/*:nodoc:*
   * class ActionAppend
   *
   * This action stores a list, and appends each argument value to the list.
   * This is useful to allow an option to be specified multiple times.
   * This class inherided from [[Action]]
   *
   **/
  
  'use strict';
  
  var util = require('util');
  
  var Action = require('../action');
  
  // Constants
  var c = require('../const');
  
  /*:nodoc:*
   * new ActionAppend(options)
   * - options (object): options hash see [[Action.new]]
   *
   * Note: options.nargs should be optional for constants
   * and more then zero for other
   **/
  var ActionAppend = module.exports = function ActionAppend(options) {
    options = options || {};
    if (this.nargs <= 0) {
      throw new Error('nargs for append actions must be > 0; if arg ' +
          'strings are not supplying the value to append, ' +
          'the append const action may be more appropriate');
    }
    if (!!this.constant && this.nargs !== c.OPTIONAL) {
      throw new Error('nargs must be OPTIONAL to supply const');
    }
    Action.call(this, options);
  };
  util.inherits(ActionAppend, Action);
  
  /*:nodoc:*
   * ActionAppend#call(parser, namespace, values, optionString) -> Void
   * - parser (ArgumentParser): current parser
   * - namespace (Namespace): namespace for output data
   * - values (Array): parsed values
   * - optionString (Array): input option string(not parsed)
   *
   * Call the action. Save result in namespace object
   **/
  ActionAppend.prototype.call = function (parser, namespace, values) {
    var items = (namespace[this.dest] || []).slice();
    items.push(values);
    namespace.set(this.dest, items);
  };