From 09669198ba618c267d68d2341cce417177eafe0e Mon Sep 17 00:00:00 2001
From: Jack Park <xarus01@gmail.com>
Date: Wed, 6 Nov 2019 13:54:56 +0900
Subject: [PATCH] Implemented .pop() method for list

---
 py/list.go       | 16 ++++++++++++++++
 py/tests/list.py |  7 +++++++
 2 files changed, 23 insertions(+)

diff --git a/py/list.go b/py/list.go
index eee7bf3e..267ab69d 100644
--- a/py/list.go
+++ b/py/list.go
@@ -28,6 +28,22 @@ func init() {
 		return NoneType{}, nil
 	}, 0, "append(item)")
 
+	ListType.Dict["pop"] = MustNewMethod("pop", func(self Object, args Tuple) (Object, error) {
+		var index Object = Int(0)
+		listSelf := self.(*List)
+		err := UnpackTuple(args, nil, "pop", 0, 1, &index)
+		if err != nil {
+			return nil, err
+		}
+		i, err := IndexIntCheck(index, listSelf.Len())
+		if err != nil {
+			return nil, err
+		}
+		popElement := listSelf.Items[i]
+		listSelf.Items = append(listSelf.Items[:i], listSelf.Items[i+1:]...)
+		return popElement, nil
+	}, 0, "pop(index)")
+
 	ListType.Dict["extend"] = MustNewMethod("extend", func(self Object, args Tuple) (Object, error) {
 		listSelf := self.(*List)
 		if len(args) != 1 {
diff --git a/py/tests/list.py b/py/tests/list.py
index b832b3df..30dd69fc 100644
--- a/py/tests/list.py
+++ b/py/tests/list.py
@@ -35,6 +35,13 @@
 assert repr(a) == "['a', 'b', 'c', 'd', 'e', 'f']"
 assertRaises(TypeError, lambda: [].append())
 
+doc="pop"
+a = [1,2,3,4]
+assert a.pop() == 1
+assert a.pop(2) == 4
+assert repr(a) == "[2, 3]"
+assertRaises(IndexError, lambda: [].pop())
+
 doc="mul"
 a = [1, 2, 3]
 assert a * 2  == [1, 2, 3, 1, 2, 3]