Nemerle宏的中缀格式 [英] Infix format for Nemerle macro

问题描述

说我需要一些非常特殊的乘法运算符.可以在以下宏中实现:

Say I need some very special multiplication operator. It may be implemented in following macro:

macro @<<!(op1, op2)
{
    <[ ( $op1 * $op2 ) ]>
}

我可以像使用它

def val = 2 <<! 3

及其工作.

但是我真正想要的是现在正在开发的DSL Im的一些类似于英语"的运算符:

But what I really want is some 'english'-like operator for the DSL Im developing now:

macro @multiply(op1, op2)
{
    <[ ( $op1 * $op2 ) ]>
}

如果我尝试使用它

def val = 2 multiply 3

编译器失败，显示"expected;"错误

compiler fails with 'expected ;' error

出什么问题了?如何实现此infix格式的宏?

What is the problem? How can I implement this infix-format macro?

推荐答案

直接来自编译器源代码:

Straight from the compiler source code:

namespace Nemerle.English
{
  [assembly: Nemerle.Internal.OperatorAttribute ("Nemerle.English", "and", false, 160, 161)]
  [assembly: Nemerle.Internal.OperatorAttribute ("Nemerle.English", "or", false, 150, 151)]
  [assembly: Nemerle.Internal.OperatorAttribute ("Nemerle.English", "not", true, 181, 180)]  

  macro @and (e1, e2) {
    <[ $e1 && $e2 ]>
  }

  macro @or (e1, e2) {
    <[ $e1 || $e2 ]>
  }

  macro @not (e) {
    <[ ! $e ]>
  }

您需要在周围撒上OperatorAttributes，它将起作用.顺便说一句，OperatorAttribute定义如下:

You need to sprinkle OperatorAttributes around and it will work. Btw, OperatorAttribute is defined as follows:

public class OperatorAttribute : NemerleAttribute
{
  public mutable env : string;
  public mutable name : string;
  public mutable IsUnary : bool;
  public mutable left : int;
  public mutable right : int;
}

这篇关于Nemerle宏的中缀格式的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！