
+  };
+  
+  
+  /**
+   * Convert a diff array into a pretty HTML report.
+   * @param {!Array.} diffs Array of diff tuples.
+   * @return {string} HTML representation.
+   */
+  diff_match_patch.prototype.diff_prettyHtml = function(diffs) {
+    var html = [];
+    var pattern_amp = /&/g;
+    var pattern_lt = //g;
+    var pattern_para = /\n/g;
+    for (var x = 0; x < diffs.length; x++) {
+      var op = diffs[x][0];    // Operation (insert, delete, equal)
+      var data = diffs[x][1];  // Text of change.
+      var text = data.replace(pattern_amp, '&').replace(pattern_lt, '<')
+          .replace(pattern_gt, '>').replace(pattern_para, '¶
');
+      switch (op) {
+        case DIFF_INSERT:
+          html[x] = '' + text + '';
+          break;
+        case DIFF_DELETE:
+          html[x] = '' + text + '';
+          break;
+        case DIFF_EQUAL:
+          html[x] = '' + text + '';
+          break;
+      }
+    }
+    return html.join('');
+  };
+  
+  
+  /**
+   * Compute and return the source text (all equalities and deletions).
+   * @param {!Array.} diffs Array of diff tuples.
+   * @return {string} Source text.
+   */
+  diff_match_patch.prototype.diff_text1 = function(diffs) {
+    var text = [];
+    for (var x = 0; x < diffs.length; x++) {
+      if (diffs[x][0] !== DIFF_INSERT) {
+        text[x] = diffs[x][1];
+      }
+    }
+    return text.join('');
+  };
+  
+  
+  /**
+   * Compute and return the destination text (all equalities and insertions).
+   * @param {!Array.} diffs Array of diff tuples.
+   * @return {string} Destination text.
+   */
+  diff_match_patch.prototype.diff_text2 = function(diffs) {
+    var text = [];
+    for (var x = 0; x < diffs.length; x++) {
+      if (diffs[x][0] !== DIFF_DELETE) {
+        text[x] = diffs[x][1];
+      }
+    }
+    return text.join('');
+  };
+  
+  
+  /**
+   * Compute the Levenshtein distance; the number of inserted, deleted or
+   * substituted characters.
+   * @param {!Array.} diffs Array of diff tuples.
+   * @return {number} Number of changes.
+   */
+  diff_match_patch.prototype.diff_levenshtein = function(diffs) {
+    var levenshtein = 0;
+    var insertions = 0;
+    var deletions = 0;
+    for (var x = 0; x < diffs.length; x++) {
+      var op = diffs[x][0];
+      var data = diffs[x][1];
+      switch (op) {
+        case DIFF_INSERT:
+          insertions += data.length;
+          break;
+        case DIFF_DELETE:
+          deletions += data.length;
+          break;
+        case DIFF_EQUAL:
+          // A deletion and an insertion is one substitution.
+          levenshtein += Math.max(insertions, deletions);
+          insertions = 0;
+          deletions = 0;
+          break;
+      }
+    }
+    levenshtein += Math.max(insertions, deletions);
+    return levenshtein;
+  };
+  
+  
+  /**
+   * Crush the diff into an encoded string which describes the operations
+   * required to transform text1 into text2.
+   * E.g. =3\t-2\t+ing  -> Keep 3 chars, delete 2 chars, insert 'ing'.
+   * Operations are tab-separated.  Inserted text is escaped using %xx notation.
+   * @param {!Array.} diffs Array of diff tuples.
+   * @return {string} Delta text.
+   */
+  diff_match_patch.prototype.diff_toDelta = function(diffs) {
+    var text = [];
+    for (var x = 0; x < diffs.length; x++) {
+      switch (diffs[x][0]) {
+        case DIFF_INSERT:
+          text[x] = '+' + encodeURI(diffs[x][1]);
+          break;
+        case DIFF_DELETE:
+          text[x] = '-' + diffs[x][1].length;
+          break;
+        case DIFF_EQUAL:
+          text[x] = '=' + diffs[x][1].length;
+          break;
+      }
+    }
+    return text.join('\t').replace(/%20/g, ' ');
+  };
+  
+  
+  /**
+   * Given the original text1, and an encoded string which describes the
+   * operations required to transform text1 into text2, compute the full diff.
+   * @param {string} text1 Source string for the diff.
+   * @param {string} delta Delta text.
+   * @return {!Array.} Array of diff tuples.
+   * @throws {!Error} If invalid input.
+   */
+  diff_match_patch.prototype.diff_fromDelta = function(text1, delta) {
+    var diffs = [];
+    var diffsLength = 0;  // Keeping our own length var is faster in JS.
