mirror of
https://github.com/storytold/storyteller-bevy.git
synced 2026-10-17 00:13:17 +00:00
Single-canvas juggling (#15)
This PR adds a `CanvasProviderElement` to `@storyteller/studio-web` to manage the complexity of maintaining a single concrete `HTMLCanvasElement` for `@storyteller/studio`, while still being able to treat components like the `ViewerElement` as self-contained "views" that behave as expected with regards to CSS styling, DOM placement, etc. Consuming applications should wrap the new `<sts-canvas-provider />` element around some common ancestor of all views into the `@storyteller/studio` app, similar to a React context provider. The `react-frontend` application has been updated to take advantage of the new `CanvasProviderElement` by demonstrating a more realistic use case for the `ViewerElement`. The new demo presents a grid of "thumbnails," one for each object in our hard-coded "object library." Clicking on one of these thumbnails will render a `ViewerElement` for that object in a modal dialog.
This commit is contained in:
@@ -1,2 +1,3 @@
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export * from "./lib/decorators/on";
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export * from "./lib/decorators";
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export * from "./lib/di";
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export { default as spread } from "./lib/directives/spread";
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@@ -0,0 +1 @@
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export * from "./on";
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@@ -0,0 +1,65 @@
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import { Method } from "@storyteller/utility";
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import { LitElement } from "lit";
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/**
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* Modifies the prototype function at `proto[key]` by adding an invocation of
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* `callback` to the end of the method body.
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*/
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export function appendRoutine<
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E extends LitElement,
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M extends Method<E>,
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>(proto: E, key: string | number | symbol, callback: M): void {
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const original = getMethodDescriptor(proto, key)?.value;
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if (!original || typeof original !== "function")
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return;
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Object.defineProperty(proto, key, {
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value(this: E): void {
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original.call(this);
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callback.call(this);
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},
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configurable: true,
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});
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}
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/**
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* Modifies the prototype function at `proto[key]` by adding an invocation of
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* `callback` to the start of the method body.
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*/
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export function prependRoutine<
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E extends LitElement,
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M extends Method<E>,
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>(proto: E, key: string | number | symbol, callback: M): void {
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const original = getMethodDescriptor(proto, key)?.value;
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if (!original || typeof original !== "function")
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return;
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Object.defineProperty(proto, key, {
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value(this: E): void {
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callback.call(this);
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original.call(this);
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},
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configurable: true,
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});
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}
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/**
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* Looks for a member in the prototype chain named `key`, starting at `proto`
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* and recursing up the inheritance tree. If it reaches `HTMLElement` without
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* finding a match, it stops and returns `undefined` -- otherwise, it returns
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* the matching property descriptor.
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*/
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export function getMethodDescriptor<E extends LitElement>(proto: E, key: string | number | symbol)
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: TypedPropertyDescriptor<Method<E, [], void>> | undefined
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{
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let result = Object.getOwnPropertyDescriptor(proto, key);
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while (!result) {
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proto = Object.getPrototypeOf(proto);
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if (!proto || proto === HTMLElement.prototype)
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break;
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result = Object.getOwnPropertyDescriptor(proto, key);
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}
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return result;
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}
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@@ -1,5 +1,6 @@
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import { match } from "@storyteller/utility";
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import type { LitElement } from "lit";
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import { getMethodDescriptor, prependRoutine } from "./internal";
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/**
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* Adds the decorated method as an event listener for the given event name, and
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@@ -21,29 +22,16 @@ export function on(eventSelector: string) {
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});
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return <T extends LitElement>(proto: T, propName: keyof T, desc: PropertyDescriptor) => {
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const handler = desc?.value ?? proto[propName] ?? (() => {});
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const handler = getMethodDescriptor(proto, propName)?.value ?? (() => {});
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const connectedCb = proto.connectedCallback;
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const disconnectedCb = proto.disconnectedCallback;
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Object.defineProperty(proto, "connectedCallback", {
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value: function (this: HTMLElement) {
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target ??= this;
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target.addEventListener(eventName, handler.bind(this));
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connectedCb.call(this);
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},
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configurable: true,
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writable: true,
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prependRoutine(proto, "connectedCallback", function (this: T) {
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target ??= this;
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target.addEventListener(eventName, handler.bind(this));
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});
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Object.defineProperty(proto, "disconnectedCallback", {
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value: function (this: HTMLElement) {
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target ??= this;
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target.removeEventListener(eventName, handler.bind(this));
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disconnectedCb.call(this);
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},
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configurable: true,
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writable: true,
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prependRoutine(proto, "disconnectedCallback", function (this: T) {
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target ??= this;
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target.removeEventListener(eventName, handler.bind(this));
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});
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return desc;
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@@ -0,0 +1,53 @@
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This module is a simple implementation of hierarchical [dependency injection](https://en.wikipedia.org/wiki/Dependency_injection),
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inspired by [Angular](https://angular.io/guide/hierarchical-dependency-injection),
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based on [this talk](https://www.youtube.com/watch?v=6o5zaKHedTE) by Polymer/Lit
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engineer Justin Fagnani, and adapted from [this StackBlitz experiment](https://stackblitz.com/edit/vitejs-vite-6tenu8?file=src%2Fapp.ts).
