mermaid
Version:
Markdownish syntax for generating flowcharts, sequence diagrams and gantt charts.
1,088 lines (1,030 loc) • 46.4 kB
JavaScript
/*istanbul ignore next */
// jscs:disable maximumLineLength
/*
* This file is a modified version of google-diff-match-patch's JavaScript implementation
* (https://code.google.com/p/google-diff-match-patch/source/browse/trunk/javascript/diff_match_patch_uncompressed.js),
* modifications are licensed as more fully set forth in LICENSE.txt.
*
* The original source of google-diff-match-patch is attributable and licensed as follows:
*
* 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.
*
* More Info:
* https://code.google.com/p/google-diff-match-patch/
*
* Usage: QUnit.diff(expected, actual)
*
* QUnit.diff( "the quick brown fox jumped over", "the quick fox jumps over" ) === "the quick <del>brown </del> fox jump<ins>s</ins><del>ed</del over"
*/
QUnit.diff = (function() {
function DiffMatchPatch() {
// Defaults.
// Redefine these in your program to override the defaults.
// Number of seconds to map a diff before giving up (0 for infinity).
this.DiffTimeout = 1.0;
// Cost of an empty edit operation in terms of edit characters.
this.DiffEditCost = 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,
DIFF_INSERT = 1,
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=} optChecklines 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} optDeadline Optional time when the diff should be complete
* by. Used internally for recursive calls. Users should set DiffTimeout
* instead.
* @return {!Array.<!DiffMatchPatch.Diff>} Array of diff tuples.
*/
DiffMatchPatch.prototype.DiffMain = function( text1, text2, optChecklines, optDeadline ) {
var deadline, checklines, commonlength,
commonprefix, commonsuffix, diffs;
// Set a deadline by which time the diff must be complete.
if ( typeof optDeadline === "undefined" ) {
if ( this.DiffTimeout <= 0 ) {
optDeadline = Number.MAX_VALUE;
} else {
optDeadline = ( new Date() ).getTime() + this.DiffTimeout * 1000;
}
}
deadline = optDeadline;
// Check for null inputs.
if ( text1 === null || text2 === null ) {
throw new Error( "Null input. (DiffMain)" );
}
// Check for equality (speedup).
if ( text1 === text2 ) {
if ( text1 ) {
return [
[ DIFF_EQUAL, text1 ]
];
}
return [];
}
if ( typeof optChecklines === "undefined" ) {
optChecklines = true;
}
checklines = optChecklines;
// Trim off common prefix (speedup).
commonlength = this.diffCommonPrefix( text1, text2 );
commonprefix = text1.substring( 0, commonlength );
text1 = text1.substring( commonlength );
text2 = text2.substring( commonlength );
// Trim off common suffix (speedup).
/////////
commonlength = this.diffCommonSuffix( text1, text2 );
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.
diffs = this.diffCompute( text1, text2, checklines, deadline );
// Restore the prefix and suffix.
if ( commonprefix ) {
diffs.unshift( [ DIFF_EQUAL, commonprefix ] );
}
if ( commonsuffix ) {
diffs.push( [ DIFF_EQUAL, commonsuffix ] );
}
this.diffCleanupMerge( diffs );
return diffs;
};
/**
* Reduce the number of edits by eliminating operationally trivial equalities.
* @param {!Array.<!DiffMatchPatch.Diff>} diffs Array of diff tuples.
*/
DiffMatchPatch.prototype.diffCleanupEfficiency = function( diffs ) {
var changes, equalities, equalitiesLength, lastequality,
pointer, preIns, preDel, postIns, postDel;
changes = false;
equalities = []; // Stack of indices where equalities are found.
equalitiesLength = 0; // Keeping our own length var is faster in JS.
/** @type {?string} */
lastequality = null;
// Always equal to diffs[equalities[equalitiesLength - 1]][1]
pointer = 0; // Index of current position.
