feat: tokenizer

pkg/iterator/iterator.go

@@ -0,0 +1,39 @@
+package iterator
+
+import "fmt"
+
+type Iterator[T any] struct {
+	data []T
+	index int
+}
+
+func New[T any](items []T) Iterator[T] {
+	return Iterator[T]{ data: items, index: 0 }
+}
+
+func (i Iterator[T]) Index() int {
+	return i.index
+}
+
+func (i Iterator[T]) IsDone() bool {
+	return i.index == len(i.data)
+}
+
+func (i Iterator[T]) Peek() (T, error) {
+	var null T
+
+	if i.IsDone() {
+		return null, fmt.Errorf("Iterator is exhausted.")
+	}
+
+	return i.data[i.index], nil
+}
+
+func (i *Iterator[T]) Next() (T, error) {
+	if val, err := i.Peek(); err != nil {
+		return val, err
+	} else {
+		i.index++
+		return val, nil
+	}
+}