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### Design Goals
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* Enable [dependency inversion](https://en.wikipedia.org/wiki/Dependency_inversion_principle)
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by declaring dependencies as abstract interfaces which can be swapped out with
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different concrete implementations without necessitating downstream code
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changes
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* Enable bottom-up _injection_ of dependencies (i.e., descendants can inject
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dependencies provided by ancestors)
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* Enable top-down _querying_ for dependencies (i.e., ancestors can query for
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dependencies provided by descendants)
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* Enable these features through [water-tight](https://en.wikipedia.org/wiki/Leaky_abstraction),
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intuitive abstractions
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### Core Concepts
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* Abstract dependencies are represented by a "token," which serves as a runtime
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representation of a dependency described by a TypeScript interface
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* Dependency tokens are "provided" by custom elements annotated with a `provide`
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decorator
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* Dependencies can be "injected" by descendants of a provider (using the
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`inject` decorator to annotate a custom element property) or "queried" by
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ancestors of a provider (using the `queryProviders` decorator)
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### Implementation
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These features are implemented through an exchange of [`CustomEvent`](https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent)
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extensions.
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* Providers dispatch a `DependencyProvision` event just before their
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`connectedCallback` method is invoked, and a `ProviderRemoval` event just
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after `disconnectedCallback`.
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* Elements with `queryProviders`-decorated properties listen for
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`DependencyProvision` and `ProviderRemoval` events, updating the decorated
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property's array accordingly.
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* Elements with `inject`-decorated properties dispatch an `InjectionRequest`
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event just before their `connectedCallback` method is invoked. Providers
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listen for this event. If they provide a token matching the one specified
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by the `inject` decorator, the provider will:
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- Mutate the event's `detail` property to insert the provided `value`
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- `stopImmediatePropagation` of the event to prevent it from bubbling further
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up the DOM tree
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Because JavaScript event bubbling and event listener invocations happen
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synchronously, the injector can check the `detail` property of the dispatched
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event immediately after dispatching it to retrieve the injected value. This
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value is then assigned to a field returned by the decorated property's `get`
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accessor.
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@@ -0,0 +1,184 @@
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import { Ctor, Fn, Method } from "@storyteller/utility";
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import { LitElement } from "lit";
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import { appendRoutine, prependRoutine } from "../decorators/internal";
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import { DIEvent, DependencyProvision, InjectionRequest, ProviderRemoval } from "./events";
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import { Token } from "./types";
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const $injector = Symbol("injector");
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const $$injector = Symbol("#injector");
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export type ProviderOptions<T, E extends LitElement>
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= Token<T>
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| CustomProvider<T, E>;
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export interface CustomProvider<T, E extends LitElement> {
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token: Token<T>;
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/**
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* A method which is invoked just before `connectedCallback` to resolve the
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* provided value.
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*/
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provide(this: E): T;
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}
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/**
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* Registers the decorated custom element as a provider of the given `token`.
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* Descendants who `inject` the `token`, and ancestors who `queryProviders` for
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* `token`, will receive a reference to the instance of this element.
