# Maputil

Package maputil includes some functions to manipulate map.

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## Source:

-   [https://github.com/duke-git/lancet/blob/main/maputil/map.go](https://github.com/duke-git/lancet/blob/main/maputil/map.go)

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## Example:

```go
import (
    "github.com/duke-git/lancet/v2/maputil"
)
```

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## Index

-   [MapTo](#MapTo)
-   [ForEach](#ForEach)
-   [Filter](#Filter)
-   [FilterByKeys](#FilterByKeys)
-   [FilterByValues](#FilterByValues)
-   [OmitBy](#OmitBy)
-   [OmitByKeys](#OmitByKeys)
-   [OmitByValues](#OmitByValues)
-   [Intersect](#Intersect)
-   [Keys](#Keys)
-   [Values](#Values)
-   [KeysBy](#KeysBy)
-   [ValuesBy](#ValuesBy)
-   [MapKeys](#MapKeys)
-   [MapValues](#MapValues)
-   [Entries](#Entries)
-   [FromEntries](#FromEntries)
-   [Transform](#Transform)
-   [Merge](#Merge)
-   [Minus](#Minus)
-   [IsDisjoint](#IsDisjoint)
-   [HasKey](#HasKey)
-   [ToSortedSlicesDefault](#ToSortedSlicesDefault)
-   [ToSortedSlicesWithComparator](#ToSortedSlicesWithComparator)
-   [NewConcurrentMap](#NewConcurrentMap)
-   [ConcurrentMap_Get](#ConcurrentMap_Get)
-   [ConcurrentMap_Set](#ConcurrentMap_Set)
-   [ConcurrentMap_GetOrSet](#ConcurrentMap_GetOrSet)
-   [ConcurrentMap_Delete](#ConcurrentMap_Delete)
-   [ConcurrentMap_GetAndDelete](#ConcurrentMap_GetAndDelete)
-   [ConcurrentMap_Has](#ConcurrentMap_Has)
-   [ConcurrentMap_Range](#ConcurrentMap_Range)

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## Documentation

### <span id="MapTo">MapTo</span>

<p>Rry to map any interface to struct or base type.</p>

<b>Signature:</b>

```go
func MapTo(src any, dst any) error
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/4K7KBEPgS5M)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    type (
        Person struct {
            Name  string  `json:"name"`
            Age   int     `json:"age"`
            Phone string  `json:"phone"`
            Addr  Address `json:"address"`
        }

        Address struct {
            Street string `json:"street"`
            Number int    `json:"number"`
        }
    )

    personInfo := map[string]interface{}{
        "name":  "Nothin",
        "age":   28,
        "phone": "123456789",
        "address": map[string]interface{}{
            "street": "test",
            "number": 1,
        },
    }

    var p Person
    err := MapTo(personInfo, &p)

    fmt.Println(err)
    fmt.Println(p)

    // Output:
    // <nil>
    // {Nothin 28 123456789 {test 1}}
}
```

### <span id="ForEach">ForEach</span>

<p>Executes iteratee funcation for every key and value pair in map.</p>

<b>Signature:</b>

```go
func ForEach[K comparable, V any](m map[K]V, iteratee func(key K, value V))
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/OaThj6iNVXK)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
    }

    var sum int

    maputil.ForEach(m, func(_ string, value int) {
        sum += value
    })

    fmt.Println(sum)

    // Output:
    // 10
}
```

### <span id="Filter">Filter</span>

<p>Iterates over map, return a new map contains all key and value pairs pass the predicate function.</p>

<b>Signature:</b>

```go
func Filter[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/fSvF3wxuNG7)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
        "e": 5,
    }
    isEven := func(_ string, value int) bool {
        return value%2 == 0
    }

    maputil.Filter(m, func(_ string, value int) {
        sum += value
    })

    result := maputil.Filter(m, isEven)

    fmt.Println(result)

    // Output:
    // map[b:2 d:4]
}
```

