Refactor Super Graph into a library #26

core/internal/util/stack.go

@@ -0,0 +1,47 @@
+package util
+
+type Stack struct {
+	stA [20]interface{}
+	st  []interface{}
+	top int
+}
+
+// Create a new Stack
+func NewStack() *Stack {
+	s := &Stack{top: -1}
+	s.st = s.stA[:0]
+	return s
+}
+
+// Return the number of items in the Stack
+func (s *Stack) Len() int {
+	return (s.top + 1)
+}
+
+// View the top item on the Stack
+func (s *Stack) Peek() interface{} {
+	if s.top == -1 {
+		return -1
+	}
+	return s.st[s.top]
+}
+
+// Pop the top item of the Stack and return it
+func (s *Stack) Pop() interface{} {
+	if s.top == -1 {
+		return -1
+	}
+
+	s.top--
+	return s.st[(s.top + 1)]
+}
+
+// Push a value onto the top of the Stack
+func (s *Stack) Push(value interface{}) {
+	s.top++
+	if len(s.st) <= s.top {
+		s.st = append(s.st, value)
+	} else {
+		s.st[s.top] = value
+	}
+}