+    var pointer = 0;  // Cursor in text1
+    var tokens = delta.split(/\t/g);
+    for (var x = 0; x < tokens.length; x++) {
+      // Each token begins with a one character parameter which specifies the
+      // operation of this token (delete, insert, equality).
+      var param = tokens[x].substring(1);
+      switch (tokens[x].charAt(0)) {
+        case '+':
+          try {
+            diffs[diffsLength++] =
+                new diff_match_patch.Diff(DIFF_INSERT, decodeURI(param));
+          } catch (ex) {
+            // Malformed URI sequence.
+            throw new Error('Illegal escape in diff_fromDelta: ' + param);
+          }
+          break;
+        case '-':
+          // Fall through.
+        case '=':
+          var n = parseInt(param, 10);
+          if (isNaN(n) || n < 0) {
+            throw new Error('Invalid number in diff_fromDelta: ' + param);
+          }
+          var text = text1.substring(pointer, pointer += n);
+          if (tokens[x].charAt(0) == '=') {
+            diffs[diffsLength++] = new diff_match_patch.Diff(DIFF_EQUAL, text);
+          } else {
+            diffs[diffsLength++] = new diff_match_patch.Diff(DIFF_DELETE, text);
+          }
+          break;
+        default:
+          // Blank tokens are ok (from a trailing \t).
+          // Anything else is an error.
+          if (tokens[x]) {
+            throw new Error('Invalid diff operation in diff_fromDelta: ' +
+                            tokens[x]);
+          }
+      }
+    }
+    if (pointer != text1.length) {
+      throw new Error('Delta length (' + pointer +
+          ') does not equal source text length (' + text1.length + ').');
+    }
+    return diffs;
+  };
+  
+  
+  //  MATCH FUNCTIONS
+  
+  
+  /**
+   * Locate the best instance of 'pattern' in 'text' near 'loc'.
+   * @param {string} text The text to search.
+   * @param {string} pattern The pattern to search for.
+   * @param {number} loc The location to search around.
+   * @return {number} Best match index or -1.
+   */
+  diff_match_patch.prototype.match_main = function(text, pattern, loc) {
+    // Check for null inputs.
+    if (text == null || pattern == null || loc == null) {
+      throw new Error('Null input. (match_main)');
+    }
+  
+    loc = Math.max(0, Math.min(loc, text.length));
+    if (text == pattern) {
+      // Shortcut (potentially not guaranteed by the algorithm)
+      return 0;
+    } else if (!text.length) {
+      // Nothing to match.
+      return -1;
+    } else if (text.substring(loc, loc + pattern.length) == pattern) {
+      // Perfect match at the perfect spot!  (Includes case of null pattern)
+      return loc;
+    } else {
+      // Do a fuzzy compare.
+      return this.match_bitap_(text, pattern, loc);
+    }
+  };
+  
+  
+  /**
+   * Locate the best instance of 'pattern' in 'text' near 'loc' using the
+   * Bitap algorithm.
+   * @param {string} text The text to search.
+   * @param {string} pattern The pattern to search for.
+   * @param {number} loc The location to search around.
+   * @return {number} Best match index or -1.
+   * @private
+   */
+  diff_match_patch.prototype.match_bitap_ = function(text, pattern, loc) {
+    if (pattern.length > this.Match_MaxBits) {
+      throw new Error('Pattern too long for this browser.');
+    }
+  
+    // Initialise the alphabet.
+    var s = this.match_alphabet_(pattern);
+  
+    var dmp = this;  // 'this' becomes 'window' in a closure.
+  
+    /**
+     * Compute and return the score for a match with e errors and x location.
+     * Accesses loc and pattern through being a closure.
+     * @param {number} e Number of errors in match.
+     * @param {number} x Location of match.
+     * @return {number} Overall score for match (0.0 = good, 1.0 = bad).
+     * @private
+     */
+    function match_bitapScore_(e, x) {
+      var accuracy = e / pattern.length;
+      var proximity = Math.abs(loc - x);
+      if (!dmp.Match_Distance) {
+        // Dodge divide by zero error.
+        return proximity ? 1.0 : accuracy;
+      }
+      return accuracy + (proximity / dmp.Match_Distance);
+    }
+  
+    // Highest score beyond which we give up.
+    var score_threshold = this.Match_Threshold;
+    // Is there a nearby exact match? (speedup)
+    var best_loc = text.indexOf(pattern, loc);
+    if (best_loc != -1) {
+      score_threshold = Math.min(match_bitapScore_(0, best_loc), score_threshold);
+      // What about in the other direction? (speedup)
+      best_loc = text.lastIndexOf(pattern, loc + pattern.length);
+      if (best_loc != -1) {
+        score_threshold =
+            Math.min(match_bitapScore_(0, best_loc), score_threshold);
+      }
+    }
+  
+    // Initialise the bit arrays.
