(function (global, factory) {
	typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
	typeof define === 'function' && define.amd ? define(factory) :
	(global.page = factory());
}(this, (function () { 'use strict';

var isarray = Array.isArray || function (arr) {
  return Object.prototype.toString.call(arr) == '[object Array]';
};

/**
 * Expose `pathToRegexp`.
 */
var pathToRegexp_1 = pathToRegexp;
var parse_1 = parse;
var compile_1 = compile;
var tokensToFunction_1 = tokensToFunction;
var tokensToRegExp_1 = tokensToRegExp;

/**
 * The main path matching regexp utility.
 *
 * @type {RegExp}
 */
var PATH_REGEXP = new RegExp([
  // Match escaped characters that would otherwise appear in future matches.
  // This allows the user to escape special characters that won't transform.
  '(\\\\.)',
  // Match Express-style parameters and un-named parameters with a prefix
  // and optional suffixes. Matches appear as:
  //
  // "/:test(\\d+)?" => ["/", "test", "\d+", undefined, "?", undefined]
  // "/route(\\d+)"  => [undefined, undefined, undefined, "\d+", undefined, undefined]
  // "/*"            => ["/", undefined, undefined, undefined, undefined, "*"]
  '([\\/.])?(?:(?:\\:(\\w+)(?:\\(((?:\\\\.|[^()])+)\\))?|\\(((?:\\\\.|[^()])+)\\))([+*?])?|(\\*))'
].join('|'), 'g');

/**
 * Parse a string for the raw tokens.
 *
 * @param  {String} str
 * @return {Array}
 */
function parse (str) {
  var tokens = [];
  var key = 0;
  var index = 0;
  var path = '';
  var res;

  while ((res = PATH_REGEXP.exec(str)) != null) {
    var m = res[0];
    var escaped = res[1];
    var offset = res.index;
    path += str.slice(index, offset);
    index = offset + m.length;

    // Ignore already escaped sequences.
    if (escaped) {
      path += escaped[1];
      continue
    }

    // Push the current path onto the tokens.
    if (path) {
      tokens.push(path);
      path = '';
    }

    var prefix = res[2];
    var name = res[3];
    var capture = res[4];
    var group = res[5];
    var suffix = res[6];
    var asterisk = res[7];

    var repeat = suffix === '+' || suffix === '*';
    var optional = suffix === '?' || suffix === '*';
    var delimiter = prefix || '/';
    var pattern = capture || group || (asterisk ? '.*' : '[^' + delimiter + ']+?');

    tokens.push({
      name: name || key++,
      prefix: prefix || '',
      delimiter: delimiter,
      optional: optional,
      repeat: repeat,
      pattern: escapeGroup(pattern)
    });
  }

  // Match any characters still remaining.
  if (index < str.length) {
    path += str.substr(index);
  }

  // If the path exists, push it onto the end.
  if (path) {
    tokens.push(path);
  }

  return tokens
}

/**
 * Compile a string to a template function for the path.
 *
 * @param  {String}   str
 * @return {Function}
 */
function compile (str) {
  return tokensToFunction(parse(str))
}

/**
 * Expose a method for transforming tokens into the path function.
 */
function tokensToFunction (tokens) {
  // Compile all the tokens into regexps.
  var matches = new Array(tokens.length);

  // Compile all the patterns before compilation.
  for (var i = 0; i < tokens.length; i++) {
    if (typeof tokens[i] === 'object') {
      matches[i] = new RegExp('^' + tokens[i].pattern + '$');
    }
  }

  return function (obj) {
    var path = '';
    var data = obj || {};

    for (var i = 0; i < tokens.length; i++) {
      var token = tokens[i];

      if (typeof token === 'string') {
        path += token;

        continue
      }

      var value = data[token.name];
      var segment;

      if (value == null) {
        if (token.optional) {
          continue
        } else {
          throw new TypeError('Expected "' + token.name + '" to be defined')
        }
      }

