Add Linkedmap library

libs/linkedmap/linkedmap.go

@@ -0,0 +1,79 @@
+package linkedmap
+
+import (
+	"container/list"
+)
+
+type pair struct {
+	key, value interface{}
+}
+
+type LinkedMap struct {
+	list     *list.List
+	hashmap  map[interface{}]*list.Element
+	capacity int
+}
+
+func NewLinkedMap(capacity int) *LinkedMap {
+	return &LinkedMap{
+		list:     list.New(),
+		hashmap:  make(map[interface{}]*list.Element),
+		capacity: capacity,
+	}
+}
+
+func (lm *LinkedMap) SetCapacity(capacity int) {
+	lm.capacity = capacity
+}
+
+func (lm *LinkedMap) Has(key interface{}) bool {
+	_, found := lm.hashmap[key]
+	return found
+}
+
+func (lm *LinkedMap) PushBack(key interface{}, value interface{}) {
+	_, found := lm.hashmap[key]
+	if found {
+		return
+	}
+
+	if lm.list.Len() == lm.capacity {
+		front := lm.list.Front()
+		key := front.Value.(pair).key
+		lm.list.Remove(front)
+		delete(lm.hashmap, key)
+	}
+
+	el := lm.list.PushBack(pair{key, value})
+	lm.hashmap[key] = el
+}
+
+func (lm *LinkedMap) Get(key interface{}) (interface{}, bool) {
+	el, found := lm.hashmap[key]
+	if found {
+		return el.Value.(pair).value, true
+
+	}
+	return nil, false
+}
+
+func (lm *LinkedMap) Remove(key interface{}) {
+	el, found := lm.hashmap[key]
+	if found {
+		lm.list.Remove(el)
+		delete(lm.hashmap, el.Value.(pair).key)
+	}
+}
+
+func (lm *LinkedMap) Empty() bool {
+	return lm.Size() == 0
+}
+
+func (lm *LinkedMap) Size() int {
+	return lm.list.Len()
+}
+
+func (lm *LinkedMap) Clear() {
+	lm.list = list.New()
+	lm.hashmap = make(map[interface{}]*list.Element)
+}

libs/linkedmap/linkedmap_test.go

@@ -0,0 +1,45 @@
+package linkedmap
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLinkedMap(t *testing.T) {
+	lm := NewLinkedMap(4)
+
+	assert.True(t, lm.Empty())
+	lm.PushBack(2, "b")
+	lm.PushBack(1, "a")
+
+	value, found := lm.Get(2)
+	assert.Equal(t, found, true)
+	assert.Equal(t, value, "b")
+
+	value, found = lm.Get(5)
+	assert.Equal(t, found, false)
+	assert.Equal(t, value, nil)
+
+	lm.Remove(2)
+
+	value, found = lm.Get(2)
+	assert.Equal(t, found, false)
+	assert.Equal(t, value, nil)
+
+	lm.PushBack(3, "c")
+	lm.PushBack(3, "c")
+	assert.Equal(t, lm.Size(), 2)
+
+	lm.PushBack(4, "d")
+	lm.PushBack(5, "e")
+
+	value, found = lm.Get(1)
+	assert.Equal(t, found, true)
+	assert.Equal(t, value, "a")
+	lm.PushBack(6, "f")
+
+	value, found = lm.Get(1)
+	assert.Equal(t, found, false)
+	assert.Equal(t, value, nil)
+}