在ANTLR中编写语言转换器 [英] Writing language converter in ANTLR

问题描述

我正在编写一种使用相同编程语言的方言之间的转换器.我在网上发现了一种语法-它很复杂，可以处理所有情况.现在，我正在尝试编写适当的操作.

I'm writing a converter between some dialects of the same programming language. I've found a grammar on the net - it's complex and handles all the cases. Now I'm trying to write the appropriate actions.

大多数输入将被重写为输出.我需要做的是解析函数调用，做我的魔术(重命名函数，重新排列参数等)并将其编写.

Most of the input is just going to be rewritten to output. What I need to do is parse function calls, do my magic (rename function, reorder arguments, etc) and write it.

我正在使用AST作为输出.遇到函数调用时，我将构建一个自定义对象结构(从目标语言中定义的类中)，调用适当的函数，然后有一个字符串表示要获取的已转换函数.

I'm using AST as output. When I come across a function call, I build a custom object structure (from classes defined in my target language), call the appropriate function and I have a string that represents the transformed function that I want to get.

问题是，我应该如何处理该字符串?我想替换封闭规则的.text属性，但是setText()仅在词法分析器规则上可用，并且规则的.text属性为只读.如何解决这个问题?

The problem is, what I'm supposed to do with that string? I'd like to replace the .text attribute of the enclosing rule, but setText() is only available on lexer rules and the rule's .text attribute is read-only. How to solve this problem?

program
    : statement_list            { output = $statement_list.text; }
    ;

//...

statement
    :   expression_statement
    // ...
    ;

expression_statement
    : function_call
    // ...
    ;

function_call
    : ID '('                    { /* build the object, assign name */
                                  Function function = new Function();
                                  //...
                                }
      (
      arg1 = expression         { /* add first parameter */ }
      ( ',' arg2 = expression   { /* add the rest of parameters */ }
      )*
      )?
      ')'                       { /* convert the function call */
                                  string converted = Tools.Convert(function);
                                  // $setText(converted);               // doesn't work
                                  // $functionCall.text = converted;    // doesn't work
                                }
    ;

推荐答案

最简单的方法是创建重写器.设置语法以重写，使用模板并就地创建模板.然后使用TokenRewriteStream及其ToString()方法.

The easiest way is to create a rewriter. Set grammar to rewrite, use templates and create a template in-place. Then use TokenRewriteStream and it's ToString() method.

grammar Test;

options {
    language = CSharp2;
    output = template;
    rewrite = true;
}

program
    : statement_list
    ;

//...

statement
    :   expression_statement
    // ...
    ;

expression_statement
    : function_call
    // ...
    ;

function_call
    : ID '('                    { /* build the object, assign name */
                                  Function function = new Function();
                                  //...
                                }
      (
      arg1 = expression         { /* add first parameter */ }
      ( ',' arg2 = expression   { /* add the rest of parameters */ }
      )*
      )?
      ')' -> { new StringTemplate(Tools.Convert(function)) }
    ;

和驱动程序:

    string input = "....";

    var stream = new ANTLRStringStream(input);
    var lexer = new TestLexer(stream);

    // need to use TokenRewriteStream
    var tokenStream = new TokenRewriteStream(lexer);
    var parser = new TestParser(tokenStream);

    parser.program();

    // original text
    Console.WriteLine(tokenStream.ToOriginalString());
    // rewritten text
    Console.WriteLine(tokenStream.ToString());

这篇关于在ANTLR中编写语言转换器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！