File: //usr/share/opensearch-dashboards/node_modules/text-diff/diff.js
/**
* This library was modified by Harrison Liddiard. The source code to this
* modified version can be found at https://github.com/liddiard/google-diff/.
* The original source code can be found at
* http://code.google.com/p/google-diff-match-patch/. This unofficial fork is
* not maintained by or affiliated with Google Inc. The original attribution
* and licensing information follows.
*/
/**
* 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.
* @constructor
*/
function diff(options) {
var options = options || {};
// Defaults.
// Redefine these in your program to override the defaults.
// Number of seconds to map a diff before giving up (0 for infinity).
this.Timeout = options.timeout || 1.0;
// Cost of an empty edit operation in terms of edit characters.
this.EditCost = options.editCost || 4;
}
// 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;
/** @typedef {{0: number, 1: string}} */
diff.Diff;
/**
* 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.<!diff.Diff>} Array of diff tuples.
*/
diff.prototype.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.Timeout <= 0) {
opt_deadline = Number.MAX_VALUE;
} else {
opt_deadline = (new Date).getTime() + this.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 [[DIFF_EQUAL, text1]];
}
return [];
}
if (typeof opt_checklines == 'undefined') {
opt_checklines = true;
}
var checklines = opt_checklines;
// Trim off common prefix (speedup).
var commonlength = this.commonPrefix(text1, text2);
var commonprefix = text1.substring(0, commonlength);
text1 = text1.substring(commonlength);
text2 = text2.substring(commonlength);
// Trim off common suffix (speedup).
commonlength = this.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.compute_(text1, text2, checklines, deadline);
// Restore the prefix and suffix.
if (commonprefix) {
diffs.unshift([DIFF_EQUAL, commonprefix]);
}
if (commonsuffix) {
diffs.push([DIFF_EQUAL, commonsuffix]);
}
this.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.<!diff.Diff>} Array of diff tuples.
* @private
*/
diff.prototype.compute_ = function(text1, text2, checklines,
deadline) {
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;
}
if (shorttext.length == 1) {
// Single character string.
// After the previous speedup, the character can't be an equality.
return [[DIFF_DELETE, text1], [DIFF_INSERT, text2]];
}
// Check to see if the problem can be split in two.
var hm = this.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.main(text1_a, text2_a, checklines, deadline);
var diffs_b = this.main(text1_b, text2_b, checklines, deadline);
// Merge the results.
return diffs_a.concat([[DIFF_EQUAL, mid_common]], diffs_b);
}
if (checklines && text1.length > 100 && text2.length > 100) {
return this.lineMode_(text1, text2, deadline);
}
return this.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.<!diff.Diff>} Array of diff tuples.
* @private
*/
diff.prototype.lineMode_ = function(text1, text2, deadline) {
// Scan the text on a line-by-line basis first.
var a = this.linesToChars_(text1, text2);
text1 = a.chars1;
text2 = a.chars2;
var linearray = a.lineArray;
var diffs = this.main(text1, text2, false, deadline);
// Convert the diff back to original text.
this.charsToLines_(diffs, linearray);
// Eliminate freak matches (e.g. blank lines)
this.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.
diffs.splice(pointer - count_delete - count_insert,
count_delete + count_insert);
pointer = pointer - count_delete - count_insert;
var a = this.main(text_delete, text_insert, false, deadline);
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;
};
/**
* 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.<!diff.Diff>} Array of diff tuples.
* @private
*/
diff.prototype.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.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.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 [[DIFF_DELETE, text1], [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.<!diff.Diff>} Array of diff tuples.
* @private
*/
diff.prototype.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.main(text1a, text2a, false, deadline);
var diffsb = this.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.<string>}}
* 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.prototype.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: chars1, chars2: chars2, lineArray: lineArray};
};
/**
* Rehydrate the text in a diff from a string of line hashes to real lines of
* text.
* @param {!Array.<!diff.Diff>} diffs Array of diff tuples.
* @param {!Array.<string>} lineArray Array of unique strings.
* @private
*/
diff.prototype.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('');
}
};
/**
* 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.prototype.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: 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.prototype.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: 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;
};
/**
* 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.prototype.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: http://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.<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.
