@surface/custom-element/internal/aot/statements/choice-statement.js

Provides support of directives and data binding on custom elements.

import { CancellationTokenSource } from "@surface/core";
import { scheduler } from "../../singletons.js";
import observe from "../observe.js";
export default class ChoiceStatement {
    constructor(context) {
        this.context = context;
        this.cancellationTokenSource = new CancellationTokenSource();
        this.subscriptions = [];
        this.currentDisposable = null;
        this.disposed = false;
        this.task = () => {
            for (const branch of this.context.branches) {
                if (branch.expression(this.context.scope)) {
                    if (branch != this.currentBranch) {
                        this.currentBranch = branch;
                        this.currentDisposable?.dispose();
                        this.context.block.clear();
                        const [content, activator] = branch.factory();
                        this.context.block.setContent(content);
                        this.currentDisposable = activator(this.context.parent, this.context.host, this.context.scope, this.context.directives);
                    }
                    return;
                }
            }
            this.currentDisposable?.dispose();
            this.context.block.clear();
            this.currentBranch = undefined;
        };
        const listener = () => void scheduler.enqueue(this.task, "normal", this.cancellationTokenSource.token);
        for (const branch of this.context.branches) {
            this.subscriptions.push(observe(context.scope, branch.observables, () => listener(), true));
        }
        listener();
    }
    dispose() {
        if (!this.disposed) {
            this.cancellationTokenSource.cancel();
            this.currentDisposable?.dispose();
            this.subscriptions.forEach(x => x.unsubscribe());
            this.context.block.dispose();
            this.disposed = true;
        }
    }
}