etherpad-lite/static/js/broadcast_revisions.js

128 lines
4 KiB
JavaScript

/**
* This code is mostly from the old Etherpad. Please help us to comment this code.
* This helps other people to understand this code better and helps them to improve it.
* TL;DR COMMENTS ON THIS FILE ARE HIGHLY APPRECIATED
*/
/**
* Copyright 2009 Google Inc.
*
* 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.
*/
// revision info is a skip list whos entries represent a particular revision
// of the document. These revisions are connected together by various
// changesets, or deltas, between any two revisions.
function loadBroadcastRevisionsJS()
{
function Revision(revNum)
{
this.rev = revNum;
this.changesets = [];
}
Revision.prototype.addChangeset = function(destIndex, changeset, timeDelta)
{
var changesetWrapper = {
deltaRev: destIndex - this.rev,
deltaTime: timeDelta,
getValue: function()
{
return changeset;
}
};
this.changesets.push(changesetWrapper);
this.changesets.sort(function(a, b)
{
return (b.deltaRev - a.deltaRev)
});
}
revisionInfo = {};
revisionInfo.addChangeset = function(fromIndex, toIndex, changeset, backChangeset, timeDelta)
{
var startRevision = revisionInfo[fromIndex] || revisionInfo.createNew(fromIndex);
var endRevision = revisionInfo[toIndex] || revisionInfo.createNew(toIndex);
startRevision.addChangeset(toIndex, changeset, timeDelta);
endRevision.addChangeset(fromIndex, backChangeset, -1 * timeDelta);
}
revisionInfo.latest = clientVars.totalRevs || -1;
revisionInfo.createNew = function(index)
{
revisionInfo[index] = new Revision(index);
if (index > revisionInfo.latest)
{
revisionInfo.latest = index;
}
return revisionInfo[index];
}
// assuming that there is a path from fromIndex to toIndex, and that the links
// are laid out in a skip-list format
revisionInfo.getPath = function(fromIndex, toIndex)
{
var changesets = [];
var spans = [];
var times = [];
var elem = revisionInfo[fromIndex] || revisionInfo.createNew(fromIndex);
if (elem.changesets.length != 0 && fromIndex != toIndex)
{
var reverse = !(fromIndex < toIndex)
while (((elem.rev < toIndex) && !reverse) || ((elem.rev > toIndex) && reverse))
{
var couldNotContinue = false;
var oldRev = elem.rev;
for (var i = reverse ? elem.changesets.length - 1 : 0;
reverse ? i >= 0 : i < elem.changesets.length;
i += reverse ? -1 : 1)
{
if (((elem.changesets[i].deltaRev < 0) && !reverse) || ((elem.changesets[i].deltaRev > 0) && reverse))
{
couldNotContinue = true;
break;
}
if (((elem.rev + elem.changesets[i].deltaRev <= toIndex) && !reverse) || ((elem.rev + elem.changesets[i].deltaRev >= toIndex) && reverse))
{
var topush = elem.changesets[i];
changesets.push(topush.getValue());
spans.push(elem.changesets[i].deltaRev);
times.push(topush.deltaTime);
elem = revisionInfo[elem.rev + elem.changesets[i].deltaRev];
break;
}
}
if (couldNotContinue || oldRev == elem.rev) break;
}
}
var status = 'partial';
if (elem.rev == toIndex) status = 'complete';
return {
'fromRev': fromIndex,
'rev': elem.rev,
'status': status,
'changesets': changesets,
'spans': spans,
'times': times
};
}
}
exports.loadBroadcastRevisionsJS = loadBroadcastRevisionsJS;