Function liftReducerWith

modules/store-devtools/src/reducer.ts:162–559

(
  initialCommittedState: any,
  initialLiftedState: LiftedState,
  errorHandler: ErrorHandler,
  monitorReducer?: any,
  options: Partial<StoreDevtoolsConfig> = {}
)

 * Creates a history state reducer from an app's reducer.
 */
export function liftReducerWith(
  initialCommittedState: any,
  initialLiftedState: LiftedState,
  errorHandler: ErrorHandler,
  monitorReducer?: any,
  options: Partial<StoreDevtoolsConfig> = {}
) {
  /**
   * Manages how the history actions modify the history state.
   */
  return (
      reducer: ActionReducer<any, any>
    ): ActionReducer<LiftedState, Actions> =>
    (liftedState, liftedAction) => {
      let {
        monitorState,
        actionsById,
        nextActionId,
        stagedActionIds,
        skippedActionIds,
        committedState,
        currentStateIndex,
        computedStates,
        isLocked,
        isPaused,
      } = liftedState || initialLiftedState;

      if (!liftedState) {
        // Prevent mutating initialLiftedState
        actionsById = Object.create(actionsById);
      }

      function commitExcessActions(n: number) {
        // Auto-commits n-number of excess actions.
        let excess = n;
        let idsToDelete = stagedActionIds.slice(1, excess + 1);

        for (let i = 0; i < idsToDelete.length; i++) {
          if (computedStates[i + 1].error) {
            // Stop if error is found. Commit actions up to error.
            excess = i;
            idsToDelete = stagedActionIds.slice(1, excess + 1);
            break;
          } else {
            delete actionsById[idsToDelete[i]];
          }
        }

        skippedActionIds = skippedActionIds.filter(
          (id) => idsToDelete.indexOf(id) === -1
        );
        stagedActionIds = [0, ...stagedActionIds.slice(excess + 1)];
        committedState = computedStates[excess].state;
        computedStates = computedStates.slice(excess);
        currentStateIndex =
          currentStateIndex > excess ? currentStateIndex - excess : 0;
      }