/**
 * @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.io/license
 */
import { DoCheck, IterableDiffers, NgIterable, TemplateRef, TrackByFunction, ViewContainerRef } from '@angular/core';
import * as i0 from "@angular/core";
/**
 * @publicApi
 */
export declare class NgForOfContext<T, U extends NgIterable<T> = NgIterable<T>> {
    $implicit: T;
    ngForOf: U;
    index: number;
    count: number;
    __templateName: string;
    constructor($implicit: T, ngForOf: U, index: number, count: number, __templateName: string);
    get first(): boolean;
    get last(): boolean;
    get even(): boolean;
    get odd(): boolean;
}
/**
 * A [structural directive](guide/structural-directives) that renders
 * a template for each item in a collection.
 * The directive is placed on an element, which becomes the parent
 * of the cloned templates.
 *
 * The `ngForOf` directive is generally used in the
 * [shorthand form](guide/structural-directives#asterisk) `*ngFor`.
 * In this form, the template to be rendered for each iteration is the content
 * of an anchor element containing the directive.
 *
 * The following example shows the shorthand syntax with some options,
 * contained in an `<li>` element.
 *
 * ```
 * <li *ngFor="let item of items; index as i; trackBy: trackByFn">...</li>
 * ```
 *
 * The shorthand form expands into a long form that uses the `ngForOf` selector
 * on an `<ng-template>` element.
 * The content of the `<ng-template>` element is the `<li>` element that held the
 * short-form directive.
 *
 * Here is the expanded version of the short-form example.
 *
 * ```
 * <ng-template ngFor let-item [ngForOf]="items" let-i="index" [ngForTrackBy]="trackByFn">
 *   <li>...</li>
 * </ng-template>
 * ```
 *
 * Angular automatically expands the shorthand syntax as it compiles the template.
 * The context for each embedded view is logically merged to the current component
 * context according to its lexical position.
 *
 * When using the shorthand syntax, Angular allows only [one structural directive
 * on an element](guide/structural-directives#one-per-element).
 * If you want to iterate conditionally, for example,
 * put the `*ngIf` on a container element that wraps the `*ngFor` element.
 * For further discussion, see
 * [Structural Directives](guide/structural-directives#one-per-element).
 *
 * @usageNotes
 *
 * ### Local variables
 *
 * `NgForOf` provides exported values that can be aliased to local variables.
 * For example:
 *
 *  ```
 * <li *ngFor="let user of users; index as i; first as isFirst">
 *    {{i}}/{{users.length}}. {{user}} <span *ngIf="isFirst">default</span>
 * </li>
 * ```
 *
 * The following exported values can be aliased to local variables:
 *
 * - `$implicit: T`: The value of the individual items in the iterable (`ngForOf`).
 * - `ngForOf: NgIterable<T>`: The value of the iterable expression. Useful when the expression is
 * more complex then a property access, for example when using the async pipe (`userStreams |
 * async`).
 * - `index: number`: The index of the current item in the iterable.
 * - `count: number`: The length of the iterable.
 * - `first: boolean`: True when the item is the first item in the iterable.
 * - `last: boolean`: True when the item is the last item in the iterable.
 * - `even: boolean`: True when the item has an even index in the iterable.
 * - `odd: boolean`: True when the item has an odd index in the iterable.
 *
 * ### Change propagation
 *
 * When the contents of the iterator changes, `NgForOf` makes the corresponding changes to the DOM:
 *
 * * When an item is added, a new instance of the template is added to the DOM.
 * * When an item is removed, its template instance is removed from the DOM.
 * * When items are reordered, their respective templates are reordered in the DOM.
 *
 * Angular uses object identity to track insertions and deletions within the iterator and reproduce
 * those changes in the DOM. This has important implications for animations and any stateful
 * controls that are present, such as `<input>` elements that accept user input. Inserted rows can
 * be animated in, deleted rows can be animated out, and unchanged rows retain any unsaved state
 * such as user input.
 * For more on animations, see [Transitions and Triggers](guide/transition-and-triggers).
 *
 * The identities of elements in the iterator can change while the data does not.
 * This can happen, for example, if the iterator is produced from an RPC to the server, and that
 * RPC is re-run. Even if the data hasn't changed, the second response produces objects with
 * different identities, and Angular must tear down the entire DOM and rebuild it (as if all old
 * elements were deleted and all new elements inserted).
 *
 * To avoid this expensive operation, you can customize the default tracking algorithm.
 * by supplying the `trackBy` option to `NgForOf`.
 * `trackBy` takes a function that has two arguments: `index` and `item`.
 * If `trackBy` is given, Angular tracks changes by the return value of the function.
 *
 * @see [Structural Directives](guide/structural-directives)
 * @ngModule CommonModule
 * @publicApi
 */
export declare class NgForOf<T, U extends NgIterable<T> = NgIterable<T>> implements DoCheck {
    private _viewContainer;
    private _template;
    private _differs;
    /**
     * The value of the iterable expression, which can be used as a
     * [template input variable](guide/structural-directives#shorthand).
     */
    set ngForOf(ngForOf: (U & NgIterable<T>) | undefined | null);
    /**
     * Specifies a custom `TrackByFunction` to compute the identity of items in an iterable.
     *
     * If a custom `TrackByFunction` is not provided, `NgForOf` will use the item's [object
     * identity](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is)
     * as the key.
     *
     * `NgForOf` uses the computed key to associate items in an iterable with DOM elements
     * it produces for these items.
     *
     * A custom `TrackByFunction` is useful to provide good user experience in cases when items in an
     * iterable rendered using `NgForOf` have a natural identifier (for example, custom ID or a
     * primary key), and this iterable could be updated with new object instances that still
     * represent the same underlying entity (for example, when data is re-fetched from the server,
     * and the iterable is recreated and re-rendered, but most of the data is still the same).
     *
     * @see {@link TrackByFunction}
     */
    set ngForTrackBy(fn: TrackByFunction<T>);
    get ngForTrackBy(): TrackByFunction<T>;
    private _ngForOf;
    private _ngForOfDirty;
    private _differ;
    private _trackByFn;
    constructor(_viewContainer: ViewContainerRef, _template: TemplateRef<NgForOfContext<T, U>>, _differs: IterableDiffers);
    /**
     * A reference to the template that is stamped out for each item in the iterable.
     * @see [template reference variable](guide/template-reference-variables)
     */
    set ngForTemplate(value: TemplateRef<NgForOfContext<T, U>>);
    /**
     * Applies the changes when needed.
     * @nodoc
     */
    ngDoCheck(): void;
    private _applyChanges;
    /**
     * Asserts the correct type of the context for the template that `NgForOf` will render.
     *
     * The presence of this method is a signal to the Ivy template type-check compiler that the
     * `NgForOf` structural directive renders its template with a specific context type.
     */
    static ngTemplateContextGuard<T, U extends NgIterable<T>>(dir: NgForOf<T, U>, ctx: any): ctx is NgForOfContext<T, U>;
    static ɵfac: i0.ɵɵFactoryDeclaration<NgForOf<any, any>, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<NgForOf<any, any>, "[ngFor][ngForOf]", never, { "ngForOf": { "alias": "ngForOf"; "required": false; }; "ngForTrackBy": { "alias": "ngForTrackBy"; "required": false; }; "ngForTemplate": { "alias": "ngForTemplate"; "required": false; }; }, {}, never, never, true, never>;
}
export { NgForOf as NgFor };



declare const NgForOf_Listeners:[];
declare const NgForOf_Properties:[];