+    var matchmask = 1 << (pattern.length - 1);
+    best_loc = -1;
+  
+    var bin_min, bin_mid;
+    var bin_max = pattern.length + text.length;
+    var last_rd;
+    for (var d = 0; d < pattern.length; d++) {
+      // Scan for the best match; each iteration allows for one more error.
+      // Run a binary search to determine how far from 'loc' we can stray at this
+      // error level.
+      bin_min = 0;
+      bin_mid = bin_max;
+      while (bin_min < bin_mid) {
+        if (match_bitapScore_(d, loc + bin_mid) <= score_threshold) {
+          bin_min = bin_mid;
+        } else {
+          bin_max = bin_mid;
+        }
+        bin_mid = Math.floor((bin_max - bin_min) / 2 + bin_min);
+      }
+      // Use the result from this iteration as the maximum for the next.
+      bin_max = bin_mid;
+      var start = Math.max(1, loc - bin_mid + 1);
+      var finish = Math.min(loc + bin_mid, text.length) + pattern.length;
+  
+      var rd = Array(finish + 2);
+      rd[finish + 1] = (1 << d) - 1;
+      for (var j = finish; j >= start; j--) {
+        // The alphabet (s) is a sparse hash, so the following line generates
+        // warnings.
+        var charMatch = s[text.charAt(j - 1)];
+        if (d === 0) {  // First pass: exact match.
+          rd[j] = ((rd[j + 1] << 1) | 1) & charMatch;
+        } else {  // Subsequent passes: fuzzy match.
+          rd[j] = (((rd[j + 1] << 1) | 1) & charMatch) |
+                  (((last_rd[j + 1] | last_rd[j]) << 1) | 1) |
+                  last_rd[j + 1];
+        }
+        if (rd[j] & matchmask) {
+          var score = match_bitapScore_(d, j - 1);
+          // This match will almost certainly be better than any existing match.
+          // But check anyway.
+          if (score <= score_threshold) {
+            // Told you so.
+            score_threshold = score;
+            best_loc = j - 1;
+            if (best_loc > loc) {
+              // When passing loc, don't exceed our current distance from loc.
+              start = Math.max(1, 2 * loc - best_loc);
+            } else {
+              // Already passed loc, downhill from here on in.
+              break;
+            }
+          }
+        }
+      }
+      // No hope for a (better) match at greater error levels.
+      if (match_bitapScore_(d + 1, loc) > score_threshold) {
+        break;
+      }
+      last_rd = rd;
+    }
+    return best_loc;
+  };
+  
+  
+  /**
+   * Initialise the alphabet for the Bitap algorithm.
+   * @param {string} pattern The text to encode.
+   * @return {!Object} Hash of character locations.
+   * @private
+   */
+  diff_match_patch.prototype.match_alphabet_ = function(pattern) {
+    var s = {};
+    for (var i = 0; i < pattern.length; i++) {
+      s[pattern.charAt(i)] = 0;
+    }
+    for (var i = 0; i < pattern.length; i++) {
+      s[pattern.charAt(i)] |= 1 << (pattern.length - i - 1);
+    }
+    return s;
+  };
+  
+  
+  //  PATCH FUNCTIONS
+  
+  
+  /**
+   * Increase the context until it is unique,
+   * but don't let the pattern expand beyond Match_MaxBits.
+   * @param {!diff_match_patch.patch_obj} patch The patch to grow.
+   * @param {string} text Source text.
+   * @private
+   */
+  diff_match_patch.prototype.patch_addContext_ = function(patch, text) {
+    if (text.length == 0) {
+      return;
+    }
+    if (patch.start2 === null) {
+      throw Error('patch not initialized');
+    }
+    var pattern = text.substring(patch.start2, patch.start2 + patch.length1);
+    var padding = 0;
+  
+    // Look for the first and last matches of pattern in text.  If two different
+    // matches are found, increase the pattern length.
+    while (text.indexOf(pattern) != text.lastIndexOf(pattern) &&
+           pattern.length < this.Match_MaxBits - this.Patch_Margin -
+           this.Patch_Margin) {
+      padding += this.Patch_Margin;
+      pattern = text.substring(patch.start2 - padding,
+                               patch.start2 + patch.length1 + padding);
+    }
+    // Add one chunk for good luck.
+    padding += this.Patch_Margin;
+  
+    // Add the prefix.
+    var prefix = text.substring(patch.start2 - padding, patch.start2);
+    if (prefix) {
+      patch.diffs.unshift(new diff_match_patch.Diff(DIFF_EQUAL, prefix));
+    }
+    // Add the suffix.
