/**
 * @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 { ElementRef, OnDestroy, Renderer2 } from '@angular/core';
import { BuiltInControlValueAccessor, ControlValueAccessor } from './control_value_accessor';
import * as i0 from "@angular/core";
/**
 * @description
 * The `ControlValueAccessor` for writing select control values and listening to select control
 * changes. The value accessor is used by the `FormControlDirective`, `FormControlName`, and
 * `NgModel` directives.
 *
 * @usageNotes
 *
 * ### Using select controls in a reactive form
 *
 * The following examples show how to use a select control in a reactive form.
 *
 * {@example forms/ts/reactiveSelectControl/reactive_select_control_example.ts region='Component'}
 *
 * ### Using select controls in a template-driven form
 *
 * To use a select in a template-driven form, simply add an `ngModel` and a `name`
 * attribute to the main `<select>` tag.
 *
 * {@example forms/ts/selectControl/select_control_example.ts region='Component'}
 *
 * ### Customizing 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.
 *
 * ```ts
 * const selectedCountriesControl = new FormControl();
 * ```
 *
 * ```
 * <select [compareWith]="compareFn"  [formControl]="selectedCountriesControl">
 *     <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 IE, see:
 * https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/input_event#browser_compatibility
 *
 * @ngModule ReactiveFormsModule
 * @ngModule FormsModule
 * @publicApi
 */
export declare class SelectControlValueAccessor extends BuiltInControlValueAccessor implements ControlValueAccessor {
    /** @nodoc */
    value: any;
    /** @internal */
    _optionMap: Map<string, any>;
    /** @internal */
    _idCounter: number;
    /**
     * @description
     * Tracks the option comparison algorithm for tracking identities when
     * checking for changes.
     */
    set compareWith(fn: (o1: any, o2: any) => boolean);
    private _compareWith;
    /**
     * Sets the "value" property on the select element.
     * @nodoc
     */
    writeValue(value: any): void;
    /**
     * Registers a function called when the control value changes.
     * @nodoc
     */
    registerOnChange(fn: (value: any) => any): void;
    /** @internal */
    _registerOption(): string;
    /** @internal */
    _getOptionId(value: any): string | null;
    /** @internal */
    _getOptionValue(valueString: string): any;
    static ɵfac: i0.ɵɵFactoryDeclaration<SelectControlValueAccessor, never>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<SelectControlValueAccessor, "select:not([multiple])[formControlName],select:not([multiple])[formControl],select:not([multiple])[ngModel]", never, { "compareWith": { "alias": "compareWith"; "required": false; }; }, {}, never, never, false, never>;
}
/**
 * @description
 * Marks `<option>` as dynamic, so Angular can be notified when options change.
 *
 * @see {@link SelectControlValueAccessor}
 *
 * @ngModule ReactiveFormsModule
 * @ngModule FormsModule
 * @publicApi
 */
export declare class NgSelectOption implements OnDestroy {
    private _element;
    private _renderer;
    private _select;
    /**
     * @description
     * ID of the option element
     */
    id: string;
    constructor(_element: ElementRef, _renderer: Renderer2, _select: SelectControlValueAccessor);
    /**
     * @description
     * Tracks the value bound to the option element. Unlike the value binding,
     * ngValue supports binding to objects.
     */
    set ngValue(value: any);
    /**
     * @description
     * Tracks simple string values bound to the option element.
     * For objects, use the `ngValue` input binding.
     */
    set value(value: any);
    /** @internal */
    _setElementValue(value: string): void;
    /** @nodoc */
    ngOnDestroy(): void;
    static ɵfac: i0.ɵɵFactoryDeclaration<NgSelectOption, [null, null, { optional: true; host: true; }]>;
    static ɵdir: i0.ɵɵDirectiveDeclaration<NgSelectOption, "option", never, { "ngValue": { "alias": "ngValue"; "required": false; }; "value": { "alias": "value"; "required": false; }; }, {}, never, never, false, never>;
}



declare const SelectControlValueAccessor_Listeners:["change","blur"];
declare const SelectControlValueAccessor_Properties:[];
declare const NgSelectOption_Listeners:[];
declare const NgSelectOption_Properties:[];