(function (tree) {

tree.Variable = function (name, index, file) { this.name = name, this.index = index, this.file = file }; tree.Variable.prototype = {

eval: function (env) {
    var variable, v, name = this.name;

    if (name.indexOf('@@') == 0) {
        name = '@' + new(tree.Variable)(name.slice(1)).eval(env).value;
    }

    if (variable = tree.find(env.frames, function (frame) {
        if (v = frame.variable(name)) {
            return v.value.eval(env);
        }
    })) { return variable }
    else {
        throw { type: 'Name',
                message: "variable " + name + " is undefined",
                filename: this.file,
                index: this.index };
    }
}

};

})(require('../tree'));