// Is there an insertion operation before the last equality.
preIns = false;
// Is there a deletion operation before the last equality.
preDel = false;
// Is there an insertion operation after the last equality.
postIns = false;
// Is there a deletion operation after the last equality.
postDel = false;
while ( pointer < diffs.length ) {
if ( diffs[ pointer ][ 0 ] === DIFF_EQUAL ) { // Equality found.
if ( diffs[ pointer ][ 1 ].length < this.DiffEditCost && ( postIns || postDel ) ) {
// Candidate found.
equalities[ equalitiesLength++ ] = pointer;
preIns = postIns;
preDel = postDel;
lastequality = diffs[ pointer ][ 1 ];
} else {
// Not a candidate, and can never become one.
equalitiesLength = 0;
lastequality = null;
}
postIns = postDel = false;
} else { // An insertion or deletion.
if ( diffs[ pointer ][ 0 ] === DIFF_DELETE ) {
postDel = true;
} else {
postIns = 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 && ( ( preIns && preDel && postIns && postDel ) ||
( ( lastequality.length < this.DiffEditCost / 2 ) &&
( preIns + preDel + postIns + postDel ) === 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 (preIns && preDel) {
// No changes made which could affect previous entry, keep going.
postIns = postDel = true;
equalitiesLength = 0;
} else {
equalitiesLength--; // Throw away the previous equality.
pointer = equalitiesLength > 0 ? equalities[ equalitiesLength - 1 ] : -1;
postIns = postDel = false;
}
changes = true;
}
}
pointer++;
}
if ( changes ) {
this.diffCleanupMerge( diffs );
}
};
/**
* Convert a diff array into a pretty HTML report.
* @param {!Array.<!DiffMatchPatch.Diff>} diffs Array of diff tuples.
* @param {integer} string to be beautified.
* @return {string} HTML representation.
*/
DiffMatchPatch.prototype.diffPrettyHtml = function( diffs ) {
var op, data, x, html = [];
for ( x = 0; x < diffs.length; x++ ) {
op = diffs[x][0]; // Operation (insert, delete, equal)
data = diffs[x][1]; // Text of change.
switch ( op ) {
case DIFF_INSERT:
html[x] = "<ins>" + data + "</ins>";
break;
case DIFF_DELETE:
html[x] = "<del>" + data + "</del>";
break;
case DIFF_EQUAL:
html[x] = "<span>" + data + "</span>";
break;
}
}
return html.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.
*/
DiffMatchPatch.prototype.diffCommonPrefix = function( text1, text2 ) {
var pointermid, pointermax, pointermin, pointerstart;
// 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/
pointermin = 0;
pointermax = Math.min( text1.length, text2.length );
pointermid = pointermax;
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.
*/
DiffMatchPatch.prototype.diffCommonSuffix = function( text1, text2 ) {
var pointermid, pointermax, pointermin, pointerend;
// 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/
pointermin = 0;
pointermax = Math.min(text1.length, text2.length);
pointermid = pointermax;
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;
};
/**
* 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.<!DiffMatchPatch.Diff>} Array of diff tuples.
* @private
*/
DiffMatchPatch.prototype.diffCompute = function( text1, text2, checklines, deadline ) {
var diffs, longtext, shorttext, i, hm,
text1A, text2A, text1B, text2B,
midCommon, diffsA, diffsB;
if ( !text1 ) {
// Just add some text (speedup).
return [
[ DIFF_INSERT, text2 ]
];
}
if (!text2) {
// Just delete some text (speedup).
return [
[ DIFF_DELETE, text1 ]
];
}
longtext = text1.length > text2.length ? text1 : text2;
shorttext = text1.length > text2.length ? text2 : text1;
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.
hm = this.diffHalfMatch(text1, text2);
if (hm) {
// A half-match was found, sort out the return data.
text1A = hm[0];
text1B = hm[1];
text2A = hm[2];
text2B = hm[3];
midCommon = hm[4];
// Send both pairs off for separate processing.
diffsA = this.DiffMain(text1A, text2A, checklines, deadline);
diffsB = this.DiffMain(text1B, text2B, checklines, deadline);
// Merge the results.
return diffsA.concat([
[ DIFF_EQUAL, midCommon ]
], diffsB);
}
if (checklines && text1.length > 100 && text2.length > 100) {
return this.diffLineMode(text1, text2, deadline);
}
return this.diffBisect(text1, text2, deadline);
};
/**
* 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
*/
DiffMatchPatch.prototype.diffHalfMatch = function(text1, text2) {
var longtext, shorttext, dmp,
text1A, text2B, text2A, text1B, midCommon,
hm1, hm2, hm;
if (this.DiffTimeout <= 0) {
// Don't risk returning a non-optimal diff if we have unlimited time.
return null;
}
longtext = text1.length > text2.length ? text1 : text2;
shorttext = text1.length > text2.length ? text2 : text1;
if (longtext.length < 4 || shorttext.length * 2 < longtext.length) {
return null; // Pointless.
