Diff Match and Patch
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/**
* Diff Match and Patch
*
* Copyright 2006 Google Inc.
* http://code.google.com/p/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
*/
function diff_match_patch() {
// 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;
// The size beyond which the double-ended diff activates.
// Double-ending is twice as fast, but less accurate.
this.Diff_DualThreshold = 32;
// 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 does
// the contents have 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;
/**
* Compute the number of bits in an int.
* The normal answer for JavaScript is 32.
* @return {number} Max bits
*/
function getMaxBits() {
var maxbits = 0;
var oldi = 1;
var newi = 2;
while (oldi != newi) {
maxbits++;
oldi = newi;
newi = newi << 1;
}
return maxbits;
}
// How many bits in a number?
this.Match_MaxBits = getMaxBits();
}
// 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;
/**
* 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
* @return {Array.<Array.<number|string>>} Array of diff tuples.
*/
diff_match_patch.prototype.diff_main = function(text1, text2, opt_checklines) {
// Check for equality (speedup)
if (text1 == text2) {
return [[DIFF_EQUAL, text1]];
}
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);
// Restore the prefix and suffix
if (commonprefix) {
diffs.unshift([DIFF_EQUAL, commonprefix]);
}
if (commonsuffix) {
diffs.push([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
* @return {Array.<Array.<number|string>>} Array of diff tuples.
* @private
*/
diff_match_patch.prototype.diff_compute = function(text1, text2, checklines) {
var diffs;
if (!text1) {
// Just add some text (speedup)
return [[DIFF_INSERT, text2]];
}
if (!text2) {
// Just delete some text (speedup)
return [[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 = [[DIFF_INSERT, longtext.substring(0, i)],
[DIFF_EQUAL, shorttext],
[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;
}
longtext = shorttext = null; // Garbage collect.
// 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);
var diffs_b = this.diff_main(text1_b, text2_b, checklines);
// Merge the results.
return diffs_a.concat([[DIFF_EQUAL, mid_common]], diffs_b);
}
// Perform a real diff.
if (checklines && (text1.length < 100 || text2.length < 100)) {
// Too trivial for the overhead.
checklines = false;
}
var linearray;
if (checklines) {
// Scan the text on a line-by-line basis first.
var a = this.diff_linesToChars(text1, text2);
text1 = a[0];
text2 = a[1];
linearray = a[2];
}
diffs = this.diff_map(text1, text2);
if (!diffs) {
// No acceptable result.
diffs = [[DIFF_DELETE, text1], [DIFF_INSERT, text2]];
}
if (checklines) {
// 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([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.
var a = this.diff_main(text_delete, text_insert, false);
diffs.splice(pointer - count_delete - count_insert,
count_delete + count_insert);
pointer = pointer - count_delete - count_insert;
for (var j = a.length - 1; j >= 0; j--) {
diffs.splice(pointer, 0, a[j]);
}
pointer = pointer + a.length;
}
count_insert = 0;
count_delete = 0;
text_delete = '';
text_insert = '';
break;
}
pointer++;
}
diffs.pop(); // Remove the dummy entry at the end.
}
return diffs;
};
/**
* 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 {Array.<string|Array.<string>>} Three element Array, 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);
lineStart = lineEnd + 1;
if (lineHash.hasOwnProperty ? lineHash.hasOwnProperty(line) :
(lineHash[line] !== undefined)) {
chars += String.fromCharCode(lineHash[line]);
} else {
chars += String.fromCharCode(lineArrayLength);
lineHash[line] = lineArrayLength;
lineArray[lineArrayLength++] = line;
}
}
return chars;
}
var chars1 = diff_linesToCharsMunge(text1);
var chars2 = diff_linesToCharsMunge(text2);
return [chars1, chars2, lineArray];
};
/**
* Rehydrate the text in a diff from a string of line hashes to real lines of
* text.
* @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
* @param {Array.<string>} lineArray Array of unique strings.