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*/
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export function provide<T, E extends LitElement>(token: Token<T>): Fn<[Ctor<E>], void>;
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/**
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* Registers the decorated custom element as a custom provider for the
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* configured `token`. Descendants who `inject` the `token`, and ancestors who
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* `queryProviders` for `token`, will receive the return value of the configured
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* `provide` method, which is invoked just before this element's
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* `connectedCallback`.
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*/
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export function provide<T, E extends LitElement>(config: CustomProvider<T, E>): Fn<[Ctor<E>], void>;
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export function provide<T, E extends LitElement>(options: ProviderOptions<T, E>) {
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type Decorated = E & {
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[$$injector]?: Map<Token<any>, any> | undefined;
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readonly [$injector]: Map<Token<any>, any>;
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}
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return (Target: Ctor<E>) => {
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const proto = Target.prototype;
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assertType<Decorated>(proto);
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let descriptor = Object.getOwnPropertyDescriptor(proto, $injector);
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let needsInit = false;
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if (!($injector in proto) || !descriptor) {
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needsInit = true;
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Object.defineProperty(proto, $injector, {
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get(this: Decorated) { return this[$$injector] ??= new Map() },
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configurable: false,
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enumerable: true,
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});
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}
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function fulfillInjectionRequest<T>(this: Decorated, event: InjectionRequest<T>): void {
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if (this[$injector].has(event.detail.token)) {
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event.detail.value = this[$injector].get(event.detail.token);
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event.stopImmediatePropagation();
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}
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}
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prependRoutine(proto, "connectedCallback", function (this: Decorated): void {
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const { token, value } = "token" in options
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? { token: options.token, value: options.provide.call(this) }
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: { token: options, value: this as T };
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this[$injector].set(token, value);
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this.dispatchEvent(new DependencyProvision(token, value));
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if (needsInit) {
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const fulfill = fulfillInjectionRequest.bind(this);
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this.addEventListener(DIEvent.InjectionRequest, fulfill as Method<HTMLElement>);
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}
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});
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appendRoutine(proto, "disconnectedCallback", function (this: Decorated): void {
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const token = "token" in options ? options.token : options;
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const value = this[$injector].get(token);
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this.dispatchEvent(new ProviderRemoval(token, value));
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});
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}
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}
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/**
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* Initializes the decorated property just before `connectedCallback` by looking
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* up the nearest ancestor element configured to `provide` the given `token`.
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*
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* @note If no provider for the given `token` is found among this element's
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* ancestors, the decorated property will remain `undefined` unless initialized
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* with a default value.
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*/
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export function inject<T, E extends LitElement>(token: Token<T>) {
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return <K extends keyof E>(proto: E, key: K) => {
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const $field = Symbol(String(key));
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const initial = proto[key];
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type Decorated = E & {
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[$field]?: E[K] | undefined;
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}
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assertType<Decorated>(proto);
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Object.defineProperty(proto, key, {
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get(this: Decorated): E[K] {
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return this[$field] ??= initial;
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},
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set(this: Decorated, value: E[K]): void {
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this[$field] = value;
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},
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configurable: true,
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enumerable: true,
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});
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prependRoutine(proto, "connectedCallback", function (this: E): void {
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const event = new InjectionRequest(token);
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this.dispatchEvent(event);
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if (event.detail.value != null) {
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this[key] = event.detail.value as E[K];
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}
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});
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}
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}
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/**
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* Initializes the decorated property just after `connectedCallback` by looking
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* for descendants configured to `provide` the given `token`.
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*
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* @note It's strongly recommended to default-initialize the decorated property
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* to an empty array. The decorated property will be immutably updated at
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* runtime (via `Array.prototype.concat` and `Array.prototype.filter`) when
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* providers are added to or removed from the DOM sub-tree.