}
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 diffHalfMatchI(longtext, shorttext, i) {
var seed, j, bestCommon, prefixLength, suffixLength,
bestLongtextA, bestLongtextB, bestShorttextA, bestShorttextB;
// Start with a 1/4 length substring at position i as a seed.
seed = longtext.substring(i, i + Math.floor(longtext.length / 4));
j = -1;
bestCommon = "";
while ((j = shorttext.indexOf(seed, j + 1)) !== -1) {
prefixLength = dmp.diffCommonPrefix(longtext.substring(i),
shorttext.substring(j));
suffixLength = dmp.diffCommonSuffix(longtext.substring(0, i),
shorttext.substring(0, j));
if (bestCommon.length < suffixLength + prefixLength) {
bestCommon = shorttext.substring(j - suffixLength, j) +
shorttext.substring(j, j + prefixLength);
bestLongtextA = longtext.substring(0, i - suffixLength);
bestLongtextB = longtext.substring(i + prefixLength);
bestShorttextA = shorttext.substring(0, j - suffixLength);
bestShorttextB = shorttext.substring(j + prefixLength);
}
}
if (bestCommon.length * 2 >= longtext.length) {
return [ bestLongtextA, bestLongtextB,
bestShorttextA, bestShorttextB, bestCommon
];
} else {
return null;
}
}
// First check if the second quarter is the seed for a half-match.
hm1 = diffHalfMatchI(longtext, shorttext,
Math.ceil(longtext.length / 4));
// Check again based on the third quarter.
hm2 = diffHalfMatchI(longtext, shorttext,
Math.ceil(longtext.length / 2));
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.
text1A, text1B, text2A, text2B;
if (text1.length > text2.length) {
text1A = hm[0];
text1B = hm[1];
text2A = hm[2];
text2B = hm[3];
} else {
text2A = hm[0];
text2B = hm[1];
text1A = hm[2];
text1B = hm[3];
}
midCommon = hm[4];
return [ text1A, text1B, text2A, text2B, midCommon ];
};
/**
* 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.<!DiffMatchPatch.Diff>} Array of diff tuples.
* @private
*/
DiffMatchPatch.prototype.diffLineMode = function(text1, text2, deadline) {
var a, diffs, linearray, pointer, countInsert,
countDelete, textInsert, textDelete, j;
// Scan the text on a line-by-line basis first.
a = this.diffLinesToChars(text1, text2);
text1 = a.chars1;
text2 = a.chars2;
linearray = a.lineArray;
diffs = this.DiffMain(text1, text2, false, deadline);
// Convert the diff back to original text.
this.diffCharsToLines(diffs, linearray);
// Eliminate freak matches (e.g. blank lines)
this.diffCleanupSemantic(diffs);
// Rediff any replacement blocks, this time character-by-character.
// Add a dummy entry at the end.
diffs.push( [ DIFF_EQUAL, "" ] );
pointer = 0;
countDelete = 0;
countInsert = 0;
textDelete = "";
textInsert = "";
while (pointer < diffs.length) {
switch ( diffs[pointer][0] ) {
case DIFF_INSERT:
countInsert++;
textInsert += diffs[pointer][1];
break;
case DIFF_DELETE:
countDelete++;
textDelete += diffs[pointer][1];
break;
case DIFF_EQUAL:
// Upon reaching an equality, check for prior redundancies.
if (countDelete >= 1 && countInsert >= 1) {
// Delete the offending records and add the merged ones.
diffs.splice(pointer - countDelete - countInsert,
countDelete + countInsert);
pointer = pointer - countDelete - countInsert;
a = this.DiffMain(textDelete, textInsert, false, deadline);
for (j = a.length - 1; j >= 0; j--) {
diffs.splice( pointer, 0, a[j] );
}
pointer = pointer + a.length;
}
countInsert = 0;
countDelete = 0;
textDelete = "";
textInsert = "";
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.<!DiffMatchPatch.Diff>} Array of diff tuples.
