mirror of
https://github.com/jimeh/rands.git
synced 2026-02-19 03:16:39 +00:00
Jim Myhrberg
a141938394
Add equivalent to `Shuffle` function from `math/rand` and `math/rand/v2` packages, but based on randomness from `crypto/rand` package. This allows cryptographically secure shuffling of data. Also add `ShuffleSlice` function that shuffles a slice of any type. BREAKING CHANGE: Minimum required Go version is now 1.18 due the `ShuffleSlice` using generics.
52 lines
1.2 KiB
Go
52 lines
1.2 KiB
Go
package rands
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import (
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"fmt"
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)
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var (
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ErrShuffle = fmt.Errorf("%w: shuffle", Err)
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ErrInvalidShuffleNegativeN = fmt.Errorf(
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"%w: n must not be negative", ErrShuffle,
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)
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)
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// Shuffle randomizes the order of a collection of n elements using
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// cryptographically secure random values from crypto/rand. It implements the
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// Fisher-Yates shuffle algorithm.
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//
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// The swap function is called to exchange values at indices i and j. This
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// signature is compatible with Shuffle from math/rand and math/rand/v2 for easy
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// migration.
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func Shuffle(n int, swap func(i, j int)) error {
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if n < 0 {
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return ErrInvalidShuffleNegativeN
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}
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for i := n - 1; i > 0; i-- {
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j, err := Int(i + 1)
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if err != nil {
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return err
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}
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swap(i, j)
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}
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return nil
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}
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// ShuffleSlice randomizes the order of elements in a slice in-place using
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// cryptographically secure random values from crypto/rand.
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//
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// It implements the Fisher-Yates shuffle algorithm.
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func ShuffleSlice[T any](slice []T) error {
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// If the slice has one or no elements, there's nothing to shuffle.
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if len(slice) < 2 {
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return nil
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}
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return Shuffle(len(slice), func(i, j int) {
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slice[i], slice[j] = slice[j], slice[i]
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})
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}
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