      if (isarray(value)) {
        if (!token.repeat) {
          throw new TypeError('Expected "' + token.name + '" to not repeat, but received "' + value + '"')
        }

        if (value.length === 0) {
          if (token.optional) {
            continue
          } else {
            throw new TypeError('Expected "' + token.name + '" to not be empty')
          }
        }

        for (var j = 0; j < value.length; j++) {
          segment = encodeURIComponent(value[j]);

          if (!matches[i].test(segment)) {
            throw new TypeError('Expected all "' + token.name + '" to match "' + token.pattern + '", but received "' + segment + '"')
          }

          path += (j === 0 ? token.prefix : token.delimiter) + segment;
        }

        continue
      }

      segment = encodeURIComponent(value);

      if (!matches[i].test(segment)) {
        throw new TypeError('Expected "' + token.name + '" to match "' + token.pattern + '", but received "' + segment + '"')
      }

      path += token.prefix + segment;
    }

    return path
  }
}

/**
 * Escape a regular expression string.
 *
 * @param  {String} str
 * @return {String}
 */
function escapeString (str) {
  return str.replace(/([.+*?=^!:${}()[\]|\/])/g, '\\$1')
}

/**
 * Escape the capturing group by escaping special characters and meaning.
 *
 * @param  {String} group
 * @return {String}
 */
function escapeGroup (group) {
  return group.replace(/([=!:$\/()])/g, '\\$1')
}

/**
 * Attach the keys as a property of the regexp.
 *
 * @param  {RegExp} re
 * @param  {Array}  keys
 * @return {RegExp}
 */
function attachKeys (re, keys) {
  re.keys = keys;
  return re
}

/**
 * Get the flags for a regexp from the options.
 *
 * @param  {Object} options
 * @return {String}
 */
function flags (options) {
  return options.sensitive ? '' : 'i'
}

/**
 * Pull out keys from a regexp.
 *
 * @param  {RegExp} path
 * @param  {Array}  keys
 * @return {RegExp}
 */
function regexpToRegexp (path, keys) {
  // Use a negative lookahead to match only capturing groups.
  var groups = path.source.match(/\((?!\?)/g);

  if (groups) {
    for (var i = 0; i < groups.length; i++) {
      keys.push({
        name: i,
        prefix: null,
        delimiter: null,
        optional: false,
        repeat: false,
        pattern: null
      });
    }
  }

  return attachKeys(path, keys)
}

/**
 * Transform an array into a regexp.
 *
 * @param  {Array}  path
 * @param  {Array}  keys
 * @param  {Object} options
 * @return {RegExp}
 */
function arrayToRegexp (path, keys, options) {
  var parts = [];

  for (var i = 0; i < path.length; i++) {
    parts.push(pathToRegexp(path[i], keys, options).source);
  }

  var regexp = new RegExp('(?:' + parts.join('|') + ')', flags(options));

  return attachKeys(regexp, keys)
}

/**
 * Create a path regexp from string input.
 *
 * @param  {String} path
 * @param  {Array}  keys
 * @param  {Object} options
 * @return {RegExp}
 */
function stringToRegexp (path, keys, options) {
  var tokens = parse(path);
  var re = tokensToRegExp(tokens, options);

  // Attach keys back to the regexp.
  for (var i = 0; i < tokens.length; i++) {
    if (typeof tokens[i] !== 'string') {
      keys.push(tokens[i]);
    }
  }

  return attachKeys(re, keys)
}

/**
 * Expose a function for taking tokens and returning a RegExp.
 *
 * @param  {Array}  tokens
 * @param  {Array}  keys
 * @param  {Object} options
 * @return {RegExp}
 */
function tokensToRegExp (tokens, options) {
  options = options || {};

  var strict = options.strict;
  var end = options.end !== false;
  var route = '';
  var lastToken = tokens[tokens.length - 1];
  var endsWithSlash = typeof lastToken === 'string' && /\/$/.test(lastToken);

