从自定义源代码生成xml

Question

I have a source code of new kind of small programming language;

 method M(n: int) returns (r: int)
  ensures r == n;
{
  var i := 0;
  while (i < n)
  {
    i := i + 1;
  }
  r := i;
}

I want to read this source file of this code (just one file without any dependencies) using Java and create XML for function name, input parameters,return types,keyword ensures etc.

In order to do that, I need to analyse given source code maybe create a kind of a tree structure to see hierarchical view. (at least I am thinking that way)

Is there any kind of framework that could help me to customize the keywords in order to analyse this kind of material and generate XML out of it or should I just read this file line by line and try to create XML parser by myself.

My main purpose in here to represent this code in XML format.In order to generate some UML kind diagrams.I am not aiming to create new compiler or language. (my question was not clear enough I hope this makes it more clear)

Answer 1

Your description is a bit vague, but it sounds like you're looking for a library for parsing a custom language and converting into another language. You might start with ANTLR . Also, if you are building Java objects from your input, you might consider JAX-B for marshalling to XML.

Answer 2

You can use for that the parser generator ANTLR . The process is to define the language as a grammar consisting of rules. ANTLR uses a EBNF form for that. If the parser can derive a rule, you can specify an action in Java what to do, in your case to write some XML tags to a stream.

Answer 3

Before you can think about generating an XML file, the first part in doing what you discussed would definitely be to parse the input document. Now, regexes are not a good candidate for that job. And hand made parsers are difficult to conceive, especially for languages that support some form of operator predeceence.

Here are three good libraries to develop parsers for whatever language you may design. They are not all equivalent, though, so choosing either of them should be guided by the kind of language you are designing.

• Eclipse XText
• Antlr
• JavaCC

Using any of these, you will describe your language structure and keywords, then code to be run when each element is found. You will then add code to create a parse tree (or you may let the engine generate one for you). Then, you may write code to work upon that parse tree, and possibly, a visitor to output it to XML.

By the way, if the exact structure of your language is still undefined, then you may actually use any of the previous "parser generator" tool. In that case, if you are an actual user of Eclipse, then I might suggest that you try XText first, as it will generate an Eclipse editor, with autocompletion support, refactoring support, etc. All for free.

Update : XText can also be used to generate a graphic editor for your language, provided that it make sense. Have a look here for an example: http://vimeo.com/12824804 .

Answer 4

This is not a trivial subject (if you want to do it right). You are going to need to do most of the stages of writing a compiler (minus the actual writing out machine code part).

See this thread for lots of info to get started: Learning to write a compiler

Making a compiler is a really rewarding experience, but it is a lot of work.

Once you create a parse tree, you'll be able to export it to XML. But that part will come a lot later.

Answer 5

Assuming that ONLY the header line of each method is important, here is a completely different strategy.

read a line from your input file
    if (line match regex /^ \s* method ([a-zA-Z][a-zA-Z0-9_]*)\(([^)]*)\) returns \(([^)]*)\) /x )
        // So the line is a method header. Extract arguments
        currentMethodName = group(1);
        currentArguments = group(2);
        currentReturnType = group(3);

        methods.add(new MethodDefinition(...));
    end if


for (method : methods) {
    // Generate XML for that method...
}

Is this approach more suited to your expectations and needs?