// <nowiki>
// Three-way merge utility
//
// Extracted from Synchrotron (https://github.com/tonyg/synchrotron)
// Minor modifications by Wikipedia user Suffusion of Yellow
// Original copyright notice follows:
// Copyright (c) 2006, 2008 Tony Garnock-Jones <tonyg@lshift.net>
// Copyright (c) 2006, 2008 LShift Ltd. <query@lshift.net>
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation files
// (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software,
// and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
var Diff3 = {
longest_common_subsequence: function(file1, file2) {
/* Text diff algorithm following Hunt and McIlroy 1976.
* J. W. Hunt and M. D. McIlroy, An algorithm for differential file
* comparison, Bell Telephone Laboratories CSTR #41 (1976)
* http://www.cs.dartmouth.edu/~doug/
*
* Expects two arrays of strings.
*/
var equivalenceClasses;
var file2indices;
var newCandidate;
var candidates;
var line;
var c, i, j, jX, r, s;
equivalenceClasses = new Map();
for (j = 0; j < file2.length; j++) {
line = file2[j];
if (equivalenceClasses.get(line)) {
equivalenceClasses.get(line).push(j);
} else {
equivalenceClasses.set(line,[j]);
}
}
candidates = [{file1index: -1,
file2index: -1,
chain: null}];
for (i = 0; i < file1.length; i++) {
line = file1[i];
file2indices = equivalenceClasses.get(line) || [];
r = 0;
c = candidates[0];
for (jX = 0; jX < file2indices.length; jX++) {
j = file2indices[jX];
for (s = r; s < candidates.length; s++) {
if ((candidates[s].file2index < j) &&
((s == candidates.length - 1) ||
(candidates[s + 1].file2index > j)))
break;
}
if (s < candidates.length) {
newCandidate = {file1index: i,
file2index: j,
chain: candidates[s]};
if (r == candidates.length) {
candidates.push(c);
} else {
candidates[r] = c;
}
r = s + 1;
c = newCandidate;
if (r == candidates.length) {
break; // no point in examining further (j)s
}
}
}
candidates[r] = c;
}
// At this point, we know the LCS: it's in the reverse of the
// linked-list through .chain of
// candidates[candidates.length - 1].
return candidates[candidates.length - 1];
},
diff_indices: function(file1, file2) {
// We apply the LCS to give a simple representation of the
// offsets and lengths of mismatched chunks in the input
// files. This is used by diff3_merge_indices below.
var result = [];
var tail1 = file1.length;
var tail2 = file2.length;
for (var candidate = Diff3.longest_common_subsequence(file1, file2);
candidate !== null;
candidate = candidate.chain)
{
var mismatchLength1 = tail1 - candidate.file1index - 1;
var mismatchLength2 = tail2 - candidate.file2index - 1;
tail1 = candidate.file1index;
tail2 = candidate.file2index;
if (mismatchLength1 || mismatchLength2) {
result.push({file1: [tail1 + 1, mismatchLength1],
file2: [tail2 + 1, mismatchLength2]});
}
}
result.reverse();
return result;
},
diff3_merge_indices: function (a, o, b) {
// Given three files, A, O, and B, where both A and B are
// independently derived from O, returns a fairly complicated
// internal representation of merge decisions it's taken. The
// interested reader may wish to consult
//
// Sanjeev Khanna, Keshav Kunal, and Benjamin C. Pierce. "A
// Formal Investigation of Diff3." In Arvind and Prasad,
// editors, Foundations of Software Technology and Theoretical
// Computer Science (FSTTCS), December 2007.