  // Iterate over the tokens and create our regexp string.
  for (var i = 0; i < tokens.length; i++) {
    var token = tokens[i];

    if (typeof token === 'string') {
      route += escapeString(token);
    } else {
      var prefix = escapeString(token.prefix);
      var capture = token.pattern;

      if (token.repeat) {
        capture += '(?:' + prefix + capture + ')*';
      }

      if (token.optional) {
        if (prefix) {
          capture = '(?:' + prefix + '(' + capture + '))?';
        } else {
          capture = '(' + capture + ')?';
        }
      } else {
        capture = prefix + '(' + capture + ')';
      }

      route += capture;
    }
  }

  // In non-strict mode we allow a slash at the end of match. If the path to
  // match already ends with a slash, we remove it for consistency. The slash
  // is valid at the end of a path match, not in the middle. This is important
  // in non-ending mode, where "/test/" shouldn't match "/test//route".
  if (!strict) {
    route = (endsWithSlash ? route.slice(0, -2) : route) + '(?:\\/(?=$))?';
  }

  if (end) {
    route += '$';
  } else {
    // In non-ending mode, we need the capturing groups to match as much as
    // possible by using a positive lookahead to the end or next path segment.
    route += strict && endsWithSlash ? '' : '(?=\\/|$)';
  }

  return new RegExp('^' + route, flags(options))
}

/**
 * Normalize the given path string, returning a regular expression.
 *
 * An empty array can be passed in for the keys, which will hold the
 * placeholder key descriptions. For example, using `/user/:id`, `keys` will
 * contain `[{ name: 'id', delimiter: '/', optional: false, repeat: false }]`.
 *
 * @param  {(String|RegExp|Array)} path
 * @param  {Array}                 [keys]
 * @param  {Object}                [options]
 * @return {RegExp}
 */
function pathToRegexp (path, keys, options) {
  keys = keys || [];

  if (!isarray(keys)) {
    options = keys;
    keys = [];
  } else if (!options) {
    options = {};
  }

  if (path instanceof RegExp) {
    return regexpToRegexp(path, keys, options)
  }

  if (isarray(path)) {
    return arrayToRegexp(path, keys, options)
  }

  return stringToRegexp(path, keys, options)
}

pathToRegexp_1.parse = parse_1;
pathToRegexp_1.compile = compile_1;
pathToRegexp_1.tokensToFunction = tokensToFunction_1;
pathToRegexp_1.tokensToRegExp = tokensToRegExp_1;

/**
   * Module dependencies.
   */

  

  /**
   * Short-cuts for global-object checks
   */

  var hasDocument = ('undefined' !== typeof document);
  var hasWindow = ('undefined' !== typeof window);
  var hasHistory = ('undefined' !== typeof history);
  var hasProcess = typeof process !== 'undefined';

  /**
   * Detect click event
   */
  var clickEvent = hasDocument && document.ontouchstart ? 'touchstart' : 'click';

  /**
   * To work properly with the URL
   * history.location generated polyfill in https://github.com/devote/HTML5-History-API
   */

  var isLocation = hasWindow && !!(window.history.location || window.location);

  /**
   * The page instance
   * @api private
   */
  function Page(options) {
    // public things
    this.callbacks = [];
    this.exits = [];
    this.current = '';
    this.len = 0;

    // private things
    this._dispatch = true;
    this._decodeURLComponents = true;
    this._base = '';
    this._strict = false;
    this._running = false;
    this._hashbang = false;

    // bound functions
    this._onclick = this._onclick.bind(this);
    this._onpopstate = this._onpopstate.bind(this);

    this.configure(options);
  }

  /**
   * Configure the instance of page. This can be called multiple times.
   *
   * @param {Object} options
   * @api public
   */