* @private
*/
diff.prototype.halfMatch_ = function(text1, text2) {
if (this.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.<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.commonPrefix(longtext.substring(i),
shorttext.substring(j));
var suffixLength = dmp.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.<!diff.Diff>} diffs Array of diff tuples.
*/
diff.prototype.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,
[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.cleanupMerge(diffs);
}
this.cleanupSemanticLossless(diffs);
// Find any overlaps between deletions and insertions.
// e.g: <del>abcxxx</del><ins>xxxdef</ins>
// -> <del>abc</del>xxx<ins>def</ins>
// e.g: <del>xxxabc</del><ins>defxxx</ins>
// -> <ins>def</ins>xxx<del>abc</del>
// 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.commonOverlap_(deletion, insertion);
var overlap_length2 = this.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,
[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,
[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 c<ins>at c</ins>ame. -> The <ins>cat </ins>came.
* @param {!Array.<!diff.Diff>} diffs Array of diff tuples.
*/
diff.prototype.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.nonAlphaNumericRegex_);
var nonAlphaNumeric2 = char2.match(diff.nonAlphaNumericRegex_);
var whitespace1 = nonAlphaNumeric1 &&
char1.match(diff.whitespaceRegex_);
var whitespace2 = nonAlphaNumeric2 &&
char2.match(diff.whitespaceRegex_);
var lineBreak1 = whitespace1 &&
char1.match(diff.linebreakRegex_);
var lineBreak2 = whitespace2 &&
char2.match(diff.linebreakRegex_);
var blankLine1 = lineBreak1 &&
one.match(diff.blanklineEndRegex_);
var blankLine2 = lineBreak2 &&
two.match(diff.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.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.nonAlphaNumericRegex_ = /[^a-zA-Z0-9]/;
diff.whitespaceRegex_ = /\s/;
diff.linebreakRegex_ = /[\r\n]/;
diff.blanklineEndRegex_ = /\n\r?\n$/;
diff.blanklineStartRegex_ = /^\r?\n\r?\n/;
/**
* Reduce the number of edits by eliminating operationally trivial equalities.
* @param {!Array.<!diff.Diff>} diffs Array of diff tuples.
*/
diff.prototype.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.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:
* <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.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 = 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.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.<!diff.Diff>} diffs Array of diff tuples.
*/
diff.prototype.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 + count_insert > 1) {
if (count_delete !== 0 && count_insert !== 0) {
// Factor out any common prefixies.
commonlength = this.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.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_insert,
count_delete + count_insert, [DIFF_INSERT, text_insert]);
} else if (count_insert === 0) {
diffs.splice(pointer - count_delete,
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.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.<!diff.Diff>} diffs Array of diff tuples.
* @param {number} loc Location within text1.
* @return {number} Location within text2.
*/
diff.prototype.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.<!diff.Diff>} diffs Array of diff tuples.
* @return {string} HTML representation.
*/
diff.prototype.prettyHtml = function(diffs) {
var html = [];
var pattern_amp = /&/g;
var pattern_lt = /</g;
var pattern_gt = />/g;
var pattern_br = /\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_br, '<br/>');
switch (op) {
case DIFF_INSERT:
html[x] = '<ins>' + text + '</ins>';
break;
case DIFF_DELETE:
html[x] = '<del>' + text + '</del>';
break;
case DIFF_EQUAL:
html[x] = '<span>' + text + '</span>';
break;
}
}
return html.join('');
};
/**
* Compute and return the source text (all equalities and deletions).
* @param {!Array.<!diff.Diff>} diffs Array of diff tuples.
* @return {string} Source text.
*/
diff.prototype.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.<!diff.Diff>} diffs Array of diff tuples.
* @return {string} Destination text.
*/
diff.prototype.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.<!diff.Diff>} diffs Array of diff tuples.
* @return {number} Number of changes.
*/
diff.prototype.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.<!diff.Diff>} diffs Array of diff tuples.
* @return {string} Delta text.
*/
diff.prototype.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.<!diff.Diff>} Array of diff tuples.
* @throws {!Error} If invalid input.
*/
diff.prototype.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++] = [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;
};
// 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.
this['diff'] = diff;
this['DIFF_DELETE'] = DIFF_DELETE;
this['DIFF_INSERT'] = DIFF_INSERT;
this['DIFF_EQUAL'] = DIFF_EQUAL;
module.exports = diff;