/*!
 * Stylus - stack - Scope
 * Copyright (c) Automattic <developer.wordpress.com>
 * MIT Licensed
 */

/**
 * Initialize a new `Scope`.
 *
 * @api private
 */

var Scope = module.exports = function Scope() {
  this.locals = {};
};

/**
 * Add `ident` node to the current scope.
 *
 * @param {Ident} ident
 * @api private
 */

Scope.prototype.add = function(ident){
  this.locals[ident.name] = ident.val;
};

/**
 * Lookup the given local variable `name`.
 *
 * @param {String} name
 * @return {Node}
 * @api private
 */

Scope.prototype.lookup = function(name){
  return hasOwnProperty(this.locals, name) ? this.locals[name] : undefined;
};

/**
 * Custom inspect.
 *
 * @return {String}
 * @api public
 */

Scope.prototype.inspect = function(){
  var keys = Object.keys(this.locals).map(function(key){ return '@' + key; });
  return '[Scope'
    + (keys.length ? ' ' + keys.join(', ') : '')
    + ']';
};

/**
 * @param {Object} obj
 * @param {String} propName
 * @returns {Boolean}
 */
function hasOwnProperty(obj, propName) {
  return Object.prototype.hasOwnProperty.call(obj, propName);
}