🐛 Fix SequenceSet#max(n) when cardinality < n <= size#580
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When `SequenceSet#max(n)` is called with `n > cardinality`, it _should_ return a duplicate of the whole set. But, `#max(n)` is implemented using `#slice(-n..)`, and (copying the behavior of `Array`), when a slicing starts from an out-of-range index, it returns `nil`. It was using `-[count, size].min` to keep the index from going out-of-range. Prior to #564, `#size` was the same as `#count`, so it would give incorrect results when the set contains an endless range. After #564, this gives incorrect results when the ordered list contains duplicates. This change should also give a small performance boost, because it bypasses the complexity of `#slice(range)` and just calls `#dup` (or returns `self` when the set is frozen). This issue was one of the motivations for #563 (and #564), but then I forgot about the bug, so it wasn't fixed in time for 0.6.0!
nevans added bug nevans merged commit ce176b4 into master 32 checks passed
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nevans changed the title SequenceSet#max(n) when cardinality < n <= sizenevans added a commit that referenced this pull request Dec 17, 2025
This backports #580 to `v0.5-stable`. When `SequenceSet#max(n)` is called with `n > cardinality`, it _should_ return a duplicate of the whole set. But, `#max(n)` is implemented using `#slice(-n..)`, and (copying the behavior of `Array`), when a slicing starts from an out-of-range index, it returns `nil`. It was using `-[count, size].min` to keep the index from going out-of-range. Prior to 0.6.0, `#size` is the same as `#count`, so it gives incorrect results when the set contains an endless range. `SequenceSet#cardinality` has not been backported to 0.5, so this makes that calculation inline. This change should also give a small performance boost, because it bypasses the complexity of `#slice(range)` and just calls `#dup` (or returns `self` when the set is frozen).
nevans added a commit that referenced this pull request Dec 17, 2025
This backports #580 to `v0.5-stable`. When `SequenceSet#max(n)` is called with `n > cardinality`, it _should_ return a duplicate of the whole set. But, `#max(n)` is implemented using `#slice(-n..)`, and (copying the behavior of `Array`), when a slicing starts from an out-of-range index, it returns `nil`. It was using `-[count, size].min` to keep the index from going out-of-range. Prior to 0.6.0, `#size` is the same as `#count`, so it gives incorrect results when the set contains an endless range. `SequenceSet#cardinality` has not been backported to 0.5, so this makes that calculation inline. This change should also give a small performance boost, because it bypasses the complexity of `#slice(range)` and just calls `#dup` (or returns `self` when the set is frozen).
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This issue was one of the motivations for #563 (and #564), but then I forgot about the bug, so it wasn't fixed in time for 0.6.0!
When
SequenceSet#max(n)is called withn > cardinality, it should return a duplicate of the whole set. But,#max(n)is implemented using#slice(-n..), and (copying the behavior ofArray), when a slicing starts from an out-of-range index, it returnsnil.It was using
-[count, size].minto keep the index from going out-of-range. Prior to #564,#sizewas the same as#count, so it would give incorrect results when the set contains an endless range. After #564, this gives incorrect results when the ordered list contains duplicates.This change should also give a small performance boost, because it bypasses the complexity of
#slice(range)and just calls#dup(or returnsselfwhen the set is frozen).