packages/core/src/render3/instructions/advance.ts - main - githubmirror/angular

packages/core/src/render3/instructions/advance.ts
84 строки3 KB
Joey Perrott
refactor: update license text to point to angular.dev (#57901)
24 сен 2024, 16:33
24 сен 2024, 16:339dbe6fc
/**
 * @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 {assertGreaterThan} from '../../util/assert';
import {assertIndexInDeclRange} from '../assert';
import {executeCheckHooks, executeInitAndCheckHooks} from '../hooks';
import {FLAGS, InitPhaseState, LView, LViewFlags, TVIEW, TView} from '../interfaces/view';
import {
  getLView,
  getSelectedIndex,
  getTView,
  isInCheckNoChangesMode,
  setSelectedIndex,
} from '../state';

/**
 * Advances to an element for later binding instructions.
 *
 * Used in conjunction with instructions like {@link property} to act on elements with specified
 * indices, for example those created with {@link element} or {@link elementStart}.
 *
 * ```ts
 * (rf: RenderFlags, ctx: any) => {
 *   if (rf & 1) {
 *     text(0, 'Hello');
 *     text(1, 'Goodbye')
 *     element(2, 'div');
 *   }
 *   if (rf & 2) {
 *     advance(2); // Advance twice to the <div>.
 *     property('title', 'test');
 *   }
 *  }
 * ```
 * @param delta Number of elements to advance forwards by.
 *
 * @codeGenApi
 */
export function ɵɵadvance(delta: number = 1): void {
  ngDevMode && assertGreaterThan(delta, 0, 'Can only advance forward');
  selectIndexInternal(
    getTView(),
    getLView(),
    getSelectedIndex() + delta,
    !!ngDevMode && isInCheckNoChangesMode(),
  );
}

export function selectIndexInternal(
  tView: TView,
  lView: LView,
  index: number,
  checkNoChangesMode: boolean,
) {
  ngDevMode && assertIndexInDeclRange(lView[TVIEW], index);

  // Flush the initial hooks for elements in the view that have been added up to this point.
  // PERF WARNING: do NOT extract this to a separate function without running benchmarks
  if (!checkNoChangesMode) {
    const hooksInitPhaseCompleted =
      (lView[FLAGS] & LViewFlags.InitPhaseStateMask) === InitPhaseState.InitPhaseCompleted;
    if (hooksInitPhaseCompleted) {
      const preOrderCheckHooks = tView.preOrderCheckHooks;
      if (preOrderCheckHooks !== null) {
        executeCheckHooks(lView, preOrderCheckHooks, index);
      }
    } else {
      const preOrderHooks = tView.preOrderHooks;
      if (preOrderHooks !== null) {
        executeInitAndCheckHooks(lView, preOrderHooks, InitPhaseState.OnInitHooksToBeRun, index);
      }
    }
  }

  // We must set the selected index *after* running the hooks, because hooks may have side-effects
  // that cause other template functions to run, thus updating the selected index, which is global
  // state. If we run `setSelectedIndex` *before* we run the hooks, in some cases the selected index
  // will be altered by the time we leave the `ɵɵadvance` instruction.
  setSelectedIndex(index);
}