sets

README

sets

Sets and Set operations in golang

Internally as simple as a map[T]struct{} but with additional helper functions, operations like Union, Intersect, XOR, to/from Slices conversion, to/from JSON, etc... and hiding the struct{}{} etc...

See https://pkg.go.dev/fortio.org/sets

Documentation

Overview

Sets and Set type and operations of any comparable type (go 1.18+ generics) Intersection, Union, Set.Subset, difference aka Set.Minus, XOR, JSON serialization and deserialization and more.

Index

• func RemoveCommon[T comparable](a, b Set[T])
• func Sort[Q constraints.Ordered](s Set[Q]) []Q
• func Tuplets[Q constraints.Ordered](s Set[Q], n int) [][]Q
• func XOR[T comparable](a, b Set[T])
• type Set
  • func FromSlice[T comparable](items []T) Set[T]
  • func Intersection[T comparable](sets ...Set[T]) Set[T]
  • func New[T comparable](item ...T) Set[T]
  • func Union[T comparable](sets ...Set[T]) Set[T]
  • func (s Set[T]) Add(item ...T)
  • func (s Set[T]) Clear()
  • func (s Set[T]) Clone() Set[T]
  • func (s Set[T]) Elements() []T
  • func (s Set[T]) Equals(other Set[T]) bool
  • func (s Set[T]) Has(item T) bool
  • func (s Set[T]) Len() int
  • func (s Set[T]) MarshalJSON() ([]byte, error)
  • func (s Set[T]) Minus(other Set[T]) Set[T]
  • func (s Set[T]) Plus(others ...Set[T]) Set[T]
  • func (s Set[T]) Remove(item ...T)
  • func (s Set[T]) String() string
  • func (s Set[T]) Subset(bigger Set[T]) bool
  • func (s *Set[T]) UnmarshalJSON(data []byte) error

Functions

func RemoveCommon

func RemoveCommon[T comparable](a, b Set[T])

RemoveCommon removes elements from both sets that are in both, leaving only the delta. Useful when a is an old value and b is new and you want to apply some operation on all removed and added elements.

func Sort

func Sort[Q constraints.Ordered](s Set[Q]) []Q

Sort returns a sorted slice of the elements in the set. Only applicable for when the type is sortable.

func Tuplets

func Tuplets[Q constraints.Ordered](s Set[Q], n int) [][]Q

Tuplets generates all the combinations of N of elements of the set. for n = 2, it would return all pairs of elements. for n = 3, all triplets, etc.

func XOR

func XOR[T comparable](a, b Set[T])

XOR is an alias for RemoveCommon, efficiently removes from each set the common elements.

Types

type Set

type Set[T comparable] map[T]struct{}

Set defines a low memory footprint set of any comparable type. Based on `map[T]struct{}`.

func FromSlice

func FromSlice[T comparable](items []T) Set[T]

FromSlice constructs a Set from a slice. [Elements] is the inverse function, getting back a slice from the Set. This is a short cut/alias for New[T](items...).

func Intersection

func Intersection[T comparable](sets ...Set[T]) Set[T]

Intersection returns a new set that has the elements common to all the input sets.

func New

func New[T comparable](item ...T) Set[T]

New returns a new set containing the given elements.

func Union

func Union[T comparable](sets ...Set[T]) Set[T]

Union returns a new set that has all the elements of all the sets. Note that Union(s1) == s1.Clone() and Union[T]() == New[T]().

func (Set[T]) Add

func (s Set[T]) Add(item ...T)

Add items to the set. Add and thus its callers will panic() if NaN is passed in.

func (Set[T]) Clear

func (s Set[T]) Clear()

Clear removes all elements from the set.

func (Set[T]) Clone

func (s Set[T]) Clone() Set[T]

Clone returns a copy of the set.

func (Set[T]) Elements

func (s Set[T]) Elements() []T

Elements returns a slice of the elements in the set.

func (Set[T]) Equals

func (s Set[T]) Equals(other Set[T]) bool

Equals returns true if the two sets have the same elements.

func (Set[T]) Has

func (s Set[T]) Has(item T) bool

Has returns true if the item is present in the set.

func (Set[T]) Len

func (s Set[T]) Len() int

Len returns the number of elements in the set (same as len(s) but as a method).

func (Set[T]) MarshalJSON

func (s Set[T]) MarshalJSON() ([]byte, error)

MarshalJSON implements the json.Marshaler interface and only gets the elements as an array.

func (Set[T]) Minus

func (s Set[T]) Minus(other Set[T]) Set[T]

Minus mutates the receiver to remove all the elements of the passed in set. If you want a copy use s.Clone().Minus(other). Returns the receiver for chaining.

func (Set[T]) Plus

func (s Set[T]) Plus(others ...Set[T]) Set[T]

Plus is similar to Union but mutates the receiver. Added for symmetry with Minus. Returns the receiver for chaining.

func (Set[T]) Remove

func (s Set[T]) Remove(item ...T)

Remove items from the set.

func (Set[T]) String

func (s Set[T]) String() string

String() returns a coma separated list of the elements in the set. This is mostly for troubleshooting/debug output unless the [T] serializes to a string that doesn't contain commas.

func (Set[T]) Subset

func (s Set[T]) Subset(bigger Set[T]) bool

Subset returns true if all elements of s are in the passed in set.

func (*Set[T]) UnmarshalJSON

func (s *Set[T]) UnmarshalJSON(data []byte) error

UnmarshalJSON implements the json.Unmarshaler interface turns the slice back to a Set.