Improved variable definitions

src/build/Function.go

@@ -137,19 +137,35 @@ func (f *Function) CompileVariableDefinition(expr *expression.Expression) error
 
 	value := expr.Children[1]
 
+	err := value.EachLeaf(func(leaf *expression.Expression) error {
+		if leaf.Token.Kind == token.Identifier && !f.identifierExists(leaf.Token.Text()) {
+			return errors.New(&errors.UnknownIdentifier{Name: leaf.Token.Text()}, f.File, leaf.Token.Position)
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		return err
+	}
+
 	// All expressions are returned to the memory pool.
 	// To avoid losing variable values, we will detach it from the expression.
 	expr.RemoveChild(value)
 
 	f.Variables[name] = &Variable{
-		Name:    name,
-		Value:   value,
-		IsConst: true,
+		Name:  name,
+		Value: value,
 	}
 
 	return nil
 }
 
+func (f *Function) identifierExists(name string) bool {
+	_, exists := f.Variables[name]
+	return exists
+}
+
 // CompileFunctionCall compiles a function call.
 func (f *Function) CompileFunctionCall(expr *expression.Expression) error {
 	funcName := expr.Children[0].Token.Text()
@@ -193,18 +209,7 @@ func (f *Function) TokenToRegister(t token.Token, register cpu.Register) error {
 			return errors.New(&errors.UnknownIdentifier{Name: name}, f.File, t.Position)
 		}
 
-		if !variable.IsConst {
-			return errors.New(errors.NotImplemented, f.File, t.Position)
-		}
-
-		n, err := strconv.Atoi(variable.Value.Token.Text())
-
-		if err != nil {
-			return err
-		}
-
-		f.Assembler.MoveRegisterNumber(register, uint64(n))
-		return nil
+		return f.ExpressionToRegister(variable.Value, register)
 
 	case token.Number:
 		value := t.Text()