respond-framework/dist/proxy/useSnapshotPrevState.js

create as fast you think

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _react = require("react");
var _createSnapProxy = require("./createSnapProxy.js");
var _isChanged = require("./helpers/isChanged.js");
const useSnapshotPrevState = proxy => {
  const last = (0, _react.useRef)();
  const respond = proxy.respond;
  const subscribe = (0, _react.useCallback)(cb => respond.subscribe(cb), [respond]);
  const getSnapshot = () => {
    const next = proxy.prevState;
    const {
      snapshot,
      affected
    } = last.current ?? {};
    return inRender || (0, _isChanged.default)(snapshot, next, affected) ? next : snapshot; // not changed -- referentially equal
  };
  let inRender = true;
  const snapshot = (0, _react.useSyncExternalStore)(subscribe, getSnapshot, () => proxy.prevState);
  inRender = false;
  const affected = new WeakMap();
  const cache = (0, _react.useMemo)(() => new WeakMap(), []); // per-hook proxy cache

  (0, _react.useLayoutEffect)(() => {
    last.current = {
      snapshot,
      affected
    };
  });
  return (0, _createSnapProxy.default)(snapshot, {
    affected,
    cache
  });
};
var _default = exports.default = useSnapshotPrevState;