* @private
*/
diff_match_patch.prototype.diff_charsToLines = function(diffs, lineArray) {
for (var x = 0; x < diffs.length; x++) {
var chars = diffs[x][1];
var text = [];
for (var y = 0; y < chars.length; y++) {
text[y] = lineArray[chars.charCodeAt(y)];
}
diffs[x][1] = text.join('');
}
};
/**
* Explore the intersection points between the two texts.
* @param {string} text1 Old string to be diffed.
* @param {string} text2 New string to be diffed.
* @return {Array.<Array.<number|string>>?} Array of diff tuples or null if no
* diff available.
* @private
*/
diff_match_patch.prototype.diff_map = function(text1, text2) {
// Don't run for too long.
var ms_end = (new Date()).getTime() + this.Diff_Timeout * 1000;
// Cache the text lengths to prevent multiple calls.
var text1_length = text1.length;
var text2_length = text2.length;
var max_d = text1_length + text2_length - 1;
var doubleEnd = this.Diff_DualThreshold * 2 < max_d;
var v_map1 = [];
var v_map2 = [];
var v1 = {};
var v2 = {};
v1[1] = 0;
v2[1] = 0;
var x, y;
var footstep; // Used to track overlapping paths.
var footsteps = {};
var done = false;
// Safari 1.x doesn't have hasOwnProperty
var hasOwnProperty = !!(footsteps.hasOwnProperty);
// If the total number of characters is odd, then the front path will collide
// with the reverse path.
var front = (text1_length + text2_length) % 2;
for (var d = 0; d < max_d; d++) {
// Bail out if timeout reached.
if (this.Diff_Timeout > 0 && (new Date()).getTime() > ms_end) {
return null;
}
// Walk the front path one step.
v_map1[d] = {};
for (var k = -d; k <= d; k += 2) {
if (k == -d || k != d && v1[k - 1] < v1[k + 1]) {
x = v1[k + 1];
} else {
x = v1[k - 1] + 1;
}
y = x - k;
if (doubleEnd) {
footstep = x + ',' + y;
if (front && (hasOwnProperty ? footsteps.hasOwnProperty(footstep) :
(footsteps[footstep] !== undefined))) {
done = true;
}
if (!front) {
footsteps[footstep] = d;
}
}
while (!done && x < text1_length && y < text2_length &&
text1.charAt(x) == text2.charAt(y)) {
x++;
y++;
if (doubleEnd) {
footstep = x + ',' + y;
if (front && (hasOwnProperty ? footsteps.hasOwnProperty(footstep) :
(footsteps[footstep] !== undefined))) {
done = true;
}
if (!front) {
footsteps[footstep] = d;
}
}
}
v1[k] = x;
v_map1[d][x + ',' + y] = true;
if (x == text1_length && y == text2_length) {
// Reached the end in single-path mode.
return this.diff_path1(v_map1, text1, text2);
} else if (done) {
// Front path ran over reverse path.
v_map2 = v_map2.slice(0, footsteps[footstep] + 1);
var a = this.diff_path1(v_map1, text1.substring(0, x),
text2.substring(0, y));
return a.concat(this.diff_path2(v_map2, text1.substring(x),
text2.substring(y)));
}
}
if (doubleEnd) {
// Walk the reverse path one step.
v_map2[d] = {};
for (var k = -d; k <= d; k += 2) {
if (k == -d || k != d && v2[k - 1] < v2[k + 1]) {
x = v2[k + 1];
} else {
x = v2[k - 1] + 1;
}
y = x - k;
footstep = (text1_length - x) + ',' + (text2_length - y);
if (!front && (hasOwnProperty ? footsteps.hasOwnProperty(footstep) :
(footsteps[footstep] !== undefined))) {
done = true;
}
if (front) {
footsteps[footstep] = d;
}
while (!done && x < text1_length && y < text2_length &&
text1.charAt(text1_length - x - 1) ==
text2.charAt(text2_length - y - 1)) {
x++;
y++;
footstep = (text1_length - x) + ',' + (text2_length - y);
if (!front && (hasOwnProperty ? footsteps.hasOwnProperty(footstep) :
(footsteps[footstep] !== undefined))) {
done = true;
}
if (front) {
footsteps[footstep] = d;
}
}
v2[k] = x;
v_map2[d][x + ',' + y] = true;
if (done) {
// Reverse path ran over front path.
