GoDS (Go Data Structures)

Implementation of various data structures and algorithms in Go.

Data Structures

Containers
- Lists
- Sets
- Stacks
  - LinkedListStack
  - ArrayStack
- Maps
- Trees
  - RedBlackTree
  - AVLTree
  - BTree
  - BinaryHeap
- Queues
Functions
Appendix

Containers

All data structures implement the container interface with the following methods:

type Container interface {
	Empty() bool
	Size() int
	Clear()
	Values() []interface{}
	String() string
}

Containers are either ordered or unordered. All ordered containers provide stateful iterators and some of them allow enumerable functions.

Data	Structure	Ordered	Iterator	Enumerable	Referenced by
Lists
	ArrayList	yes	yes*	yes	index
	SinglyLinkedList	yes	yes	yes	index
	DoublyLinkedList	yes	yes*	yes	index
Sets
	HashSet	no	no	no	index
	TreeSet	yes	yes*	yes	index
	LinkedHashSet	yes	yes*	yes	index
Stacks
	LinkedListStack	yes	yes	no	index
	ArrayStack	yes	yes*	no	index
Maps
	HashMap	no	no	no	key
	TreeMap	yes	yes*	yes	key
	LinkedHashMap	yes	yes*	yes	key
	HashBidiMap	no	no	no	key*
	TreeBidiMap	yes	yes*	yes	key*
Trees
	RedBlackTree	yes	yes*	no	key
	AVLTree	yes	yes*	no	key
	BTree	yes	yes*	no	key
	BinaryHeap	yes	yes*	no	index
Queues
	LinkedListQueue	yes	yes	no	index
	ArrayQueue	yes	yes*	no	index
	CircularBuffer	yes	yes*	no	index
	PriorityQueue	yes	yes*	no	index
			<sub><sup>*reversible</sup></sub>		<sub><sup>*bidirectional</sup></sub>

Lists

A list is a data structure that stores values and may have repeated values.

Implements Container interface.

type List interface {
	Get(index int) (interface{}, bool)
	Remove(index int)
	Add(values ...interface{})
	Contains(values ...interface{}) bool
	Sort(comparator utils.Comparator)
	Swap(index1, index2 int)
	Insert(index int, values ...interface{})
	Set(index int, value interface{})

	containers.Container
	// Empty() bool
	// Size() int
	// Clear()
	// Values() []interface{}
    // String() string
}

ArrayList

A list backed by a dynamic array that grows and shrinks implicitly.

Implements List, ReverseIteratorWithIndex, EnumerableWithIndex, JSONSerializer and JSONDeserializer interfaces.

package main

import (
	"github.com/emirpasic/gods/lists/arraylist"
	"github.com/emirpasic/gods/utils"
)

func main() {
	list := arraylist.New()
	list.Add("a")                         // ["a"]
	list.Add("c", "b")                    // ["a","c","b"]
	list.Sort(utils.StringComparator)     // ["a","b","c"]
	_, _ = list.Get(0)                    // "a",true
	_, _ = list.Get(100)                  // nil,false
	_ = list.Contains("a", "b", "c")      // true
	_ = list.Contains("a", "b", "c", "d") // false
	list.Swap(0, 1)                       // ["b","a",c"]
	list.Remove(2)                        // ["b","a"]
	list.Remove(1)                        // ["b"]
	list.Remove(0)                        // []
	list.Remove(0)                        // [] (ignored)
	_ = list.Empty()                      // true
	_ = list.Size()                       // 0
	list.Add("a")                         // ["a"]
	list.Clear()                          // []
	list.Insert(0, "b")                   // ["b"]
	list.Insert(0, "a")                   // ["a","b"]
}

SinglyLinkedList

A list where each element points to the next element in the list.

Implements List, IteratorWithIndex, EnumerableWithIndex, JSONSerializer and JSONDeserializer interfaces.

package main

import (
	sll "github.com/emirpasic/gods/lists/singlylinkedlist"
	"github.com/emirpasic/gods/utils"
)

func main() {
	list := sll.New()
	list.Add("a")                         // ["a"]
	list.Add("c", "b")                    // ["a","c","b"]
	list.Sort(utils.StringComparator)     // ["a","b","c"]
	_, _ = list.Get(0)                    // "a",true
	_, _ = list.Get(100)                  // nil,false
	_ = list.Contains("a", "b", "c")      // true
	_ = list.Contains("a", "b", "c", "d") // false
	list.Swap(0, 1)                       // ["b","a",c"]
	list.Remove(2)                        // ["b","a"]
	list.Remove(1)                        // ["b"]
	list.Remove(0)                        // []
	list.Remove(0)                        // [] (ignored)
	_ = list.Empty()                      // true
	_ = list.Size()                       // 0
	list.Add("a")                         // ["a"]
	list.Clear()                          // []
	list.Insert(0, "b")                   // ["b"]
	list.Insert(0, "a")                   // ["a","b"]
}

DoublyLinkedList

A list where each element points to the next and previous elements in the list.