### <span id="FilterByKeys">FilterByKeys</span>

<p>Iterates over map, return a new map whose keys are all given keys.</p>

<b>Signature:</b>

```go
func FilterByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/7ov6BJHbVqh)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
        "e": 5,
    }

    result := maputil.FilterByKeys(m, []string{"a", "b"})

    fmt.Println(result)

    // Output:
    // map[a:1 b:2]
}
```

### <span id="FilterByValues">FilterByValues</span>

<p>Iterates over map, return a new map whose values are all given values.</p>

<b>Signature:</b>

```go
func FilterByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/P3-9MdcXegR)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
        "e": 5,
    }

    result := maputil.FilterByValues(m, []int{3, 4})

    fmt.Println(result)

    // Output:
    // map[c:3 d:4]
}
```

### <span id="OmitBy">OmitBy</span>

<p>OmitBy is the opposite of Filter, removes all the map elements for which the predicate function returns true.</p>

<b>Signature:</b>

```go
func OmitBy[K comparable, V any](m map[K]V, predicate func(key K, value V) bool) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/YJM4Hj5hNwm)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
        "e": 5,
    }
    isEven := func(_ string, value int) bool {
        return value%2 == 0
    }

    result := maputil.OmitBy(m, isEven)

    fmt.Println(result)

    // Output:
    // map[a:1 c:3 e:5]
}
```

### <span id="OmitByKeys">OmitByKeys</span>

<p>The opposite of FilterByKeys, extracts all the map elements which keys are not omitted.</p>

<b>Signature:</b>

```go
func OmitByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/jXGrWDBfSRp)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
        "e": 5,
    }

    result := maputil.OmitByKeys(m, []string{"a", "b"})

    fmt.Println(result)

    // Output:
    // map[c:3 d:4 e:5]
}
```

### <span id="OmitByValues">OmitByValues</span>

<p>The opposite of FilterByValues. remov all elements whose value are in the give slice.</p>

<b>Signature:</b>

```go
func OmitByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/XB7Y10uw20_U)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
        "d": 4,
        "e": 5,
    }

    result := maputil.OmitByValues(m, []int{4, 5})

    fmt.Println(result)

    // Output:
    // map[a:1 b:2 c:3]
}
```

### <span id="Intersect">Intersect</span>

<p>Iterates over maps, return a new map of key and value pairs in all given maps.</p>

<b>Signature:</b>

```go
func Intersect[K comparable, V any](maps ...map[K]V) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/Zld0oj3sjcC)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m1 := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    m2 := map[string]int{
        "a": 1,
        "b": 2,
        "c": 6,
        "d": 7,
    }

    m3 := map[string]int{
        "a": 1,
        "b": 9,
        "e": 9,
    }

    result1 := maputil.Intersect(m1)
    result2 := maputil.Intersect(m1, m2)
    result3 := maputil.Intersect(m1, m2, m3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // map[a:1 b:2 c:3]
    // map[a:1 b:2]
    // map[a:1]
}
```

### <span id="Keys">Keys</span>

<p>Returns a slice of the map's keys.</p>

<b>Signature:</b>

```go
func Keys[K comparable, V any](m map[K]V) []K
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/xNB5bTb97Wd)</span></b>

```go
package main

import (
    "fmt"
    "sort"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[int]string{
        1: "a",
        2: "a",
        3: "b",
        4: "c",
        5: "d",
    }

    keys := maputil.Keys(m)
    sort.Ints(keys)

    fmt.Println(keys)

    // Output:
    // [1 2 3 4 5]
}
```

### <span id="Merge">Merge</span>

<p>Merge maps, next key will overwrite previous key.</p>

<b>Signature:</b>

```go
func Merge[K comparable, V any](maps ...map[K]V) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/H95LENF1uB-)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m1 := map[int]string{
        1: "a",
        2: "b",
    }
    m2 := map[int]string{
        1: "1",
        3: "2",
    }

    result := maputil.Merge(m1, m2)

    fmt.Println(result)

    // Output:
    // map[1:c 2:b 3:d]
}
```

### <span id="Minus">Minus</span>

<p>Creates an map of whose key in mapA but not in mapB.</p>

<b>Signature:</b>