v_map1 = v_map1.slice(0, footsteps[footstep] + 1);
var a = this.diff_path1(v_map1, text1.substring(0, text1_length - x),
text2.substring(0, text2_length - y));
return a.concat(this.diff_path2(v_map2,
text1.substring(text1_length - x),
text2.substring(text2_length - y)));
}
}
}
}
// Number of diffs equals number of characters, no commonality at all.
return null;
};
/**
* Work from the middle back to the start to determine the path.
* @param {Array.<Object>} v_map Array of paths.
* @param {string} text1 Old string fragment to be diffed.
* @param {string} text2 New string fragment to be diffed.
* @return {Array.<Array.<number|string>>} Array of diff tuples.
* @private
*/
diff_match_patch.prototype.diff_path1 = function(v_map, text1, text2) {
var path = [];
var x = text1.length;
var y = text2.length;
/** @type {number?} */
var last_op = null;
for (var d = v_map.length - 2; d >= 0; d--) {
while (1) {
if (v_map[d].hasOwnProperty ? v_map[d].hasOwnProperty((x - 1) + ',' + y) :
(v_map[d][(x - 1) + ',' + y] !== undefined)) {
x--;
if (last_op === DIFF_DELETE) {
path[0][1] = text1.charAt(x) + path[0][1];
} else {
path.unshift([DIFF_DELETE, text1.charAt(x)]);
}
last_op = DIFF_DELETE;
break;
} else if (v_map[d].hasOwnProperty ?
v_map[d].hasOwnProperty(x + ',' + (y - 1)) :
(v_map[d][x + ',' + (y - 1)] !== undefined)) {
y--;
if (last_op === DIFF_INSERT) {
path[0][1] = text2.charAt(y) + path[0][1];
} else {
path.unshift([DIFF_INSERT, text2.charAt(y)]);
}
last_op = DIFF_INSERT;
break;
} else {
x--;
y--;
//if (text1.charAt(x) != text2.charAt(y)) {
// throw new Error('No diagonal. Can\'t happen. (diff_path1)');
//}
if (last_op === DIFF_EQUAL) {
path[0][1] = text1.charAt(x) + path[0][1];
} else {
path.unshift([DIFF_EQUAL, text1.charAt(x)]);
}
last_op = DIFF_EQUAL;
}
}
}
return path;
};
/**
* Work from the middle back to the end to determine the path.
* @param {Array.<Object>} v_map Array of paths.
* @param {string} text1 Old string fragment to be diffed.
* @param {string} text2 New string fragment to be diffed.
* @return {Array.<Array.<number|string>>} Array of diff tuples.
* @private
*/
diff_match_patch.prototype.diff_path2 = function(v_map, text1, text2) {
var path = [];
var pathLength = 0;
var x = text1.length;
var y = text2.length;
/** @type {number?} */
var last_op = null;
for (var d = v_map.length - 2; d >= 0; d--) {
while (1) {
if (v_map[d].hasOwnProperty ? v_map[d].hasOwnProperty((x - 1) + ',' + y) :
(v_map[d][(x - 1) + ',' + y] !== undefined)) {
x--;
if (last_op === DIFF_DELETE) {
path[pathLength - 1][1] += text1.charAt(text1.length - x - 1);
} else {
path[pathLength++] =
[DIFF_DELETE, text1.charAt(text1.length - x - 1)];
}
last_op = DIFF_DELETE;
break;
} else if (v_map[d].hasOwnProperty ?
