0.2.0 - Mid migration

web/node_modules/history/esm/history.js

@@ -0,0 +1,919 @@
+import _extends from '@babel/runtime/helpers/esm/extends';
+import resolvePathname from 'resolve-pathname';
+import valueEqual from 'value-equal';
+import warning from 'tiny-warning';
+import invariant from 'tiny-invariant';
+
+function addLeadingSlash(path) {
+  return path.charAt(0) === '/' ? path : '/' + path;
+}
+function stripLeadingSlash(path) {
+  return path.charAt(0) === '/' ? path.substr(1) : path;
+}
+function hasBasename(path, prefix) {
+  return path.toLowerCase().indexOf(prefix.toLowerCase()) === 0 && '/?#'.indexOf(path.charAt(prefix.length)) !== -1;
+}
+function stripBasename(path, prefix) {
+  return hasBasename(path, prefix) ? path.substr(prefix.length) : path;
+}
+function stripTrailingSlash(path) {
+  return path.charAt(path.length - 1) === '/' ? path.slice(0, -1) : path;
+}
+function parsePath(path) {
+  var pathname = path || '/';
+  var search = '';
+  var hash = '';
+  var hashIndex = pathname.indexOf('#');
+
+  if (hashIndex !== -1) {
+    hash = pathname.substr(hashIndex);
+    pathname = pathname.substr(0, hashIndex);
+  }
+
+  var searchIndex = pathname.indexOf('?');
+
+  if (searchIndex !== -1) {
+    search = pathname.substr(searchIndex);
+    pathname = pathname.substr(0, searchIndex);
+  }
+
+  return {
+    pathname: pathname,
+    search: search === '?' ? '' : search,
+    hash: hash === '#' ? '' : hash
+  };
+}
+function createPath(location) {
+  var pathname = location.pathname,
+      search = location.search,
+      hash = location.hash;
+  var path = pathname || '/';
+  if (search && search !== '?') path += search.charAt(0) === '?' ? search : "?" + search;
+  if (hash && hash !== '#') path += hash.charAt(0) === '#' ? hash : "#" + hash;
+  return path;
+}
+
+function createLocation(path, state, key, currentLocation) {
+  var location;
+
+  if (typeof path === 'string') {
+    // Two-arg form: push(path, state)
+    location = parsePath(path);
+    location.state = state;
+  } else {
+    // One-arg form: push(location)
+    location = _extends({}, path);
+    if (location.pathname === undefined) location.pathname = '';
+
+    if (location.search) {
+      if (location.search.charAt(0) !== '?') location.search = '?' + location.search;
+    } else {
+      location.search = '';
+    }
+
+    if (location.hash) {
+      if (location.hash.charAt(0) !== '#') location.hash = '#' + location.hash;
+    } else {
+      location.hash = '';
+    }
+
+    if (state !== undefined && location.state === undefined) location.state = state;
+  }
+
+  try {
+    location.pathname = decodeURI(location.pathname);
+  } catch (e) {
+    if (e instanceof URIError) {
+      throw new URIError('Pathname "' + location.pathname + '" could not be decoded. ' + 'This is likely caused by an invalid percent-encoding.');
+    } else {
+      throw e;
+    }
+  }
+
+  if (key) location.key = key;
+
+  if (currentLocation) {
+    // Resolve incomplete/relative pathname relative to current location.
+    if (!location.pathname) {
+      location.pathname = currentLocation.pathname;
+    } else if (location.pathname.charAt(0) !== '/') {
+      location.pathname = resolvePathname(location.pathname, currentLocation.pathname);
+    }
+  } else {
+    // When there is no prior location and pathname is empty, set it to /
+    if (!location.pathname) {
+      location.pathname = '/';
+    }
+  }
+
+  return location;
+}
+function locationsAreEqual(a, b) {
+  return a.pathname === b.pathname && a.search === b.search && a.hash === b.hash && a.key === b.key && valueEqual(a.state, b.state);
+}
+
+function createTransitionManager() {
+  var prompt = null;
+
+  function setPrompt(nextPrompt) {
+    process.env.NODE_ENV !== "production" ? warning(prompt == null, 'A history supports only one prompt at a time') : void 0;
+    prompt = nextPrompt;
+    return function () {
+      if (prompt === nextPrompt) prompt = null;
+    };
+  }
+
+  function confirmTransitionTo(location, action, getUserConfirmation, callback) {
+    // TODO: If another transition starts while we're still confirming
+    // the previous one, we may end up in a weird state. Figure out the
+    // best way to handle this.