+    var suffix = text.substring(patch.start2 + patch.length1,
+                                patch.start2 + patch.length1 + padding);
+    if (suffix) {
+      patch.diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, suffix));
+    }
+  
+    // Roll back the start points.
+    patch.start1 -= prefix.length;
+    patch.start2 -= prefix.length;
+    // Extend the lengths.
+    patch.length1 += prefix.length + suffix.length;
+    patch.length2 += prefix.length + suffix.length;
+  };
+  
+  
+  /**
+   * Compute a list of patches to turn text1 into text2.
+   * Use diffs if provided, otherwise compute it ourselves.
+   * There are four ways to call this function, depending on what data is
+   * available to the caller:
+   * Method 1:
+   * a = text1, b = text2
+   * Method 2:
+   * a = diffs
+   * Method 3 (optimal):
+   * a = text1, b = diffs
+   * Method 4 (deprecated, use method 3):
+   * a = text1, b = text2, c = diffs
+   *
+   * @param {string|!Array.} a text1 (methods 1,3,4) or
+   * Array of diff tuples for text1 to text2 (method 2).
+   * @param {string|!Array.=} opt_b text2 (methods 1,4) or
+   * Array of diff tuples for text1 to text2 (method 3) or undefined (method 2).
+   * @param {string|!Array.=} opt_c Array of diff tuples
+   * for text1 to text2 (method 4) or undefined (methods 1,2,3).
+   * @return {!Array.} Array of Patch objects.
+   */
+  diff_match_patch.prototype.patch_make = function(a, opt_b, opt_c) {
+    var text1, diffs;
+    if (typeof a == 'string' && typeof opt_b == 'string' &&
+        typeof opt_c == 'undefined') {
+      // Method 1: text1, text2
+      // Compute diffs from text1 and text2.
+      text1 = /** @type {string} */(a);
+      diffs = this.diff_main(text1, /** @type {string} */(opt_b), true);
+      if (diffs.length > 2) {
+        this.diff_cleanupSemantic(diffs);
+        this.diff_cleanupEfficiency(diffs);
+      }
+    } else if (a && typeof a == 'object' && typeof opt_b == 'undefined' &&
+        typeof opt_c == 'undefined') {
+      // Method 2: diffs
+      // Compute text1 from diffs.
+      diffs = /** @type {!Array.} */(a);
+      text1 = this.diff_text1(diffs);
+    } else if (typeof a == 'string' && opt_b && typeof opt_b == 'object' &&
+        typeof opt_c == 'undefined') {
+      // Method 3: text1, diffs
+      text1 = /** @type {string} */(a);
+      diffs = /** @type {!Array.} */(opt_b);
+    } else if (typeof a == 'string' && typeof opt_b == 'string' &&
+        opt_c && typeof opt_c == 'object') {
+      // Method 4: text1, text2, diffs
+      // text2 is not used.
+      text1 = /** @type {string} */(a);
+      diffs = /** @type {!Array.} */(opt_c);
+    } else {
+      throw new Error('Unknown call format to patch_make.');
+    }
+  
+    if (diffs.length === 0) {
+      return [];  // Get rid of the null case.
+    }
+    var patches = [];
+    var patch = new diff_match_patch.patch_obj();
+    var patchDiffLength = 0;  // Keeping our own length var is faster in JS.
+    var char_count1 = 0;  // Number of characters into the text1 string.
+    var char_count2 = 0;  // Number of characters into the text2 string.
+    // Start with text1 (prepatch_text) and apply the diffs until we arrive at
+    // text2 (postpatch_text).  We recreate the patches one by one to determine
+    // context info.
+    var prepatch_text = text1;
+    var postpatch_text = text1;
+    for (var x = 0; x < diffs.length; x++) {
+      var diff_type = diffs[x][0];
+      var diff_text = diffs[x][1];
+  
+      if (!patchDiffLength && diff_type !== DIFF_EQUAL) {
+        // A new patch starts here.
+        patch.start1 = char_count1;
+        patch.start2 = char_count2;
+      }
+  
+      switch (diff_type) {
+        case DIFF_INSERT:
+          patch.diffs[patchDiffLength++] = diffs[x];
+          patch.length2 += diff_text.length;
+          postpatch_text = postpatch_text.substring(0, char_count2) + diff_text +
+                           postpatch_text.substring(char_count2);
+          break;
+        case DIFF_DELETE:
+          patch.length1 += diff_text.length;
+          patch.diffs[patchDiffLength++] = diffs[x];
+          postpatch_text = postpatch_text.substring(0, char_count2) +
+                           postpatch_text.substring(char_count2 +
+                               diff_text.length);
+          break;
+        case DIFF_EQUAL:
+          if (diff_text.length <= 2 * this.Patch_Margin &&
+              patchDiffLength && diffs.length != x + 1) {
+            // Small equality inside a patch.
