Simplify minterm generation in Regex NonBacktracking engine #61232
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PartitionTree had a holdover from when it was tracking the predicates that made up each minterm, which caused it to use order n too much memory for some patterns. Nodes with the same predicate as the parent are no longer created. This also significantly simplified the algorithm.
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Tagging subscribers to this area: @eerhardt, @dotnet/area-system-text-regularexpressions Issue DetailsPartitionTree had a holdover from when it was tracking the predicates that made up each minterm, which caused it to use order n too much memory for some patterns: nodes with the same predicate as the parent are no longer created. This also significantly simplified the algorithm. The effect is particularly evident in patterns with lots of non-overlapping predicates. For the pattern "qwertyuuiopasdfghjklzxcvbnm" this dropped the number of PartitionTree nodes created from 378 to 53.
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| @@ -41,25 +40,17 @@ public MintermGenerator(IBooleanAlgebra<TPredicate> algebra) | |||
| /// <returns>all minterms of the given predicate sequence</returns> | |||
| public List<TPredicate> GenerateMinterms(params TPredicate[] preds) | |||
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As long as you're improving things here, does this need to be params or could that be removed?
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Good question, I don't think it has to be. I'll change it to match what this is called with.
Also remove the deduplication in there, since its now optional and the only call site already passes in a unique set of predicates.
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PartitionTree had a holdover from when it was tracking the predicates that made up each minterm, which caused it to use order n too much memory for some patterns: nodes with the same predicate as the parent are no longer created. This also significantly simplified the algorithm.
The effect is particularly evident in patterns with lots of non-overlapping predicates. For the pattern "qwertyuuiopasdfghjklzxcvbnm" this dropped the number of PartitionTree nodes created from 378 to 53.