+    if (prompt != null) {
+      var result = typeof prompt === 'function' ? prompt(location, action) : prompt;
+
+      if (typeof result === 'string') {
+        if (typeof getUserConfirmation === 'function') {
+          getUserConfirmation(result, callback);
+        } else {
+          process.env.NODE_ENV !== "production" ? warning(false, 'A history needs a getUserConfirmation function in order to use a prompt message') : void 0;
+          callback(true);
+        }
+      } else {
+        // Return false from a transition hook to cancel the transition.
+        callback(result !== false);
+      }
+    } else {
+      callback(true);
+    }
+  }
+
+  var listeners = [];
+
+  function appendListener(fn) {
+    var isActive = true;
+
+    function listener() {
+      if (isActive) fn.apply(void 0, arguments);
+    }
+
+    listeners.push(listener);
+    return function () {
+      isActive = false;
+      listeners = listeners.filter(function (item) {
+        return item !== listener;
+      });
+    };
+  }
+
+  function notifyListeners() {
+    for (var _len = arguments.length, args = new Array(_len), _key = 0; _key < _len; _key++) {
+      args[_key] = arguments[_key];
+    }
+
+    listeners.forEach(function (listener) {
+      return listener.apply(void 0, args);
+    });
+  }
+
+  return {
+    setPrompt: setPrompt,
+    confirmTransitionTo: confirmTransitionTo,
+    appendListener: appendListener,
+    notifyListeners: notifyListeners
+  };
+}
+
+var canUseDOM = !!(typeof window !== 'undefined' && window.document && window.document.createElement);
+function getConfirmation(message, callback) {
+  callback(window.confirm(message)); // eslint-disable-line no-alert
+}
+/**
+ * Returns true if the HTML5 history API is supported. Taken from Modernizr.
+ *
+ * https://github.com/Modernizr/Modernizr/blob/master/LICENSE
+ * https://github.com/Modernizr/Modernizr/blob/master/feature-detects/history.js
+ * changed to avoid false negatives for Windows Phones: https://github.com/reactjs/react-router/issues/586
+ */
+
+function supportsHistory() {
+  var ua = window.navigator.userAgent;
+  if ((ua.indexOf('Android 2.') !== -1 || ua.indexOf('Android 4.0') !== -1) && ua.indexOf('Mobile Safari') !== -1 && ua.indexOf('Chrome') === -1 && ua.indexOf('Windows Phone') === -1) return false;
+  return window.history && 'pushState' in window.history;
+}
+/**
+ * Returns true if browser fires popstate on hash change.
+ * IE10 and IE11 do not.
+ */
+
+function supportsPopStateOnHashChange() {
+  return window.navigator.userAgent.indexOf('Trident') === -1;
+}
+/**
+ * Returns false if using go(n) with hash history causes a full page reload.
+ */
+
+function supportsGoWithoutReloadUsingHash() {
+  return window.navigator.userAgent.indexOf('Firefox') === -1;
+}
+/**
+ * Returns true if a given popstate event is an extraneous WebKit event.
+ * Accounts for the fact that Chrome on iOS fires real popstate events
+ * containing undefined state when pressing the back button.
+ */
+
+function isExtraneousPopstateEvent(event) {
+  return event.state === undefined && navigator.userAgent.indexOf('CriOS') === -1;
+}
+
+var PopStateEvent = 'popstate';
+var HashChangeEvent = 'hashchange';
+
+function getHistoryState() {
+  try {
+    return window.history.state || {};
+  } catch (e) {
+    // IE 11 sometimes throws when accessing window.history.state
+    // See https://github.com/ReactTraining/history/pull/289
+    return {};
+  }
+}
+/**
+ * Creates a history object that uses the HTML5 history API including
+ * pushState, replaceState, and the popstate event.
