fix build, migrate test backend

packages/netlify-cms-lib-util/src/Cursor.js

@@ -0,0 +1,115 @@
+import { fromJS, Map, Set } from "immutable";
+
+const jsToMap = obj => {
+  if (obj === undefined) {
+    return Map();
+  }
+  const immutableObj = fromJS(obj);
+  if (!Map.isMap(immutableObj)) {
+    throw new Error("Object must be equivalent to a Map.");
+  }
+  return immutableObj;
+};
+
+const knownMetaKeys = Set(["index", "count", "pageSize", "pageCount", "usingOldPaginationAPI"]);
+const filterUnknownMetaKeys = meta => meta.filter((v, k) => knownMetaKeys.has(k));
+
+/*
+  createCursorMap takes one of three signatures:
+  - () -> cursor with empty actions, data, and meta
+  - (cursorMap: <object/Map with optional actions, data, and meta keys>) -> cursor
+  - (actions: <array/List>, data: <object/Map>, meta: <optional object/Map>) -> cursor
+*/
+const createCursorMap = (...args) => {
+  const { actions, data, meta } = args.length === 1
+    ? jsToMap(args[0]).toObject()
+    : { actions: args[0], data: args[1], meta: args[2] };
+  return Map({
+    // actions are a Set, rather than a List, to ensure an efficient .has
+    actions: Set(actions),
+
+    // data and meta are Maps
+    data: jsToMap(data),
+    meta: jsToMap(meta).update(filterUnknownMetaKeys),
+  });
+};
+
+const hasAction = (cursorMap, action) => cursorMap.hasIn(["actions", action]);
+
+const getActionHandlers = (cursorMap, handler) =>
+  cursorMap.get("actions", Set()).toMap().map(action => handler(action));
+
+// The cursor logic is entirely functional, so this class simply
+// provides a chainable interface
+export default class Cursor {
+  static create(...args) {
+    return new Cursor(...args);
+  }
+
+  constructor(...args) {
+    if (args[0] instanceof Cursor) {
+      return args[0];
+    }
+
+    this.store = createCursorMap(...args);
+    this.actions = this.store.get("actions");
+    this.data = this.store.get("data");
+    this.meta = this.store.get("meta");
+  }
+
+  updateStore(...args) {
+    return new Cursor(this.store.update(...args));
+  }
+  updateInStore(...args) {
+    return new Cursor(this.store.updateIn(...args));
+  }
+
+  hasAction(action) {
+    return hasAction(this.store, action);
+  }
+  addAction(action) {
+    return this.updateStore("actions", actions => actions.add(action));
+  }
+  removeAction(action) {
+    return this.updateStore("actions", actions => actions.delete(action));
+  }
+  setActions(actions) {
+    return this.updateStore(store => store.set("actions", Set(actions)));
+  }
+  mergeActions(actions) {
+    return this.updateStore("actions", oldActions => oldActions.union(actions));
+  }
+  getActionHandlers(handler) {
+    return getActionHandlers(this.store, handler);
+  }
+
+  setData(data) {
+    return new Cursor(this.store.set("data", jsToMap(data)));
+  }
+  mergeData(data) {
+    return new Cursor(this.store.mergeIn(["data"], jsToMap(data)));
+  }
+  wrapData(data) {
+    return this.updateStore("data", oldData => jsToMap(data).set("wrapped_cursor_data", oldData));
+  }
+  unwrapData() {
+    return [this.store.get("data").delete("wrapped_cursor_data"), this.updateStore("data", data => data.get("wrapped_cursor_data"))];
+  }
+  clearData() {
+    return this.updateStore("data", data => Map());
+  }
+
+  setMeta(meta) {
+    return this.updateStore(store => store.set("meta", jsToMap(meta)));
+  }
+  mergeMeta(meta) {
+    return this.updateStore(store => store.update("meta", oldMeta => oldMeta.merge(jsToMap(meta))))
+  }
+}
+
+// This is a temporary hack to allow cursors to be added to the
+// interface between backend.js and backends without modifying old
+// backends at all. This should be removed in favor of wrapping old
+// backends with a compatibility layer, as part of the backend API
+// refactor.
+export const CURSOR_COMPATIBILITY_SYMBOL = Symbol("cursor key for compatibility with old backends");