BitwiseCmd/app/dispatcher.js

(function(app, is){

    var handlers = [];

    var dispatcher = {
        $resultView:null,
        debug:true,
        dispatch: function(rawInput) {
            var input = rawInput.trim();
            var handler = this.findHandler(input);

            if(handler != null) {

                if(this.debug) {
                    this.invokeHandler(input, handler);
                } else {
                    try {
                        this.invokeHandler(input, handler);
                    } catch (e) {
                        this.displayCommandError(input, "Error: " + e);
                    }
                }
            }
            else {
                this.displayCommandError(input, "Unknown expression: " + input.trim());
            }

            // app.command('dispatchInput').execute({input:input});
        },
        command: function(cmd, handler) {
            var h = this.createHandler(cmd, handler);
            if(h == null){
                console.warn('unexpected set of arguments: ', Array.prototype.splice.call(arguments));
                return;
            }

            if(!is.aFunction(h.canHandle)) {
                console.warn('handler is missing "canHandle" function. registration denied.');
                return;
            }

            if(!is.aFunction(h.handle)) {
                console.warn('handler is missing "handle" function. registration denied.');
                return;
            }

            app.di.resolveProperties(h);
            handlers.push(h);
        },
        createHandler: function(cmd, handler) {
            if(is.plainObject(cmd)) {
                return cmd;
            }

            if(is.string(cmd)) {
                return { canHandle: function (input) { return input === cmd; }, handle: handler };
            }

            return null;
        },
        findHandler: function (input) {
            var i= 0, h;
            for(i;i<handlers.length; i++) {
                if(handlers[i].canHandle(input)) {
                    return handlers[i];
                }
            }
        },
        invokeHandler: function (input, handler) {
            var cmdResult = handler.handle(input);
            if(cmdResult != null) {
                var r = new app.models.DisplayResult(input, cmdResult);
                this.$resultView.display(r);
            }
        },
        displayCommandError: function (input, message) {
            var error = new app.models.ErrorResult(message);
            this.$resultView.display(new app.models.DisplayResult(input, error));
        }
    };

    dispatcher.command('clear', function() {
       app.get('resultView').clear();
    });

    app.service('dispatcher', dispatcher);

})(window.app, window.is);