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

define(["../buildControl"], function(bc) {
        var evalPragma= function(code, kwArgs, fileName) {
                        return !!eval("(" + code + ")");
                };

        return function(resource) {
                if(!bc.applyDojoPragmas){
                        return;
                }
                if(typeof resource.text!="string"){
                        return;
                }

                var
                        foundIndex = -1,
                        startIndex = 0,
                        text= resource.text;
                while((foundIndex = text.indexOf("//>>", startIndex)) != -1){
                        //Found a conditional. Get the conditional line.
                        var lineEndIndex = text.indexOf("\n", foundIndex);
                        if(lineEndIndex == -1){
                                lineEndIndex = text.length - 1;
                        }

                        //Increment startIndex past the line so the next conditional search can be done.
                        startIndex = lineEndIndex + 1;

                        //Break apart the conditional.
                        var conditionLine = text.substring(foundIndex, lineEndIndex + 1);
                        var matches = conditionLine.match(/(exclude|include)Start\s*\(\s*["'](\w+)["']\s*,(.*)\)/);
                        if(matches){
                                var type = matches[1];
                                var marker = matches[2];
                                var condition = matches[3];
                                var isTrue = false;
                                //See if the condition is true.
                                try{
                                        isTrue = evalPragma(condition, bc, resource.src);
                                }catch(e){
                                        bc.log("dojoPragmaEvalFail", ["module", resource.mid, "expression", conditionLine, "error", e]);
                                        return;
                                }

                                //Find the endpoint marker.
                                var endRegExp = new RegExp('\\/\\/\\>\\>\\s*' + type + 'End\\(\\s*[\'"]' + marker + '[\'"]\\s*\\)', "g");
                                var endMatches = endRegExp.exec(text.substring(startIndex, text.length));
                                if(endMatches){

                                        var endMarkerIndex = startIndex + endRegExp.lastIndex - endMatches[0].length;

                                        //Find the next line return based on the match position.
                                        lineEndIndex = text.indexOf("\n", endMarkerIndex);
                                        if(lineEndIndex == -1){
                                                lineEndIndex = text.length - 1;
                                        }

                                        //Should we include the segment?
                                        var shouldInclude = ((type == "exclude" && !isTrue) || (type == "include" && isTrue));

                                        //Remove the conditional comments, and optionally remove the content inside
                                        //the conditional comments.
                                        var startLength = startIndex - foundIndex;
                                        text = text.substring(0, foundIndex)
                                                + (shouldInclude ? text.substring(startIndex, endMarkerIndex) : "")
                                                + text.substring(lineEndIndex + 1, text.length);

                                        //Move startIndex to foundIndex, since that is the new position in the file
                                        //where we need to look for more conditionals in the next while loop pass.
                                        startIndex = foundIndex;
                                }else{
                                        bc.log("dojoPragmaInvalid", ["module", resource.mid, "expression", conditionLine]);
                                        return;
                                }
                        }else if(/^\/\/>>\s*noBuildResolver\s*$/.test(conditionLine)){
                                resource.noBuildResolver = 1;
                        }
                }
                resource.text= text;
        };
});