Basic Queue package

1 files changed, 50 insertions, 0 deletions

diff --git a/queue.adb b/queue.adb
index e69de29..2869984 100644
--- a/queue.adb
+++ b/queue.adb
@@ -0,0 +1,50 @@
+package body Queue is
+
+	procedure Enqueue(queue: in out T_Queue; data: T_Data) is
+		element: T_List_Node;
+		new_back: T_List;
+	begin
+		element.data := data;
+		element.next := null;
+		new_back := new T_List_Node'(element);
+
+		if Empty(queue) then
+			queue.front := new_back;
+			queue.back := new_back;
+			return;
+		end if;
+
+		queue.back.next := new_back;
+		queue.back := new_back;
+	end Enqueue;
+
+	procedure Dequeue(queue: in out T_Queue) is
+	begin
+		if Empty(queue) then
+			return;
+		end if;
+		if queue.front.next = null then
+			queue.front := null;
+			queue.back := null;
+			return;
+		end if;
+		queue.front := queue.front.next;
+	end Dequeue;
+
+	function Length(queue: T_Queue) return Natural is
+		tmp: T_List := queue.front;
+		i:   Natural := 0;
+	begin
+		while tmp /= null loop
+			tmp := tmp.next;
+			i := i + 1;
+		end loop;
+		return i;
+	end Length;
+
+	function Empty(queue: T_Queue) return Boolean is
+	begin
+		return queue.front = null and queue.back = null;
+	end Empty;
+
+end Queue;