Implements List, ReverseIteratorWithIndex, EnumerableWithIndex, JSONSerializer and JSONDeserializer interfaces.

package main

import (
	dll "github.com/emirpasic/gods/lists/doublylinkedlist"
	"github.com/emirpasic/gods/utils"
)

func main() {
	list := dll.New()
	list.Add("a")                         // ["a"]
	list.Add("c", "b")                    // ["a","c","b"]
	list.Sort(utils.StringComparator)     // ["a","b","c"]
	_, _ = list.Get(0)                    // "a",true
	_, _ = list.Get(100)                  // nil,false
	_ = list.Contains("a", "b", "c")      // true
	_ = list.Contains("a", "b", "c", "d") // false
	list.Swap(0, 1)                       // ["b","a",c"]
	list.Remove(2)                        // ["b","a"]
	list.Remove(1)                        // ["b"]
	list.Remove(0)                        // []
	list.Remove(0)                        // [] (ignored)
	_ = list.Empty()                      // true
	_ = list.Size()                       // 0
	list.Add("a")                         // ["a"]
	list.Clear()                          // []
	list.Insert(0, "b")                   // ["b"]
	list.Insert(0, "a")                   // ["a","b"]
}

Sets

A set is a data structure that can store elements and has no repeated values. It is a computer implementation of the mathematical concept of a finite set. Unlike most other collection types, rather than retrieving a specific element from a set, one typically tests an element for membership in a set. This structure is often used to ensure that no duplicates are present in a container.

Set additionally allow set operations such as intersection, union, difference, etc.

Implements Container interface.

type Set interface {
	Add(elements ...interface{})
	Remove(elements ...interface{})
	Contains(elements ...interface{}) bool
    // Intersection(another *Set) *Set
    // Union(another *Set) *Set
    // Difference(another *Set) *Set
	
	containers.Container
	// Empty() bool
	// Size() int
	// Clear()
	// Values() []interface{}
	// String() string
}

HashSet

A set backed by a hash table (actually a Go's map). It makes no guarantees as to the iteration order of the set.

Implements Set, JSONSerializer and JSONDeserializer interfaces.

package main

import "github.com/emirpasic/gods/sets/hashset"

func main() {
	set := hashset.New()   // empty
	set.Add(1)             // 1
	set.Add(2, 2, 3, 4, 5) // 3, 1, 2, 4, 5 (random order, duplicates ignored)
	set.Remove(4)          // 5, 3, 2, 1 (random order)
	set.Remove(2, 3)       // 1, 5 (random order)
	set.Contains(1)        // true
	set.Contains(1, 5)     // true
	set.Contains(1, 6)     // false
	_ = set.Values()       // []int{5,1} (random order)
	set.Clear()            // empty
	set.Empty()            // true
	set.Size()             // 0
}

TreeSet

A set backed by a red-black tree to keep the elements ordered with respect to the comparator.

Implements Set, ReverseIteratorWithIndex, EnumerableWithIndex, JSONSerializer and JSONDeserializer interfaces.

package main

import "github.com/emirpasic/gods/sets/treeset"

func main() {
	set := treeset.NewWithIntComparator() // empty (keys are of type int)
	set.Add(1)                            // 1
	set.Add(2, 2, 3, 4, 5)                // 1, 2, 3, 4, 5 (in order, duplicates ignored)
	set.Remove(4)                         // 1, 2, 3, 5 (in order)
	set.Remove(2, 3)                      // 1, 5 (in order)
	set.Contains(1)                       // true
	set.Contains(1, 5)                    // true
	set.Contains(1, 6)                    // false
	_ = set.Values()                      // []int{1,5} (in order)
	set.Clear()                           // empty
	set.Empty()                           // true
	set.Size()                            // 0
}

LinkedHashSet

A set that preserves insertion-order. Data structure is backed by a hash table to store values and doubly-linked list to store insertion ordering.

Implements Set, ReverseIteratorWithIndex, EnumerableWithIndex, JSONSerializer and JSONDeserializer interfaces.

package main

import "github.com/emirpasic/gods/sets/linkedhashset"

func main() {
	set := linkedhashset.New() // empty
	set.Add(5)                 // 5
	set.Add(4, 4, 3, 2, 1)     // 5, 4, 3, 2, 1 (in insertion-order, duplicates ignored)
	set.Add(4)                 // 5, 4, 3, 2, 1 (duplicates ignored, insertion-order unchanged)
	set.Remove(4)              // 5, 3, 2, 1 (in insertion-order)
	set.Remove(2, 3)           // 5, 1 (in insertion-order)
	set.Contains(1)            // true
	set.Contains(1, 5)         // true
	set.Contains(1, 6)         // false
	_ = set.Values()           // []int{5, 1} (in insertion-order)
	set.Clear()                // empty
	set.Empty()                // true
	set.Size()                 // 0
}

Stacks

A stack that represents a last-in-first-out (LIFO) data structure. The usual push and pop operations are provided, as well as a method to peek at the top item on the stack.

Implements Container interface.

type Stack interface {
	Push(value interface{})
	Pop() (value interface{}, ok bool)
	Peek() (value interface{}, ok bool)

	containers.Container
	// Empty() bool
	// Size() int
	// Clear()
	// Values() []interface{}
	// String() string
}