etherpad-lite/static/js/changesettracker.js

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/**
* 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
*/
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/**
* Copyright 2009 Google Inc.
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*
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* 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
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* 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.
*/
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function makeChangesetTracker(scheduler, apool, aceCallbacksProvider)
{
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// latest official text from server
var baseAText = Changeset.makeAText("\n");
// changes applied to baseText that have been submitted
var submittedChangeset = null;
// changes applied to submittedChangeset since it was prepared
var userChangeset = Changeset.identity(1);
// is the changesetTracker enabled
var tracking = false;
// stack state flag so that when we change the rep we don't
// handle the notification recursively. When setting, always
// unset in a "finally" block. When set to true, the setter
// takes change of userChangeset.
var applyingNonUserChanges = false;
var changeCallback = null;
var changeCallbackTimeout = null;
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function setChangeCallbackTimeout()
{
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// can call this multiple times per call-stack, because
// we only schedule a call to changeCallback if it exists
// and if there isn't a timeout already scheduled.
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if (changeCallback && changeCallbackTimeout === null)
{
changeCallbackTimeout = scheduler.setTimeout(function()
{
try
{
changeCallback();
}
finally
{
changeCallbackTimeout = null;
}
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}, 0);
}
}
var self;
return self = {
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isTracking: function()
{
return tracking;
},
setBaseText: function(text)
{
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self.setBaseAttributedText(Changeset.makeAText(text), null);
},
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setBaseAttributedText: function(atext, apoolJsonObj)
{
aceCallbacksProvider.withCallbacks("setBaseText", function(callbacks)
{
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tracking = true;
baseAText = Changeset.cloneAText(atext);
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if (apoolJsonObj)
{
var wireApool = (new AttribPool()).fromJsonable(apoolJsonObj);
baseAText.attribs = Changeset.moveOpsToNewPool(baseAText.attribs, wireApool, apool);
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}
submittedChangeset = null;
userChangeset = Changeset.identity(atext.text.length);
applyingNonUserChanges = true;
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try
{
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callbacks.setDocumentAttributedText(atext);
}
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finally
{
applyingNonUserChanges = false;
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}
});
},
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composeUserChangeset: function(c)
{
if (!tracking) return;
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if (applyingNonUserChanges) return;
if (Changeset.isIdentity(c)) return;
userChangeset = Changeset.compose(userChangeset, c, apool);
setChangeCallbackTimeout();
},
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applyChangesToBase: function(c, optAuthor, apoolJsonObj)
{
if (!tracking) return;
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aceCallbacksProvider.withCallbacks("applyChangesToBase", function(callbacks)
{
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if (apoolJsonObj)
{
var wireApool = (new AttribPool()).fromJsonable(apoolJsonObj);
c = Changeset.moveOpsToNewPool(c, wireApool, apool);
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}
baseAText = Changeset.applyToAText(c, baseAText, apool);
var c2 = c;
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if (submittedChangeset)
{
var oldSubmittedChangeset = submittedChangeset;
submittedChangeset = Changeset.follow(c, oldSubmittedChangeset, false, apool);
c2 = Changeset.follow(oldSubmittedChangeset, c, true, apool);
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}
var preferInsertingAfterUserChanges = true;
var oldUserChangeset = userChangeset;
userChangeset = Changeset.follow(c2, oldUserChangeset, preferInsertingAfterUserChanges, apool);
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var postChange = Changeset.follow(oldUserChangeset, c2, !preferInsertingAfterUserChanges, apool);
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var preferInsertionAfterCaret = true; //(optAuthor && optAuthor > thisAuthor);
applyingNonUserChanges = true;
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try
{
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callbacks.applyChangesetToDocument(postChange, preferInsertionAfterCaret);
}
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finally
{
applyingNonUserChanges = false;
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}
});
},
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prepareUserChangeset: function()
{
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// If there are user changes to submit, 'changeset' will be the
// changeset, else it will be null.
var toSubmit;
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if (submittedChangeset)
{
// submission must have been canceled, prepare new changeset
// that includes old submittedChangeset
toSubmit = Changeset.compose(submittedChangeset, userChangeset, apool);
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}
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else
{
if (Changeset.isIdentity(userChangeset)) toSubmit = null;
else toSubmit = userChangeset;
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}
var cs = null;
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if (toSubmit)
{
submittedChangeset = toSubmit;
userChangeset = Changeset.identity(Changeset.newLen(toSubmit));
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cs = toSubmit;
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}
var wireApool = null;
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if (cs)
{
var forWire = Changeset.prepareForWire(cs, apool);
wireApool = forWire.pool.toJsonable();
cs = forWire.translated;
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}
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var data = {
changeset: cs,
apool: wireApool
};
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return data;
},
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applyPreparedChangesetToBase: function()
{
if (!submittedChangeset)
{
// violation of protocol; use prepareUserChangeset first
throw new Error("applySubmittedChangesToBase: no submitted changes to apply");
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}
//bumpDebug("applying committed changeset: "+submittedChangeset.encodeToString(false));
baseAText = Changeset.applyToAText(submittedChangeset, baseAText, apool);
submittedChangeset = null;
},
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setUserChangeNotificationCallback: function(callback)
{
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changeCallback = callback;
},
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hasUncommittedChanges: function()
{
return !!(submittedChangeset || (!Changeset.isIdentity(userChangeset)));
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}
};
}