```go
func Minus[K comparable, V any](mapA, mapB map[K]V) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/3u5U9K7YZ9m)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m1 := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    m2 := map[string]int{
        "a": 11,
        "b": 22,
        "d": 33,
    }

    result := maputil.Minus(m1, m2)

    fmt.Println(result)

    // Output:
    // map[c:3]
}
```

### <span id="Values">Values</span>

<p>Returns a slice of the map's values.</p>

<b>Signature:</b>

```go
func Values[K comparable, V any](m map[K]V) []V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/CBKdUc5FTW6)</span></b>

```go
package main

import (
    "fmt"
    "sort"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[int]string{
        1: "a",
        2: "a",
        3: "b",
        4: "c",
        5: "d",
    }

    values := maputil.Values(m)
    sort.Strings(values)

    fmt.Println(values)

    // Output:
    // [a a b c d]
}
```

### <span id="KeysBy">KeysBy</span>

<p>Creates a slice whose element is the result of function mapper invoked by every map's key.</p>

<b>Signature:</b>

```go
func KeysBy[K comparable, V any, T any](m map[K]V, mapper func(item K) T) []T
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/hI371iB8Up8)</span></b>

```go
package main

import (
    "fmt"
    "sort"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[int]string{
        1: "a",
        2: "a",
        3: "b",
    }

    keys := maputil.KeysBy(m, func(n int) int {
        return n + 1
    })

    sort.Ints(keys)

    fmt.Println(keys)

    // Output:
    // [2 3 4]
}
```

### <span id="ValuesBy">ValuesBy</span>

<p>Creates a slice whose element is the result of function mapper invoked by every map's value.</p>

<b>Signature:</b>

```go
func ValuesBy[K comparable, V any, T any](m map[K]V, mapper func(item V) T) []T
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/sg9-oRidh8f)</span></b>

```go
package main

import (
    "fmt"
    "sort"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[int]string{
        1: "a",
        2: "b",
        3: "c",
    }
    values := maputil.ValuesBy(m, func(v string) string {
        switch v {
        case "a":
            return "a-1"
        case "b":
            return "b-2"
        case "c":
            return "c-3"
        default:
            return ""
        }
    })

    sort.Strings(values)

    fmt.Println(values)

    // Output:
    // [a-1 b-2 c-3]
}
```

### <span id="MapKeys">MapKeys</span>

<p>Transforms a map to other type map by manipulating it's keys.</p>

<b>Signature:</b>

```go
func MapKeys[K comparable, V any, T comparable](m map[K]V, iteratee func(key K, value V) T) map[T]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/8scDxWeBDKd)</span></b>

```go
package main

import (
    "fmt"
    "strconv"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[int]string{
        1: "a",
        2: "b",
        3: "c",
    }

    result := maputil.MapKeys(m, func(k int, _ string) string {
        return strconv.Itoa(k)
    })

    fmt.Println(result)

    // Output:
    // map[1:a 2:b 3:c]
}
```

### <span id="MapValues">MapValues</span>

<p>Transforms a map to other type map by manipulating it's values.</p>

<b>Signature:</b>

```go
func MapValues[K comparable, V any, T any](m map[K]V, iteratee func(key K, value V) T) map[K]T
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/g92aY3fc7Iw)</span></b>

```go
package main

import (
    "fmt"
    "strconv"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[int]string{
        1: "a",
        2: "b",
        3: "c",
    }

    result := maputil.MapValues(m, func(k int, v string) string {
        return v + strconv.Itoa(k)
    })

    fmt.Println(result)

    // Output:
    // map[1:a1 2:b2 3:c3]
}
```

### <span id="Entry">Entry</span>

<p>Transforms a map into array of key/value pairs.</p>

<b>Signature:</b>

```go
type Entry[K comparable, V any] struct {
    Key   K
    Value V
}
func Entries[K comparable, V any](m map[K]V) []Entry[K, V]
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/Ltb11LNcElY)</span></b>

```go
package main

import (
    "fmt"
    "sort"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    result := maputil.Entries(m)

    sort.Slice(result, func(i, j int) bool {
        return result[i].Value < result[j].Value
    })

    fmt.Println(result)

