content: function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
  
  function _possibleConstructorReturn(self, call) { if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return call && (typeof call === "object" || typeof call === "function") ? call : self; }
  
  function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
  
  import React from 'react';
  import PropTypes from 'prop-types';
  import invariant from 'invariant';
  
  /**
   * The public API for prompting the user before navigating away
   * from a screen with a component.
   */
  
  var Prompt = function (_React$Component) {
    _inherits(Prompt, _React$Component);
  
    function Prompt() {
      _classCallCheck(this, Prompt);
  
      return _possibleConstructorReturn(this, _React$Component.apply(this, arguments));
    }
  
    Prompt.prototype.enable = function enable(message) {
      if (this.unblock) this.unblock();
  
      this.unblock = this.context.router.history.block(message);
    };
  
    Prompt.prototype.disable = function disable() {
      if (this.unblock) {
        this.unblock();
        this.unblock = null;
      }
    };
  
    Prompt.prototype.componentWillMount = function componentWillMount() {
      invariant(this.context.router, 'You should not use <Prompt> outside a <Router>');
  
      if (this.props.when) this.enable(this.props.message);
    };
  
    Prompt.prototype.componentWillReceiveProps = function componentWillReceiveProps(nextProps) {
      if (nextProps.when) {
        if (!this.props.when || this.props.message !== nextProps.message) this.enable(nextProps.message);
      } else {
        this.disable();
      }
    };
  
    Prompt.prototype.componentWillUnmount = function componentWillUnmount() {
      this.disable();
    };
  
    Prompt.prototype.render = function render() {
      return null;
    };
  
    return Prompt;
  }(React.Component);
  
  Prompt.propTypes = {
    when: PropTypes.bool,
    message: PropTypes.oneOfType([PropTypes.func, PropTypes.string]).isRequired
  };
  Prompt.defaultProps = {
    when: true
  };
  Prompt.contextTypes = {
    router: PropTypes.shape({
      history: PropTypes.shape({
        block: PropTypes.func.isRequired
      }).isRequired
    }).isRequired
  };
  
  
  export default Prompt;