@react-navigation/core/lib/module/useOnAction.js

Core utilities for building navigators

import * as React from 'react';
import NavigationBuilderContext from './NavigationBuilderContext';
import useOnPreventRemove, { shouldPreventRemove } from './useOnPreventRemove';
/**
 * Hook to handle actions for a navigator, including state updates and bubbling.
 *
 * Bubbling an action is achieved in 2 ways:
 * 1. To bubble action to parent, we expose the action handler in context and then access the parent context
 * 2. To bubble action to child, child adds event listeners subscribing to actions from parent
 *
 * When the action handler handles as action, it returns `true`, otherwise `false`.
 */
export default function useOnAction(_ref) {
  let {
    router,
    getState,
    setState,
    key,
    actionListeners,
    beforeRemoveListeners,
    routerConfigOptions,
    emitter
  } = _ref;
  const {
    onAction: onActionParent,
    onRouteFocus: onRouteFocusParent,
    addListener: addListenerParent,
    onDispatchAction
  } = React.useContext(NavigationBuilderContext);
  const routerConfigOptionsRef = React.useRef(routerConfigOptions);
  React.useEffect(() => {
    routerConfigOptionsRef.current = routerConfigOptions;
  });
  const onAction = React.useCallback(function (action) {
    let visitedNavigators = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : new Set();
    const state = getState();

    // Since actions can bubble both up and down, they could come to the same navigator again
    // We keep track of navigators which have already tried to handle the action and return if it's already visited
    if (visitedNavigators.has(state.key)) {
      return false;
    }
    visitedNavigators.add(state.key);
    if (typeof action.target !== 'string' || action.target === state.key) {
      let result = router.getStateForAction(state, action, routerConfigOptionsRef.current);

      // If a target is specified and set to current navigator, the action shouldn't bubble
      // So instead of `null`, we use the state object for such cases to signal that action was handled
      result = result === null && action.target === state.key ? state : result;
      if (result !== null) {
        onDispatchAction(action, state === result);
        if (state !== result) {
          const isPrevented = shouldPreventRemove(emitter, beforeRemoveListeners, state.routes, result.routes, action);
          if (isPrevented) {
            return true;
          }
          setState(result);
        }
        if (onRouteFocusParent !== undefined) {
          // Some actions such as `NAVIGATE` also want to bring the navigated route to focus in the whole tree
          // This means we need to focus all of the parent navigators of this navigator as well
          const shouldFocus = router.shouldActionChangeFocus(action);
          if (shouldFocus && key !== undefined) {
            onRouteFocusParent(key);
          }
        }
        return true;
      }
    }
    if (onActionParent !== undefined) {
      // Bubble action to the parent if the current navigator didn't handle it
      if (onActionParent(action, visitedNavigators)) {
        return true;
      }
    }

    // If the action wasn't handled by current navigator or a parent navigator, let children handle it
    for (let i = actionListeners.length - 1; i >= 0; i--) {
      const listener = actionListeners[i];
      if (listener(action, visitedNavigators)) {
        return true;
      }
    }
    return false;
  }, [actionListeners, beforeRemoveListeners, emitter, getState, key, onActionParent, onDispatchAction, onRouteFocusParent, router, setState]);
  useOnPreventRemove({
    getState,
    emitter,
    beforeRemoveListeners
  });
  React.useEffect(() => addListenerParent === null || addListenerParent === void 0 ? void 0 : addListenerParent('action', onAction), [addListenerParent, onAction]);
  return onAction;
}
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