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Mini Shell
Mini Shell
import { options } from 'preact';
/** @type {number} */
let currentIndex;
/** @type {import('./internal').Component} */
let currentComponent;
/**
* Keep track of the previous component so that we can set
* `currentComponent` to `null` and throw when a hook is invoked
* outside of render
* @type {import('./internal').Component}
*/
let previousComponent;
/** @type {number} */
let currentHook = 0;
/** @type {Array<import('./internal').Component>} */
let afterPaintEffects = [];
let oldBeforeDiff = options._diff;
let oldBeforeRender = options._render;
let oldAfterDiff = options.diffed;
let oldCommit = options._commit;
let oldBeforeUnmount = options.unmount;
const RAF_TIMEOUT = 100;
let prevRaf;
options._diff = vnode => {
currentComponent = null;
if (oldBeforeDiff) oldBeforeDiff(vnode);
};
options._render = vnode => {
if (oldBeforeRender) oldBeforeRender(vnode);
currentComponent = vnode._component;
currentIndex = 0;
const hooks = currentComponent.__hooks;
if (hooks) {
hooks._pendingEffects.forEach(invokeCleanup);
hooks._pendingEffects.forEach(invokeEffect);
hooks._pendingEffects = [];
}
};
options.diffed = vnode => {
if (oldAfterDiff) oldAfterDiff(vnode);
const c = vnode._component;
if (c && c.__hooks && c.__hooks._pendingEffects.length) {
afterPaint(afterPaintEffects.push(c));
}
currentComponent = previousComponent;
};
options._commit = (vnode, commitQueue) => {
commitQueue.some(component => {
try {
component._renderCallbacks.forEach(invokeCleanup);
component._renderCallbacks = component._renderCallbacks.filter(cb =>
cb._value ? invokeEffect(cb) : true
);
} catch (e) {
commitQueue.some(c => {
if (c._renderCallbacks) c._renderCallbacks = [];
});
commitQueue = [];
options._catchError(e, component._vnode);
}
});
if (oldCommit) oldCommit(vnode, commitQueue);
};
options.unmount = vnode => {
if (oldBeforeUnmount) oldBeforeUnmount(vnode);
const c = vnode._component;
if (c && c.__hooks) {
try {
c.__hooks._list.forEach(invokeCleanup);
} catch (e) {
options._catchError(e, c._vnode);
}
}
};
/**
* Get a hook's state from the currentComponent
* @param {number} index The index of the hook to get
* @param {number} type The index of the hook to get
* @returns {any}
*/
function getHookState(index, type) {
if (options._hook) {
options._hook(currentComponent, index, currentHook || type);
}
currentHook = 0;
// Largely inspired by:
// * https://github.com/michael-klein/funcy.js/blob/f6be73468e6ec46b0ff5aa3cc4c9baf72a29025a/src/hooks/core_hooks.mjs
// * https://github.com/michael-klein/funcy.js/blob/650beaa58c43c33a74820a3c98b3c7079cf2e333/src/renderer.mjs
// Other implementations to look at:
// * https://codesandbox.io/s/mnox05qp8
const hooks =
currentComponent.__hooks ||
(currentComponent.__hooks = {
_list: [],
_pendingEffects: []
});
if (index >= hooks._list.length) {
hooks._list.push({});
}
return hooks._list[index];
}
/**
* @param {import('./index').StateUpdater<any>} [initialState]
*/
export function useState(initialState) {
currentHook = 1;
return useReducer(invokeOrReturn, initialState);
}
/**
* @param {import('./index').Reducer<any, any>} reducer
* @param {import('./index').StateUpdater<any>} initialState
* @param {(initialState: any) => void} [init]
* @returns {[ any, (state: any) => void ]}
*/
export function useReducer(reducer, initialState, init) {
/** @type {import('./internal').ReducerHookState} */
const hookState = getHookState(currentIndex++, 2);
hookState._reducer = reducer;
if (!hookState._component) {
hookState._value = [
!init ? invokeOrReturn(undefined, initialState) : init(initialState),
action => {
const nextValue = hookState._reducer(hookState._value[0], action);
if (hookState._value[0] !== nextValue) {
hookState._value = [nextValue, hookState._value[1]];
hookState._component.setState({});
}
}
];
hookState._component = currentComponent;
}
return hookState._value;
}
/**
* @param {import('./internal').Effect} callback
* @param {any[]} args
*/
export function useEffect(callback, args) {
/** @type {import('./internal').EffectHookState} */
const state = getHookState(currentIndex++, 3);
if (!options._skipEffects && argsChanged(state._args, args)) {
state._value = callback;
state._args = args;
currentComponent.__hooks._pendingEffects.push(state);
}
}
/**
* @param {import('./internal').Effect} callback
* @param {any[]} args
*/
export function useLayoutEffect(callback, args) {
/** @type {import('./internal').EffectHookState} */
const state = getHookState(currentIndex++, 4);
if (!options._skipEffects && argsChanged(state._args, args)) {
state._value = callback;
state._args = args;
currentComponent._renderCallbacks.push(state);
}
}
export function useRef(initialValue) {
currentHook = 5;
return useMemo(() => ({ current: initialValue }), []);
}
/**
* @param {object} ref
* @param {() => object} createHandle
* @param {any[]} args
*/
export function useImperativeHandle(ref, createHandle, args) {
currentHook = 6;
useLayoutEffect(
() => {
if (typeof ref == 'function') ref(createHandle());
else if (ref) ref.current = createHandle();
},
args == null ? args : args.concat(ref)
);
}
/**
* @param {() => any} factory
* @param {any[]} args
*/
export function useMemo(factory, args) {
/** @type {import('./internal').MemoHookState} */
const state = getHookState(currentIndex++, 7);
if (argsChanged(state._args, args)) {
state._value = factory();
state._args = args;
state._factory = factory;
}
return state._value;
}
/**
* @param {() => void} callback
* @param {any[]} args
*/
export function useCallback(callback, args) {
currentHook = 8;
return useMemo(() => callback, args);
}
/**
* @param {import('./internal').PreactContext} context
*/
export function useContext(context) {
const provider = currentComponent.context[context._id];
// We could skip this call here, but than we'd not call
// `options._hook`. We need to do that in order to make
// the devtools aware of this hook.