    // Output:
    // [{a 1} {b 2} {c 3}]
}
```

### <span id="FromEntries">FromEntries</span>

<p>Creates a map based on a slice of key/value pairs.</p>

<b>Signature:</b>

```go
type Entry[K comparable, V any] struct {
    Key   K
    Value V
}
func FromEntries[K comparable, V any](entries []Entry[K, V]) map[K]V
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/fTdu4sCNjQO)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    result := maputil.FromEntries([]Entry[string, int]{
        {Key: "a", Value: 1},
        {Key: "b", Value: 2},
        {Key: "c", Value: 3},
    })

    fmt.Println(result)

    // Output:
    // map[a:1 b:2 c:3]
}
```

### <span id="Transform">Transform</span>

<p>Transform a map to another type map.</p>

<b>Signature:</b>

```go
func Transform[K1 comparable, V1 any, K2 comparable, V2 any](m map[K1]V1, iteratee func(key K1, value V1) (K2, V2)) map[K2]V2
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/P6ovfToM3zj)</span></b>

```go
package main

import (
    "fmt"
    "strconv"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    result := Transform(m, func(k string, v int) (string, string) {
        return k, strconv.Itoa(v)
    })

    fmt.Println(result)

    // Output:
    // map[a:1 b:2 c:3]
}
```

### <span id="IsDisjoint">IsDisjoint</span>

<p>Checks two maps are disjoint if they have no keys in common.</p>

<b>Signature:</b>

```go
func IsDisjoint[K comparable, V any](mapA, mapB map[K]V) bool
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/N9qgYg_Ho6f)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m1 := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    m2 := map[string]int{
        "d": 22,
    }

    m3 := map[string]int{
        "a": 22,
    }

    result1 := maputil.IsDisjoint(m1, m2)
    result2 := maputil.IsDisjoint(m1, m3)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // true
    // false
}
```

### <span id="HasKey">HasKey</span>

<p>Checks if map has key or not. This function is used to replace the following boilerplate code:</p>

```go
_, haskey := amap["baz"];

if haskey {
    fmt.Println("map has key baz")
}
```

<b>Signature:</b>

```go
func HasKey[K comparable, V any](m map[K]V, key K) bool
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/isZZHOsDhFc)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[string]int{
        "a": 1,
        "b": 2,
    }

    result1 := maputil.HasKey(m, "a")
    result2 := maputil.HasKey(m, "c")

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // true
    // false
}
```

### <span id="ToSortedSlicesDefault">ToSortedSlicesDefault</span>

<p>
Translate the key and value of the map into two slices that are sorted in ascending order according to the key’s value, with the position of the elements in the value slice corresponding to the key.</p>

<b>Signature:</b>

```go
func ToSortedSlicesDefault[K constraints.Ordered, V any](m map[K]V) ([]K, []V)
```

<b>Example:<span style="float:right;display:inline-block;">[Run](Todo)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m := map[int]string{
		1: "a",
		3: "c",
		2: "b",
	}

	keys, values := ToSortedSlicesDefault(m)

	fmt.Println(keys)
	fmt.Println(values)

	// Output:
	// [1 2 3]
	// [a b c]
}
```

### <span id="ToSortedSlicesWithComparator">ToSortedSlicesWithComparator</span>

<p>
Translate the key and value of the map into two slices that are sorted according to a custom sorting rule defined by a comparator function based on the key's value, with the position of the elements in the value slice corresponding to the key.
</p>

<b>Signature:</b>

