1 files changed, 186 insertions, 0 deletions
diff --git a/history/modules/createMemoryHistory.js b/history/modules/createMemoryHistory.js
new file mode 100644
index 0000000..8b541ea
--- /dev/null
+++ b/history/modules/createMemoryHistory.js
@@ -0,0 +1,186 @@
+import { createPath } from './PathUtils.js';
+import { createLocation } from './LocationUtils.js';
+import createTransitionManager from './createTransitionManager.js';
+import warning from './warning.js';
+
+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 = {}) {
+  const {
+    getUserConfirmation,
+    initialEntries = ['/'],
+    initialIndex = 0,
+    keyLength = 6
+  } = props;
+
+  const transitionManager = createTransitionManager();
+
+  function setState(nextState) {
+    Object.assign(history, nextState);
+    history.length = history.entries.length;
+    transitionManager.notifyListeners(history.location, history.action);
+  }
+
+  function createKey() {
+    return Math.random()
+      .toString(36)
+      .substr(2, keyLength);
+  }
+
+  const index = clamp(initialIndex, 0, initialEntries.length - 1);
+  const entries = initialEntries.map(entry =>
+    typeof entry === 'string'
+      ? createLocation(entry, undefined, createKey())
+      : createLocation(entry, undefined, entry.key || createKey())
+  );
+
+  // Public interface
+
+  const createHref = createPath;
+
+  function push(path, state) {
+    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'
+    );
+
+    const action = 'PUSH';
+    const location = createLocation(path, state, createKey(), history.location);
+
+    transitionManager.confirmTransitionTo(
+      location,
+      action,
+      getUserConfirmation,
+      ok => {
+        if (!ok) return;
+
+        const prevIndex = history.index;
+        const nextIndex = prevIndex + 1;
+
+        const nextEntries = history.entries.slice(0);
+        if (nextEntries.length > nextIndex) {
+          nextEntries.splice(
+            nextIndex,
+            nextEntries.length - nextIndex,
+            location
+          );
+        } else {
+          nextEntries.push(location);
+        }
+
+        setState({
+          action,
+          location,
+          index: nextIndex,
+          entries: nextEntries
+        });
+      }
+    );
+  }
+
+  function replace(path, state) {
+    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'
+    );
+
+    const action = 'REPLACE';
+    const location = createLocation(path, state, createKey(), history.location);
+
+    transitionManager.confirmTransitionTo(
+      location,
+      action,
+      getUserConfirmation,
+      ok => {
+        if (!ok) return;
+
+        history.entries[history.index] = location;
+
+        setState({ action, location });
+      }
+    );
+  }
+
+  function go(n) {
+    const nextIndex = clamp(history.index + n, 0, history.entries.length - 1);
+
+    const action = 'POP';
+    const location = history.entries[nextIndex];
+
+    transitionManager.confirmTransitionTo(
+      location,
+      action,
+      getUserConfirmation,
+      ok => {
+        if (ok) {
+          setState({
+            action,
+            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) {
+    const nextIndex = history.index + n;
+    return nextIndex >= 0 && nextIndex < history.entries.length;
+  }
+
+  function block(prompt = false) {
+    return transitionManager.setPrompt(prompt);
+  }
+
+  function listen(listener) {
+    return transitionManager.appendListener(listener);
+  }
+
+  const history = {
+    length: entries.length,
+    action: 'POP',
+    location: entries[index],
+    index,
+    entries,
+    createHref,
+    push,
+    replace,
+    go,
+    goBack,
+    goForward,
+    canGo,
+    block,
+    listen
+  };
+
+  return history;
+}
+
+export default createMemoryHistory;