/**
* context.ts — Setup context for pure function DI
*
* The setup context lets pure functions (inject(), listen(), effect())
* access the component they belong to without needing `this`.
*
* The context exists ONLY during component initialization (setup()).
* It is NOT a runtime thing — it's a synchronous initialization-time concept.
*
* Same pattern as Angular's inject(), Solid's createSignal(), Vue's setup().
*/
// ── Types ───────────────────────────────────────────────────────────
/**
* Minimal interface for a component host. component.ts provides the
* full implementation; this file only needs the disposal hook.
*/
export interface ComponentHost {
/** Register a cleanup function to run on disconnectedCallback */
addDisposer(fn: () => void): void;
/** The raw HTMLElement */
element: HTMLElement;
}
// ── Context state ───────────────────────────────────────────────────
let currentComponent: ComponentHost | null = null;
// ── Public API ──────────────────────────────────────────────────────
/**
* Run a function with a component as the active context.
* Pure functions called during `fn` can access the component via
* `getCurrentComponent()`.
*
* Context is strictly synchronous — it does NOT survive across
* await boundaries or microtasks.
*/
export function runWithContext(component: ComponentHost, fn: () => void): void {
const prev = currentComponent;
currentComponent = component;
try {
fn();
} finally {
currentComponent = prev;
}
}
/**
* Get the currently active component host.
* Throws if called outside a setup() context.
*
* This is framework-internal — component authors use inject(), effect(),
* etc., which call this internally.
*/
export function getCurrentComponent(): ComponentHost {
if (!currentComponent) {
throw new Error(
'getCurrentComponent() called outside setup(). ' +
'inject(), effect(), and other context-dependent functions ' +
'can only be called during component initialization.'
);
}
return currentComponent;
}
/**
* Check if there is an active setup context.
* Returns true during component setup, false otherwise.
*/
export function hasContext(): boolean {
return currentComponent !== null;
}
