168 lines
3.0 KiB
Go
168 lines
3.0 KiB
Go
// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
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package utils
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import (
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"fmt"
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"sort"
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"golang.org/x/exp/constraints"
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"golang.org/x/exp/slices"
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)
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var _ = fmt.Print
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func Reverse[T any](s []T) []T {
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for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
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s[i], s[j] = s[j], s[i]
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}
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return s
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}
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func Reversed[T any](s []T) []T {
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ans := make([]T, len(s))
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for i, x := range s {
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ans[len(s)-1-i] = x
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}
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return ans
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}
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func Remove[T comparable](s []T, q T) []T {
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idx := slices.Index(s, q)
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if idx > -1 {
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return slices.Delete(s, idx, idx+1)
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}
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return s
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}
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func RemoveAll[T comparable](s []T, q T) []T {
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ans := s
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for {
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idx := slices.Index(ans, q)
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if idx < 0 {
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break
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}
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ans = slices.Delete(ans, idx, idx+1)
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}
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return ans
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}
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func Filter[T any](s []T, f func(x T) bool) []T {
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ans := make([]T, 0, len(s))
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for _, x := range s {
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if f(x) {
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ans = append(ans, x)
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}
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}
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return ans
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}
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func Sort[T any](s []T, less func(a, b T) bool) []T {
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sort.Slice(s, func(i, j int) bool { return less(s[i], s[j]) })
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return s
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}
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func StableSort[T any](s []T, less func(a, b T) bool) []T {
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sort.SliceStable(s, func(i, j int) bool { return less(s[i], s[j]) })
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return s
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}
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func SortWithKey[T any, C constraints.Ordered](s []T, key func(a T) C) []T {
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mem := make([]C, len(s))
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for i, x := range s {
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mem[i] = key(x)
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}
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sort.Slice(s, func(i, j int) bool { return mem[i] < mem[j] })
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return s
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}
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func StableSortWithKey[T any, C constraints.Ordered](s []T, key func(a T) C) []T {
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mem := make([]C, len(s))
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for i, x := range s {
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mem[i] = key(x)
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}
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sort.SliceStable(s, func(i, j int) bool { return mem[i] < mem[j] })
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return s
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}
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func Max[T constraints.Ordered](a T, items ...T) (ans T) {
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ans = a
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for _, q := range items {
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if q > ans {
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ans = q
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}
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}
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return ans
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}
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func Min[T constraints.Ordered](a T, items ...T) (ans T) {
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ans = a
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for _, q := range items {
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if q < ans {
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ans = q
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}
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}
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return ans
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}
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func Index[T comparable](haystack []T, needle T) int {
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for i, x := range haystack {
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if x == needle {
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return i
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}
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}
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return -1
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}
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func Contains[T comparable](haystack []T, needle T) bool {
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return Index(haystack, needle) > -1
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}
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// Keys returns the keys of the map m.
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// The keys will be an indeterminate order.
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func Keys[M ~map[K]V, K comparable, V any](m M) []K {
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r := make([]K, len(m))
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i := 0
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for k := range m {
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r[i] = k
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i++
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}
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return r
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}
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// Values returns the values of the map m.
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// The values will be an indeterminate order.
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func Values[M ~map[K]V, K comparable, V any](m M) []V {
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r := make([]V, len(m))
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i := 0
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for _, v := range m {
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r[i] = v
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i++
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}
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return r
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}
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func Memset[T any](dest []T, pattern ...T) []T {
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if len(pattern) == 0 {
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var zero T
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switch any(zero).(type) {
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case byte: // special case this as the compiler can generate efficient code for memset of a byte slice to zero
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bd := any(dest).([]byte)
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for i := range bd {
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bd[i] = 0
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}
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default:
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for i := range dest {
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dest[i] = zero
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}
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}
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return dest
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}
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bp := copy(dest, pattern)
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for bp < len(dest) {
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copy(dest[bp:], dest[:bp])
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bp *= 2
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}
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return dest
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}
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