  Page.prototype.configure = function(options) {
    var opts = options || {};

    this._window = opts.window || (hasWindow && window);
    this._dispatch = opts.dispatch !== false;
    this._decodeURLComponents = opts.decodeURLComponents !== false;
    this._popstate = opts.popstate !== false && hasWindow;
    this._click = opts.click !== false && hasDocument;
    this._hashbang = !!opts.hashbang;

    var _window = this._window;
    if(this._popstate) {
      _window.addEventListener('popstate', this._onpopstate, false);
    } else if(hasWindow) {
      _window.removeEventListener('popstate', this._onpopstate, false);
    }

    if (this._click) {
      _window.document.addEventListener(clickEvent, this._onclick, false);
    } else if(hasDocument) {
      _window.document.removeEventListener(clickEvent, this._onclick, false);
    }

    if(this._hashbang && hasWindow && !hasHistory) {
      _window.addEventListener('hashchange', this._onpopstate, false);
    } else if(hasWindow) {
      _window.removeEventListener('hashchange', this._onpopstate, false);
    }
  };

  /**
   * Get or set basepath to `path`.
   *
   * @param {string} path
   * @api public
   */

  Page.prototype.base = function(path) {
    if (0 === arguments.length) return this._base;
    this._base = path;
  };

  /**
   * Gets the `base`, which depends on whether we are using History or
   * hashbang routing.

   * @api private
   */
  Page.prototype._getBase = function() {
    var base = this._base;
    if(!!base) return base;
    var loc = hasWindow && this._window && this._window.location;
    return (hasWindow && this._hashbang && loc && loc.protocol === 'file:') ? loc.pathname : base;
  };

  /**
   * Get or set strict path matching to `enable`
   *
   * @param {boolean} enable
   * @api public
   */

  Page.prototype.strict = function(enable) {
    if (0 === arguments.length) return this._strict;
    this._strict = enable;
  };


  /**
   * Bind with the given `options`.
   *
   * Options:
   *
   *    - `click` bind to click events [true]
   *    - `popstate` bind to popstate [true]
   *    - `dispatch` perform initial dispatch [true]
   *
   * @param {Object} options
   * @api public
   */

  Page.prototype.start = function(options) {
    this.configure(options);

    if (!this._dispatch) return;
    this._running = true;

    var url;
    if(isLocation) {
      var window = this._window;
      var loc = window.location;

      if(this._hashbang && ~loc.hash.indexOf('#!')) {
        url = loc.hash.substr(2) + loc.search;
      } else if (this._hashbang) {
        url = loc.search + loc.hash;
      } else {
        url = loc.pathname + loc.search + loc.hash;
      }
    }

    this.replace(url, null, true, this._dispatch);
  };

  /**
   * Unbind click and popstate event handlers.
   *
   * @api public
   */

  Page.prototype.stop = function() {
    if (!this._running) return;
    this.current = '';
    this.len = 0;
    this._running = false;

    var window = this._window;
    hasDocument && window.document.removeEventListener(clickEvent, this._onclick, false);
    hasWindow && window.removeEventListener('popstate', this._onpopstate, false);
    hasWindow && window.removeEventListener('hashchange', this._onpopstate, false);
  };

  /**
   * Show `path` with optional `state` object.
   *
   * @param {string} path
   * @param {Object=} state
   * @param {boolean=} dispatch
   * @param {boolean=} push
   * @return {!Context}
   * @api public
   */

  Page.prototype.show = function(path, state, dispatch, push) {
    var ctx = new Context(path, state, this),
      prev = this.prevContext;
    this.prevContext = ctx;
    this.current = ctx.path;
    if (this._dispatch) this.dispatch(ctx, prev);
    if (false !== ctx.handled && false !== push) ctx.pushState();
    return ctx;
  };

  /**
   * Goes back in the history
   * Back should always let the current route push state and then go back.
   *
   * @param {string} path - fallback path to go back if no more history exists, if undefined defaults to page.base
   * @param {Object=} state
   * @api public
   */

