cspace.permissions.expander = function (options, container, key, config) {
        fluid.expect("Permissions expander", ["tree", "permissions", "operations", "method"], options);

        // If the path isn't provided take a whole model as a driver to expand permissions.
        var path = fluid.extractContextualPath(options.controlledBy, {ELstyle: "ALL"}, fluid.threadLocal()) || "";
        var model = fluid.model.getBeanValue(config.model, path);
        var togo = {};
        if (!model) {
            return options.ifEmpty? config.expander(options.ifEmpty) : togo;
        }

        var permManager = cspace.permissions.manager({
            permissions: options.permissions
        });

        // Go through the model and remove fields that are not permitted.
        fluid.remove_if(model, function (elem) {
            return !permManager["resolve" + (options.method || "")](elem, options.operations);
        });
        var expanded = {};
        fluid.withEnvironment({model: model},
            function () {
                expanded = fluid.expander.expandLight(options.tree);
            }
        );
        return expanded;
    };