```go
func ToSortedSlicesWithComparator[K comparable, V any](m map[K]V, comparator func(a, b K) bool) ([]K, []V) 
```

<b>Example:<span style="float:right;display:inline-block;">[Run](Todo)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    m1 := map[time.Time]string{
		time.Date(2024, 3, 31, 0, 0, 0, 0, time.UTC): "today",
		time.Date(2024, 3, 30, 0, 0, 0, 0, time.UTC): "yesterday",
		time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC):  "tomorrow",
	}

	keys1, values1 := ToSortedSlicesWithComparator(m1, func(a, b time.Time) bool {
		return a.Before(b)
	})

	m2 := map[int]string{
		1: "a",
		3: "c",
		2: "b",
	}
	keys2, values2 := ToSortedSlicesWithComparator(m2, func(a, b int) bool {
		return a > b
	})

	fmt.Println(keys2)
	fmt.Println(values2)

	fmt.Println(keys1)
	fmt.Println(values1)

	// Output:
	// [2024-03-30 00:00:00 +0000 UTC 2024-03-31 00:00:00 +0000 UTC 2024-04-01 00:00:00 +0000 UTC]
	// [yesterday today tomorrow]
	// [3 2 1]
	// [c b a]
}
```

### <span id="NewConcurrentMap">NewConcurrentMap</span>

<p>ConcurrentMap is like map, but is safe for concurrent use by multiple goroutines.</p>

<b>Signature:</b>

```go
// NewConcurrentMap create a ConcurrentMap with specific shard count.
func NewConcurrentMap[K comparable, V any](shardCount int) *ConcurrentMap[K, V]
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/3PenTPETJT0)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    // create a ConcurrentMap whose key type is string, value type is int
    cm := maputil.NewConcurrentMap[string, int](100)
}
```

### <span id="ConcurrentMap_Set">ConcurrentMap_Set</span>

<p>Set the value for a key.</p>

<b>Signature:</b>

```go
func (cm *ConcurrentMap[K, V]) Set(key K, value V)
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/3PenTPETJT0)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    cm := maputil.NewConcurrentMap[string, int](100)

    var wg1 sync.WaitGroup
    wg1.Add(5)

    for i := 0; i < 5; i++ {
        go func(n int) {
            cm.Set(fmt.Sprintf("%d", n), n)
            wg1.Done()
        }(i)
    }
    wg1.Wait()


    var wg2 sync.WaitGroup
	wg2.Add(5)
	for j := 0; j < 5; j++ {
		go func(n int) {
			val, ok := cm.Get(fmt.Sprintf("%d", n))
			fmt.Println(val, ok)
			wg2.Done()
		}(j)
	}
	wg2.Wait()

    // output: (order may change)
    // 1 true
    // 3 true
    // 2 true
    // 0 true
    // 4 true
}
```

### <span id="ConcurrentMap_Get">ConcurrentMap_Get</span>

<p>Get the value stored in the map for a key, or nil if no.</p>

<b>Signature:</b>

```go
func (cm *ConcurrentMap[K, V]) Get(key K) (V, bool)
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/3PenTPETJT0)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    cm := maputil.NewConcurrentMap[string, int](100)

    var wg1 sync.WaitGroup
    wg1.Add(5)

    for i := 0; i < 5; i++ {
        go func(n int) {
            cm.Set(fmt.Sprintf("%d", n), n)
            wg1.Done()
        }(i)
    }
    wg1.Wait()


    var wg2 sync.WaitGroup
	wg2.Add(5)
	for j := 0; j < 5; j++ {
		go func(n int) {
			val, ok := cm.Get(fmt.Sprintf("%d", n))
			fmt.Println(val, ok)
			wg2.Done()
		}(j)
	}
	wg2.Wait()

    // output: (order may change)
    // 1 true
    // 3 true
    // 2 true
    // 0 true
    // 4 true
}
```

### <span id="ConcurrentMap_GetOrSet">ConcurrentMap_GetOrSet</span>

<p>Returns the existing value for the key if present. Otherwise, it sets and returns the given value.</p>

<b>Signature:</b>

```go
func (cm *ConcurrentMap[K, V]) GetOrSet(key K, value V) (actual V, ok bool)
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/aDcDApOK01a)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    cm := maputil.NewConcurrentMap[string, int](100)

    var wg sync.WaitGroup
    wg.Add(5)

    for i := 0; i < 5; i++ {
        go func(n int) {
            val, ok := cm.GetOrSet(fmt.Sprintf("%d", n), n)
            fmt.Println(val, ok)
            wg.Done()
        }(i)
    }
    wg.Wait()

    // output: (order may change)
    // 1 false
    // 3 false
    // 2 false
    // 0 false
    // 4 false
}
```