  Page.prototype.back = function(path, state) {
    var page = this;
    if (this.len > 0) {
      var window = this._window;
      // this may need more testing to see if all browsers
      // wait for the next tick to go back in history
      hasHistory && window.history.back();
      this.len--;
    } else if (path) {
      setTimeout(function() {
        page.show(path, state);
      });
    } else {
      setTimeout(function() {
        page.show(page._getBase(), state);
      });
    }
  };

  /**
   * Register route to redirect from one path to other
   * or just redirect to another route
   *
   * @param {string} from - if param 'to' is undefined redirects to 'from'
   * @param {string=} to
   * @api public
   */
  Page.prototype.redirect = function(from, to) {
    var inst = this;

    // Define route from a path to another
    if ('string' === typeof from && 'string' === typeof to) {
      page.call(this, from, function(e) {
        setTimeout(function() {
          inst.replace(/** @type {!string} */ (to));
        }, 0);
      });
    }

    // Wait for the push state and replace it with another
    if ('string' === typeof from && 'undefined' === typeof to) {
      setTimeout(function() {
        inst.replace(from);
      }, 0);
    }
  };

  /**
   * Replace `path` with optional `state` object.
   *
   * @param {string} path
   * @param {Object=} state
   * @param {boolean=} init
   * @param {boolean=} dispatch
   * @return {!Context}
   * @api public
   */


  Page.prototype.replace = function(path, state, init, dispatch) {
    var ctx = new Context(path, state, this),
      prev = this.prevContext;
    this.prevContext = ctx;
    this.current = ctx.path;
    ctx.init = init;
    ctx.save(); // save before dispatching, which may redirect
    if (false !== dispatch) this.dispatch(ctx, prev);
    return ctx;
  };

  /**
   * Dispatch the given `ctx`.
   *
   * @param {Context} ctx
   * @api private
   */

  Page.prototype.dispatch = function(ctx, prev) {
    var i = 0, j = 0, page = this;

    function nextExit() {
      var fn = page.exits[j++];
      if (!fn) return nextEnter();
      fn(prev, nextExit);
    }

    function nextEnter() {
      var fn = page.callbacks[i++];

      if (ctx.path !== page.current) {
        ctx.handled = false;
        return;
      }
      if (!fn) return unhandled.call(page, ctx);
      fn(ctx, nextEnter);
    }

    if (prev) {
      nextExit();
    } else {
      nextEnter();
    }
  };

  /**
   * Register an exit route on `path` with
   * callback `fn()`, which will be called
   * on the previous context when a new
   * page is visited.
   */
  Page.prototype.exit = function(path, fn) {
    if (typeof path === 'function') {
      return this.exit('*', path);
    }

    var route = new Route(path, null, this);
    for (var i = 1; i < arguments.length; ++i) {
      this.exits.push(route.middleware(arguments[i]));
    }
  };

  /**
   * Handle "click" events.
   */

  /* jshint +W054 */
  Page.prototype._onclick = function(e) {
    if (1 !== this._which(e)) return;

    if (e.metaKey || e.ctrlKey || e.shiftKey) return;
    if (e.defaultPrevented) return;

    // ensure link
    // use shadow dom when available if not, fall back to composedPath()
    // for browsers that only have shady
    var el = e.target;
    var eventPath = e.path || (e.composedPath ? e.composedPath() : null);

    if(eventPath) {
      for (var i = 0; i < eventPath.length; i++) {
        if (!eventPath[i].nodeName) continue;
        if (eventPath[i].nodeName.toUpperCase() !== 'A') continue;
        if (!eventPath[i].href) continue;

        el = eventPath[i];
        break;
      }
    }

    // continue ensure link
    // el.nodeName for svg links are 'a' instead of 'A'
    while (el && 'A' !== el.nodeName.toUpperCase()) el = el.parentNode;
    if (!el || 'A' !== el.nodeName.toUpperCase()) return;

