refactor(core): move SharedStylesHost interface into @angular/core with a dedicated InjectionToken

This allows code in `@angular/core` to inject and use `SharedStylesHost`, even though the implementation is defined in `@angular/platform-browser`.

packages/core/src/core_private_export.ts

@@ -61,6 +61,10 @@ export {
   DeferBlockState as ɵDeferBlockState,
 } from './defer/interfaces';
 export {getDocument as ɵgetDocument} from './render3/interfaces/document';
+export {
+  SHARED_STYLES_HOST as ɵSHARED_STYLES_HOST,
+  SharedStylesHost as ɵSharedStylesHost,
+} from './render3/interfaces/shared_styles_host';
 export {
   convertToBitFlags as ɵconvertToBitFlags,
   setCurrentInjector as ɵsetCurrentInjector,

packages/core/src/render3/interfaces/shared_styles_host.ts

@@ -0,0 +1,47 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.dev/license
+ */
+
+import {InjectionToken} from '../../di/injection_token';
+
+/** Token used to retrieve the `SharedStylesHost`. */
+export const SHARED_STYLES_HOST = new InjectionToken<SharedStylesHost>(
+  typeof ngDevMode !== 'undefined' && ngDevMode ? 'SHARED_STYLES_HOST' : '',
+);
+
+/** Manages stylesheets for components in the application. */
+export interface SharedStylesHost {
+  /**
+   * Adds embedded styles to the DOM via HTML `style` elements.
+   * @param styles An array of style content strings.
+   * @param urls An array of URLs to be added as link tags.
+   */
+  addStyles(styles: string[], urls?: string[]): void;
+
+  /**
+   * Removes embedded styles from the DOM that were added as HTML `style` elements.
+   * @param styles An array of style content strings.
+   * @param urls An array of URLs to be removed as link tags.
+   */
+  removeStyles(styles: string[], urls?: string[]): void;
+
+  /**
+   * Adds a host node to contain styles added to the DOM and adds all existing style usage to
+   * the newly added host node.
+   *
+   * @param hostNode The node to contain styles added to the DOM.
+   */
+  addHost(hostNode: Node): void;
+
+  /**
+   * Removes a host node from the set of style hosts and removes all existing style usage from
+   * the removed host node.
+   *
+   * @param hostNode The node to remove from the set of style hosts.
+   */
+  removeHost(hostNode: Node): void;
+}

packages/core/test/bundling/animations-standalone/bundle.golden_symbols.json

@@ -226,6 +226,7 @@
       "SELF_TOKEN",
       "SELF_TOKEN_REGEX",
       "SHARED_ANIMATION_PROVIDERS",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIMPLE_CHANGES_STORE",
       "STABILITY_WARNING_THRESHOLD",

packages/core/test/bundling/create_component/bundle.golden_symbols.json

@@ -173,6 +173,7 @@
       "RuntimeError",
       "SCHEDULE_IN_ROOT_ZONE",
       "SCHEDULE_IN_ROOT_ZONE_DEFAULT",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIGNAL_NODE",
       "SIMPLE_CHANGES_STORE",

packages/core/test/bundling/defer/bundle.golden_symbols.json

@@ -216,6 +216,7 @@
       "RuntimeError",
       "SCHEDULE_IN_ROOT_ZONE",
       "SCHEDULE_IN_ROOT_ZONE_DEFAULT",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIMPLE_CHANGES_STORE",
       "SSR_BLOCK_STATE",

packages/core/test/bundling/forms_reactive/bundle.golden_symbols.json

@@ -238,6 +238,7 @@
       "RuntimeError",
       "SCHEDULE_IN_ROOT_ZONE",
       "SCHEDULE_IN_ROOT_ZONE_DEFAULT",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIGNAL_NODE",
       "SIMPLE_CHANGES_STORE",

packages/core/test/bundling/forms_template_driven/bundle.golden_symbols.json

@@ -230,6 +230,7 @@
       "RuntimeError",
       "SCHEDULE_IN_ROOT_ZONE",
       "SCHEDULE_IN_ROOT_ZONE_DEFAULT",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIGNAL_NODE",
       "SIMPLE_CHANGES_STORE",

packages/core/test/bundling/hydration/bundle.golden_symbols.json

@@ -255,6 +255,7 @@
       "RuntimeError",
       "SCHEDULE_IN_ROOT_ZONE",
       "SCHEDULE_IN_ROOT_ZONE_DEFAULT",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIMPLE_CHANGES_STORE",
       "SKIP_HYDRATION_ATTR_NAME",