### <span id="ConcurrentMap_Delete">ConcurrentMap_Delete</span>

<p>Delete the value for a key.</p>

<b>Signature:</b>

```go
func (cm *ConcurrentMap[K, V]) Delete(key K)
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/uTIJZYhpVMS)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    cm := maputil.NewConcurrentMap[string, int](100)

    var wg1 sync.WaitGroup
    wg1.Add(5)

    for i := 0; i < 5; i++ {
        go func(n int) {
            cm.Set(fmt.Sprintf("%d", n), n)
            wg1.Done()
        }(i)
    }
    wg1.Wait()

    var wg2 sync.WaitGroup
	wg2.Add(5)
    for j := 0; j < 5; j++ {
        go func(n int) {
            cm.Delete(fmt.Sprintf("%d", n))
            wg2.Done()
        }(j)
    }

    wg2.Wait()
}
```

### <span id="ConcurrentMap_GetAndDelete">ConcurrentMap_GetAndDelete</span>

<p>Returns the existing value for the key if present and then delete the value for the key. Otherwise, do nothing, just return false.</p>

<b>Signature:</b>

```go
func (cm *ConcurrentMap[K, V]) GetAndDelete(key K) (actual V, ok bool)
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/ZyxeIXSZUiM)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    cm := maputil.NewConcurrentMap[string, int](100)

    var wg1 sync.WaitGroup
    wg1.Add(5)

    for i := 0; i < 5; i++ {
        go func(n int) {
            cm.Set(fmt.Sprintf("%d", n), n)
            wg1.Done()
        }(i)
    }
    wg1.Wait()

    var wg2 sync.WaitGroup
	wg2.Add(5)
    for j := 0; j < 5; j++ {
        go func(n int) {
            val, ok := cm.GetAndDelete(fmt.Sprintf("%d", n))
            fmt.Println(val, ok) //n, true

            _, ok = cm.Get(fmt.Sprintf("%d", n))
            fmt.Println(val, ok) //false

            wg2.Done()
        }(j)
    }

    wg2.Wait()
}
```

### <span id="ConcurrentMap_Has">ConcurrentMap_Has</span>

<p>Checks if map has the value for a key.</p>

<b>Signature:</b>

```go
func (cm *ConcurrentMap[K, V]) Has(key K) bool
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/C8L4ul9TVwf)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    cm := maputil.NewConcurrentMap[string, int](100)

    var wg1 sync.WaitGroup
    wg1.Add(5)

    for i := 0; i < 5; i++ {
        go func(n int) {
            cm.Set(fmt.Sprintf("%d", n), n)
            wg1.Done()
        }(i)
    }
    wg1.Wait()

    var wg2 sync.WaitGroup
	wg2.Add(5)
    for j := 0; j < 5; j++ {
        go func(n int) {
            ok := cm.Has(fmt.Sprintf("%d", n))
            fmt.Println(ok) // true
            wg2.Done()
        }(j)
    }
    wg2.Wait()
}
```

### <span id="ConcurrentMap_Range">ConcurrentMap_Range</span>

<p>Calls iterator sequentially for each key and value present in each of the shards in the map. If iterator returns false, range stops the iteration.</p>

<b>Signature:</b>

```go
func (cm *ConcurrentMap[K, V]) Range(iterator func(key K, value V) bool)
```

<b>Example:<span style="float:right;display:inline-block;">[Run](https://go.dev/play/p/iqcy7P8P0Pr)</span></b>

```go
package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/maputil"
)

func main() {
    cm := maputil.NewConcurrentMap[string, int](100)

    var wg1 sync.WaitGroup
    wg1.Add(5)

    for i := 0; i < 5; i++ {
        go func(n int) {
            cm.Set(fmt.Sprintf("%d", n), n)
            wg1.Done()
        }(i)
    }
    wg1.Wait()


    cm.Range(func(key string, value int) bool {
        fmt.Println(value)
        return true
    })
}
```