/**
* @license
* Copyright 2023 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import { LitElement } from 'lit';
import { WithElementInternals } from './element-internals.js';
import { MixinBase, MixinReturn } from './mixin.js';
/**
* A form-associated element.
*
* IMPORTANT: Requires declares for lit-analyzer
* @example
* ```ts
* const base = mixinFormAssociated(mixinElementInternals(LitElement));
* class MyControl extends base {
* // Writable mixin properties for lit-html binding, needed for lit-analyzer
* declare disabled: boolean;
* declare name: string;
* }
* ```
*/
export interface FormAssociated {
/**
* The associated form element with which this element's value will submit.
*/
readonly form: HTMLFormElement | null;
/**
* The labels this element is associated with.
*/
readonly labels: NodeList;
/**
* The HTML name to use in form submission.
*/
name: string;
/**
* Whether or not the element is disabled.
*/
disabled: boolean;
/**
* Gets the current form value of a component.
*
* @return The current form value.
*/
[getFormValue](): FormValue | null;
/**
* Gets the current form state of a component. Defaults to the component's
* `[formValue]`.
*
* Use this when the state of an element is different from its value, such as
* checkboxes (internal boolean state and a user string value).
*
* @return The current form state, defaults to the form value.
*/
[getFormState](): FormValue | null;
/**
* A callback for when a form component should be disabled or enabled. This
* can be called in a variety of situations, such as disabled `<fieldset>`s.
*
* @param disabled Whether or not the form control should be disabled.
*/
formDisabledCallback(disabled: boolean): void;
/**
* A callback for when the form requests to reset its value. Typically, the
* default value that is reset is represented in the attribute of an element.
*
* This means the attribute used for the value should not update as the value
* changes. For example, a checkbox should not change its default `checked`
* attribute when selected. Ensure form values do not reflect.
*/
formResetCallback(): void;
/**
* A callback for when the form restores the state of a component. For
* example, when a page is reloaded or forms are autofilled.
*
* @param state The state to restore, or null to reset the form control's
* value.
* @param reason The reason state was restored, either `'restore'` or
* `'autocomplete'`.
*/
formStateRestoreCallback(state: FormRestoreState | null, reason: FormRestoreReason): void;
/**
* An optional callback for when the associated form changes.
*
* @param form The new associated form, or `null` if there is none.
*/
formAssociatedCallback?(form: HTMLFormElement | null): void;
}
/**
* The constructor of a `FormAssociated` element.
*/
export interface FormAssociatedConstructor {
/**
* Indicates that an element is participating in form association.
*/
readonly formAssociated: true;
}
/**
* A symbol property to retrieve the form value for an element.
*/
export declare const getFormValue: unique symbol;
/**
* A symbol property to retrieve the form state for an element.
*/
export declare const getFormState: unique symbol;
/**
* Mixes in form-associated behavior for a class. This allows an element to add
* values to `<form>` elements.
*
* Implementing classes should provide a `[formValue]` to return the current
* value of the element, as well as reset and restore callbacks.
*
* @example
* ```ts
* const base = mixinFormAssociated(mixinElementInternals(LitElement));
*
* class MyControl extends base {
* \@property()
* value = '';
*
* override [getFormValue]() {
* return this.value;
* }
*
* override formResetCallback() {
* const defaultValue = this.getAttribute('value');
* this.value = defaultValue;
* }
*
* override formStateRestoreCallback(state: string) {
* this.value = state;
* }
* }
* ```
*
* Elements may optionally provide a `[formState]` if their values do not
* represent the state of the component.
*
* @example
* ```ts
* const base = mixinFormAssociated(mixinElementInternals(LitElement));
*
* class MyCheckbox extends base {
* \@property()
* value = 'on';
*
* \@property({type: Boolean})
* checked = false;
*
* override [getFormValue]() {
* return this.checked ? this.value : null;
* }
*
* override [getFormState]() {
* return String(this.checked);
* }
*
* override formResetCallback() {
* const defaultValue = this.hasAttribute('checked');
* this.checked = defaultValue;
* }
*
* override formStateRestoreCallback(state: string) {
* this.checked = Boolean(state);
* }
* }
* ```
*
* IMPORTANT: Requires declares for lit-analyzer
* @example
* ```ts
* const base = mixinFormAssociated(mixinElementInternals(LitElement));
* class MyControl extends base {
* // Writable mixin properties for lit-html binding, needed for lit-analyzer
* declare disabled: boolean;
* declare name: string;
* }
* ```
*
* @param base The class to mix functionality into. The base class must use
* `mixinElementInternals()`.
* @return The provided class with `FormAssociated` mixed in.
*/
export declare function mixinFormAssociated<T extends MixinBase<LitElement & WithElementInternals>>(base: T): MixinReturn<T & FormAssociatedConstructor, FormAssociated>;
/**
* A value that can be provided for form submission and state.
*/
export type FormValue = File | string | FormData;
/**
* A value to be restored for a component's form value. If a component's form
* state is a `FormData` object, its entry list of name and values will be
* provided.
*/
export type FormRestoreState = File | string | Array<[string, FormDataEntryValue]>;
/**
* The reason a form component is being restored for, either `'restore'` for
* browser restoration or `'autocomplete'` for restoring user values.
*/
export type FormRestoreReason = 'restore' | 'autocomplete';
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