//
// (http://www.cis.upenn.edu/~bcpierce/papers/diff3-short.pdf)
var i;
var m1 = Diff3.diff_indices(o, a);
var m2 = Diff3.diff_indices(o, b);
var hunks = [];
function addHunk(h, side) {
hunks.push([h.file1[0], side, h.file1[1], h.file2[0], h.file2[1]]);
}
for (i = 0; i < m1.length; i++) { addHunk(m1[i], 0); }
for (i = 0; i < m2.length; i++) { addHunk(m2[i], 2); }
hunks.sort(function (x, y) { return x[0] - y[0]; });
var result = [];
var commonOffset = 0;
function copyCommon(targetOffset) {
if (targetOffset > commonOffset) {
result.push([1, commonOffset, targetOffset - commonOffset]);
commonOffset = targetOffset;
}
}
for (var hunkIndex = 0; hunkIndex < hunks.length; hunkIndex++) {
var firstHunkIndex = hunkIndex;
var hunk = hunks[hunkIndex];
var regionLhs = hunk[0];
var regionRhs = regionLhs + hunk[2];
while (hunkIndex < hunks.length - 1) {
var maybeOverlapping = hunks[hunkIndex + 1];
var maybeLhs = maybeOverlapping[0];
if (maybeLhs > regionRhs) break;
regionRhs = Math.max(regionRhs, maybeLhs + maybeOverlapping[2]);
hunkIndex++;
}
copyCommon(regionLhs);
if (firstHunkIndex == hunkIndex) {
// The "overlap" was only one hunk long, meaning that
// there's no conflict here. Either a and o were the
// same, or b and o were the same.
if (hunk[4] > 0) {
result.push([hunk[1], hunk[3], hunk[4]]);
}
} else {
// A proper conflict. Determine the extents of the
// regions involved from a, o and b. Effectively merge
// all the hunks on the left into one giant hunk, and
// do the same for the right; then, correct for skew
// in the regions of o that each side changed, and
// report appropriate spans for the three sides.
var regions = {
0: [a.length, -1, o.length, -1],
2: [b.length, -1, o.length, -1]
};
for (i = firstHunkIndex; i <= hunkIndex; i++) {
hunk = hunks[i];
var side = hunk[1];
var r = regions[side];
var oLhs = hunk[0];
var oRhs = oLhs + hunk[2];
var abLhs = hunk[3];
var abRhs = abLhs + hunk[4];
r[0] = Math.min(abLhs, r[0]);
r[1] = Math.max(abRhs, r[1]);
r[2] = Math.min(oLhs, r[2]);
r[3] = Math.max(oRhs, r[3]);
}
var aLhs = regions[0][0] + (regionLhs - regions[0][2]);
var aRhs = regions[0][1] + (regionRhs - regions[0][3]);
var bLhs = regions[2][0] + (regionLhs - regions[2][2]);
var bRhs = regions[2][1] + (regionRhs - regions[2][3]);
result.push([-1,
aLhs, aRhs - aLhs,
regionLhs, regionRhs - regionLhs,
bLhs, bRhs - bLhs]);
}
commonOffset = regionRhs;
}
copyCommon(o.length);
return result;
},
diff3_merge: function (a, o, b, excludeFalseConflicts) {
// Applies the output of Diff.diff3_merge_indices to actually
// construct the merged file; the returned result alternates
// between "ok" and "conflict" blocks.
var result = [];
var files = [a, o, b];
var indices = Diff3.diff3_merge_indices(a, o, b);
var okLines = [];
function flushOk() {
if (okLines.length) {
result.push({ok: okLines});
}
okLines = [];
}
function pushOk(xs) {
for (var j = 0; j < xs.length; j++) {
okLines.push(xs[j]);
}
}
function isTrueConflict(rec) {
if (rec[2] != rec[6]) return true;
var aoff = rec[1];
var boff = rec[5];
for (var j = 0; j < rec[2]; j++) {
if (a[j + aoff] != b[j + boff]) return true;
}
return false;
}
for (var i = 0; i < indices.length; i++) {
var x = indices[i];
var side = x[0];
if (side == -1) {
if (excludeFalseConflicts && !isTrueConflict(x)) {
pushOk(files[0].slice(x[1], x[1] + x[2]));
} else {
flushOk();
result.push({conflict: {a: a.slice(x[1], x[1] + x[2]),
aIndex: x[1],
o: o.slice(x[3], x[3] + x[4]),
oIndex: x[3],
b: b.slice(x[5], x[5] + x[6]),
bIndex: x[5]}});
}
} else {
pushOk(files[side].slice(x[1], x[1] + x[2]));
}
}
flushOk();
return result;
}
};
// </nowiki>
