From cc93dc4a6adc72a9a92e208fc61598f6fee66870 Mon Sep 17 00:00:00 2001
From: maxwellgithinji <maxwellgithinji@gmail.com>
Date: Thu, 1 Feb 2024 19:26:13 -0500
Subject: [PATCH] feat: extends the environment structure to support scoping

Signed-off-by: maxwellgithinji <maxwellgithinji@gmail.com>
---
 pkg/object/environment.go | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/pkg/object/environment.go b/pkg/object/environment.go
index e7302a5..9650f24 100644
--- a/pkg/object/environment.go
+++ b/pkg/object/environment.go
@@ -9,18 +9,38 @@ package object
 type Environment struct {
 	// store is the hashmap that stores the objects
 	store map[string]Object
+
+	// outer helps with scoping of the environment.
+	// its helpful when separating program and function variables
+	outer *Environment
 }
 
 // NewEnvironment creates a new instance of the environment
 func NewEnvironment() *Environment {
 	s := make(map[string]Object)
 
-	return &Environment{store: s}
+	return &Environment{store: s, outer: nil}
+}
+
+// NewEnclosedEnvironment creates a new instance of an scoped environment
+// it extends the Environment instance to cater for enclosed environments
+func NewEnclosedEnvironment(outer *Environment) *Environment {
+	env := NewEnvironment()
+
+	env.outer = outer
+
+	return env
 }
 
 // Get returns the object associated with the given key from the environment
+// it also checks for values both in the inner and outer scopes
 func (e *Environment) Get(key string) (Object, bool) {
 	obj, ok := e.store[key]
+
+	if !ok && e.outer != nil {
+		obj, ok = e.outer.Get(key)
+	}
+
 	return obj, ok
 }