From 7c785439fca59b3801ca2a1118ae25a98d03750d Mon Sep 17 00:00:00 2001
From: tomsmeding <tom.smeding@gmail.com>
Date: Fri, 3 Feb 2017 22:00:23 +0100
Subject: Initial

---
 list.squig | 136 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 list.squig

(limited to 'list.squig')

diff --git a/list.squig b/list.squig
new file mode 100644
index 0000000..ea0d333
--- /dev/null
+++ b/list.squig
@@ -0,0 +1,136 @@
+new_list := ??{
+	front := nil
+	back := nil
+}
+
+list_push_front := ??(list, item){
+	list {
+		if front == nil {
+			front = {
+				value := item
+				next := nil
+				prev := nil
+			}
+			back = front
+		} else {
+			front = {
+				value := item
+				next := front
+				prev := nil
+			}
+		}
+	}
+}
+
+list_push_back := ??(list, item){
+	list {
+		if back == nil {
+			front = {
+				value := item
+				next := nil
+				prev := nil
+			}
+			back = front
+		} else {
+			back = {
+				value := item
+				next := nil
+				prev := back
+			}
+		}
+	}
+}
+
+list_pop_front := ??(list){
+	x := nil
+	list {
+		if front == nil {
+			throw_error("Call to 'list_pop_front' on empty list")
+		}
+		front {
+			x = value
+			front = next
+		}
+		if front == nil {
+			back = nil
+		}
+	}
+}
+
+list_pop_back := ??(list){
+	x := nil
+	list {
+		if back == nil {
+			throw_error("Call to 'list_pop_back' on empty list")
+		}
+		back {
+			x = value
+			back = prev
+		}
+		if back == nil {
+			front = nil
+		}
+	}
+}
+
+list_get := nil
+{
+	get_helper := ??(front, idx){
+		if front == nil {
+			throw_error("Index past end of list in 'list_get'")
+		}
+		x := nil
+		if idx == 0 {
+			front {
+				x = value
+			}
+		} else {
+			front {
+				found := nil
+				get_helper(next, idx - 1){
+					found = x
+				}
+				x = found
+			}
+		}
+	}
+	list_get = ??(list, idx){
+		if idx < 0 {
+			throw_error("Negative index in 'list_get'")
+		}
+		x := nil
+		list {
+			found := nil
+			get_helper(front, idx){
+				found = x
+			}
+			x = found
+		}
+	}
+}
+
+list_set := nil
+{
+	set_helper := ??(front, idx, val){
+		if front == nil {
+			throw_error("Index past end of list in 'list_set'")
+		}
+		if idx == 0 {
+			front {
+				value = val
+			}
+		} else {
+			front {
+				set_helper(next, idx - 1, val){}
+			}
+		}
+	}
+	list_set = ??(list, idx, val){
+		if idx < 0 {
+			throw_error("Negative index in 'list_set'")
+		}
+		list {
+			set_helper(front, idx, val)
+		}
+	}
+}
-- 
cgit v1.2.3-54-g00ecf