    // check if link is inside an svg
    // in this case, both href and target are always inside an object
    var svg = (typeof el.href === 'object') && el.href.constructor.name === 'SVGAnimatedString';

    // Ignore if tag has
    // 1. "download" attribute
    // 2. rel="external" attribute
    if (el.hasAttribute('download') || el.getAttribute('rel') === 'external') return;

    // ensure non-hash for the same path
    var link = el.getAttribute('href');
    if(!this._hashbang && this._samePath(el) && (el.hash || '#' === link)) return;

    // Check for mailto: in the href
    if (link && link.indexOf('mailto:') > -1) return;

    // check target
    // svg target is an object and its desired value is in .baseVal property
    if (svg ? el.target.baseVal : el.target) return;

    // x-origin
    // note: svg links that are not relative don't call click events (and skip page.js)
    // consequently, all svg links tested inside page.js are relative and in the same origin
    if (!svg && !this.sameOrigin(el.href)) return;

    // rebuild path
    // There aren't .pathname and .search properties in svg links, so we use href
    // Also, svg href is an object and its desired value is in .baseVal property
    var path = svg ? el.href.baseVal : (el.pathname + el.search + (el.hash || ''));

    path = path[0] !== '/' ? '/' + path : path;

    // strip leading "/[drive letter]:" on NW.js on Windows
    if (hasProcess && path.match(/^\/[a-zA-Z]:\//)) {
      path = path.replace(/^\/[a-zA-Z]:\//, '/');
    }

    // same page
    var orig = path;
    var pageBase = this._getBase();

    if (path.indexOf(pageBase) === 0) {
      path = path.substr(pageBase.length);
    }

    if (this._hashbang) path = path.replace('#!', '');

    if (pageBase && orig === path) return;

    e.preventDefault();
    this.show(orig);
  };

  /**
   * Handle "populate" events.
   * @api private
   */

  Page.prototype._onpopstate = (function () {
    var loaded = false;
    if ( ! hasWindow ) {
      return;
    }
    if (hasDocument && document.readyState === 'complete') {
      loaded = true;
    } else {
      window.addEventListener('load', function() {
        setTimeout(function() {
          loaded = true;
        }, 0);
      });
    }
    return function onpopstate(e) {
      if (!loaded) return;
      var page = this;
      if (e.state) {
        var path = e.state.path;
        page.replace(path, e.state);
      } else if (isLocation) {
        var loc = page._window.location;
        page.show(loc.pathname + loc.search + loc.hash, undefined, undefined, false);
      }
    };
  })();

  /**
   * Event button.
   */
  Page.prototype._which = function(e) {
    e = e || (hasWindow && this._window.event);
    return null == e.which ? e.button : e.which;
  };

  /**
   * Convert to a URL object
   * @api private
   */
  Page.prototype._toURL = function(href) {
    var window = this._window;
    if(typeof URL === 'function' && isLocation) {
      return new URL(href, window.location.toString());
    } else if (hasDocument) {
      var anc = window.document.createElement('a');
      anc.href = href;
      return anc;
    }
  };

  /**
   * Check if `href` is the same origin.
   * @param {string} href
   * @api public
   */

  Page.prototype.sameOrigin = function(href) {
    if(!href || !isLocation) return false;

    var url = this._toURL(href);
    var window = this._window;

    var loc = window.location;
    return loc.protocol === url.protocol &&
      loc.hostname === url.hostname &&
      loc.port === url.port;
  };

  /**
   * @api private
   */
  Page.prototype._samePath = function(url) {
    if(!isLocation) return false;
    var window = this._window;
    var loc = window.location;
    return url.pathname === loc.pathname &&
      url.search === loc.search;
  };

  /**
   * Remove URL encoding from the given `str`.
   * Accommodates whitespace in both x-www-form-urlencoded
   * and regular percent-encoded form.
   *
   * @param {string} val - URL component to decode
   * @api private
   */
  Page.prototype._decodeURLEncodedURIComponent = function(val) {
    if (typeof val !== 'string') { return val; }
    return this._decodeURLComponents ? decodeURIComponent(val.replace(/\+/g, ' ')) : val;
  };

