mirror of
https://github.com/tailscale/tailscale.git
synced 2024-11-25 19:15:34 +00:00
5f5c9142cc
Then use it in tailcfg which had it duplicated a couple times. I think we have it a few other places too. And use slices.Equal in wgengine/router too. (found while looking for callers) Updates #cleanup Change-Id: If5350eee9b3ef071882a3db29a305081e4cd9d23 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
80 lines
2.1 KiB
Go
80 lines
2.1 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
|
|
// SPDX-License-Identifier: BSD-3-Clause
|
|
|
|
// Package slicesx contains some helpful generic slice functions.
|
|
package slicesx
|
|
|
|
import "math/rand"
|
|
|
|
// Interleave combines two slices of the form [a, b, c] and [x, y, z] into a
|
|
// slice with elements interleaved; i.e. [a, x, b, y, c, z].
|
|
func Interleave[S ~[]T, T any](a, b S) S {
|
|
// Avoid allocating an empty slice.
|
|
if a == nil && b == nil {
|
|
return nil
|
|
}
|
|
|
|
var (
|
|
i int
|
|
ret = make([]T, 0, len(a)+len(b))
|
|
)
|
|
for i = 0; i < len(a) && i < len(b); i++ {
|
|
ret = append(ret, a[i], b[i])
|
|
}
|
|
ret = append(ret, a[i:]...)
|
|
ret = append(ret, b[i:]...)
|
|
return ret
|
|
}
|
|
|
|
// Shuffle randomly shuffles a slice in-place, similar to rand.Shuffle.
|
|
func Shuffle[S ~[]T, T any](s S) {
|
|
// TODO(andrew): use a pooled Rand?
|
|
|
|
// This is the same Fisher-Yates shuffle implementation as rand.Shuffle
|
|
n := len(s)
|
|
i := n - 1
|
|
for ; i > 1<<31-1-1; i-- {
|
|
j := int(rand.Int63n(int64(i + 1)))
|
|
s[i], s[j] = s[j], s[i]
|
|
}
|
|
for ; i > 0; i-- {
|
|
j := int(rand.Int31n(int32(i + 1)))
|
|
s[i], s[j] = s[j], s[i]
|
|
}
|
|
}
|
|
|
|
// Partition returns two slices, the first containing the elements of the input
|
|
// slice for which the callback evaluates to true, the second containing the rest.
|
|
//
|
|
// This function does not mutate s.
|
|
func Partition[S ~[]T, T any](s S, cb func(T) bool) (trues, falses S) {
|
|
for _, elem := range s {
|
|
if cb(elem) {
|
|
trues = append(trues, elem)
|
|
} else {
|
|
falses = append(falses, elem)
|
|
}
|
|
}
|
|
return
|
|
}
|
|
|
|
// EqualSameNil reports whether two slices are equal: the same length, same
|
|
// nilness (notably when length zero), and all elements equal. If the lengths
|
|
// are different or their nilness differs, Equal returns false. Otherwise, the
|
|
// elements are compared in increasing index order, and the comparison stops at
|
|
// the first unequal pair. Floating point NaNs are not considered equal.
|
|
//
|
|
// It is identical to the standard library's slices.Equal but adds the matching
|
|
// nilness check.
|
|
func EqualSameNil[S ~[]E, E comparable](s1, s2 S) bool {
|
|
if len(s1) != len(s2) || (s1 == nil) != (s2 == nil) {
|
|
return false
|
|
}
|
|
for i := range s1 {
|
|
if s1[i] != s2[i] {
|
|
return false
|
|
}
|
|
}
|
|
return true
|
|
}
|