+            patch.diffs[patchDiffLength++] = diffs[x];
+            patch.length1 += diff_text.length;
+            patch.length2 += diff_text.length;
+          } else if (diff_text.length >= 2 * this.Patch_Margin) {
+            // Time for a new patch.
+            if (patchDiffLength) {
+              this.patch_addContext_(patch, prepatch_text);
+              patches.push(patch);
+              patch = new diff_match_patch.patch_obj();
+              patchDiffLength = 0;
+              // Unlike Unidiff, our patch lists have a rolling context.
+              // https://github.com/google/diff-match-patch/wiki/Unidiff
+              // Update prepatch text & pos to reflect the application of the
+              // just completed patch.
+              prepatch_text = postpatch_text;
+              char_count1 = char_count2;
+            }
+          }
+          break;
+      }
+  
+      // Update the current character count.
+      if (diff_type !== DIFF_INSERT) {
+        char_count1 += diff_text.length;
+      }
+      if (diff_type !== DIFF_DELETE) {
+        char_count2 += diff_text.length;
+      }
+    }
+    // Pick up the leftover patch if not empty.
+    if (patchDiffLength) {
+      this.patch_addContext_(patch, prepatch_text);
+      patches.push(patch);
+    }
+  
+    return patches;
+  };
+  
+  
+  /**
+   * Given an array of patches, return another array that is identical.
+   * @param {!Array.} patches Array of Patch objects.
+   * @return {!Array.} Array of Patch objects.
+   */
+  diff_match_patch.prototype.patch_deepCopy = function(patches) {
+    // Making deep copies is hard in JavaScript.
+    var patchesCopy = [];
+    for (var x = 0; x < patches.length; x++) {
+      var patch = patches[x];
+      var patchCopy = new diff_match_patch.patch_obj();
+      patchCopy.diffs = [];
+      for (var y = 0; y < patch.diffs.length; y++) {
+        patchCopy.diffs[y] =
+            new diff_match_patch.Diff(patch.diffs[y][0], patch.diffs[y][1]);
+      }
+      patchCopy.start1 = patch.start1;
+      patchCopy.start2 = patch.start2;
+      patchCopy.length1 = patch.length1;
+      patchCopy.length2 = patch.length2;
+      patchesCopy[x] = patchCopy;
+    }
+    return patchesCopy;
+  };
+  
+  
+  /**
+   * Merge a set of patches onto the text.  Return a patched text, as well
+   * as a list of true/false values indicating which patches were applied.
+   * @param {!Array.} patches Array of Patch objects.
+   * @param {string} text Old text.
+   * @return {!Array.>} Two element Array, containing the
+   *      new text and an array of boolean values.
+   */
+  diff_match_patch.prototype.patch_apply = function(patches, text) {
+    if (patches.length == 0) {
+      return [text, []];
+    }
+  
+    // Deep copy the patches so that no changes are made to originals.
+    patches = this.patch_deepCopy(patches);
+  
+    var nullPadding = this.patch_addPadding(patches);
+    text = nullPadding + text + nullPadding;
+  
+    this.patch_splitMax(patches);
+    // delta keeps track of the offset between the expected and actual location
+    // of the previous patch.  If there are patches expected at positions 10 and
+    // 20, but the first patch was found at 12, delta is 2 and the second patch
+    // has an effective expected position of 22.
+    var delta = 0;
+    var results = [];
+    for (var x = 0; x < patches.length; x++) {
+      var expected_loc = patches[x].start2 + delta;
+      var text1 = this.diff_text1(patches[x].diffs);
+      var start_loc;
+      var end_loc = -1;
+      if (text1.length > this.Match_MaxBits) {
+        // patch_splitMax will only provide an oversized pattern in the case of
+        // a monster delete.
+        start_loc = this.match_main(text, text1.substring(0, this.Match_MaxBits),
+                                    expected_loc);
+        if (start_loc != -1) {
+          end_loc = this.match_main(text,
+              text1.substring(text1.length - this.Match_MaxBits),
+              expected_loc + text1.length - this.Match_MaxBits);
+          if (end_loc == -1 || start_loc >= end_loc) {
+            // Can't find valid trailing context.  Drop this patch.
+            start_loc = -1;
+          }
+        }
+      } else {
+        start_loc = this.match_main(text, text1, expected_loc);
+      }
+      if (start_loc == -1) {
+        // No match found.  :(
+        results[x] = false;
+        // Subtract the delta for this failed patch from subsequent patches.