  /**
   * Create a new `page` instance and function
   */
  function createPage(options) {
    var pageInstance = new Page();

    function pageFn(/* args */) {
      return page.apply(pageInstance, arguments);
    }

    // Copy all of the things over. In 2.0 maybe we use setPrototypeOf
    pageFn.callbacks = pageInstance.callbacks;
    pageFn.exits = pageInstance.exits;
    pageFn.base = pageInstance.base.bind(pageInstance);
    pageFn.strict = pageInstance.strict.bind(pageInstance);
    pageFn.start = pageInstance.start.bind(pageInstance);
    pageFn.stop = pageInstance.stop.bind(pageInstance);
    pageFn.show = pageInstance.show.bind(pageInstance);
    pageFn.back = pageInstance.back.bind(pageInstance);
    pageFn.redirect = pageInstance.redirect.bind(pageInstance);
    pageFn.replace = pageInstance.replace.bind(pageInstance);
    pageFn.dispatch = pageInstance.dispatch.bind(pageInstance);
    pageFn.exit = pageInstance.exit.bind(pageInstance);
    pageFn.configure = pageInstance.configure.bind(pageInstance);
    pageFn.sameOrigin = pageInstance.sameOrigin.bind(pageInstance);

    pageFn.create = createPage;

    Object.defineProperty(pageFn, 'len', {
      get: function(){
        return pageInstance.len;
      },
      set: function(val) {
        pageInstance.len = val;
      }
    });

    Object.defineProperty(pageFn, 'current', {
      get: function(){
        return pageInstance.current;
      },
      set: function(val) {
        pageInstance.current = val;
      }
    });

    // In 2.0 these can be named exports
    pageFn.Context = Context;
    pageFn.Route = Route;

    return pageFn;
  }

  /**
   * Register `path` with callback `fn()`,
   * or route `path`, or redirection,
   * or `page.start()`.
   *
   *   page(fn);
   *   page('*', fn);
   *   page('/user/:id', load, user);
   *   page('/user/' + user.id, { some: 'thing' });
   *   page('/user/' + user.id);
   *   page('/from', '/to')
   *   page();
   *
   * @param {string|!Function|!Object} path
   * @param {Function=} fn
   * @api public
   */

  function page(path, fn) {
    // <callback>
    if ('function' === typeof path) {
      return page.call(this, '*', path);
    }

    // route <path> to <callback ...>
    if ('function' === typeof fn) {
      var route = new Route(/** @type {string} */ (path), null, this);
      for (var i = 1; i < arguments.length; ++i) {
        this.callbacks.push(route.middleware(arguments[i]));
      }
      // show <path> with [state]
    } else if ('string' === typeof path) {
      this['string' === typeof fn ? 'redirect' : 'show'](path, fn);
      // start [options]
    } else {
      this.start(path);
    }
  }

  /**
   * Unhandled `ctx`. When it's not the initial
   * popstate then redirect. If you wish to handle
   * 404s on your own use `page('*', callback)`.
   *
   * @param {Context} ctx
   * @api private
   */
  function unhandled(ctx) {
    if (ctx.handled) return;
    var current;
    var page = this;
    var window = page._window;

    if (page._hashbang) {
      current = isLocation && this._getBase() + window.location.hash.replace('#!', '');
    } else {
      current = isLocation && window.location.pathname + window.location.search;
    }

    if (current === ctx.canonicalPath) return;
    page.stop();
    ctx.handled = false;
    isLocation && (window.location.href = ctx.canonicalPath);
  }