+ */
+
+
+function createBrowserHistory(props) {
+  if (props === void 0) {
+    props = {};
+  }
+
+  !canUseDOM ? process.env.NODE_ENV !== "production" ? invariant(false, 'Browser history needs a DOM') : invariant(false) : void 0;
+  var globalHistory = window.history;
+  var canUseHistory = supportsHistory();
+  var needsHashChangeListener = !supportsPopStateOnHashChange();
+  var _props = props,
+      _props$forceRefresh = _props.forceRefresh,
+      forceRefresh = _props$forceRefresh === void 0 ? false : _props$forceRefresh,
+      _props$getUserConfirm = _props.getUserConfirmation,
+      getUserConfirmation = _props$getUserConfirm === void 0 ? getConfirmation : _props$getUserConfirm,
+      _props$keyLength = _props.keyLength,
+      keyLength = _props$keyLength === void 0 ? 6 : _props$keyLength;
+  var basename = props.basename ? stripTrailingSlash(addLeadingSlash(props.basename)) : '';
+
+  function getDOMLocation(historyState) {
+    var _ref = historyState || {},
+        key = _ref.key,
+        state = _ref.state;
+
+    var _window$location = window.location,
+        pathname = _window$location.pathname,
+        search = _window$location.search,
+        hash = _window$location.hash;
+    var path = pathname + search + hash;
+    process.env.NODE_ENV !== "production" ? warning(!basename || hasBasename(path, basename), 'You are attempting to use a basename on a page whose URL path does not begin ' + 'with the basename. Expected path "' + path + '" to begin with "' + basename + '".') : void 0;
+    if (basename) path = stripBasename(path, basename);
+    return createLocation(path, state, key);
+  }
+
+  function createKey() {
+    return Math.random().toString(36).substr(2, keyLength);
+  }
+
+  var transitionManager = createTransitionManager();
+
+  function setState(nextState) {
+    _extends(history, nextState);
+
+    history.length = globalHistory.length;
+    transitionManager.notifyListeners(history.location, history.action);
+  }
+
+  function handlePopState(event) {
+    // Ignore extraneous popstate events in WebKit.
+    if (isExtraneousPopstateEvent(event)) return;
+    handlePop(getDOMLocation(event.state));
+  }
+
+  function handleHashChange() {
+    handlePop(getDOMLocation(getHistoryState()));
+  }
+
+  var forceNextPop = false;
+
+  function handlePop(location) {
+    if (forceNextPop) {
+      forceNextPop = false;
+      setState();
+    } else {
+      var action = 'POP';
+      transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+        if (ok) {
+          setState({
+            action: action,
+            location: location
+          });
+        } else {
+          revertPop(location);
+        }
+      });
+    }
+  }
+
+  function revertPop(fromLocation) {
+    var toLocation = history.location; // TODO: We could probably make this more reliable by
+    // keeping a list of keys we've seen in sessionStorage.
+    // Instead, we just default to 0 for keys we don't know.
+
+    var toIndex = allKeys.indexOf(toLocation.key);
+    if (toIndex === -1) toIndex = 0;
+    var fromIndex = allKeys.indexOf(fromLocation.key);
+    if (fromIndex === -1) fromIndex = 0;
+    var delta = toIndex - fromIndex;
+
+    if (delta) {
+      forceNextPop = true;
+      go(delta);
+    }
+  }
+
+  var initialLocation = getDOMLocation(getHistoryState());
+  var allKeys = [initialLocation.key]; // Public interface
+
+  function createHref(location) {
+    return basename + createPath(location);
+  }
+
+  function push(path, state) {
+    process.env.NODE_ENV !== "production" ? warning(!(typeof path === 'object' && path.state !== undefined && state !== undefined), 'You should avoid providing a 2nd state argument to push when the 1st ' + 'argument is a location-like object that already has state; it is ignored') : void 0;
+    var action = 'PUSH';
+    var location = createLocation(path, state, createKey(), history.location);
+    transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+      if (!ok) return;
+      var href = createHref(location);
+      var key = location.key,
+          state = location.state;
+
+      if (canUseHistory) {
+        globalHistory.pushState({
+          key: key,
+          state: state
+        }, null, href);
+
+        if (forceRefresh) {
+          window.location.href = href;