v_map[d].hasOwnProperty(x + ',' + (y - 1)) :
(v_map[d][x + ',' + (y - 1)] !== undefined)) {
y--;
if (last_op === DIFF_INSERT) {
path[pathLength - 1][1] += text2.charAt(text2.length - y - 1);
} else {
path[pathLength++] =
[DIFF_INSERT, text2.charAt(text2.length - y - 1)];
}
last_op = DIFF_INSERT;
break;
} else {
x--;
y--;
//if (text1.charAt(text1.length - x - 1) !=
// text2.charAt(text2.length - y - 1)) {
// throw new Error('No diagonal. Can\'t happen. (diff_path2)');
//}
if (last_op === DIFF_EQUAL) {
path[pathLength - 1][1] += text1.charAt(text1.length - x - 1);
} else {
path[pathLength++] =
[DIFF_EQUAL, text1.charAt(text1.length - x - 1)];
}
last_op = DIFF_EQUAL;
}
}
}
return path;
};
/**
* 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.charCodeAt(0) !== text2.charCodeAt(0)) {
return 0;
}
// Binary search.
// Performance analysis: http://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.charCodeAt(text1.length - 1) !==
text2.charCodeAt(text2.length - 1)) {
return 0;
}
// Binary search.
// Performance analysis: http://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;
};
/**
* Do the two texts share a substring which is at least half the length of the
* longer text?
* @param {string} text1 First string.
* @param {string} text2 Second string.
* @return {Array.<string>?} 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.
*/
diff_match_patch.prototype.diff_halfMatch = function(text1, text2) {
var longtext = text1.length > text2.length ? text1 : text2;
var shorttext = text1.length > text2.length ? text2 : text1;
if (longtext.length < 10 || shorttext.length < 1) {
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.<string>?} 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 >= longtext.length / 2) {
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.<Array.<number|string>>} 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.
var lastequality = null; // Always equal to equalities[equalitiesLength-1][1]
var pointer = 0; // Index of current position.
// Number of characters that changed prior to the equality.
var length_changes1 = 0;
// Number of characters that changed after the equality.
var length_changes2 = 0;
while (pointer < diffs.length) {
if (diffs[pointer][0] == DIFF_EQUAL) { // equality found
equalities[equalitiesLength++] = pointer;
length_changes1 = length_changes2;
length_changes2 = 0;
lastequality = diffs[pointer][1];
} else { // an insertion or deletion
length_changes2 += diffs[pointer][1].length;
if (lastequality !== null && (lastequality.length <= length_changes1) &&
(lastequality.length <= length_changes2)) {
// Duplicate record
diffs.splice(equalities[equalitiesLength - 1], 0,
[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_changes1 = 0; // Reset the counters.
length_changes2 = 0;
lastequality = null;
changes = true;
}
}
pointer++;
}
if (changes) {
this.diff_cleanupMerge(diffs);
}
this.diff_cleanupSemanticLossless(diffs);
};
/**
* 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 c<ins>at c</ins>ame. -> The <ins>cat </ins>came.
* @param {Array.<Array.<number|string>>} diffs Array of diff tuples.
*/
diff_match_patch.prototype.diff_cleanupSemanticLossless = function(diffs) {
// Define some regex patterns for matching boundaries.
var punctuation = /[^a-zA-Z0-9]/;
var whitespace = /\s/;
var linebreak = /[\r\n]/;
var blanklineEnd = /\n\r?\n$/;
var blanklineStart = /^\r?\n\r?\n/;
/**
* Given two strings, compute a score representing whether the internal
* boundary falls on logical boundaries.
* Scores range from 5 (best) to 0 (worst).
* Closure, makes reference to regex patterns defined above.
* @param {string} one First string.
* @param {string} two Second string.
* @return {number} The score.
*/
function diff_cleanupSemanticScore(one, two) {
if (!one || !two) {
// Edges are the best.
return 5;
}
// 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 score = 0;
// One point for non-alphanumeric.
if (one.charAt(one.length - 1).match(punctuation) ||
two.charAt(0).match(punctuation)) {
score++;
// Two points for whitespace.
if (one.charAt(one.length - 1).match(whitespace) ||
two.charAt(0).match(whitespace)) {
score++;
// Three points for line breaks.
if (one.charAt(one.length - 1).match(linebreak) ||
two.charAt(0).match(linebreak)) {
score++;
// Four points for blank lines.
if (one.match(blanklineEnd) || two.match(blanklineStart)) {
score++;
}
}
}
}
return score;
}
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++;
}
};
/**
* Reduce the number of edits by eliminating operationally trivial equalities.
