Added filter function

Collection.go

@@ -13,6 +13,7 @@ type Collection[T any] interface {
 	Clear()
 	Delete(key string)
 	Exists(key string) bool
+	Filter(func(*T) bool) <-chan *T
 	Get(key string) (value *T, err error)
 	Set(key string, value *T)
 }
@@ -66,6 +67,25 @@ func (c *collection[T]) All() <-chan *T {
 	return channel
 }
 
+// Filter returns a channel of all objects that pass the given filter function.
+func (c *collection[T]) Filter(filter func(*T) bool) <-chan *T {
+	channel := make(chan *T)
+
+	go func() {
+		c.data.Range(func(key, value any) bool {
+			if filter(value.(*T)) {
+				channel <- value.(*T)
+			}
+
+			return true
+		})
+
+		close(channel)
+	}()
+
+	return channel
+}
+
 // Get returns the value for the given key.
 func (c *collection[T]) Get(key string) (*T, error) {
 	value, exists := c.data.Load(key)

Collection_test.go

@@ -19,13 +19,35 @@ func TestAll(t *testing.T) {
 
 	users.Set("1", &User{Name: "User 1"})
 	users.Set("2", &User{Name: "User 2"})
+	users.Set("3", &User{Name: "User 3"})
 	count := 0
 
 	for range users.All() {
 		count++
 	}
 
-	assert.Equal(t, count, 2)
+	assert.Equal(t, count, 3)
+}
+
+func TestFilter(t *testing.T) {
+	users, err := ocean.New[User]("test")
+	assert.Nil(t, err)
+	defer users.Clear()
+
+	users.Set("1", &User{Name: "User 1"})
+	users.Set("2", &User{Name: "User 2"})
+	users.Set("3", &User{Name: "User 3"})
+	count := 0
+
+	f := func(user *User) bool {
+		return user.Name == "User 2"
+	}
+
+	for range users.Filter(f) {
+		count++
+	}
+
+	assert.Equal(t, count, 1)
 }
 
 func TestGet(t *testing.T) {