RoaringBitmap / RoaringBitmap/roaring

Implement in-place xOrProduceAnd()

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#261 2 comments 0 reactions 0 assignees View on GitHub

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Dominant language
Go
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Description

The pseudocode for addDigit in https://github.com/RoaringBitmap/roaring/issues/260
includes the two lines

    carry := roaring.And(bsi.bA[i], bitmap)
    bsi.bA[i].Xor(bitmap)

And() and Xor() do basically the same operations. In both they iterate forward through the container keys, comparing them, then making a decision about should happen at each step. This could be optimized by doing both operations in a single pass. I'm not sure the best name for the method, but the signature would look like

func (bitmap *Bitmap) XorWithAndReturned(other *Bitmap) *Bitmap {}

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the addDigit pseudocode in issue #260 and compare Bitmap.And with Bitmap.Xor, focusing on their forward container-key iteration. Implement the proposed Bitmap.XorWithAndReturned entry point so it combines both operations in one pass, returns the And result, and preserves the existing Xor behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
go
Domain
data
Issue type
Refactor
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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