+        } else {
+          var prevIndex = allKeys.indexOf(history.location.key);
+          var nextKeys = allKeys.slice(0, prevIndex + 1);
+          nextKeys.push(location.key);
+          allKeys = nextKeys;
+          setState({
+            action: action,
+            location: location
+          });
+        }
+      } else {
+        process.env.NODE_ENV !== "production" ? warning(state === undefined, 'Browser history cannot push state in browsers that do not support HTML5 history') : void 0;
+        window.location.href = href;
+      }
+    });
+  }
+
+  function replace(path, state) {
+    process.env.NODE_ENV !== "production" ? warning(!(typeof path === 'object' && path.state !== undefined && state !== undefined), 'You should avoid providing a 2nd state argument to replace when the 1st ' + 'argument is a location-like object that already has state; it is ignored') : void 0;
+    var action = 'REPLACE';
+    var location = createLocation(path, state, createKey(), history.location);
+    transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+      if (!ok) return;
+      var href = createHref(location);
+      var key = location.key,
+          state = location.state;
+
+      if (canUseHistory) {
+        globalHistory.replaceState({
+          key: key,
+          state: state
+        }, null, href);
+
+        if (forceRefresh) {
+          window.location.replace(href);
+        } else {
+          var prevIndex = allKeys.indexOf(history.location.key);
+          if (prevIndex !== -1) allKeys[prevIndex] = location.key;
+          setState({
+            action: action,
+            location: location
+          });
+        }
+      } else {
+        process.env.NODE_ENV !== "production" ? warning(state === undefined, 'Browser history cannot replace state in browsers that do not support HTML5 history') : void 0;
+        window.location.replace(href);
+      }
+    });
+  }
+
+  function go(n) {
+    globalHistory.go(n);
+  }
+
+  function goBack() {
+    go(-1);
+  }
+
+  function goForward() {
+    go(1);
+  }
+
+  var listenerCount = 0;
+
+  function checkDOMListeners(delta) {
+    listenerCount += delta;
+
+    if (listenerCount === 1 && delta === 1) {
+      window.addEventListener(PopStateEvent, handlePopState);
+      if (needsHashChangeListener) window.addEventListener(HashChangeEvent, handleHashChange);
+    } else if (listenerCount === 0) {
+      window.removeEventListener(PopStateEvent, handlePopState);
+      if (needsHashChangeListener) window.removeEventListener(HashChangeEvent, handleHashChange);
+    }
+  }
+
+  var isBlocked = false;
+
+  function block(prompt) {
+    if (prompt === void 0) {
+      prompt = false;
+    }
+
+    var unblock = transitionManager.setPrompt(prompt);
+
+    if (!isBlocked) {
+      checkDOMListeners(1);
+      isBlocked = true;
+    }
+
+    return function () {
+      if (isBlocked) {
+        isBlocked = false;
+        checkDOMListeners(-1);
+      }
+
+      return unblock();
+    };
+  }
+
+  function listen(listener) {
+    var unlisten = transitionManager.appendListener(listener);
+    checkDOMListeners(1);
+    return function () {
+      checkDOMListeners(-1);
+      unlisten();
+    };
+  }
+
+  var history = {
+    length: globalHistory.length,
+    action: 'POP',
+    location: initialLocation,
+    createHref: createHref,
+    push: push,
+    replace: replace,
+    go: go,
+    goBack: goBack,
+    goForward: goForward,
+    block: block,
+    listen: listen
+  };
+  return history;
+}
+
+var HashChangeEvent$1 = 'hashchange';
+var HashPathCoders = {
+  hashbang: {
+    encodePath: function encodePath(path) {
+      return path.charAt(0) === '!' ? path : '!/' + stripLeadingSlash(path);
+    },
+    decodePath: function decodePath(path) {
+      return path.charAt(0) === '!' ? path.substr(1) : path;
+    }
+  },
+  noslash: {
+    encodePath: stripLeadingSlash,
+    decodePath: addLeadingSlash
+  },
+  slash: {
+    encodePath: addLeadingSlash,
+    decodePath: addLeadingSlash
+  }
+};
+
+function stripHash(url) {
+  var hashIndex = url.indexOf('#');
+  return hashIndex === -1 ? url : url.slice(0, hashIndex);
+}
+
+function getHashPath() {
+  // We can't use window.location.hash here because it's not
+  // consistent across browsers - Firefox will pre-decode it!
