angular-cn/modules/@angular/core/src/metadata.ts

/**
 * @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
 */

/**
 * This indirection is needed to free up Component, etc symbols in the public API
 * to be used by the decorator versions of these annotations.
 */

import {AttributeMetadata, ContentChildMetadata, ContentChildrenMetadata, QueryMetadata, ViewChildMetadata, ViewChildrenMetadata, ViewQueryMetadata} from './metadata/di';
import {ComponentMetadata, ComponentMetadataType, DirectiveMetadata, DirectiveMetadataType, HostBindingMetadata, HostListenerMetadata, InputMetadata, OutputMetadata, PipeMetadata, PipeMetadataType} from './metadata/directives';
import {ModuleWithProviders, NgModuleMetadata, NgModuleMetadataType, SchemaMetadata} from './metadata/ng_module';
import {ViewEncapsulation} from './metadata/view';
import {Type} from './type';
import {TypeDecorator, makeDecorator, makeParamDecorator, makePropDecorator} from './util/decorators';

export {ANALYZE_FOR_ENTRY_COMPONENTS, AttributeMetadata, ContentChildMetadata, ContentChildrenMetadata, QueryMetadata, ViewChildMetadata, ViewChildrenMetadata, ViewQueryMetadata} from './metadata/di';
export {ComponentMetadata, ComponentMetadataType, DirectiveMetadata, DirectiveMetadataType, HostBindingMetadata, HostListenerMetadata, InputMetadata, OutputMetadata, PipeMetadata, PipeMetadataType} from './metadata/directives';
export {AfterContentChecked, AfterContentInit, AfterViewChecked, AfterViewInit, DoCheck, OnChanges, OnDestroy, OnInit} from './metadata/lifecycle_hooks';
export {CUSTOM_ELEMENTS_SCHEMA, ModuleWithProviders, NO_ERRORS_SCHEMA, NgModuleMetadata, NgModuleMetadataType, SchemaMetadata} from './metadata/ng_module';
export {ViewEncapsulation} from './metadata/view';



/**
 * Interface for the {@link DirectiveMetadata} decorator function.
 *
 * See {@link DirectiveMetadataFactory}.
 *
 * @stable
 */
export interface DirectiveDecorator extends TypeDecorator {}

/**
 * Interface for the {@link ComponentMetadata} decorator function.
 *
 * See {@link ComponentFactory}.
 *
 * @stable
 */
export interface ComponentDecorator extends TypeDecorator {}

/**
 * Interface for the {@link NgModuleMetadata} decorator function.
 *
 * See {@link NgModuleMetadataFactory}.
 *
 * @stable
 */
export interface NgModuleDecorator extends TypeDecorator {}


/**
 * {@link DirectiveMetadata} factory for creating annotations, decorators or DSL.
 *
 * ### Example as TypeScript Decorator
 *
 * {@example core/ts/metadata/metadata.ts region='directive'}
 *
 * ### Example as ES5 DSL
 *
 * ```
 * var MyDirective = ng
 *   .Directive({...})
 *   .Class({
 *     constructor: function() {
 *       ...
 *     }
 *   })
 * ```
 *
 * ### Example as ES5 annotation
 *
 * ```
 * var MyDirective = function() {
 *   ...
 * };
 *
 * MyDirective.annotations = [
 *   new ng.Directive({...})
 * ]
 * ```
 *
 * @stable
 */
export interface DirectiveMetadataFactory {
  (obj: DirectiveMetadataType): DirectiveDecorator;
  new (obj: DirectiveMetadataType): DirectiveMetadata;
}

/**
 * {@link ComponentMetadata} factory for creating annotations, decorators or DSL.
 *
 * ### Example as TypeScript Decorator
 *
 * {@example core/ts/metadata/metadata.ts region='component'}
 *
 * ### Example as ES5 DSL
 *
 * ```
 * var MyComponent = ng
 *   .Component({...})
 *   .Class({
 *     constructor: function() {
 *       ...
 *     }
 *   })
 * ```
 *
 * ### Example as ES5 annotation
 *
 * ```
 * var MyComponent = function() {
 *   ...
 * };
 *
 * MyComponent.annotations = [
 *   new ng.Component({...})
 * ]
 * ```
 *
 * @stable
 */
export interface ComponentMetadataFactory {
  (obj: ComponentMetadataType): ComponentDecorator;
  new (obj: ComponentMetadataType): ComponentMetadata;
}

/**
 * {@link AttributeMetadata} factory for creating annotations, decorators or DSL.
 *
 * ### Example as TypeScript Decorator
 *
 * {@example core/ts/metadata/metadata.ts region='attributeFactory'}
 *
 * ### Example as ES5 DSL
 *
 * ```
 * var MyComponent = ng
 *   .Component({...})
 *   .Class({
 *     constructor: [new ng.Attribute('title'), function(title) {
 *       ...
 *     }]
 *   })
 * ```
 *
 * ### Example as ES5 annotation
 *
 * ```
 * var MyComponent = function(title) {
 *   ...
 * };
 *
 * MyComponent.annotations = [
 *   new ng.Component({...})
 * ]
 * MyComponent.parameters = [
 *   [new ng.Attribute('title')]
 * ]
 * ```
 *
 * @stable
 */
export interface AttributeMetadataFactory {
  (name: string): TypeDecorator;
  new (name: string): AttributeMetadata;
}

