StateUtils.js
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import invariant from './utils/invariant';
/**
* Utilities to perform atomic operation with navigate state and routes.
*
* ```javascript
* const state1 = {key: 'screen 1'};
* const state2 = NavigationStateUtils.push(state1, {key: 'screen 2'});
* ```
*/
const StateUtils = {
/**
* Gets a route by key. If the route isn't found, returns `null`.
*/
get(state, key) {
return state.routes.find(route => route.key === key) || null;
},
/**
* Returns the first index at which a given route's key can be found in the
* routes of the navigation state, or -1 if it is not present.
*/
indexOf(state, key) {
return state.routes.map(route => route.key).indexOf(key);
},
/**
* Returns `true` at which a given route's key can be found in the
* routes of the navigation state.
*/
has(state, key) {
return !!state.routes.some(route => route.key === key);
},
/**
* Pushes a new route into the navigation state.
* Note that this moves the index to the positon to where the last route in the
* stack is at.
*/
push(state, route) {
invariant(StateUtils.indexOf(state, route.key) === -1, 'should not push route with duplicated key %s', route.key);
const routes = state.routes.slice();
routes.push(route);
return {
...state,
index: routes.length - 1,
routes
};
},
/**
* Pops out a route from the navigation state.
* Note that this moves the index to the positon to where the last route in the
* stack is at.
*/
pop(state) {
if (state.index <= 0) {
// [Note]: Over-popping does not throw error. Instead, it will be no-op.
return state;
}
const routes = state.routes.slice(0, -1);
return {
...state,
index: routes.length - 1,
routes
};
},
/**
* Sets the focused route of the navigation state by index.
*/
jumpToIndex(state, index) {
if (index === state.index) {
return state;
}
invariant(!!state.routes[index], 'invalid index %s to jump to', index);
return {
...state,
index
};
},
/**
* Sets the focused route of the navigation state by key.
*/
jumpTo(state, key) {
const index = StateUtils.indexOf(state, key);
return StateUtils.jumpToIndex(state, index);
},
/**
* Sets the focused route to the previous route.
*/
back(state) {
const index = state.index - 1;
const route = state.routes[index];
return route ? StateUtils.jumpToIndex(state, index) : state;
},
/**
* Sets the focused route to the next route.
*/
forward(state) {
const index = state.index + 1;
const route = state.routes[index];
return route ? StateUtils.jumpToIndex(state, index) : state;
},
/**
* Replace a route by a key.
* Note that this moves the index to the positon to where the new route in the
* stack is at.
*/
replaceAt(state, key, route) {
const index = StateUtils.indexOf(state, key);
return StateUtils.replaceAtIndex(state, index, route);
},
/**
* Replace a route by a index.
* Note that this moves the index to the positon to where the new route in the
* stack is at.
*/
replaceAtIndex(state, index, route) {
invariant(!!state.routes[index], 'invalid index %s for replacing route %s', index, route.key);
if (state.routes[index] === route) {
return state;
}
const routes = state.routes.slice();
routes[index] = route;
return {
...state,
index,
routes
};
},
/**
* Resets all routes.
* Note that this moves the index to the positon to where the last route in the
* stack is at if the param `index` isn't provided.
*/
reset(state, routes, index) {
invariant(routes.length && Array.isArray(routes), 'invalid routes to replace');
const nextIndex = index === undefined ? routes.length - 1 : index;
if (state.routes.length === routes.length && state.index === nextIndex) {
const compare = (route, ii) => routes[ii] === route;
if (state.routes.every(compare)) {
return state;
}
}
invariant(!!routes[nextIndex], 'invalid index %s to reset', nextIndex);
return {
...state,
index: nextIndex,
routes
};
}
};
export default StateUtils;