maputil

Documentation

Overview

Package maputil provides a collection of map utility functions.

Index

• func Filter[M ~map[K]V, K comparable, V any](m M, f func(K, V) bool) M
• func Invert[M ~map[K]V, K, V comparable](m M) map[V]K
• func Map[M ~map[K]V, K, J comparable, V, U any](m M, f func(K, V) (J, U)) map[J]U
• func Reduce[M ~map[K]V, K comparable, V, U any](m M, init U, f func(K, V, U) U) U

Examples

• Filter
• Invert
• Map
• Reduce

Functions

func Filter

func Filter[M ~map[K]V, K comparable, V any](m M, f func(K, V) bool) M

Filter returns a new map containing only the elements in the input map m for which the specified function f is true.

Example

package main

import (
	"fmt"

	"github.com/Vonage/gosrvlib/pkg/maputil"
)

func main() {
	m := map[int]string{0: "Hello", 1: "World"}

	filterFn := func(_ int, v string) bool { return v == "World" }

	s2 := maputil.Filter(m, filterFn)

	fmt.Println(s2)

}

Output:

map[1:World]

func Invert

func Invert[M ~map[K]V, K, V comparable](m M) map[V]K

Invert returns a new map were keys and values are swapped.

Example

package main

import (
	"fmt"

	"github.com/Vonage/gosrvlib/pkg/maputil"
)

func main() {
	m := map[int]int{1: 10, 2: 20}

	s2 := maputil.Invert(m)

	fmt.Println(s2)

}

Output:

map[10:1 20:2]

func Map

func Map[M ~map[K]V, K, J comparable, V, U any](m M, f func(K, V) (J, U)) map[J]U

Map returns a new map that contains each of the elements of the input map m mutated by the specified function.

Example

package main

import (
	"fmt"

	"github.com/Vonage/gosrvlib/pkg/maputil"
)

func main() {
	m := map[int]string{0: "Hello", 1: "World"}

	mapFn := func(k int, v string) (string, int) { return "_" + v, k + 1 }

	s2 := maputil.Map(m, mapFn)

	fmt.Println(s2)

}

Output:

map[_Hello:1 _World:2]

func Reduce

func Reduce[M ~map[K]V, K comparable, V, U any](m M, init U, f func(K, V, U) U) U

Reduce applies the reducing function f to each element of the input map m, and returns the value of the last call to f. The first parameter of the reducing function f is initialized with init.

Example

package main

import (
	"fmt"

	"github.com/Vonage/gosrvlib/pkg/maputil"
)

func main() {
	m := map[int]int{0: 2, 1: 3, 2: 5, 3: 7, 4: 11}
	init := 97
	reduceFn := func(k, v, r int) int { return k + v + r }

	r := maputil.Reduce(m, init, reduceFn)

	fmt.Println(r)

}

Output:

135