initial

1 files changed, 23 insertions, 0 deletions

diff --git a/stack.go b/stack.go
new file mode 100644
index 0000000..5f60315
--- /dev/null
+++ b/stack.go
@@ -0,0 +1,23 @@
+package lexpr
+
+type TokenStack []Token
+
+func (s *TokenStack) Push(item Token) {
+	*s = append(*s, item)
+}
+
+func (s *TokenStack) Pop() (item Token) {
+	if len(*s) == 0 {
+		return
+	}
+
+	*s, item = (*s)[:len(*s)-1], (*s)[len(*s)-1]
+	return item
+}
+
+func (s *TokenStack) Head() (item Token) {
+	if len(*s) == 0 {
+		return
+	}
+	return (*s)[len(*s)-1]
+}