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https://github.com/samber/lo.git
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Samuel Berthe
dc372c082b
Replace make([]T, 0, count) + append with make([]T, count) + result[i] = ... since the final size is known upfront. Eliminates per-element append overhead. Also adds comprehensive benchmark coverage for all helpers across core, it, mutable, and parallel packages (282 benchmark functions).
34 lines
1.9 KiB
Plaintext
34 lines
1.9 KiB
Plaintext
# Performance Optimizations Report
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## PR #827 - Reject / RejectErr / RejectMap
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- Preallocate result slice with `make(Slice, 0, len(collection))` instead of `Slice{}`
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- Avoids repeated grow-and-copy reallocations as elements are appended
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## PR #829 - UniqMap
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- Collect results directly during the single map-building pass instead of calling `Keys(seen)` afterward
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- Eliminates a second full iteration over the map to extract keys
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- Eliminates a separate slice allocation inside `Keys()`
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- Preserves insertion order (old code returned non-deterministic map iteration order)
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## PR #830 - Difference
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- Preallocate result slices with `make(Slice, 0, len(listN))` instead of `Slice{}`
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- Avoids repeated grow-and-copy reallocations as elements are appended
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## PR #831 - FromSlicePtr / FromSlicePtrOr
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- Replace indirect `Map()` call with closure by a direct loop
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- Eliminates per-element function call overhead from the closure indirection
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## PR #833 - CountValues, UniqKeys, UniqValues, FilterKeys, FilterValues, FilterKeysErr, FilterValuesErr
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- Add size hint to map allocation in CountValues: `make(map[T]int)` → `make(map[T]int, len(collection))`
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- Avoids repeated map rehashing as entries are added
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- Add capacity hint to result slice in UniqKeys/UniqValues: `make([]K, 0)` → `make([]K, 0, size)`
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- Avoids repeated slice grow-and-copy reallocations
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- Add capacity hint to result slice in FilterKeys/FilterValues/FilterKeysErr/FilterValuesErr: `make([]K, 0)` → `make([]K, 0, len(in))`
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- Avoids repeated slice grow-and-copy reallocations
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## PR #??? - RepeatBy / Fill / Repeat
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- Replace `make([]T, 0, count)` + `append(result, ...)` with `make([]T, count)` + `result[i] = ...`
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- Eliminates per-element append overhead (bounds check, length increment, slice header update)
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- Size is known upfront so direct index assignment is safe and faster
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- RepeatByErr left unchanged: early error return makes direct index problematic (would allocate full slice then discard)
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