@spectrum-web-components/shared/src/observe-slot-presence.dev.js

The `@spectrum-web-components/shared` package provides essential base classes, mixins, and utilities that support developing Spectrum Web Components. This package contains foundational tools for focus management, slot observation, accessibility enhancemen

"use strict";
import { MutationController } from "@lit-labs/observers/mutation-controller.js";
const slotContentIsPresent = Symbol("slotContentIsPresent");
export function ObserveSlotPresence(constructor, lightDomSelector) {
  var _a, _b;
  const lightDomSelectors = Array.isArray(lightDomSelector) ? lightDomSelector : [lightDomSelector];
  class SlotPresenceObservingElement extends (_b = constructor, _a = slotContentIsPresent, _b) {
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    constructor(...args) {
      super(...args);
      this[_a] = /* @__PURE__ */ new Map();
      /**
       * @internal
       */
      this.managePresenceObservedSlot = () => {
        let changes = false;
        lightDomSelectors.forEach((selector) => {
          const nextValue = !!this.querySelector(`:scope > ${selector}`);
          const previousValue = this[slotContentIsPresent].get(selector) || false;
          changes = changes || previousValue !== nextValue;
          this[slotContentIsPresent].set(
            selector,
            !!this.querySelector(`:scope > ${selector}`)
          );
        });
        if (changes) {
          this.updateComplete.then(() => {
            this.requestUpdate();
          });
        }
      };
      new MutationController(this, {
        config: {
          childList: true,
          subtree: true
        },
        callback: () => {
          this.managePresenceObservedSlot();
        }
      });
      this.managePresenceObservedSlot();
    }
    /**
     *  @internal
     */
    get slotContentIsPresent() {
      if (lightDomSelectors.length === 1) {
        return this[slotContentIsPresent].get(lightDomSelectors[0]) || false;
      } else {
        throw new Error(
          "Multiple selectors provided to `ObserveSlotPresence` use `getSlotContentPresence(selector: string)` instead."
        );
      }
    }
    /**
     * @internal
     */
    getSlotContentPresence(selector) {
      if (this[slotContentIsPresent].has(selector)) {
        return this[slotContentIsPresent].get(selector) || false;
      }
      throw new Error(
        `The provided selector \`${selector}\` is not being observed.`
      );
    }
  }
  return SlotPresenceObservingElement;
}
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