packages/core/test/bundling/router/bundle.golden_symbols.json

@@ -276,6 +276,7 @@
       "SCHEDULE_IN_ROOT_ZONE",
       "SCHEDULE_IN_ROOT_ZONE_DEFAULT",
       "SEGMENT_RE",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIGNAL_NODE",
       "SIMPLE_CHANGES_STORE",

packages/core/test/bundling/standalone_bootstrap/bundle.golden_symbols.json

@@ -165,6 +165,7 @@
       "RuntimeError",
       "SCHEDULE_IN_ROOT_ZONE",
       "SCHEDULE_IN_ROOT_ZONE_DEFAULT",
+      "SHARED_STYLES_HOST",
       "SIGNAL",
       "SIMPLE_CHANGES_STORE",
       "STABILITY_WARNING_THRESHOLD",

packages/platform-browser/src/browser.ts

@@ -37,6 +37,7 @@ import {
   ɵTESTABILITY_GETTER as TESTABILITY_GETTER,
   inject,
   ɵresolveComponentResources as resolveComponentResources,
+  ɵSHARED_STYLES_HOST as SHARED_STYLES_HOST,
 } from '@angular/core';
 
 import {BrowserDomAdapter} from './browser/browser_adapter';
@@ -266,7 +267,9 @@ const BROWSER_MODULE_PROVIDERS: Provider[] = [
   },
   {provide: EVENT_MANAGER_PLUGINS, useClass: KeyEventsPlugin, multi: true},
   DomRendererFactory2,
-  SharedStylesHost,
+  {provide: SHARED_STYLES_HOST, useClass: SharedStylesHost},
+  // Only remains for backwards compatibility, should be removed once g3 no longer needs it.
+  {provide: SharedStylesHost, useExisting: SHARED_STYLES_HOST},
   EventManager,
   {provide: RendererFactory2, useExisting: DomRendererFactory2},
   {provide: XhrFactory, useClass: BrowserXhr},

packages/platform-browser/src/dom/dom_renderer.ts

@@ -26,6 +26,7 @@ import {
   ɵTracingSnapshot as TracingSnapshot,
   Optional,
   ɵallLeavingAnimations as allLeavingAnimations,
+  ɵSHARED_STYLES_HOST as SHARED_STYLES_HOST,
 } from '@angular/core';
 
 import {RuntimeErrorCode} from '../errors';
@@ -137,7 +138,7 @@ export class DomRendererFactory2 implements RendererFactory2, OnDestroy {
 
   constructor(
     private readonly eventManager: EventManager,
-    private readonly sharedStylesHost: SharedStylesHost,
+    @Inject(SHARED_STYLES_HOST) private readonly sharedStylesHost: SharedStylesHost,
     @Inject(APP_ID) private readonly appId: string,
     @Inject(REMOVE_STYLES_ON_COMPONENT_DESTROY) private removeStylesOnCompDestroy: boolean,
     @Inject(DOCUMENT) private readonly doc: Document,

packages/platform-browser/src/dom/shared_styles_host.ts

@@ -15,6 +15,7 @@ import {
   OnDestroy,
   Optional,
   PLATFORM_ID,
+  ɵSharedStylesHost,
 } from '@angular/core';
 
 /** The style elements attribute name used to set value of `APP_ID` token. */
@@ -102,7 +103,7 @@ export function createLinkElement(url: string, doc: Document): HTMLLinkElement {
 }
 
 @Injectable()
-export class SharedStylesHost implements OnDestroy {
+export class SharedStylesHost implements ɵSharedStylesHost, OnDestroy {
   /**
    * Provides usage information for active inline style content and associated HTML <style> elements.
    * Embedded styles typically originate from the `styles` metadata of a rendered component.
@@ -132,10 +133,6 @@ export class SharedStylesHost implements OnDestroy {
     this.hosts.add(doc.head);
   }
 
-  /**
-   * Adds embedded styles to the DOM via HTML `style` elements.
-   * @param styles An array of style content strings.
-   */
   addStyles(styles: string[], urls?: string[]): void {
     for (const value of styles) {
       this.addUsage(value, this.inline, createStyleElement);
@@ -206,12 +203,6 @@ export class SharedStylesHost implements OnDestroy {
     this.hosts.clear();
   }
 
-  /**
-   * Adds a host node to the set of style hosts and adds all existing style usage to
-   * the newly added host node.
-   *
-   * This is currently only used for Shadow DOM encapsulation mode.
-   */
   addHost(hostNode: Node): void {
     this.hosts.add(hostNode);