Implemented definitions

src/build/VariableDefinition.go

@@ -25,25 +25,32 @@ func (f *Function) CompileVariableDefinition(expr *expression.Expression) error
 		return errors.New(&errors.UnusedVariable{Name: name}, f.File, expr.Children[0].Token.Position)
 	}
 
-	reg, exists := f.cpu.FindFree(f.cpu.General)
+	value := expr.Children[1]
 
-	if !exists {
-		panic("no free registers")
-	}
+	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)
+		}
 
-	err := f.ExpressionToRegister(expr.Children[1], reg)
+		return nil
+	})
 
 	if err != nil {
 		return err
 	}
 
-	f.addVariable(&Variable{
-		Name:     name,
-		Register: reg,
-		Alive:    uses,
-	})
+	if uses == 1 {
+		expr.RemoveChild(value)
 
-	return nil
+		f.definitions[name] = &Definition{
+			Name:  name,
+			Value: value,
+		}
+
+		return nil
+	}
+
+	return f.storeVariableInRegister(name, value, uses)
 }
 
 func (f *Function) addVariable(variable *Variable) {
@@ -75,6 +82,24 @@ func (f *Function) useVariable(variable *Variable) {
 	}
 }
 
+func (f *Function) storeVariableInRegister(name string, value *expression.Expression, uses int) error {
+	reg, exists := f.cpu.FindFree(f.cpu.General)
+
+	if !exists {
+		panic("no free registers")
+	}
+
+	err := f.ExpressionToRegister(value, reg)
+
+	f.addVariable(&Variable{
+		Name:     name,
+		Register: reg,
+		Alive:    uses,
+	})
+
+	return err
+}
+
 func countIdentifier(tokens token.List, name string) int {
 	count := 0