basic linked list and node. generic for ints or strings. TODO: make generic for anything.

Author: killbot99

.gitignore

@@ -0,0 +1,2 @@
+.tool-versions
+.vscode

go.mod

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+module github.com/killbot99/ds
+
+go 1.18
+
+require github.com/stretchr/testify v1.8.2
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -0,0 +1,17 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ8=
+github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

pkg/linkedlist.go

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+package ds
+
+type Node[T int | string] interface {
+	// Returns the next node
+	Next() Node[T]
+
+	// creates a new node and sets it as the Next of the current node
+	SetNext(T) Node[T]
+
+	// Return the value of the Node data
+	Value() T
+}
+
+type node[T int | string] struct {
+	data T
+	next Node[T]
+}
+
+// returns the next
+func (n *node[T]) Next() Node[T] {
+	return n.next
+}
+
+func (n *node[T]) Value() T {
+	return n.data
+}
+
+func (n *node[T]) SetNext(val T) Node[T] {
+	n.next = NewNode(val)
+	return n.Next()
+}
+
+type List[T int | string] interface {
+	First() Node[T]
+	Last() Node[T]
+	Append(T)
+}
+
+func (l *list[T]) First() Node[T] {
+	return l.first
+}
+
+func (l *list[T]) Last() Node[T] {
+	current := l.First()
+
+	for current.Next() != nil {
+		current = current.Next()
+	}
+
+	return current
+}
+
+func (l *list[T]) Append(val T) {
+	last := l.Last()
+	last.SetNext(val)
+}
+
+type list[T int | string] struct {
+	first Node[T]
+}
+
+func NewLinkedList[T int | string](data T) List[T] {
+	n := NewNode(data)
+	return &list[T]{
+		first: n,
+	}
+}
+
+func NewNode[T int | string](data T) Node[T] {
+	n := node[T]{
+		data: data,
+	}
+	return &n
+}

pkg/linkedlist_test.go

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+package ds
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_LinkedList(t *testing.T) {
+	t.Run("single node with int", func(t *testing.T) {
+		ll := NewLinkedList[int](5)
+		assert.NotNil(t, ll)
+		assert.Equal(t, 5, ll.First().Value())
+		assert.Equal(t, 5, ll.Last().Value())
+		assert.Nil(t, ll.Last().Next())
+	})
+	t.Run("list with three int values", func(t *testing.T) {
+		ll := NewLinkedList[int](10)
+		ll.Append(5)
+		ll.Append(7)
+		assert.Equal(t, 10, ll.First().Value())
+		assert.Equal(t, 7, ll.Last().Value())
+		assert.Nil(t, ll.Last().Next())
+	})
+}