Single-pass merge for lists #13
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Any comments on this? If nobody has objections, I will merge it a day or two from now (and then rebase #12 ). |
| | R i :: p, _ :: l -> | ||
| linear_merge ~acc i p l | ||
| | R _ :: _, [] -> | ||
| failwith "ReactiveData.RList.linear_merge: remove from empty" |
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Either invalid_arg or a custom exception. Avoid failwith.
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I find the invariant you use (list of patches in increasing order of indices) quite restrictive, but I suppose it's the common case in practice ? I suppose your implementation of diffing emits precisely this kind of patches ? |
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In any cases, I think the fast path should be documented. |
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The invariant is OK in practice, and indeed the diffing algorithm produces such patches. Documentation of a special case (of an internal operation) is meaningless when the general case and the whole API is not documented, so #3 :). |
This patch implements a one-pass merge operation for lists, when the patch permits. We accept patches with insert, remove, and update operations at increasing offsets The operation is now O(n + m), where n is the previous size and m is the patch size.
Diffing as per hhugo/reactiveData#12 produces patches in the above format, and the two play nicely together, but technically the two PRs can be considered independently.
We fall back to the old merging code when the patch does not meet our requirements.
This makes plain lists more tolerable, but it would still be a good idea to consider an alternative data structure (as discussed in hhugo/reactiveData#11).