+  var href = window.location.href;
+  var hashIndex = href.indexOf('#');
+  return hashIndex === -1 ? '' : href.substring(hashIndex + 1);
+}
+
+function pushHashPath(path) {
+  window.location.hash = path;
+}
+
+function replaceHashPath(path) {
+  window.location.replace(stripHash(window.location.href) + '#' + path);
+}
+
+function createHashHistory(props) {
+  if (props === void 0) {
+    props = {};
+  }
+
+  !canUseDOM ? process.env.NODE_ENV !== "production" ? invariant(false, 'Hash history needs a DOM') : invariant(false) : void 0;
+  var globalHistory = window.history;
+  var canGoWithoutReload = supportsGoWithoutReloadUsingHash();
+  var _props = props,
+      _props$getUserConfirm = _props.getUserConfirmation,
+      getUserConfirmation = _props$getUserConfirm === void 0 ? getConfirmation : _props$getUserConfirm,
+      _props$hashType = _props.hashType,
+      hashType = _props$hashType === void 0 ? 'slash' : _props$hashType;
+  var basename = props.basename ? stripTrailingSlash(addLeadingSlash(props.basename)) : '';
+  var _HashPathCoders$hashT = HashPathCoders[hashType],
+      encodePath = _HashPathCoders$hashT.encodePath,
+      decodePath = _HashPathCoders$hashT.decodePath;
+
+  function getDOMLocation() {
+    var path = decodePath(getHashPath());
+    process.env.NODE_ENV !== "production" ? warning(!basename || hasBasename(path, basename), 'You are attempting to use a basename on a page whose URL path does not begin ' + 'with the basename. Expected path "' + path + '" to begin with "' + basename + '".') : void 0;
+    if (basename) path = stripBasename(path, basename);
+    return createLocation(path);
+  }
+
+  var transitionManager = createTransitionManager();
+
+  function setState(nextState) {
+    _extends(history, nextState);
+
+    history.length = globalHistory.length;
+    transitionManager.notifyListeners(history.location, history.action);
+  }
+
+  var forceNextPop = false;
+  var ignorePath = null;
+
+  function locationsAreEqual$$1(a, b) {
+    return a.pathname === b.pathname && a.search === b.search && a.hash === b.hash;
+  }
+
+  function handleHashChange() {
+    var path = getHashPath();
+    var encodedPath = encodePath(path);
+
+    if (path !== encodedPath) {
+      // Ensure we always have a properly-encoded hash.
+      replaceHashPath(encodedPath);
+    } else {
+      var location = getDOMLocation();
+      var prevLocation = history.location;
+      if (!forceNextPop && locationsAreEqual$$1(prevLocation, location)) return; // A hashchange doesn't always == location change.
+
+      if (ignorePath === createPath(location)) return; // Ignore this change; we already setState in push/replace.
+
+      ignorePath = null;
+      handlePop(location);
+    }
+  }
+
+  function handlePop(location) {
+    if (forceNextPop) {
+      forceNextPop = false;
+      setState();
+    } else {
+      var action = 'POP';
+      transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+        if (ok) {
+          setState({
+            action: action,
+            location: location
+          });
+        } else {
+          revertPop(location);
+        }
+      });
+    }
+  }
+
+  function revertPop(fromLocation) {
+    var toLocation = history.location; // TODO: We could probably make this more reliable by
+    // keeping a list of paths we've seen in sessionStorage.
+    // Instead, we just default to 0 for paths we don't know.
+
+    var toIndex = allPaths.lastIndexOf(createPath(toLocation));
+    if (toIndex === -1) toIndex = 0;
+    var fromIndex = allPaths.lastIndexOf(createPath(fromLocation));
+    if (fromIndex === -1) fromIndex = 0;
+    var delta = toIndex - fromIndex;
+
+    if (delta) {
+      forceNextPop = true;
+      go(delta);
+    }
+  } // Ensure the hash is encoded properly before doing anything else.
