在C#中行走ANTLR AST的教程? [英] Tutorial for walking ANTLR ASTs in C#?

问题描述

有人知道在C#中使用ANTLR生成的AST的教程吗?我能找到的最接近的是此，但不是很有帮助.

Is anyone aware of tutorials for walking ANTLR-generated ASTs in C#? The closest I was able to find is this, but it's not terribly helpful.

我的目标是浏览我正在使用的基于特定领域语言的生成树，并使用这些树输出生成的C#代码.

My goal is to walk through trees that I'm generating based on a domain-specific language that I'm working on, and to use the trees to output generated C# code.

基于Java的教程也将有所帮助-任何提供了如何遍历ANTLR AST的清晰示例的事物.

A Java-based tutorial would be helpful, too -- anything that provides clear examples of how to traverse ANTLR ASTs.

推荐答案

我通过修改这是我的版本，我刚好用它来将已解析的代码转换为C#. 这些是步骤:

Here's my version, which I happen to be using to convert parsed code to C#. These are the steps:

1. 使用您的输入实例化 ANTLRStringStream 或子类(可以是文件或字符串).
2. 实例化生成的词法分析器，并传入该字符串流.
3. 使用词法分析器实例化令牌流.
4. 使用该令牌流实例化解析器.
5. 从解析器获取顶级值，并将其转换为CommonTree.
6. 遍历树:

1. Instantiate an ANTLRStringStream or subclass with your input (it can be a file or string).
2. Instantiate your generated lexer, passing in that string stream.
3. Instantiate a token stream with the lexer.
4. Instantiate your parser with that token stream.
5. Get the top-level value from your parser, and turn it into a CommonTree.
6. Traverse the tree:

要获取节点的文字，请使用node.Text. 要获取节点的令牌名称，请使用node.Token.Text.

To get the literal text of a node, use node.Text. To get the token name of a node, use node.Token.Text.

请注意，如果node.Token.Text是虚构的令牌且没有相应的字符串，则只会为您提供令牌的实际名称.如果它是真实令牌，则node.Token.Text将返回其字符串.

Note that node.Token.Text will only give you the actual name of your token if it's an imaginary token with no corresponding string. If it's a real token, then node.Token.Text will return its string.

例如，如果语法中包含以下内容:

For example, if you had the following in your grammar:

tokens { PROGRAM, FUNCDEC }

EQUALS : '==';
ASSIGN : '=';

然后您将从相应的node.Token.Text访问中获得"PROGRAM"，"FUNCDEC"，"=="和"=".

Then you'll get "PROGRAM", "FUNCDEC", "==", and "=" from the corresponding accesses of node.Token.Text.

您可以在下面看到我的示例的一部分，也可以浏览

You can see part of my example below, or you can browse the full version.

public static string Convert(string input)
{
    ANTLRStringStream sStream = new ANTLRStringStream(input);
    MyGrammarLexer lexer = new MyGrammarLexer(sStream);

    CommonTokenStream tStream = new CommonTokenStream(lexer);

    MyGrammarParser parser = new MyGrammarParser (tStream);
    MyGrammarParser.program_return parserResult = parser.program();

    CommonTree ast = (CommonTree)parserResult.Tree;

    Print(ast);
    string output = header + body + footer;

    return output;
}

public static void PrintChildren(CT ast)
{
    PrintChildren(ast, " ", true);
}

public static void PrintChildren(CT ast, string delim, bool final)
{
    if (ast.Children == null)
    {
        return;
    }

    int num = ast.Children.Count;

    for (int i = 0; i < num; ++i)
    {
        CT d = (CT)(ast.Children[i]);
        Print(d);
        if (final || i < num - 1)
        {
            body += delim;
        }
    }
}

public static void Print(CommonTree ast)
{
    switch (ast.Token.Text)
    {
        case "PROGRAM":
            //body += header;
            PrintChildren(ast);
            //body += footer;
            break;
        case "GLOBALS":
            body += "\r\n\r\n// GLOBALS\r\n";
            PrintChildren(ast);
            break;
        case "GLOBAL":
            body += "public static ";
            PrintChildren(ast);
            body += ";\r\n";
            break;

      ....
    }
}

这篇关于在C#中行走ANTLR AST的教程?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！