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*/
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export function queryProviders<T, E extends LitElement>(token: Token<T>) {
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return <K extends keyof E>(proto: E, key: K) => {
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function onProvided(this: E, event: DependencyProvision<T>): void {
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const array = this[key] ?? [];
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assertType<E[K] & T[]>(array);
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if (event.detail.token === token)
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this[key] = array.concat(event.detail.value) as E[K];
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}
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function onRemoved(this: E, event: ProviderRemoval<T>): void {
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const array = this[key] ?? [];
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assertType<E[K] & T[]>(array);
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if (event.detail.token === token)
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this[key] = array.filter(el => el !== event.detail.value) as E[K];
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}
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appendRoutine(proto, "connectedCallback", function (this: E): void {
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this[key] = [] as E[K];
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this.addEventListener(
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DIEvent.DependencyProvision,
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onProvided.bind(this) as Method<HTMLElement>,
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);
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this.addEventListener(
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DIEvent.ProviderRemoval,
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onRemoved.bind(this) as Method<HTMLElement>,
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);
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});
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appendRoutine(proto, "disconnectedCallback", function (this: E): void {
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this.removeEventListener(
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DIEvent.DependencyProvision,
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onProvided.bind(this) as Method<HTMLElement>,
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);
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this.removeEventListener(
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DIEvent.ProviderRemoval,
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onRemoved.bind(this) as Method<HTMLElement>,
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);
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});
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}
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}
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function assertType<T>(value: unknown): asserts value is T {}
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@@ -0,0 +1,73 @@
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import { WithOpt } from "@storyteller/utility";
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import { Provider, Token } from "./types";
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export enum DIEvent {
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InjectionRequest = "di-inject",
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DependencyProvision = "di-provide",
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ProviderRemoval = "di-remove",
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}
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type PendingProvider<T> = WithOpt<Provider<T>, "value">;
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/**
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* An event that can be dispatched to inject a dependency provided by an
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* ancestor node.
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*
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* Providers should listen for this event. If they provide a match for the
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* event's `detail.token`, they should populate its `detail.value` property and
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* call `stopPropagation()` to prevent further bubbling.
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*/
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export class InjectionRequest<T> extends CustomEvent<PendingProvider<T>> {
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declare readonly type: DIEvent.InjectionRequest;
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constructor (token: Token<T>) {
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super(DIEvent.InjectionRequest, {
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bubbles: true,
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cancelable: true,
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composed: true,
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detail: { token },
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});
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||||
}
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}
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|
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/**
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* An event that can be dispatched to inform ancestors that this node provides a
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* dependency.
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*/
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export class DependencyProvision<T> extends CustomEvent<Provider<T>> {
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declare readonly type: DIEvent.DependencyProvision;
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|
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constructor (token: Token<T>, value: T) {
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super(DIEvent.DependencyProvision, {
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bubbles: true,
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cancelable: true,
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composed: true,
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detail: { token, value },
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||||
});
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||||
}
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||||
}
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||||
|
||||
/**
|
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* An event that can be dispatched to inform ancestors when a node providing a
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||||
* dependency is removed from the tree.
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*/
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export class ProviderRemoval<T> extends CustomEvent<Provider<T>> {
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declare readonly type: DIEvent.ProviderRemoval;
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|
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constructor (token: Token<T>, value: T) {
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super(DIEvent.ProviderRemoval, {
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bubbles: true,
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cancelable: true,
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composed: true,
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detail: { token, value },
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||||
});
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||||
}
|
||||
}
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||||
|
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declare global {
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interface HTMLElementEventMap {
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[DIEvent.InjectionRequest]: InjectionRequest<any>;
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[DIEvent.DependencyProvision]: DependencyProvision<any>;
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[DIEvent.ProviderRemoval]: ProviderRemoval<any>;
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}
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||||
}
|
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@@ -0,0 +1,3 @@
|
||||
export * from "./decorators";
|
||||
export * from "./events";
|
||||
export * from "./types";
|
||||
@@ -0,0 +1,25 @@
|
||||
import { AbstractCtor, Ctor } from "@storyteller/utility";
|
||||
|
||||
export class UniqueToken {
|
||||
get id() { return this.#id; }
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readonly #id: symbol;
|
||||
|
||||
constructor (name: string) {
|
||||
this.#id = Symbol(name);
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||||
}
|
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|
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toString(): string {
|
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return `UniqueToken(${String(this.#id)})`;
|
||||
}
|
||||
}
|
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|
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export type Token<T>
|
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= UniqueToken
|
||||
| Ctor<T>
|
||||
| AbstractCtor<T>
|
||||
;
|
||||
|
||||
export interface Provider<T> {
|
||||
token: Token<T>;
|
||||
value: T;
|
||||
}
|
||||
Reference in New Issue
Block a user