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|
package slices
import (
"golang.org/x/exp/constraints"
"golang.org/x/exp/slices"
)
// This file contains the new functions that do not live in the official slices package.
func Some[T any](slice []T, test func(T) bool) bool {
for _, value := range slice {
if test(value) {
return true
}
}
return false
}
func Every[T any](slice []T, test func(T) bool) bool {
for _, value := range slice {
if !test(value) {
return false
}
}
return true
}
// Produces a new slice, leaves the input slice untouched.
func Map[T any, V any](slice []T, f func(T) V) []V {
result := make([]V, 0, len(slice))
for _, value := range slice {
result = append(result, f(value))
}
return result
}
// Produces a new slice, leaves the input slice untouched.
func MapWithIndex[T any, V any](slice []T, f func(T, int) V) []V {
result := make([]V, 0, len(slice))
for i, value := range slice {
result = append(result, f(value, i))
}
return result
}
func TryMap[T any, V any](slice []T, f func(T) (V, error)) ([]V, error) {
result := make([]V, 0, len(slice))
for _, value := range slice {
output, err := f(value)
if err != nil {
return nil, err
}
result = append(result, output)
}
return result, nil
}
func TryMapWithIndex[T any, V any](slice []T, f func(T, int) (V, error)) ([]V, error) {
result := make([]V, 0, len(slice))
for i, value := range slice {
output, err := f(value, i)
if err != nil {
return nil, err
}
result = append(result, output)
}
return result, nil
}
// Produces a new slice, leaves the input slice untouched.
func FlatMap[T any, V any](slice []T, f func(T) []V) []V {
// impossible to know how long this slice will be in the end but the length
// of the original slice is the lower bound
result := make([]V, 0, len(slice))
for _, value := range slice {
result = append(result, f(value)...)
}
return result
}
func FlatMapWithIndex[T any, V any](slice []T, f func(T, int) []V) []V {
// impossible to know how long this slice will be in the end but the length
// of the original slice is the lower bound
result := make([]V, 0, len(slice))
for i, value := range slice {
result = append(result, f(value, i)...)
}
return result
}
func Flatten[T any](slice [][]T) []T {
result := make([]T, 0, len(slice))
for _, subSlice := range slice {
result = append(result, subSlice...)
}
return result
}
func MapInPlace[T any](slice []T, f func(T) T) {
for i, value := range slice {
slice[i] = f(value)
}
}
// Produces a new slice, leaves the input slice untouched.
func Filter[T any](slice []T, test func(T) bool) []T {
result := make([]T, 0)
for _, element := range slice {
if test(element) {
result = append(result, element)
}
}
return result
}
// Produces a new slice, leaves the input slice untouched.
func FilterWithIndex[T any](slice []T, f func(T, int) bool) []T {
result := make([]T, 0, len(slice))
for i, value := range slice {
if f(value, i) {
result = append(result, value)
}
}
return result
}
func TryFilter[T any](slice []T, test func(T) (bool, error)) ([]T, error) {
result := make([]T, 0)
for _, element := range slice {
ok, err := test(element)
if err != nil {
return nil, err
}
if ok {
result = append(result, element)
}
}
return result, nil
}
func TryFilterWithIndex[T any](slice []T, test func(T, int) (bool, error)) ([]T, error) {
result := make([]T, 0)
for i, element := range slice {
ok, err := test(element, i)
if err != nil {
return nil, err
}
if ok {
result = append(result, element)
}
}
return result, nil
}
// Mutates original slice. Intended usage is to reassign the slice result to the input slice.
func FilterInPlace[T any](slice []T, test func(T) bool) []T {
newLength := 0
for _, element := range slice {
if test(element) {
slice[newLength] = element
newLength++
}
}
return slice[:newLength]
}
// Produces a new slice, leaves the input slice untouched
func Reverse[T any](slice []T) []T {
result := make([]T, len(slice))
for i := range slice {
result[i] = slice[len(slice)-1-i]
}
return result
}
func ReverseInPlace[T any](slice []T) {
for i, j := 0, len(slice)-1; i < j; i, j = i+1, j-1 {
slice[i], slice[j] = slice[j], slice[i]
}
}
// Produces a new slice, leaves the input slice untouched.