* @private
*/
DiffMatchPatch.prototype.diffBisect = function(text1, text2, deadline) {
var text1Length, text2Length, maxD, vOffset, vLength,
v1, v2, x, delta, front, k1start, k1end, k2start,
k2end, k2Offset, k1Offset, x1, x2, y1, y2, d, k1, k2;
// Cache the text lengths to prevent multiple calls.
text1Length = text1.length;
text2Length = text2.length;
maxD = Math.ceil((text1Length + text2Length) / 2);
vOffset = maxD;
vLength = 2 * maxD;
v1 = new Array(vLength);
v2 = new Array(vLength);
// Setting all elements to -1 is faster in Chrome & Firefox than mixing
// integers and undefined.
for (x = 0; x < vLength; x++) {
v1[x] = -1;
v2[x] = -1;
}
v1[vOffset + 1] = 0;
v2[vOffset + 1] = 0;
delta = text1Length - text2Length;
// If the total number of characters is odd, then the front path will collide
// with the reverse path.
front = (delta % 2 !== 0);
// Offsets for start and end of k loop.
// Prevents mapping of space beyond the grid.
k1start = 0;
k1end = 0;
k2start = 0;
k2end = 0;
for (d = 0; d < maxD; d++) {
// Bail out if deadline is reached.
if ((new Date()).getTime() > deadline) {
break;
}
// Walk the front path one step.
for (k1 = -d + k1start; k1 <= d - k1end; k1 += 2) {
k1Offset = vOffset + k1;
if ( k1 === -d || ( k1 !== d && v1[ k1Offset - 1 ] < v1[ k1Offset + 1 ] ) ) {
x1 = v1[k1Offset + 1];
} else {
x1 = v1[k1Offset - 1] + 1;
}
y1 = x1 - k1;
while (x1 < text1Length && y1 < text2Length &&
text1.charAt(x1) === text2.charAt(y1)) {
x1++;
y1++;
}
v1[k1Offset] = x1;
if (x1 > text1Length) {
// Ran off the right of the graph.
k1end += 2;
} else if (y1 > text2Length) {
// Ran off the bottom of the graph.
k1start += 2;
} else if (front) {
k2Offset = vOffset + delta - k1;
if (k2Offset >= 0 && k2Offset < vLength && v2[k2Offset] !== -1) {
// Mirror x2 onto top-left coordinate system.
x2 = text1Length - v2[k2Offset];
if (x1 >= x2) {
// Overlap detected.
return this.diffBisectSplit(text1, text2, x1, y1, deadline);
}
}
}
}
// Walk the reverse path one step.
for (k2 = -d + k2start; k2 <= d - k2end; k2 += 2) {
k2Offset = vOffset + k2;
if ( k2 === -d || (k2 !== d && v2[ k2Offset - 1 ] < v2[ k2Offset + 1 ] ) ) {
x2 = v2[k2Offset + 1];
} else {
x2 = v2[k2Offset - 1] + 1;
}
y2 = x2 - k2;
while (x2 < text1Length && y2 < text2Length &&
text1.charAt(text1Length - x2 - 1) ===
text2.charAt(text2Length - y2 - 1)) {
x2++;
y2++;
}
v2[k2Offset] = x2;
if (x2 > text1Length) {
// Ran off the left of the graph.
k2end += 2;
} else if (y2 > text2Length) {
// Ran off the top of the graph.
k2start += 2;
} else if (!front) {
k1Offset = vOffset + delta - k2;
if (k1Offset >= 0 && k1Offset < vLength && v1[k1Offset] !== -1) {
x1 = v1[k1Offset];
y1 = vOffset + x1 - k1Offset;
// Mirror x2 onto top-left coordinate system.
x2 = text1Length - x2;
if (x1 >= x2) {
// Overlap detected.
return this.diffBisectSplit(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.<!DiffMatchPatch.Diff>} Array of diff tuples.
* @private
*/
DiffMatchPatch.prototype.diffBisectSplit = function( text1, text2, x, y, deadline ) {
var text1a, text1b, text2a, text2b, diffs, diffsb;
text1a = text1.substring(0, x);
text2a = text2.substring(0, y);
text1b = text1.substring(x);
text2b = text2.substring(y);
// Compute both diffs serially.
diffs = this.DiffMain(text1a, text2a, false, deadline);
diffsb = this.DiffMain(text1b, text2b, false, deadline);
return diffs.concat(diffsb);
};
/**
* Reduce the number of edits by eliminating semantically trivial equalities.
* @param {!Array.<!DiffMatchPatch.Diff>} diffs Array of diff tuples.