+
+
+  var path = getHashPath();
+  var encodedPath = encodePath(path);
+  if (path !== encodedPath) replaceHashPath(encodedPath);
+  var initialLocation = getDOMLocation();
+  var allPaths = [createPath(initialLocation)]; // Public interface
+
+  function createHref(location) {
+    var baseTag = document.querySelector('base');
+    var href = '';
+
+    if (baseTag && baseTag.getAttribute('href')) {
+      href = stripHash(window.location.href);
+    }
+
+    return href + '#' + encodePath(basename + createPath(location));
+  }
+
+  function push(path, state) {
+    process.env.NODE_ENV !== "production" ? warning(state === undefined, 'Hash history cannot push state; it is ignored') : void 0;
+    var action = 'PUSH';
+    var location = createLocation(path, undefined, undefined, history.location);
+    transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+      if (!ok) return;
+      var path = createPath(location);
+      var encodedPath = encodePath(basename + path);
+      var hashChanged = getHashPath() !== encodedPath;
+
+      if (hashChanged) {
+        // We cannot tell if a hashchange was caused by a PUSH, so we'd
+        // rather setState here and ignore the hashchange. The caveat here
+        // is that other hash histories in the page will consider it a POP.
+        ignorePath = path;
+        pushHashPath(encodedPath);
+        var prevIndex = allPaths.lastIndexOf(createPath(history.location));
+        var nextPaths = allPaths.slice(0, prevIndex + 1);
+        nextPaths.push(path);
+        allPaths = nextPaths;
+        setState({
+          action: action,
+          location: location
+        });
+      } else {
+        process.env.NODE_ENV !== "production" ? warning(false, 'Hash history cannot PUSH the same path; a new entry will not be added to the history stack') : void 0;
+        setState();
+      }
+    });
+  }
+
+  function replace(path, state) {
+    process.env.NODE_ENV !== "production" ? warning(state === undefined, 'Hash history cannot replace state; it is ignored') : void 0;
+    var action = 'REPLACE';
+    var location = createLocation(path, undefined, undefined, history.location);
+    transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+      if (!ok) return;
+      var path = createPath(location);
+      var encodedPath = encodePath(basename + path);
+      var hashChanged = getHashPath() !== encodedPath;
+
+      if (hashChanged) {
+        // We cannot tell if a hashchange was caused by a REPLACE, so we'd
+        // rather setState here and ignore the hashchange. The caveat here
+        // is that other hash histories in the page will consider it a POP.
+        ignorePath = path;
+        replaceHashPath(encodedPath);
+      }
+
+      var prevIndex = allPaths.indexOf(createPath(history.location));
+      if (prevIndex !== -1) allPaths[prevIndex] = path;
+      setState({
+        action: action,
+        location: location
+      });
+    });
+  }
+
+  function go(n) {
+    process.env.NODE_ENV !== "production" ? warning(canGoWithoutReload, 'Hash history go(n) causes a full page reload in this browser') : void 0;
+    globalHistory.go(n);
+  }
+
+  function goBack() {
+    go(-1);
+  }
+
+  function goForward() {
+    go(1);
+  }
+
+  var listenerCount = 0;
+
+  function checkDOMListeners(delta) {
+    listenerCount += delta;
+
+    if (listenerCount === 1 && delta === 1) {
+      window.addEventListener(HashChangeEvent$1, handleHashChange);
+    } else if (listenerCount === 0) {
+      window.removeEventListener(HashChangeEvent$1, handleHashChange);
+    }
+  }
+
+  var isBlocked = false;
+
+  function block(prompt) {
+    if (prompt === void 0) {
+      prompt = false;
+    }
+
+    var unblock = transitionManager.setPrompt(prompt);
+
+    if (!isBlocked) {
+      checkDOMListeners(1);
+      isBlocked = true;
+    }
+
+    return function () {
+      if (isBlocked) {
+        isBlocked = false;
+        checkDOMListeners(-1);
+      }
+
+      return unblock();
+    };
+  }
+
+  function listen(listener) {
+    var unlisten = transitionManager.appendListener(listener);
+    checkDOMListeners(1);
+    return function () {
+      checkDOMListeners(-1);
+      unlisten();
+    };
+  }
+
+  var history = {
+    length: globalHistory.length,
+    action: 'POP',
+    location: initialLocation,
+    createHref: createHref,
+    push: push,
+    replace: replace,
+    go: go,
+    goBack: goBack,
+    goForward: goForward,
+    block: block,
+    listen: listen
+  };
+  return history;
+}
+
+function clamp(n, lowerBound, upperBound) {
+  return Math.min(Math.max(n, lowerBound), upperBound);
+}
+/**
+ * Creates a history object that stores locations in memory.
