1// Copyright 2017 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package sort
6
7import (
8	"internal/reflectlite"
9	"math/bits"
10)
11
12// Slice sorts the slice x given the provided less function.
13// It panics if x is not a slice.
14//
15// The sort is not guaranteed to be stable: equal elements
16// may be reversed from their original order.
17// For a stable sort, use [SliceStable].
18//
19// The less function must satisfy the same requirements as
20// the Interface type's Less method.
21//
22// Note: in many situations, the newer [slices.SortFunc] function is more
23// ergonomic and runs faster.
24func Slice(x any, less func(i, j int) bool) {
25	rv := reflectlite.ValueOf(x)
26	swap := reflectlite.Swapper(x)
27	length := rv.Len()
28	limit := bits.Len(uint(length))
29	pdqsort_func(lessSwap{less, swap}, 0, length, limit)
30}
31
32// SliceStable sorts the slice x using the provided less
33// function, keeping equal elements in their original order.
34// It panics if x is not a slice.
35//
36// The less function must satisfy the same requirements as
37// the Interface type's Less method.
38//
39// Note: in many situations, the newer [slices.SortStableFunc] function is more
40// ergonomic and runs faster.
41func SliceStable(x any, less func(i, j int) bool) {
42	rv := reflectlite.ValueOf(x)
43	swap := reflectlite.Swapper(x)
44	stable_func(lessSwap{less, swap}, rv.Len())
45}
46
47// SliceIsSorted reports whether the slice x is sorted according to the provided less function.
48// It panics if x is not a slice.
49//
50// Note: in many situations, the newer [slices.IsSortedFunc] function is more
51// ergonomic and runs faster.
52func SliceIsSorted(x any, less func(i, j int) bool) bool {
53	rv := reflectlite.ValueOf(x)
54	n := rv.Len()
55	for i := n - 1; i > 0; i-- {
56		if less(i, i-1) {
57			return false
58		}
59	}
60	return true
61}
62