source: Dev/trunk/src/client/util/build/transforms/optimizer/shrinksafe.js

/*jshint white:false */
define([
        "../../buildControl",
        "dojo/has!host-node?./sendJob:",
        "../../fs",
        "dojo/has"
], function(bc, sendJob, fs, has){
        if(has("host-node")){
                return function(resource, text, copyright, optimizeSwitch/*, callback*/){
                        copyright = copyright || "";
                        sendJob(resource.dest + ".uncompressed.js", resource.dest, optimizeSwitch, copyright);
                        return 0;
                };
        }

        if(has("host-rhino")){
                var sscompile = function(text, dest, optimizeSwitch, copyright){
                        /*jshint rhino:true */
                        /*global Packages:false */
                        // decode the optimize switch
                        var
                                options = optimizeSwitch.split("."),
                                comments = 0,
                                keepLines = 0,
                                strip = null;
                        while(options.length){
                                switch(options.pop()){
                                case "normal":
                                        strip = "normal";
                                        break;
                                case "warn":
                                        strip = "warn";
                                        break;
                                case "all":
                                        strip = "all";
                                        break;
                                case "keeplines":
                                        keepLines = 1;
                                        break;
                                case "comments":
                                        comments = 1;
                                        break;
                                }
                        }

                        //Use rhino to help do minifying/compressing.
                        var context = Packages.org.mozilla.javascript.Context.enter();
                        try{
                                // Use the interpreter for interactive input (copied this from Main rhino class).
                                context.setOptimizationLevel(-1);

                                if(comments){
                                        //Strip comments
                                        var script = context.compileString(text, dest, 1, null);
                                        text = new String(context.decompileScript(script, 0));

                                        //Replace the spaces with tabs.
                                        //Ideally do this in the pretty printer rhino code.
                                        text = text.replace(/    /g, "\t");
                                }else{
                                        //Apply compression using custom compression call in Dojo-modified rhino.
                                        text = new String(Packages.org.dojotoolkit.shrinksafe.Compressor.compressScript(text, 0, 1, strip));
                                        if(!keepLines){
                                                text = text.replace(/[\r\n]/g, "");
                                        }
                                }
                        }finally{
                                Packages.org.mozilla.javascript.Context.exit();
                        }
                        return copyright + "//>>built" + bc.newline + text;
                };

                return function(resource, text, copyright, optimizeSwitch, callback){
                        bc.log("optimize", ["module", resource.mid]);
                        copyright = copyright || "";
                        try{
                                var result = sscompile(text, resource.dest, optimizeSwitch, copyright);

                                fs.writeFile(resource.dest, result, resource.encoding, function(err){
                                        if(err){
                                                bc.log("optimizeFailedWrite", ["filename", result.dest]);
                                        }
                                        callback(resource, err);
                                });
                        }catch(e){
                                bc.log("optimizeFailed", ["module identifier", resource.mid, "exception", e + ""]);
                                callback(resource, 0);
                        }
                        return callback;
                };
        }

        throw new Error("Unknown host environment: only nodejs and rhino are supported by shrinksafe optimizer.");
});