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import { argumentNotNull } from "@implab/core-amd/safe";
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import { queueRenderTask, getItemDom, getPriority, getScope } from "./render";
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import { RenditionBase } from "./RenditionBase";
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import { Scope } from "./Scope";
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import { Subscribable } from "../observable";
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import { Cancellation } from "@implab/core-amd/Cancellation";
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import { collectNodes, destroy, isDocumentFragmentNode, isMounted, placeAt, startupWidgets } from "./traits";
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export class WatchRendition<T> extends RenditionBase<Node> {
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private readonly _component: (arg: T) => unknown;
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private readonly _node: Node;
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private readonly _scope = new Scope();
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private readonly _subject: Subscribable<T>;
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private _renderJob?: { value: T };
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private _ct = Cancellation.none;
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private _priority = 0;
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constructor(component: (arg: T) => unknown, subject: Subscribable<T>) {
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super();
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argumentNotNull(component, "component");
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this._component = component;
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this._subject = subject;
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this._node = document.createComment("[Watch]");
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}
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protected _create() {
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const scope = getScope();
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this._priority = getPriority() + 1;
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scope.own(() => {
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this._scope.destroy();
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destroy(this._node);
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});
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scope.own(this._subject.subscribe({ next: this._onValue }));
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this._ct = new Cancellation(cancel => scope.own(cancel));
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}
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private readonly _onValue = (value: T) => {
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if (!this._renderJob) {
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// schedule a new job
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this._renderJob = { value };
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queueRenderTask(this._render, this._scope, this._priority);
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} else {
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// update existing job
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this._renderJob = { value };
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}
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};
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private readonly _render = () => {
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// don't render destroyed rendition
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if (this._ct.isRequested())
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return;
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// remove all previous content
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this._scope.clean();
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// render the new node
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const node = getItemDom(this._renderJob ? this._component(this._renderJob.value) : undefined);
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// get actual content
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const pending = isDocumentFragmentNode(node) ?
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collectNodes(node.childNodes) :
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[node];
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placeAt(node, this._node, "after");
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if (isMounted(this._node))
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pending.forEach(n => startupWidgets(n));
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if (pending.length)
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this._scope.own(() => pending.forEach(destroy));
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this._renderJob = undefined;
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};
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protected _getDomNode() {
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if (!this._node)
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throw new Error("The instance of the widget isn't created");
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return this._node;
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}
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}
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