func FilterMap[T any, E any](slice []T, test func(T) (E, bool)) []E {
result := make([]E, 0, len(slice))
for _, element := range slice {
mapped, ok := test(element)
if ok {
result = append(result, mapped)
}
}
return result
}
func FilterMapWithIndex[T any, E any](slice []T, test func(T, int) (E, bool)) []E {
result := make([]E, 0, len(slice))
for i, element := range slice {
mapped, ok := test(element, i)
if ok {
result = append(result, mapped)
}
}
return result
}
func TryFilterMap[T any, E any](slice []T, test func(T) (E, bool, error)) ([]E, error) {
result := make([]E, 0, len(slice))
for _, element := range slice {
mapped, ok, err := test(element)
if err != nil {
return nil, err
}
if ok {
result = append(result, mapped)
}
}
return result, nil
}
func TryFilterMapWithIndex[T any, E any](slice []T, test func(T, int) (E, bool, error)) ([]E, error) {
result := make([]E, 0, len(slice))
for i, element := range slice {
mapped, ok, err := test(element, i)
if err != nil {
return nil, err
}
if ok {
result = append(result, mapped)
}
}
return result, nil
}
// Prepends items to the beginning of a slice.
// E.g. Prepend([]int{1,2}, 3, 4) = []int{3,4,1,2}
// Mutates original slice. Intended usage is to reassign the slice result to the input slice.
func Prepend[T any](slice []T, values ...T) []T {
return append(values, slice...)
}
// Removes the element at the given index. Intended usage is to reassign the result to the input slice.
func Remove[T any](slice []T, index int) []T {
return slices.Delete(slice, index, index+1)
}
// Removes the element at the 'fromIndex' and then inserts it at 'toIndex'.
// Operates on the input slice. Expected use is to reassign the result to the input slice.
func Move[T any](slice []T, fromIndex int, toIndex int) []T {
item := slice[fromIndex]
slice = Remove(slice, fromIndex)
return slices.Insert(slice, toIndex, item)
}
// Swaps two elements at the given indices.
// Operates on the input slice.
func Swap[T any](slice []T, index1 int, index2 int) {
slice[index1], slice[index2] = slice[index2], slice[index1]
}
// Similar to Append but we leave the original slice untouched and return a new slice
func Concat[T any](slice []T, values ...T) []T {
newSlice := make([]T, 0, len(slice)+len(values))
newSlice = append(newSlice, slice...)
newSlice = append(newSlice, values...)
return newSlice
}
func ContainsFunc[T any](slice []T, f func(T) bool) bool {
return IndexFunc(slice, f) != -1
}
// Pops item from the end of the slice and returns it, along with the updated slice
// Mutates original slice. Intended usage is to reassign the slice result to the input slice.
func Pop[T any](slice []T) (T, []T) {
index := len(slice) - 1
value := slice[index]
slice = slice[0:index]
return value, slice
}
// Shifts item from the beginning of the slice and returns it, along with the updated slice.
// Mutates original slice. Intended usage is to reassign the slice result to the input slice.
func Shift[T any](slice []T) (T, []T) {
value := slice[0]
slice = slice[1:]
return value, slice
}
func Partition[T any](slice []T, test func(T) bool) ([]T, []T) {
left := make([]T, 0, len(slice))
right := make([]T, 0, len(slice))
for _, value := range slice {
if test(value) {
left = append(left, value)
} else {
right = append(right, value)
}
}
return left, right
}
func MaxBy[T any, V constraints.Ordered](slice []T, f func(T) V) V {
if len(slice) == 0 {
return zero[V]()
}
max := f(slice[0])
for _, element := range slice[1:] {
value := f(element)
if value > max {
max = value
}
}
return max
}
func MinBy[T any, V constraints.Ordered](slice []T, f func(T) V) V {
if len(slice) == 0 {
return zero[V]()
}
min := f(slice[0])
for _, element := range slice[1:] {
value := f(element)
if value < min {
min = value
}
}
return min
}
func Find[T any](slice []T, f func(T) bool) (T, bool) {
for _, element := range slice {
if f(element) {
return element, true
}
}
return zero[T](), false
}
// Sometimes you need to find an element and then map it to some other value based on
// information you obtained while finding it. This function lets you do that
func FindMap[T any, V any](slice []T, f func(T) (V, bool)) (V, bool) {
for _, element := range slice {
if value, ok := f(element); ok {
return value, true
}
}
return zero[V](), false
}
func ForEach[T any](slice []T, f func(T)) {
for _, element := range slice {
f(element)
}
}
func ForEachWithIndex[T any](slice []T, f func(T, int)) {
for i, element := range slice {
f(element, i)
}
}
func TryForEach[T any](slice []T, f func(T) error) error {
for _, element := range slice {
if err := f(element); err != nil {
return err
}
}
return nil
}
func TryForEachWithIndex[T any](slice []T, f func(T, int) error) error {
for i, element := range slice {
if err := f(element, i); err != nil {
return err
}
}
return nil
}
func Sum[T constraints.Ordered](i []T) T {
sum := zero[T]()
for _, value := range i {
sum += value
}
return sum
}
func zero[T any]() T {
var value T
return value
}
|