  /**
   * Initialize a new "request" `Context`
   * with the given `path` and optional initial `state`.
   *
   * @constructor
   * @param {string} path
   * @param {Object=} state
   * @api public
   */

  function Context(path, state, pageInstance) {
    var _page = this.page = pageInstance || page;
    var window = _page._window;
    var hashbang = _page.hashbang;

    var pageBase = _page._getBase();
    if ('/' === path[0] && 0 !== path.indexOf(pageBase)) path = pageBase + (hashbang ? '#!' : '') + path;
    var i = path.indexOf('?');

    this.canonicalPath = path;
    this.path = path.replace(pageBase, '') || '/';
    if (hashbang) this.path = this.path.replace('#!', '') || '/';

    this.title = (hasDocument && window.document.title);
    this.state = state || {};
    this.state.path = path;
    this.querystring = ~i ? _page._decodeURLEncodedURIComponent(path.slice(i + 1)) : '';
    this.pathname = _page._decodeURLEncodedURIComponent(~i ? path.slice(0, i) : path);
    this.params = {};

    // fragment
    this.hash = '';
    if (!hashbang) {
      if (!~this.path.indexOf('#')) return;
      var parts = this.path.split('#');
      this.path = this.pathname = parts[0];
      this.hash = _page._decodeURLEncodedURIComponent(parts[1]) || '';
      this.querystring = this.querystring.split('#')[0];
    }
  }

  /**
   * Push state.
   *
   * @api private
   */

  Context.prototype.pushState = function() {
    var page = this.page;
    var window = page._window;
    var hashbang = page._hashbang;

    page.len++;
    if (hasHistory) {
        window.history.pushState(this.state, this.title,
          hashbang && this.path !== '/' ? '#!' + this.path : this.canonicalPath);
    }
  };

  /**
   * Save the context state.
   *
   * @api public
   */

  Context.prototype.save = function() {
    var page = this.page;
    if (hasHistory && page._window.location.protocol !== 'file:') {
        page._window.history.replaceState(this.state, this.title,
          page._hashbang && this.path !== '/' ? '#!' + this.path : this.canonicalPath);
    }
  };

  /**
   * Initialize `Route` with the given HTTP `path`,
   * and an array of `callbacks` and `options`.
   *
   * Options:
   *
   *   - `sensitive`    enable case-sensitive routes
   *   - `strict`       enable strict matching for trailing slashes
   *
   * @constructor
   * @param {string} path
   * @param {Object=} options
   * @api private
   */

  function Route(path, options, page) {
    var _page = this.page = page || globalPage;
    var opts = options || {};
    opts.strict = opts.strict || page._strict;
    this.path = (path === '*') ? '(.*)' : path;
    this.method = 'GET';
    this.regexp = pathToRegexp_1(this.path, this.keys = [], opts);
  }

  /**
   * Return route middleware with
   * the given callback `fn()`.
   *
   * @param {Function} fn
   * @return {Function}
   * @api public
   */

  Route.prototype.middleware = function(fn) {
    var self = this;
    return function(ctx, next) {
      if (self.match(ctx.path, ctx.params)) return fn(ctx, next);
      next();
    };
  };

  /**
   * Check if this route matches `path`, if so
   * populate `params`.
   *
   * @param {string} path
   * @param {Object} params
   * @return {boolean}
   * @api private
   */

  Route.prototype.match = function(path, params) {
    var keys = this.keys,
      qsIndex = path.indexOf('?'),
      pathname = ~qsIndex ? path.slice(0, qsIndex) : path,
      m = this.regexp.exec(decodeURIComponent(pathname));

    if (!m) return false;

    for (var i = 1, len = m.length; i < len; ++i) {
      var key = keys[i - 1];
      var val = this.page._decodeURLEncodedURIComponent(m[i]);
      if (val !== undefined || !(hasOwnProperty.call(params, key.name))) {
        params[key.name] = val;
      }
    }

    return true;
  };


  /**
   * Module exports.
   */

  var globalPage = createPage();
  var page_js = globalPage;
  page.default = globalPage;

return page_js;

})));