Reduced memory usage

src/build/scope/Scope.go

@@ -6,7 +6,25 @@ import (
 
 // Scope represents an independent code block.
 type Scope struct {
-	Variables map[string]*Variable
+	Variables []*Variable
 	InLoop    bool
 	cpu.State
 }
+
+// AddVariable adds a new variable to the current scope.
+func (s *Scope) AddVariable(variable *Variable) {
+	variable.Scope = s
+	s.Variables = append(s.Variables, variable)
+	s.Use(variable.Register)
+}
+
+// VariableByName returns the variable with the given name or `nil` if it doesn't exist.
+func (s *Scope) VariableByName(name string) *Variable {
+	for _, v := range s.Variables {
+		if v.Name == name {
+			return v
+		}
+	}
+
+	return nil
+}