/** @type {import('./internal').ContextHookState} */
const state = getHookState(currentIndex++, 9);
// The devtools needs access to the context object to
// be able to pull of the default value when no provider
// is present in the tree.
state._context = context;
if (!provider) return context._defaultValue;
// This is probably not safe to convert to "!"
if (state._value == null) {
state._value = true;
provider.sub(currentComponent);
}
return provider.props.value;
}
/**
* Display a custom label for a custom hook for the devtools panel
* @type {<T>(value: T, cb?: (value: T) => string | number) => void}
*/
export function useDebugValue(value, formatter) {
if (options.useDebugValue) {
options.useDebugValue(formatter ? formatter(value) : value);
}
}
/**
* @param {(error: any) => void} cb
*/
export function useErrorBoundary(cb) {
/** @type {import('./internal').ErrorBoundaryHookState} */
const state = getHookState(currentIndex++, 10);
const errState = useState();
state._value = cb;
if (!currentComponent.componentDidCatch) {
currentComponent.componentDidCatch = err => {
if (state._value) state._value(err);
errState[1](err);
};
}
return [
errState[0],
() => {
errState[1](undefined);
}
];
}
/**
* After paint effects consumer.
*/
function flushAfterPaintEffects() {
afterPaintEffects.forEach(component => {
if (component._parentDom) {
try {
component.__hooks._pendingEffects.forEach(invokeCleanup);
component.__hooks._pendingEffects.forEach(invokeEffect);
component.__hooks._pendingEffects = [];
} catch (e) {
component.__hooks._pendingEffects = [];
options._catchError(e, component._vnode);
}
}
});
afterPaintEffects = [];
}
let HAS_RAF = typeof requestAnimationFrame == 'function';
/**
* Schedule a callback to be invoked after the browser has a chance to paint a new frame.
* Do this by combining requestAnimationFrame (rAF) + setTimeout to invoke a callback after
* the next browser frame.
*
* Also, schedule a timeout in parallel to the the rAF to ensure the callback is invoked
* even if RAF doesn't fire (for example if the browser tab is not visible)
*
* @param {() => void} callback
*/
function afterNextFrame(callback) {
const done = () => {
clearTimeout(timeout);
if (HAS_RAF) cancelAnimationFrame(raf);
setTimeout(callback);
};
const timeout = setTimeout(done, RAF_TIMEOUT);
let raf;
if (HAS_RAF) {
raf = requestAnimationFrame(done);
}
}
// Note: if someone used options.debounceRendering = requestAnimationFrame,
// then effects will ALWAYS run on the NEXT frame instead of the current one, incurring a ~16ms delay.
// Perhaps this is not such a big deal.
/**
* Schedule afterPaintEffects flush after the browser paints
* @param {number} newQueueLength
*/
function afterPaint(newQueueLength) {
if (newQueueLength === 1 || prevRaf !== options.requestAnimationFrame) {
prevRaf = options.requestAnimationFrame;
(prevRaf || afterNextFrame)(flushAfterPaintEffects);
}
}
/**
* @param {import('./internal').EffectHookState} hook
*/
function invokeCleanup(hook) {
// A hook cleanup can introduce a call to render which creates a new root, this will call options.vnode
// and move the currentComponent away.
const comp = currentComponent;
if (typeof hook._cleanup == 'function') hook._cleanup();
currentComponent = comp;
}
/**
* Invoke a Hook's effect
* @param {import('./internal').EffectHookState} hook
*/
function invokeEffect(hook) {
// A hook call can introduce a call to render which creates a new root, this will call options.vnode
// and move the currentComponent away.
const comp = currentComponent;
hook._cleanup = hook._value();
currentComponent = comp;
}
/**
* @param {any[]} oldArgs
* @param {any[]} newArgs
*/
function argsChanged(oldArgs, newArgs) {
return (
!oldArgs ||
oldArgs.length !== newArgs.length ||
newArgs.some((arg, index) => arg !== oldArgs[index])
);
}
function invokeOrReturn(arg, f) {
return typeof f == 'function' ? f(arg) : f;
}
Zerion Mini Shell 1.0