/**
 * @license
 * Copyright Google Inc. 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 { ElementRef, OnDestroy, Renderer2, StaticProvider } from '@angular/core';
import { ControlValueAccessor } from './control_value_accessor';
export declare const SELECT_VALUE_ACCESSOR: StaticProvider;
/**
 * @whatItDoes Writes values and listens to changes on a select element.
 *
 * Used by {@link NgModel}, {@link FormControlDirective}, and {@link FormControlName}
 * to keep the view synced with the {@link FormControl} model.
 *
 * @howToUse
 *
 * If you have imported the {@link FormsModule} or the {@link ReactiveFormsModule}, this
 * value accessor will be active on any select control that has a form directive. You do
 * **not** need to add a special selector to activate it.
 *
 * ### How to use select controls with form directives
 *
 * To use a select in a template-driven form, simply add an `ngModel` and a `name`
 * attribute to the main `<select>` tag.
 *
 * If your option values are simple strings, you can bind to the normal `value` property
 * on the option.  If your option values happen to be objects (and you'd like to save the
 * selection in your form as an object), use `ngValue` instead:
 *
 * {@example forms/ts/selectControl/select_control_example.ts region='Component'}
 *
 * In reactive forms, you'll also want to add your form directive (`formControlName` or
 * `formControl`) on the main `<select>` tag. Like in the former example, you have the
 * choice of binding to the  `value` or `ngValue` property on the select's options.
 *
 * {@example forms/ts/reactiveSelectControl/reactive_select_control_example.ts region='Component'}
 *
 * ### Caveat: Option selection
 *
 * Angular uses object identity to select option. It's possible for the identities of items
 * to change while the data does not. This can happen, for example, if the items are produced
 * from an RPC to the server, and that RPC is re-run. Even if the data hasn't changed, the
 * second response will produce objects with different identities.
 *
 * To customize the default option comparison algorithm, `<select>` supports `compareWith` input.
 * `compareWith` takes a **function** which has two arguments: `option1` and `option2`.
 * If `compareWith` is given, Angular selects option by the return value of the function.
 *
 * #### Syntax
 *
 * ```
 * <select [compareWith]="compareFn"  [(ngModel)]="selectedCountries">
 *     <option *ngFor="let country of countries" [ngValue]="country">
 *         {{country.name}}
 *     </option>
 * </select>
 *
 * compareFn(c1: Country, c2: Country): boolean {
 *     return c1 && c2 ? c1.id === c2.id : c1 === c2;
 * }
 * ```
 *
 * Note: We listen to the 'change' event because 'input' events aren't fired
 * for selects in Firefox and IE:
 * https://bugzilla.mozilla.org/show_bug.cgi?id=1024350
 * https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/4660045/
 *
 * * **npm package**: `@angular/forms`
 *
 * @stable
 */
export declare class SelectControlValueAccessor implements ControlValueAccessor {
    private _renderer;
    private _elementRef;
    value: any;
    onChange: (_: any) => void;
    onTouched: () => void;
    compareWith: (o1: any, o2: any) => boolean;
    private _compareWith;
    constructor(_renderer: Renderer2, _elementRef: ElementRef);
    writeValue(value: any): void;
    registerOnChange(fn: (value: any) => any): void;
    registerOnTouched(fn: () => any): void;
    setDisabledState(isDisabled: boolean): void;
}
/**
 * @whatItDoes Marks `<option>` as dynamic, so Angular can be notified when options change.
 *
 * @howToUse
 *
 * See docs for {@link SelectControlValueAccessor} for usage examples.
 *
 * @stable
 */
export declare class NgSelectOption implements OnDestroy {
    private _element;
    private _renderer;
    private _select;
    id: string;
    constructor(_element: ElementRef, _renderer: Renderer2, _select: SelectControlValueAccessor);
    ngValue: any;
    value: any;
    ngOnDestroy(): void;
}