+        delta -= patches[x].length2 - patches[x].length1;
+      } else {
+        // Found a match.  :)
+        results[x] = true;
+        delta = start_loc - expected_loc;
+        var text2;
+        if (end_loc == -1) {
+          text2 = text.substring(start_loc, start_loc + text1.length);
+        } else {
+          text2 = text.substring(start_loc, end_loc + this.Match_MaxBits);
+        }
+        if (text1 == text2) {
+          // Perfect match, just shove the replacement text in.
+          text = text.substring(0, start_loc) +
+                 this.diff_text2(patches[x].diffs) +
+                 text.substring(start_loc + text1.length);
+        } else {
+          // Imperfect match.  Run a diff to get a framework of equivalent
+          // indices.
+          var diffs = this.diff_main(text1, text2, false);
+          if (text1.length > this.Match_MaxBits &&
+              this.diff_levenshtein(diffs) / text1.length >
+              this.Patch_DeleteThreshold) {
+            // The end points match, but the content is unacceptably bad.
+            results[x] = false;
+          } else {
+            this.diff_cleanupSemanticLossless(diffs);
+            var index1 = 0;
+            var index2;
+            for (var y = 0; y < patches[x].diffs.length; y++) {
+              var mod = patches[x].diffs[y];
+              if (mod[0] !== DIFF_EQUAL) {
+                index2 = this.diff_xIndex(diffs, index1);
+              }
+              if (mod[0] === DIFF_INSERT) {  // Insertion
+                text = text.substring(0, start_loc + index2) + mod[1] +
+                       text.substring(start_loc + index2);
+              } else if (mod[0] === DIFF_DELETE) {  // Deletion
+                text = text.substring(0, start_loc + index2) +
+                       text.substring(start_loc + this.diff_xIndex(diffs,
+                           index1 + mod[1].length));
+              }
+              if (mod[0] !== DIFF_DELETE) {
+                index1 += mod[1].length;
+              }
+            }
+          }
+        }
+      }
+    }
+    // Strip the padding off.
+    text = text.substring(nullPadding.length, text.length - nullPadding.length);
+    return [text, results];
+  };
+  
+  
+  /**
+   * Add some padding on text start and end so that edges can match something.
+   * Intended to be called only from within patch_apply.
+   * @param {!Array.} patches Array of Patch objects.
+   * @return {string} The padding string added to each side.
+   */
+  diff_match_patch.prototype.patch_addPadding = function(patches) {
+    var paddingLength = this.Patch_Margin;
+    var nullPadding = '';
+    for (var x = 1; x <= paddingLength; x++) {
+      nullPadding += String.fromCharCode(x);
+    }
+  
+    // Bump all the patches forward.
+    for (var x = 0; x < patches.length; x++) {
+      patches[x].start1 += paddingLength;
+      patches[x].start2 += paddingLength;
+    }
+  
+    // Add some padding on start of first diff.
+    var patch = patches[0];
+    var diffs = patch.diffs;
+    if (diffs.length == 0 || diffs[0][0] != DIFF_EQUAL) {
+      // Add nullPadding equality.
+      diffs.unshift(new diff_match_patch.Diff(DIFF_EQUAL, nullPadding));
+      patch.start1 -= paddingLength;  // Should be 0.
+      patch.start2 -= paddingLength;  // Should be 0.
+      patch.length1 += paddingLength;
+      patch.length2 += paddingLength;
+    } else if (paddingLength > diffs[0][1].length) {
+      // Grow first equality.
+      var extraLength = paddingLength - diffs[0][1].length;
+      diffs[0][1] = nullPadding.substring(diffs[0][1].length) + diffs[0][1];
+      patch.start1 -= extraLength;
+      patch.start2 -= extraLength;
+      patch.length1 += extraLength;
+      patch.length2 += extraLength;
+    }
+  
+    // Add some padding on end of last diff.
+    patch = patches[patches.length - 1];
+    diffs = patch.diffs;
+    if (diffs.length == 0 || diffs[diffs.length - 1][0] != DIFF_EQUAL) {
+      // Add nullPadding equality.
+      diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, nullPadding));
+      patch.length1 += paddingLength;
+      patch.length2 += paddingLength;
+    } else if (paddingLength > diffs[diffs.length - 1][1].length) {
+      // Grow last equality.
+      var extraLength = paddingLength - diffs[diffs.length - 1][1].length;
+      diffs[diffs.length - 1][1] += nullPadding.substring(0, extraLength);
+      patch.length1 += extraLength;
+      patch.length2 += extraLength;
+    }
+  
+    return nullPadding;
+  };
+  
+  
+  /**
+   * Look through the patches and break up any which are longer than the maximum
+   * limit of the match algorithm.
+   * Intended to be called only from within patch_apply.
