defaultmap

README

defaultmap

A map that supports default values.

Basic Example

import (
	"fmt"

	"github.com/spenserblack/go-defaultmap"
)

m := defaultmap.NewMap[string](func() string { return "I'm the default!" })
m.Insert("exists", "Hello, World!")

fmt.Println(m.Get("exists")) // Hello, World!
fmt.Println(m.Get("doesn't exist")) // I'm the default!
fmt.Println(m.GetOr("also doesn't exist", "I'm a one-time default!")) // I'm a one-time default!

Documentation

Index

• type DefaultFactory
• type Map
  • func NewMap[K comparable, V any](factory DefaultFactory[V]) Map[K, V]
  • func (m Map[K, V]) Contains(key K) bool
  • func (m Map[K, V]) Delete(key K)
  • func (m Map[K, V]) Get(key K) V
  • func (m Map[K, V]) GetOr(key K, defaultValue V) V
  • func (m Map[K, V]) Insert(key K, value V)

Examples

• Map
• Map.Contains
• Map.Get
• Map.GetOr

Types

type DefaultFactory

type DefaultFactory[D any] func() D

DefaultFactory generates default values to be used with the Map.

type Map

type Map[K comparable, V any] struct {
	// contains filtered or unexported fields
}

Map will return a set default when attempting to get a value that wasn't inserted.

Example

m := defaultmap.NewMap[string](func() string { return "I'm the default!" })
m.Insert("exists", "Hello, World!")

fmt.Println(m.Get("exists"))
fmt.Println(m.Get("doesn't exist"))
fmt.Println(m.GetOr("also doesn't exist", "I'm a one-time default!"))

Output:

Hello, World!
I'm the default!
I'm a one-time default!

func NewMap

func NewMap[K comparable, V any](factory DefaultFactory[V]) Map[K, V]

NewMap generates a new map with that returns default values for keys that have not been set.

func (Map[K, V]) Contains

func (m Map[K, V]) Contains(key K) bool

Contains checks if the key exists in the map without creating a key-value pair using the DefaultFactory.

Example

m := defaultmap.NewMap[string](func() string { return "I'm the default!" })
m.Insert("exists", "Hello, World!")

fmt.Println(m.Contains("exists"))
fmt.Println(m.Contains("doesn't exist"))

Output:

true
false

func (Map[K, V]) Delete

func (m Map[K, V]) Delete(key K)

Delete removes a key-value pair from the map. This will cause the default value to be returned instead on attempts to access the value assigned to the key.

func (Map[K, V]) Get

func (m Map[K, V]) Get(key K) V

Get tries to get the value mapped to the key, but will assign the return value from the DefaultFactory and return that instead if the key didn't exist.

Example

m := defaultmap.NewMap[string](func() string { return "I'm the default!" })
m.Insert("exists", "Hello, World!")

fmt.Println(m.Get("exists"))
fmt.Println(m.Contains("doesn't exist"))
fmt.Println(m.Get("doesn't exist"))
fmt.Println(m.Contains("doesn't exist"))

Output:

Hello, World!
false
I'm the default!
true

func (Map[K, V]) GetOr

func (m Map[K, V]) GetOr(key K, defaultValue V) V

GetOr allows you to specify the default value instead of using the DefaultFactory. Unlike Get, this will not assign the default if the key did not exist.

Example

m := defaultmap.NewMap[string](func() string { return "I'm the default!" })
m.Insert("exists", "Hello, World!")

fmt.Println(m.GetOr("exists", "other default"))
fmt.Println(m.Contains("doesn't exist"))
fmt.Println(m.GetOr("doesn't exist", "other default"))
fmt.Println(m.Contains("doesn't exist"))

Output:

Hello, World!
false
other default
false

func (Map[K, V]) Insert

func (m Map[K, V]) Insert(key K, value V)

Insert inserts a key-value pair into the map.