Add Nand functionality #110
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One useful use case for bitarrays is to do filtering of values, by removing the values in one bitarry from another. Add a Nand function that will do this sort of filtering.
| // Here, our indices match for both `sba` and `other`. | ||
| // Time to do the bitwise AND operation and add a block | ||
| // to our result list if the block has values in it. | ||
| resultBlock = sba.blocks[selfIndex].nand(other.blocks[otherIndex]) |
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I do not like this duplication. Far too fragile.
Might I suggest a style such as:
type blockOperation func(Block, Block) Block
func and(Block, Block) Block { ... }
func nand(Block, Block) Block { ... }
func compareSparseWithSparseBitArray(operation blockOperation, sba, other *sparseBitArray) BitArray {
// ...
resultBlock = operation(sba.blocks[selfIndex], other.blocks[otherIndex])
// ...
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So I started going down that road at first, but I found that the functions differed beyond just the block comparison. So I tried a way where I passed flags in to do decisioning but then the code got even messier.
As well, I realized that I actually needed to add a new function specifically for nand, to handle the extra case of dense nand sparse. With and, you can handle the dense and sparse case with a single function, since it's commutative, but nand isn't.
The binary Read function, while clean, was causing large performance hits by requiring a bytes Reader. Speed this up by removing the reader and parsing the bytes directly.
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+1 |
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One useful use case for bitarrays is to do filtering of values,
by removing the values in one bitarry from another. Add a Nand
function that will do this sort of filtering.
This is a use case that is necessary for my application, which is
doing high performance filtering.
I know that the And and Nand functionality is very similar, but it seemed
different enough to warrant a separate file. Let me know what you think.