+   * @param {!Array.} patches Array of Patch objects.
+   */
+  diff_match_patch.prototype.patch_splitMax = function(patches) {
+    var patch_size = this.Match_MaxBits;
+    for (var x = 0; x < patches.length; x++) {
+      if (patches[x].length1 <= patch_size) {
+        continue;
+      }
+      var bigpatch = patches[x];
+      // Remove the big old patch.
+      patches.splice(x--, 1);
+      var start1 = bigpatch.start1;
+      var start2 = bigpatch.start2;
+      var precontext = '';
+      while (bigpatch.diffs.length !== 0) {
+        // Create one of several smaller patches.
+        var patch = new diff_match_patch.patch_obj();
+        var empty = true;
+        patch.start1 = start1 - precontext.length;
+        patch.start2 = start2 - precontext.length;
+        if (precontext !== '') {
+          patch.length1 = patch.length2 = precontext.length;
+          patch.diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, precontext));
+        }
+        while (bigpatch.diffs.length !== 0 &&
+               patch.length1 < patch_size - this.Patch_Margin) {
+          var diff_type = bigpatch.diffs[0][0];
+          var diff_text = bigpatch.diffs[0][1];
+          if (diff_type === DIFF_INSERT) {
+            // Insertions are harmless.
+            patch.length2 += diff_text.length;
+            start2 += diff_text.length;
+            patch.diffs.push(bigpatch.diffs.shift());
+            empty = false;
+          } else if (diff_type === DIFF_DELETE && patch.diffs.length == 1 &&
+                     patch.diffs[0][0] == DIFF_EQUAL &&
+                     diff_text.length > 2 * patch_size) {
+            // This is a large deletion.  Let it pass in one chunk.
+            patch.length1 += diff_text.length;
+            start1 += diff_text.length;
+            empty = false;
+            patch.diffs.push(new diff_match_patch.Diff(diff_type, diff_text));
+            bigpatch.diffs.shift();
+          } else {
+            // Deletion or equality.  Only take as much as we can stomach.
+            diff_text = diff_text.substring(0,
+                patch_size - patch.length1 - this.Patch_Margin);
+            patch.length1 += diff_text.length;
+            start1 += diff_text.length;
+            if (diff_type === DIFF_EQUAL) {
+              patch.length2 += diff_text.length;
+              start2 += diff_text.length;
+            } else {
+              empty = false;
+            }
+            patch.diffs.push(new diff_match_patch.Diff(diff_type, diff_text));
+            if (diff_text == bigpatch.diffs[0][1]) {
+              bigpatch.diffs.shift();
+            } else {
+              bigpatch.diffs[0][1] =
+                  bigpatch.diffs[0][1].substring(diff_text.length);
+            }
+          }
+        }
+        // Compute the head context for the next patch.
+        precontext = this.diff_text2(patch.diffs);
+        precontext =
+            precontext.substring(precontext.length - this.Patch_Margin);
+        // Append the end context for this patch.
+        var postcontext = this.diff_text1(bigpatch.diffs)
+                              .substring(0, this.Patch_Margin);
+        if (postcontext !== '') {
+          patch.length1 += postcontext.length;
+          patch.length2 += postcontext.length;
+          if (patch.diffs.length !== 0 &&
+              patch.diffs[patch.diffs.length - 1][0] === DIFF_EQUAL) {
+            patch.diffs[patch.diffs.length - 1][1] += postcontext;
+          } else {
+            patch.diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, postcontext));
+          }
+        }
+        if (!empty) {
+          patches.splice(++x, 0, patch);
+        }
+      }
+    }
+  };
+  
+  
+  /**
+   * Take a list of patches and return a textual representation.
+   * @param {!Array.} patches Array of Patch objects.
+   * @return {string} Text representation of patches.
+   */
+  diff_match_patch.prototype.patch_toText = function(patches) {
+    var text = [];
+    for (var x = 0; x < patches.length; x++) {
+      text[x] = patches[x];
+    }
+    return text.join('');
+  };
+  
+  
+  /**
+   * Parse a textual representation of patches and return a list of Patch objects.
+   * @param {string} textline Text representation of patches.
+   * @return {!Array.} Array of Patch objects.
+   * @throws {!Error} If invalid input.
