将 Antlr 语法树转换为有用的对象 [英] Converting Antlr syntax tree into useful objects

问题描述

我目前正在考虑如何最好地获取使用 Antlr 生成的 AST 并将其转换为我可以在我的程序中使用的有用对象.

I'm currently pondering how best to take an AST generated using Antlr and convert it into useful objects which I can use in my program.

我的语法(除了学习)的目的是创建一种可执行(运行时解释)语言.

The purpose of my grammar (apart from learning) is to create an executable (runtime interpretted) language.

例如，我将如何获取属性子树并实例化特定的 Attribute 类.例如.

For example, how would I take an attribute sub-tree and have a specific Attribute class instanciated. E.g.

以下代码是我的语言:

Print(message:"Hello stackoverflow")

将产生以下 AST:

我目前的想法是，工厂类可以读取树，提取名称(message)，并输入(STRING) value(">Hello stackoverflow").现在，知道类型我可以实例化正确的类(例如 StringAttribute 类)并传入所需的属性数据 - name 和 value.

My current line of thinking is that a factory class could read the tree, pull out the name (message), and type(STRING) value("Hello stackoverflow"). Now, knowing the type I could instanciate the correct class (e.g. A StringAttribute class) and pass in the required attribute data - the name and value.

同样的方法可用于定义工厂，提取定义名称(Print)，实例化 Print 类，然后传入从属性工厂生成的属性.

The same approach could be used for a definition factory, pulling out the definition name (Print), instanciating the Print class, and then passing in the attributes generated from the attribute factory.

使用更复杂的程序会使事情变得更复杂:

Things do get a bit more complicated with a more complicated program:

Program(args:[1,2,3,4,5])
{
    If(isTrue:IsInArray(array:{Program.args} value:5))
    {
        Then {
            Print(message:"5 is in the array")
        } Else {
            Print(message:"More complex " + "message")
        }
    }
}

非常欢迎任何/所有帮助或想法.非常感谢.

ANY/ALL help or thoughts are very welcome. Many thanks.

我以前的相关问题(可能有用):

Previous related questions by me (Could be useful):

1. 如何制作一棵树解析器
2. 解决 LL 递归问题
3. Antrl3 条件树重写

推荐答案

我建议阅读 语言实现模式 作者:Terence Parr.

I recommend reading chapter 9, Building High-Level Interpreters, from Language Implementation Patterns by Terence Parr.

编辑

好的，为了让您度过等待那本书的时间，以下是您(至少)需要的:

Okay, to get you through the time waiting for that book, here's what you're (at least) going to need:

• 全局内存空间；
• 函数空间(每个函数空间也会有一个(本地)内存空间)；

和脑海中浮现的类(以UML 风格 风格):

and classes that spring to mind (in UML-ish style):

• 类解释器
  • 全局:内存空间
  • 函数:堆栈<函数>
  • ...
    
    
  • 变量:映射<字符串，对象>
  • ...
    
    
  • 本地:内存空间
  • execute(): void
  • ...

  这篇关于将 Antlr 语法树转换为有用的对象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！