sets

Documentation

Overview

Package sets provides set data structures. The set data structures in this package do not replace the recommended implementation in Effective Go: A set can be implemented as a map with value type bool. Set the map entry to true to put the value in the set, and then test it by simple indexing.

attended := map[string]bool{
	"Ann": true,
	"Joe": true,
	...
}
if attended[person] { // will be false if person is not in the map
	fmt.Println(person, "was at the meeting")
}

However, this package provide set types that are more efficient for Add, Remove, and Contains calls; and more functionality on top of that. Due to the lack of generics in Go, it's recommended to choose the map[string]bool when the set must be iterated many times.

Index

• type Set
  • func NewExpirableSet(initialCapacity int, ttl time.Duration) Set
  • func NewSet(initialCapacity int) Set
  • func NewSetFromStrings(strings ...string) Set
  • func NewThreadSafeExpirableSet(initialCapacity int, ttl time.Duration) Set

Types

type Set

type Set interface {
	// Add adds the specified element to the set.
	Add(element interface{})

	// Clear empties the set of all elements.
	Clear()

	// Contains checks whether or not the specified element belongs to the set.
	Contains(element interface{}) bool

	// Remove removes the specified element from the set.
	Remove(element interface{})

	// Size return the number of elements in the set.
	Size() int

	// ToSlice converts the set into a slice.
	ToSlice() []interface{}

	// ToStringSlice converts the set into a string slice.
	ToStringSlice() []string
}

Set is a set data structure. It does not replace the recommended implementation in Effective Go: A set can be implemented as a map with value type bool. Set the map entry to true to put the value in the set, and then test it by simple indexing.

attended := map[string]bool{
	"Ann": true,
	"Joe": true,
	...
}

if attended[person] { // will be false if person is not in the map
	fmt.Println(person, "was at the meeting")
}

However, this set type is more efficient for Add, Remove, and Contains calls. Due to the lack of generics in Go, it's recommended to choose the map[string]bool when the set must be iterated many times.

func NewExpirableSet

func NewExpirableSet(initialCapacity int, ttl time.Duration) Set

NewExpirableSet creates a new set. The initial capacity does not bound the set's size: sets grow to accommodate the number of elements to store. TTL (time to live) specifies the duration after which an element expires. TODO(Geish): shrink the size on expiry

func NewSet

func NewSet(initialCapacity int) Set

NewSet creates a new set. The initial capacity does not bound the set's size: sets grow to accommodate the number of elements to store.

func NewSetFromStrings

func NewSetFromStrings(strings ...string) Set

NewSetFromStrings creates a new set from the specified strings.

func NewThreadSafeExpirableSet

func NewThreadSafeExpirableSet(initialCapacity int, ttl time.Duration) Set

NewThreadSafeExpirableSet creates a new thread-safe set using a read-write mutex. The initial capacity does not bound the set's size: sets grow to accommodate the number of elements to store. TTL (time to live) specifies the duration after which an element expires.