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//
// Copyright 2022 The Sigstore Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ntpmonitor
import (
"math/rand"
)
// RandomChoice returns a random selection of n items from the slice s.
// The choice is made using a PSEUDO RANDOM selection.
// If n is greater than len(s), an empty slice is returned.
func RandomChoice[T any](s []T, n int, r *rand.Rand) []T {
if n > len(s) || n < 1 {
return []T{}
}
if n == len(s) {
return s
}
var indices = make([]int, len(s))
var result = make([]T, 0, n)
for i := range s {
indices[i] = i
}
for {
// The use of deterministic (pseudo) random generators are
// ok for this use-case.
//nolint:gosec
i := r.Intn(len(indices))
result = append(result, s[indices[i]])
if len(result) == n {
break
}
indices = append(indices[:i], indices[i+1:]...)
}
return result
}
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