Implemented variable scopes

src/build/core/Scope.go

@@ -0,0 +1,31 @@
+package core
+
+// Scope represents a map of variables.
+type Scope map[string]*Variable
+
+// Scope returns the current scope.
+func (s *state) Scope() Scope {
+	return s.scopes[len(s.scopes)-1]
+}
+
+// pushScope pushes a new scope to the top of the stack.
+func (s *state) pushScope() {
+	lastScope := s.scopes[len(s.scopes)-1]
+	newScope := make(Scope, len(lastScope))
+
+	for k, v := range lastScope {
+		newScope[k] = &Variable{
+			Value:    v.Value,
+			Name:     v.Name,
+			Register: v.Register,
+			Alive:    v.Alive,
+		}
+	}
+
+	s.scopes = append(s.scopes, newScope)
+}
+
+// popScope removes the scope at the top of the stack.
+func (s *state) popScope() {
+	s.scopes = s.scopes[:len(s.scopes)-1]
+}