+   */
+  diff_match_patch.prototype.patch_fromText = function(textline) {
+    var patches = [];
+    if (!textline) {
+      return patches;
+    }
+    var text = textline.split('\n');
+    var textPointer = 0;
+    var patchHeader = /^@@ -(\d+),?(\d*) \+(\d+),?(\d*) @@$/;
+    while (textPointer < text.length) {
+      var m = text[textPointer].match(patchHeader);
+      if (!m) {
+        throw new Error('Invalid patch string: ' + text[textPointer]);
+      }
+      var patch = new diff_match_patch.patch_obj();
+      patches.push(patch);
+      patch.start1 = parseInt(m[1], 10);
+      if (m[2] === '') {
+        patch.start1--;
+        patch.length1 = 1;
+      } else if (m[2] == '0') {
+        patch.length1 = 0;
+      } else {
+        patch.start1--;
+        patch.length1 = parseInt(m[2], 10);
+      }
+  
+      patch.start2 = parseInt(m[3], 10);
+      if (m[4] === '') {
+        patch.start2--;
+        patch.length2 = 1;
+      } else if (m[4] == '0') {
+        patch.length2 = 0;
+      } else {
+        patch.start2--;
+        patch.length2 = parseInt(m[4], 10);
+      }
+      textPointer++;
+  
+      while (textPointer < text.length) {
+        var sign = text[textPointer].charAt(0);
+        try {
+          var line = decodeURI(text[textPointer].substring(1));
+        } catch (ex) {
+          // Malformed URI sequence.
+          throw new Error('Illegal escape in patch_fromText: ' + line);
+        }
+        if (sign == '-') {
+          // Deletion.
+          patch.diffs.push(new diff_match_patch.Diff(DIFF_DELETE, line));
+        } else if (sign == '+') {
+          // Insertion.
+          patch.diffs.push(new diff_match_patch.Diff(DIFF_INSERT, line));
+        } else if (sign == ' ') {
+          // Minor equality.
+          patch.diffs.push(new diff_match_patch.Diff(DIFF_EQUAL, line));
+        } else if (sign == '@') {
+          // Start of next patch.
+          break;
+        } else if (sign === '') {
+          // Blank line?  Whatever.
+        } else {
+          // WTF?
+          throw new Error('Invalid patch mode "' + sign + '" in: ' + line);
+        }
+        textPointer++;
+      }
+    }
+    return patches;
+  };
+  
+  
+  /**
+   * Class representing one patch operation.
+   * @constructor
+   */
+  diff_match_patch.patch_obj = function() {
+    /** @type {!Array.} */
+    this.diffs = [];
+    /** @type {?number} */
+    this.start1 = null;
+    /** @type {?number} */
+    this.start2 = null;
+    /** @type {number} */
+    this.length1 = 0;
+    /** @type {number} */
+    this.length2 = 0;
+  };
+  
+  
+  /**
+   * Emulate GNU diff's format.
+   * Header: @@ -382,8 +481,9 @@
+   * Indices are printed as 1-based, not 0-based.
+   * @return {string} The GNU diff string.
+   */
+  diff_match_patch.patch_obj.prototype.toString = function() {
+    var coords1, coords2;
+    if (this.length1 === 0) {
+      coords1 = this.start1 + ',0';
+    } else if (this.length1 == 1) {
+      coords1 = this.start1 + 1;
+    } else {
+      coords1 = (this.start1 + 1) + ',' + this.length1;
+    }
+    if (this.length2 === 0) {
+      coords2 = this.start2 + ',0';
+    } else if (this.length2 == 1) {
+      coords2 = this.start2 + 1;
+    } else {
+      coords2 = (this.start2 + 1) + ',' + this.length2;
+    }
+    var text = ['@@ -' + coords1 + ' +' + coords2 + ' @@\n'];
+    var op;
+    // Escape the body of the patch with %xx notation.
+    for (var x = 0; x < this.diffs.length; x++) {
+      switch (this.diffs[x][0]) {
+        case DIFF_INSERT:
+          op = '+';
+          break;
+        case DIFF_DELETE:
+          op = '-';
+          break;
+        case DIFF_EQUAL:
+          op = ' ';
+          break;
+      }
+      text[x + 1] = op + encodeURI(this.diffs[x][1]) + '\n';
+    }
+    return text.join('').replace(/%20/g, ' ');
+  };
+  
+  // CLOSURE:begin_strip
+  // Lines below here will not be included in the Closure-compatible library.
+  
+  // Export these global variables so that they survive Google's JS compiler.
+  // In a browser, 'this' will be 'window'.
+  // Users of node.js should 'require' the uncompressed version since Google's
+  // JS compiler may break the following exports for non-browser environments.
+  /** @suppress {globalThis} */
+  this['diff_match_patch'] = diff_match_patch;
+  /** @suppress {globalThis} */
+  this['DIFF_DELETE'] = DIFF_DELETE;
+  /** @suppress {globalThis} */
+  this['DIFF_INSERT'] = DIFF_INSERT;
+  /** @suppress {globalThis} */
+  this['DIFF_EQUAL'] = DIFF_EQUAL;
\ No newline at end of file