Re: [WebODF] OpSetParagraphStyle and OT

Am Mittwoch, 26. Juni 2013, 19:58:27 schrieben Sie:

On 26 June 2013 03:26, Friedrich W. H. Kossebau wrote:

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Now here are the samples where things fail ATM (always assuming A's ops have priority): Doc: text:pText A: [<setParagraphStyle pos="0" styleNameAfter="S1" memberId="A"/>] B: [<setParagraphStyle pos="3" styleNameAfter="S2" memberId="B"/>] Obviously hard to know if both target the same paragraph. Proposal: fix by identifying the paragraph with by its first position

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Using this proposal, there is another issue:

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Doc: text:pABtext:pC

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text:p>text:p/ A: [<setParagraphStyle pos="3" styleNameAfter="S1" memberId="A"/>] B: [<removeText pos="0" length="1" memberId="B"/>] How can the setParagraphStyle op be transformed against the removeText op, in such a way that the pos attribute again points to the begin of the paragraph? There is no information in the removeText op which paragraphs are affected and how.

The desired intent is that each client end up with the same document, though the ops are processed in a different order right.

Right.

Consider the following scenario: text:pP1

A: [] B: []

Client A processes A then B, and ends up with the style applied to both paragraphs (this is the intended result). Client B splits first, then needs to realise that the style should be applied to the new paragraph as well.

Yes, another nice example where just the (starting) position of the paragraph with setParagraphStyle op would not work in OT.

If setParagraphStyle carries both the start and end of the paragraph positions, it would be trivial to tell where the old styled paragraph ended. Every paragraph up to this point is expected to carry the new style. For the above example, client B would perform the following

1. Apply splitParagraph at position 1 (just after the 'P'). This inserts a new cursor position. 2. Transform setParagraphStyle end pos (or length) by +1 3. setParagraphStyle fetches all paragraphs in the specified range and applies the style to these

Is there a glaring hole in that approach?

That basic approach should be fine, yes. Just that instead of 3) there would be instead another setParagraphStyle op created, which sets the given style for the second of the split paragraphs. This would then result in no further troubles if e.g. B not only has but also another setParagraphStyle op locally applied which sets the style to one of the two paragraphs, which should also still be present in the final document: text:pP1 A: [] B: [ ] So B not only splits the paragraph, but sets a style to the first of the resulting paragraphs. If B now transforms the op from A against its own apps, it would first transform it against the splitting op like before, and then transform the result of that against its setParagraphStyle op. vs. where the first would get some tie-breaking due to being both operating on the same object (in this case assume B's ops have priority, to see something), and the effect of second op would just do what is expected. Adding additional ops on transformation as needed is done in other places (and in other projects) as well, so that is fine. Cheers Friedrich -- Friedrich W. H. Kossebau // KO GmbH http://kogmbh.com/legal/