+ */
+
+
+function createMemoryHistory(props) {
+  if (props === void 0) {
+    props = {};
+  }
+
+  var _props = props,
+      getUserConfirmation = _props.getUserConfirmation,
+      _props$initialEntries = _props.initialEntries,
+      initialEntries = _props$initialEntries === void 0 ? ['/'] : _props$initialEntries,
+      _props$initialIndex = _props.initialIndex,
+      initialIndex = _props$initialIndex === void 0 ? 0 : _props$initialIndex,
+      _props$keyLength = _props.keyLength,
+      keyLength = _props$keyLength === void 0 ? 6 : _props$keyLength;
+  var transitionManager = createTransitionManager();
+
+  function setState(nextState) {
+    _extends(history, nextState);
+
+    history.length = history.entries.length;
+    transitionManager.notifyListeners(history.location, history.action);
+  }
+
+  function createKey() {
+    return Math.random().toString(36).substr(2, keyLength);
+  }
+
+  var index = clamp(initialIndex, 0, initialEntries.length - 1);
+  var entries = initialEntries.map(function (entry) {
+    return typeof entry === 'string' ? createLocation(entry, undefined, createKey()) : createLocation(entry, undefined, entry.key || createKey());
+  }); // Public interface
+
+  var createHref = createPath;
+
+  function push(path, state) {
+    process.env.NODE_ENV !== "production" ? warning(!(typeof path === 'object' && path.state !== undefined && state !== undefined), 'You should avoid providing a 2nd state argument to push when the 1st ' + 'argument is a location-like object that already has state; it is ignored') : void 0;
+    var action = 'PUSH';
+    var location = createLocation(path, state, createKey(), history.location);
+    transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+      if (!ok) return;
+      var prevIndex = history.index;
+      var nextIndex = prevIndex + 1;
+      var nextEntries = history.entries.slice(0);
+
+      if (nextEntries.length > nextIndex) {
+        nextEntries.splice(nextIndex, nextEntries.length - nextIndex, location);
+      } else {
+        nextEntries.push(location);
+      }
+
+      setState({
+        action: action,
+        location: location,
+        index: nextIndex,
+        entries: nextEntries
+      });
+    });
+  }
+
+  function replace(path, state) {
+    process.env.NODE_ENV !== "production" ? warning(!(typeof path === 'object' && path.state !== undefined && state !== undefined), 'You should avoid providing a 2nd state argument to replace when the 1st ' + 'argument is a location-like object that already has state; it is ignored') : void 0;
+    var action = 'REPLACE';
+    var location = createLocation(path, state, createKey(), history.location);
+    transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+      if (!ok) return;
+      history.entries[history.index] = location;
+      setState({
+        action: action,
+        location: location
+      });
+    });
+  }
+
+  function go(n) {
+    var nextIndex = clamp(history.index + n, 0, history.entries.length - 1);
+    var action = 'POP';
+    var location = history.entries[nextIndex];
+    transitionManager.confirmTransitionTo(location, action, getUserConfirmation, function (ok) {
+      if (ok) {
+        setState({
+          action: action,
+          location: location,
+          index: nextIndex
+        });
+      } else {
+        // Mimic the behavior of DOM histories by
+        // causing a render after a cancelled POP.
+        setState();
+      }
+    });
+  }
+
+  function goBack() {
+    go(-1);
+  }
+
+  function goForward() {
+    go(1);
+  }
+
+  function canGo(n) {
+    var nextIndex = history.index + n;
+    return nextIndex >= 0 && nextIndex < history.entries.length;
+  }
+
+  function block(prompt) {
+    if (prompt === void 0) {
+      prompt = false;
+    }
+
+    return transitionManager.setPrompt(prompt);
+  }
+
+  function listen(listener) {
+    return transitionManager.appendListener(listener);
+  }
+
+  var history = {
+    length: entries.length,
+    action: 'POP',
+    location: entries[index],
+    index: index,
+    entries: entries,
+    createHref: createHref,
+    push: push,
+    replace: replace,
+    go: go,
+    goBack: goBack,
+    goForward: goForward,
+    canGo: canGo,
+    block: block,
+    listen: listen
+  };
+  return history;
+}
+
+export { createBrowserHistory, createHashHistory, createMemoryHistory, createLocation, locationsAreEqual, parsePath, createPath };