* @param {Array.<Array.<number|string>>} 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.
var lastequality = ''; // Always equal to 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 = '';
}
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:
* <ins>A</ins><del>B</del>XY<ins>C</ins><del>D</del>
* <ins>A</ins>X<ins>C</ins><del>D</del>
* <ins>A</ins><del>B</del>X<ins>C</ins>
* <ins>A</del>X<ins>C</ins><del>D</del>
* <ins>A</ins><del>B</del>X<del>C</del>
*/
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,
[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 = '';
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.<Array.<number|string>>} diffs Array of diff tuples.
*/
diff_match_patch.prototype.diff_cleanupMerge = function(diffs) {
diffs.push([DIFF_EQUAL, '']); // Add a dummy entry at the end.
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 !== 0 || count_insert !== 0) {
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, [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.
if (count_delete === 0) {
diffs.splice(pointer - count_delete - count_insert,
count_delete + count_insert, [DIFF_INSERT, text_insert]);
} else if (count_insert === 0) {
diffs.splice(pointer - count_delete - count_insert,
count_delete + count_insert, [DIFF_DELETE, text_delete]);
} else {
diffs.splice(pointer - count_delete - count_insert,
count_delete + count_insert, [DIFF_DELETE, text_delete],
[DIFF_INSERT, text_insert]);
}
pointer = pointer - count_delete - count_insert +
(count_delete ? 1 : 0) + (count_insert ? 1 : 0) + 1;
} 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: A<ins>BA</ins>C -> <ins>AB</ins>AC
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.<Array.<number|string>>} 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.<Array.<number|string>>} diffs Array of diff tuples.
* @return {string} HTML representation.
*/
diff_match_patch.prototype.diff_prettyHtml = function(diffs) {
var html = [];
var i = 0;
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(/&/g, '&').replace(/</g, '<')
.replace(/>/g, '>').replace(/\n/g, '¶<BR>');
switch (op) {
case DIFF_INSERT:
html[x] = '<INS STYLE="background:#E6FFE6;" TITLE="i=' + i + '">' +
text + '</INS>';
break;
case DIFF_DELETE:
html[x] = '<DEL STYLE="background:#FFE6E6;" TITLE="i=' + i + '">' +
text + '</DEL>';
break;
case DIFF_EQUAL:
html[x] = '<SPAN TITLE="i=' + i + '">' + text + '</SPAN>';
break;
}
if (op !== DIFF_DELETE) {
i += data.length;
}
}
return html.join('');
};
/**
* Compute and return the source text (all equalities and deletions).
* @param {Array.<Array.<number|string>>} 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.<Array.<number|string>>} 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.<Array.<number|string>>} 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.<Array.<number|string>>} 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;
}
}
// Opera doesn't know how to encode char 0.
return text.join('\t').replace(/\x00/g, '%00').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.<number|string>>} 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
// Opera doesn't know how to decode char 0.
delta = delta.replace(/%00/g, '\0');
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++] = [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++] = [DIFF_EQUAL, text];
} else {
diffs[diffsLength++] = [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) {
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 {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;
}
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([DIFF_EQUAL, prefix]);
}
// Add the suffix.
var suffix = text.substring(patch.start2 + patch.length1,
patch.start2 + patch.length1 + padding);
if (suffix) {
patch.diffs.push([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.<Array.<number|string>>} a text1 (methods 1,3,4) or
* Array of diff tuples for text1 to text2 (method 2).
* @param {string|Array.<Array.<number|string>>} opt_b text2 (methods 1,4) or
* Array of diff tuples for text1 to text2 (method 3) or undefined (method 2).
* @param {string|Array.<Array.<number|string>>} opt_c Array of diff tuples for
* text1 to text2 (method 4) or undefined (methods 1,2,3).
