marcelklehr / changesets

Changeset library with operational transformation -- for node and the browser!

👋 Hi, I’m @marcelklehr

I work on Open Source projects that further freedom and privacy and allow people to use the fruits of technology with sovereignty. This is my small contribution to a world where people are not dependent on big corporations to live a life eased by technology.

changesets's Issues

There's still a BOM in Skip.js

"transformAgainst" doesn't work as expected

var Changeset = changesets.Changeset;
var dmp = new diff_match_patch();

var text1 = "Hello adventurer!",
    text2 = "Hello treasured adventurer!",//suppose user A changes text1 to text2 
    text3 = "Good day adventurers, y'all!";//suppose user B changes text1 to text3

var diff1_2 = dmp.diff_main(text1, text2);
var diff1_3 = dmp.diff_main(text1, text3);

var cs1_2 = Changeset.fromDiff(diff1_2);
var cs1_3 = Changeset.fromDiff(diff1_3);

var textFinal_1 = cs1_2.transformAgainst(cs1_3).apply(text3);
var textFinal_2 = cs1_3.transformAgainst(cs1_2).apply(text2);

console.log(textFinal_1 === textFinal_2);//the result we expected to be true, but actually false

Meaningfull errors

Sometimes, things go worng. If they do, this library should be helpful in fixing them.
This means specifying as precisely as possible where there is an error in the changeset and what exactly the problem is.

"transformAgainst" doesn't work as expected

var Changeset = changesets.Changeset;
var dmp = new diff_match_patch();

var text1 = "Hello adventurer!",
    text2 = "Hello treasured adventurer!",//suppose user A changes text1 to text2 
    text3 = "Good day adventurers, y'all!";//suppose user B changes text1 to text3

var diff1_2 = dmp.diff_main(text1, text2);
var diff1_3 = dmp.diff_main(text1, text3);

var cs1_2 = Changeset.fromDiff(diff1_2);
var cs1_3 = Changeset.fromDiff(diff1_3);

var textFinal_1 = cs1_2.transformAgainst(cs1_3).apply(text3);
var textFinal_2 = cs1_3.transformAgainst(cs1_2).apply(text2);

console.log(textFinal_1 === textFinal_2);//the result we expected to be true, but actually false

unpacking does not work for operation length > 35

The regex for unpacking of operations is /(+|-|=)\w+?/g .
If the length of an operation is > 35 the base 36 encoding gives two characters, say "10" for 36.

If we have an operation string like "=10+4|..." , the present regex matches only the first character of the length: [ "=1", "+4" ].

This is easily reproducible when operating on longer (>35) strings.

Dropping the optional - ?: /(+|-|=)\w+/g matches the whole encoded length as intended. Comparing this with the pack() function, the length is never omitted, so I think this would be the right thing to do.

Better use op streams instead of an op heap...

context-equivalent operations packed together forming one "changeset" is nice, but it doesn't play that well with merging changesets as well as other stuff.

Plus, all this transform stuff might be way simpler to do with a stream like approach (meaning you have a cursor that kinda zooms through your document, moved by the operations as they insert or delete stuff or leave stuff untouched). This means operations in a changeset will have an order!

• inclusion transform
• exclusion transform
• invert
• pack/unpack
• merge
• tie breaker

Closed

I'm just interested is it possible to use changesets module to JSON objects rather that plain text? My JSON is look like the following:

var a = {
  name: 'John',
  age: 55,
  tags: ['tag1', 'tag2', 'tag3'],
  events: {
    add: "four",
    create: 3
  }
};

Question: why must the input length match the expected length?

I'm wondering why the following code example is not considered to be correct:

var Changeset = require('changesets').Changeset;
str = 'Hans Peter';
cs = Changeset.create().retain(4).insert(' Jürgen').end();
cs.apply(str);
Error: Input length doesn't match expected length. expected: 4; actual: 10

I must retain the rest of the string to make it work:

cs = Changeset.create().retain(4).insert(' Jürgen').retain(6).end();

If I remove the validation it works like expected.

Is there a good reason for this validation?

Best Regards,
Oliver

Add shareJs API support

Allow changesets to be used as a shareJS ot type

"transformAgainst" doesn't work as expected

var Changeset = changesets.Changeset;
var dmp = new diff_match_patch();

var text1 = "Hello adventurer!",
    text2 = "Hello treasured adventurer!",//suppose user A changes text1 to text2 
    text3 = "Good day adventurers, y'all!";//suppose user B changes text1 to text3

var diff1_2 = dmp.diff_main(text1, text2);
var diff1_3 = dmp.diff_main(text1, text3);

var cs1_2 = Changeset.fromDiff(diff1_2);
var cs1_3 = Changeset.fromDiff(diff1_3);

var textFinal_1 = cs1_2.transformAgainst(cs1_3).apply(text3);
var textFinal_2 = cs1_3.transformAgainst(cs1_2).apply(text2);

console.log(textFinal_1 === textFinal_2);//the result we expected to be true, but actually false

Invert

Hello,

When i make an invert of a simple OT +2:2:c:0, i obtain an ot -2:2:c:0. I think it should be -2:3:c:0 in order to be possible to do :

var text = 'ab',
ot = cs.text.Changeset.unpack('+2:2:c:0');

text = ot.apply(text);
text = ot.invert().apply(text);

// text should be equal to 'ab'

Refactor: Turn Skips and Inserts into Moves

Everything can be represented by a move:

insert -> MOV(null, target)
skip -> MOV(target, null)

This might actually be more sane than the current stream approach...

Is this possible to support changes from ckeditor ??

Thanks for ur work. I read the doc but still not sure about this, I want to implement a editor could save diff(patches) list in database which is not required to be collaborative, so , can I use this for ckeditor?