+// 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.
+
+// source: https://bitbucket.org/lshift/synchrotron/src
+
+Diff3 = (function() {
+ 'use strict';
+
+ 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 = {};
+ for (j = 0; j < file2.length; j++) {
+ line = file2[j];
+ if (equivalenceClasses[line]) {
+ equivalenceClasses[line].push(j);
+ } else {
+ equivalenceClasses[line] = [j];
+ }
+ }
+
+ candidates = [{file1index: -1,
+ file2index: -1,
+ chain: null}];
+
+ for (i = 0; i < file1.length; i++) {
+ line = file1[i];
+ file2indices = equivalenceClasses[line] || [];
+
+ r = 0;
+ c = candidates[0];
+
+ for (jX = 0; jX < file2indices.length; jX++) {
+ j = file2indices[jX];
+
+ for (s = 0; 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_comm: function(file1, file2) {
+ // We apply the LCS to build a "comm"-style picture of the
+ // differences between file1 and file2.
+
+ var result = [];
+ var tail1 = file1.length;
+ var tail2 = file2.length;
+ var common = {common: []};
+
+ function processCommon() {
+ if (common.common.length) {
+ common.common.reverse();
+ result.push(common);
+ common = {common: []};
+ }
+ }
+
+ for (var candidate = Diff3.longest_common_subsequence(file1, file2);
+ candidate !== null;
+ candidate = candidate.chain)
+ {
+ var different = {file1: [], file2: []};
+
+ while (--tail1 > candidate.file1index) {
+ different.file1.push(file1[tail1]);
+ }
+
+ while (--tail2 > candidate.file2index) {
+ different.file2.push(file2[tail2]);
+ }
+
+ if (different.file1.length || different.file2.length) {
+ processCommon();
+ different.file1.reverse();
+ different.file2.reverse();
+ result.push(different);
+ }
+
+ if (tail1 >= 0) {
+ common.common.push(file1[tail1]);
+ }
+ }
+
+ processCommon();
+
+ result.reverse();
+ return result;
+ },
+
+ diff_patch: function(file1, file2) {
+ // We apply the LCD to build a JSON representation of a
+ // diff(1)-style patch.
+
+ var result = [];
+ var tail1 = file1.length;
+ var tail2 = file2.length;
+
+ function chunkDescription(file, offset, length) {
+ var chunk = [];
+ for (var i = 0; i < length; i++) {
+ chunk.push(file[offset + i]);
+ }
+ return {offset: offset,
+ length: length,
+ chunk: chunk};
+ }
+
+ 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: chunkDescription(file1,
+ candidate.file1index + 1,
+ mismatchLength1),
+ file2: chunkDescription(file2,
+ candidate.file2index + 1,
+ mismatchLength2)});
+ }
+ }
+
+ result.reverse();
+ return result;
+ },
+
+ strip_patch: function(patch) {
+ // Takes the output of Diff3.diff_patch(), and removes
+ // information from it. It can still be used by patch(),
+ // below, but can no longer be inverted.
+ var newpatch = [];
+ for (var i = 0; i < patch.length; i++) {
+ var chunk = patch[i];
+ newpatch.push({file1: {offset: chunk.file1.offset,
+ length: chunk.file1.length},
+ file2: {chunk: chunk.file2.chunk}});
+ }
+ return newpatch;
+ },
+
+ invert_patch: function(patch) {
+ // Takes the output of Diff3.diff_patch(), and inverts the
+ // sense of it, so that it can be applied to file2 to give
+ // file1 rather than the other way around.
+
+ for (var i = 0; i < patch.length; i++) {
+ var chunk = patch[i];
+ var tmp = chunk.file1;
+ chunk.file1 = chunk.file2;
+ chunk.file2 = tmp;
+ }
+ },
+
+ patch: function (file, patch) {
+ // Applies a patch to a file.
+ //
+ // Given file1 and file2, Diff3.patch(file1,
+ // Diff3.diff_patch(file1, file2)) should give file2.
+
+ var result = [];
+ var commonOffset = 0;
+
+ function copyCommon(targetOffset) {
+ while (commonOffset < targetOffset) {
+ result.push(file[commonOffset]);
+ commonOffset++;
+ }
+ }
+
+ for (var chunkIndex = 0; chunkIndex < patch.length; chunkIndex++) {
+ var chunk = patch[chunkIndex];
+ copyCommon(chunk.file1.offset);
+ for (var lineIndex = 0; lineIndex < chunk.file2.chunk.length; lineIndex++) {
+ result.push(chunk.file2.chunk[lineIndex]);
+ }
+ commonOffset += chunk.file1.length;
+ }
+
+ copyCommon(file.length);
+ return result;
+ },
+
+ 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();
+
+ 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 = 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 Diff3.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;
+ }
+ };
+ return diff3;
+})();
+
+if (typeof module !== 'undefined') module.exports = Diff3;
projects / rails.git / commitdiff
