way better lex function

stack.go

@@ -0,0 +1,22 @@
+package shsh
+
+type TokenStack struct {
+    buffer []*Token
+    capacity int
+}
+
+func (s *TokenStack) Push(v *Token) {
+    s.capacity++
+    s.buffer = append(s.buffer, v)
+}
+
+func (s *TokenStack) Pop() *Token {
+    if s.capacity <= 0 {
+        return nil
+    }
+
+    s.capacity--
+    res := s.buffer[len(s.buffer) - 1]
+    s.buffer = s.buffer[:len(s.buffer) - 1]
+    return res
+}