*/
DiffMatchPatch.prototype.diffCleanupSemantic = function(diffs) {
var changes, equalities, equalitiesLength, lastequality,
pointer, lengthInsertions2, lengthDeletions2, lengthInsertions1,
lengthDeletions1, deletion, insertion, overlapLength1, overlapLength2;
changes = false;
equalities = []; // Stack of indices where equalities are found.
equalitiesLength = 0; // Keeping our own length var is faster in JS.
/** @type {?string} */
lastequality = null;
// Always equal to diffs[equalities[equalitiesLength - 1]][1]
pointer = 0; // Index of current position.
// Number of characters that changed prior to the equality.
lengthInsertions1 = 0;
lengthDeletions1 = 0;
// Number of characters that changed after the equality.
lengthInsertions2 = 0;
lengthDeletions2 = 0;
while (pointer < diffs.length) {
if (diffs[pointer][0] === DIFF_EQUAL) { // Equality found.
equalities[equalitiesLength++] = pointer;
lengthInsertions1 = lengthInsertions2;
lengthDeletions1 = lengthDeletions2;
lengthInsertions2 = 0;
lengthDeletions2 = 0;
lastequality = diffs[pointer][1];
} else { // An insertion or deletion.
if (diffs[pointer][0] === DIFF_INSERT) {
lengthInsertions2 += diffs[pointer][1].length;
} else {
lengthDeletions2 += 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(lengthInsertions1, lengthDeletions1)) &&
(lastequality.length <= Math.max(lengthInsertions2,
lengthDeletions2))) {
// 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;
lengthInsertions1 = 0; // Reset the counters.
lengthDeletions1 = 0;
lengthInsertions2 = 0;
lengthDeletions2 = 0;
lastequality = null;
changes = true;
}
}
pointer++;
}
// Normalize the diff.
if (changes) {
this.diffCleanupMerge(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) {
deletion = diffs[pointer - 1][1];
insertion = diffs[pointer][1];
overlapLength1 = this.diffCommonOverlap(deletion, insertion);
overlapLength2 = this.diffCommonOverlap(insertion, deletion);
if (overlapLength1 >= overlapLength2) {
if (overlapLength1 >= deletion.length / 2 ||
overlapLength1 >= insertion.length / 2) {
// Overlap found. Insert an equality and trim the surrounding edits.
diffs.splice( pointer, 0, [ DIFF_EQUAL, insertion.substring( 0, overlapLength1 ) ] );
diffs[pointer - 1][1] =
deletion.substring(0, deletion.length - overlapLength1);
diffs[pointer + 1][1] = insertion.substring(overlapLength1);
pointer++;
}
} else {
if (overlapLength2 >= deletion.length / 2 ||
overlapLength2 >= 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, overlapLength2 ) ] );
diffs[pointer - 1][0] = DIFF_INSERT;
diffs[pointer - 1][1] =
insertion.substring(0, insertion.length - overlapLength2);
diffs[pointer + 1][0] = DIFF_DELETE;
diffs[pointer + 1][1] =
deletion.substring(overlapLength2);
pointer++;
}
}
pointer++;
}
pointer++;
}
};
/**
* 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
*/
DiffMatchPatch.prototype.diffCommonOverlap = function(text1, text2) {
var text1Length, text2Length, textLength,
best, length, pattern, found;
// Cache the text lengths to prevent multiple calls.
text1Length = text1.length;
text2Length = text2.length;
// Eliminate the null case.
if (text1Length === 0 || text2Length === 0) {
return 0;
}
// Truncate the longer string.
if (text1Length > text2Length) {
text1 = text1.substring(text1Length - text2Length);
} else if (text1Length < text2Length) {
text2 = text2.substring(0, text1Length);
}
textLength = Math.min(text1Length, text2Length);
// Quick check for the worst case.
if (text1 === text2) {
return textLength;
}
// 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/
best = 0;
length = 1;
while (true) {
pattern = text1.substring(textLength - length);
found = text2.indexOf(pattern);
if (found === -1) {
return best;
}
length += found;
if (found === 0 || text1.substring(textLength - length) ===
text2.substring(0, length)) {
best = length;
length++;
}
}
};
/**
* 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
*/
DiffMatchPatch.prototype.diffLinesToChars = function(text1, text2) {
var lineArray, lineHash, chars1, chars2;
lineArray = []; // e.g. lineArray[4] === 'Hello\n'
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 diffLinesToCharsMunge(text) {
var chars, lineStart, lineEnd, lineArrayLength, line;
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.
lineStart = 0;
lineEnd = -1;
// Keeping our own length variable is faster than looking it up.
lineArrayLength = lineArray.length;
while (lineEnd < text.length - 1) {
lineEnd = text.indexOf("\n", lineStart);
if (lineEnd === -1) {
lineEnd = text.length - 1;
}
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;
}
chars1 = diffLinesToCharsMunge(text1);
chars2 = diffLinesToCharsMunge(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.<!DiffMatchPatch.Diff>} diffs Array of diff tuples.