* @return {Array.<patch_obj>} 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 = a;
diffs = this.diff_main(text1, opt_b, true);
if (diffs.length > 2) {
this.diff_cleanupSemantic(diffs);
this.diff_cleanupEfficiency(diffs);
}
} else if (typeof a == 'object' && typeof opt_b == 'undefined' &&
typeof opt_c == 'undefined') {
// Method 2: diffs
// Compute text1 from diffs.
diffs = a;
text1 = this.diff_text1(diffs);
} else if (typeof a == 'string' && typeof opt_b == 'object' &&
typeof opt_c == 'undefined') {
// Method 3: text1, diffs
text1 = a;
diffs = opt_b;
} else if (typeof a == 'string' && typeof opt_b == 'string' &&
typeof opt_c == 'object') {
// Method 4: text1, text2, diffs
// text2 is not used.
text1 = a;
diffs = 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 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 patch_obj();
patchDiffLength = 0;
// Unlike Unidiff, our patch lists have a rolling context.
// http://code.google.com/p/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.<patch_obj>} patches Array of patch objects.
* @return {Array.<patch_obj>} 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 patch_obj();
patchCopy.diffs = [];
for (var y = 0; y < patch.diffs.length; y++) {
patchCopy.diffs[y] = patch.diffs[y].slice();
}
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.<patch_obj>} patches Array of patch objects.
* @param {string} text Old text.
* @return {Array.<string|Array.<boolean>>} 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.<patch_obj>} 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([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([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.
* @param {Array.<patch_obj>} patches Array of patch objects.
*/
diff_match_patch.prototype.patch_splitMax = function(patches) {
for (var x = 0; x < patches.length; x++) {
if (patches[x].length1 > this.Match_MaxBits) {
var bigpatch = patches[x];
// Remove the big old patch.
patches.splice(x--, 1);
var patch_size = this.Match_MaxBits;
var start1 = bigpatch.start1;
var start2 = bigpatch.start2;
var precontext = '';
while (bigpatch.diffs.length !== 0) {
// Create one of several smaller patches.
var patch = new 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([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([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([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([DIFF_EQUAL, postcontext]);
}
}
if (!empty) {
patches.splice(++x, 0, patch);
}
}
}
}
};
/**
* Take a list of patches and return a textual representation.
* @param {Array.<patch_obj>} 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.<patch_obj>} Array of patch objects.
* @throws {Error} If invalid input.
*/
diff_match_patch.prototype.patch_fromText = function(textline) {
var patches = [];
if (!textline) {
return patches;
}
// Opera doesn't know how to decode char 0.
textline = textline.replace(/%00/g, '\0');
var text = textline.split('\n');
var textPointer = 0;
while (textPointer < text.length) {
var m = text[textPointer].match(/^@@ -(\d+),?(\d*) \+(\d+),?(\d*) @@$/);
if (!m) {
throw new Error('Invalid patch string: ' + text[textPointer]);
}
var patch = new 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([DIFF_DELETE, line]);
} else if (sign == '+') {
// Insertion.
patch.diffs.push([DIFF_INSERT, line]);
} else if (sign == ' ') {
// Minor equality.
patch.diffs.push([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
*/
function patch_obj() {
/** @type {Array.<Array.<number|string>>} */
this.diffs = [];
/** @type {number?} */
this.start1 = null;
/** @type {number?} */
this.start2 = null;
/** @type {number} */
this.length1 = 0;
/** @type {number} */
this.length2 = 0;
}
/**
* Emmulate GNU diff's format.
* Header: @@ -382,8 +481,9 @@
* Indicies are printed as 1-based, not 0-based.
* @return {string} The GNU diff string.
*/
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';
}
// Opera doesn't know how to encode char 0.
return text.join('').replace(/\x00/g, '%00').replace(/%20/g, ' ');
};
// Export these global variables so that they survive Google's JS compiler.
window['diff_match_patch'] = diff_match_patch;
window['patch_obj'] = patch_obj;
window['DIFF_DELETE'] = DIFF_DELETE;
window['DIFF_INSERT'] = DIFF_INSERT;
window['DIFF_EQUAL'] = DIFF_EQUAL;