Project Schliemann

What is Schliemann Project about? You have probably already seen some programmers editors like Emacs, Vim or JEdit. They have editing support for many programming languages (~100). But they do not contain special hand coded support (module) for every language. They defines some Generic Languages Framework only. Every programming language is described in some file executed by the engine. Schliemann project implements Generic Languages Framework for NetBeans IDE.

Schliemann engine allows you to describe some programming language and define how to integrate it to the NetBeans. Each programming language is defined in one nbs (NetBeans Scripting) file. New declarative language has been created for that purpose.
So, what can you do in nbs files?

You can define lexical structure of your language. Tokens are described by regular expressions, syntax is similar to JavaCC.
Example:

    TOKEN:keyword: ( "if" | "else" | "while" | "for" | "function" )
    TOKEN:comment: ( "/*" - "*/" )
    TOKEN:line-comment: ( "//" [^ "\n" "\r"]* )
    TOKEN:number: ( ["0"-"9"]+ )
    TOKEN:whitespace: ( [" " "\t" "\n" "\r"]+ )
    TOKEN:identifier: ( ["a"-"z" "A"-"Z"]+ )

Now you can define coloring for your tokens:

    COLOR:line-comment {
        foreground-color: "lightGray";
        font-type: "bold";
    }

Definition of indentation is simple. You can define pairs of brackets that should be indented,

    INDENT "(:)"
    INDENT "{:}"

or some regular expression. If some line of code fulfills this expression, next line will be indented:

    INDENT "\\s*(((if|while)\\s*\\(|else\\s*|else\\s+if\\s*\\(|for\\s*\\(.*\\))[^{;]*)"

Sometimes its hard to define some dynamic behavior in declarative language. Thats why I have added possibility to call Java methods from Schliemann code. Following example defines tooltip value for keywords of our language.

    TOOLTIP:keyword:org.foopackage.FooClass.fooMethod

    public class FooClass {
        public static String fooMethod (Cookie cookie) {
            String keywordName = cookie.getTokenSequence ().token ().text ().toString ();
            if (keywordName.equals ("for")) return "for: for (init, expression, update) defines for cycle";
            else
            ...
        }
    }

Real parser is needed for some more advanced features like Navigator (Structure View) or Code Folding. Thats why Schliemann engine allows you to define grammar of your language. Simple example:

    S = (Statement ";")*;
    Statement = ForStatement | WhileStatement | IfStatement | FunctionDeclaration;
    ForStatement = "for" "(" Expression ";" Expression ";" Expression ")" Block;
    Block = "{" (Statement ";")* "}";
    FunctionDeclaration = "function"  "(" Parameters ")" Block;
    ...

Schliemann engine generates parser for your language, and you can base some other features on its parse tree. Following example defines code folding for blocks defined in our language, and navigator content.

    FOLD:Block
    NAVIGATOR:FunctionDeclaration {
        display-name:"$identifier$";
        icon: "org.foo.FooIcon.gif";
    }

So, Schliemann engine creates code fold for every part of source corresponding to some "Block" nonterminal in parse tree. And it creates special node in Navigator View for each FunctionDeclaration.

This is short preview of some Schiemann Project features. This project is under development, planned for NetBeans 6.0. There are about 20 prototypes of languages based on this engine now. If you would like to try it, you should download development version of NetBeans (or build NetBeans trunk) and download "Languages Support" modules from development auto update.
See NetBeans Wiki for more info.

Posted at 05:38AM Dec 23, 2006 by Jan Jancura in NetBeans  |  Comments[6]