* @param {!Array.<string>} lineArray Array of unique strings.
* @private
*/
DiffMatchPatch.prototype.diffCharsToLines = function( diffs, lineArray ) {
var x, chars, text, y;
for ( x = 0; x < diffs.length; x++ ) {
chars = diffs[x][1];
text = [];
for ( y = 0; y < chars.length; y++ ) {
text[y] = lineArray[chars.charCodeAt(y)];
}
diffs[x][1] = text.join("");
}
};
/**
* Reorder and merge like edit sections. Merge equalities.
* Any edit section can move as long as it doesn't cross an equality.
* @param {!Array.<!DiffMatchPatch.Diff>} diffs Array of diff tuples.
*/
DiffMatchPatch.prototype.diffCleanupMerge = function(diffs) {
var pointer, countDelete, countInsert, textInsert, textDelete,
commonlength, changes;
diffs.push( [ DIFF_EQUAL, "" ] ); // Add a dummy entry at the end.
pointer = 0;
countDelete = 0;
countInsert = 0;
textDelete = "";
textInsert = "";
commonlength;
while (pointer < diffs.length) {
switch ( diffs[ pointer ][ 0 ] ) {
case DIFF_INSERT:
countInsert++;
textInsert += diffs[pointer][1];
pointer++;
break;
case DIFF_DELETE:
countDelete++;
textDelete += diffs[pointer][1];
pointer++;
break;
case DIFF_EQUAL:
// Upon reaching an equality, check for prior redundancies.
if (countDelete + countInsert > 1) {
if (countDelete !== 0 && countInsert !== 0) {
// Factor out any common prefixies.
commonlength = this.diffCommonPrefix(textInsert, textDelete);
if (commonlength !== 0) {
if ((pointer - countDelete - countInsert) > 0 &&
diffs[pointer - countDelete - countInsert - 1][0] ===
DIFF_EQUAL) {
diffs[pointer - countDelete - countInsert - 1][1] +=
textInsert.substring(0, commonlength);
} else {
diffs.splice( 0, 0, [ DIFF_EQUAL,
textInsert.substring( 0, commonlength )
] );
pointer++;
}
textInsert = textInsert.substring(commonlength);
textDelete = textDelete.substring(commonlength);
}
// Factor out any common suffixies.
commonlength = this.diffCommonSuffix(textInsert, textDelete);
if (commonlength !== 0) {
diffs[pointer][1] = textInsert.substring(textInsert.length -
commonlength) + diffs[pointer][1];
textInsert = textInsert.substring(0, textInsert.length -
commonlength);
textDelete = textDelete.substring(0, textDelete.length -
commonlength);
}
}
// Delete the offending records and add the merged ones.
if (countDelete === 0) {
diffs.splice( pointer - countInsert,
countDelete + countInsert, [ DIFF_INSERT, textInsert ] );
} else if (countInsert === 0) {
diffs.splice( pointer - countDelete,
countDelete + countInsert, [ DIFF_DELETE, textDelete ] );
} else {
diffs.splice( pointer - countDelete - countInsert,
countDelete + countInsert, [ DIFF_DELETE, textDelete ], [ DIFF_INSERT, textInsert ] );
}
pointer = pointer - countDelete - countInsert +
(countDelete ? 1 : 0) + (countInsert ? 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++;
}
countInsert = 0;
countDelete = 0;
textDelete = "";
textInsert = "";
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
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.diffCleanupMerge(diffs);
}
};
return function(o, n) {
var diff, output, text;
diff = new DiffMatchPatch();
output = diff.DiffMain(o, n);
//console.log(output);
diff.diffCleanupEfficiency(output);
text = diff.diffPrettyHtml(output);
return text;
};
}());
// jscs:enable