/**
 * Factory for {@link ContentChildren}.
 * @stable
 */
export interface ContentChildrenMetadataFactory {
  (selector: Type<any>|Function|string,
   {descendants, read}?: {descendants?: boolean, read?: any}): any;
  new (
      selector: Type<any>|Function|string,
      {descendants, read}?: {descendants?: boolean, read?: any}): ContentChildrenMetadata;
}

/**
 * Factory for {@link ContentChild}.
 * @stable
 */
export interface ContentChildMetadataFactory {
  (selector: Type<any>|Function|string, {read}?: {read?: any}): any;
  new (selector: Type<any>|Function|string, {read}?: {read?: any}): ContentChildMetadataFactory;
}

/**
 * Factory for {@link ViewChildren}.
 * @stable
 */
export interface ViewChildrenMetadataFactory {
  (selector: Type<any>|Function|string, {read}?: {read?: any}): any;
  new (selector: Type<any>|Function|string, {read}?: {read?: any}): ViewChildrenMetadata;
}

/**
 * Factory for {@link ViewChild}.
 * @stable
 */
export interface ViewChildMetadataFactory {
  (selector: Type<any>|Function|string, {read}?: {read?: any}): any;
  new (selector: Type<any>|Function|string, {read}?: {read?: any}): ViewChildMetadataFactory;
}


/**
 * {@link PipeMetadata} factory for creating decorators.
 *
 * ### Example
 *
 * {@example core/ts/metadata/metadata.ts region='pipe'}
 * @stable
 */
export interface PipeMetadataFactory {
  (obj: PipeMetadataType): any;
  new (obj: PipeMetadataType): any;
}

/**
 * {@link InputMetadata} factory for creating decorators.
 *
 * See {@link InputMetadata}.
 * @stable
 */
export interface InputMetadataFactory {
  (bindingPropertyName?: string): any;
  new (bindingPropertyName?: string): any;
}

/**
 * {@link OutputMetadata} factory for creating decorators.
 *
 * See {@link OutputMetadata}.
 * @stable
 */
export interface OutputMetadataFactory {
  (bindingPropertyName?: string): any;
  new (bindingPropertyName?: string): any;
}

/**
 * {@link HostBindingMetadata} factory function.
 * @stable
 */
export interface HostBindingMetadataFactory {
  (hostPropertyName?: string): any;
  new (hostPropertyName?: string): any;
}

/**
 * {@link HostListenerMetadata} factory function.
 * @stable
 */
export interface HostListenerMetadataFactory {
  (eventName: string, args?: string[]): any;
  new (eventName: string, args?: string[]): any;
}

/**
 * {@link NgModuleMetadata} factory for creating annotations, decorators or DSL.
 *
 * @stable
 */
export interface NgModuleMetadataFactory {
  (obj?: NgModuleMetadataType): NgModuleDecorator;
  new (obj?: NgModuleMetadataType): NgModuleMetadata;
}

// TODO(alexeagle): remove the duplication of this doc. It is copied from ComponentMetadata.
/**
 * Declare reusable UI building blocks for an application.
 *
 * Each Angular component requires a single `@Component` annotation. The `@Component`
 * annotation specifies when a component is instantiated, and which properties and hostListeners it
 * binds to.
 *
 * When a component is instantiated, Angular
 * - creates a shadow DOM for the component.
 * - loads the selected template into the shadow DOM.
 * - creates all the injectable objects configured with `providers` and `viewProviders`.
 *
 * All template expressions and statements are then evaluated against the component instance.
 *
 * ## Lifecycle hooks
 *
 * When the component class implements some {@linkDocs guide/lifecycle-hooks} the
 * callbacks are called by the change detection at defined points in time during the life of the
 * component.
 *
 * ### Example
 *
 * {@example core/ts/metadata/metadata.ts region='component'}
 * @stable
 * @Annotation
 */
export var Component: ComponentMetadataFactory =
    <ComponentMetadataFactory>makeDecorator(ComponentMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from DirectiveMetadata.
/**
 * Directives allow you to attach behavior to elements in the DOM.
 *
 * {@link DirectiveMetadata}s with an embedded view are called {@link ComponentMetadata}s.
 *
 * A directive consists of a single directive annotation and a controller class. When the
 * directive's `selector` matches
 * elements in the DOM, the following steps occur:
 *
 * 1. For each directive, the `ElementInjector` attempts to resolve the directive's constructor
 * arguments.
 * 2. Angular instantiates directives for each matched element using `ElementInjector` in a
 * depth-first order,
 *    as declared in the HTML.
 *
 * ## Understanding How Injection Works
 *
 * There are three stages of injection resolution.
 * - *Pre-existing Injectors*:
 *   - The terminal {@link Injector} cannot resolve dependencies. It either throws an error or, if
 * the dependency was
 *     specified as `@Optional`, returns `null`.
 *   - The platform injector resolves browser singleton resources, such as: cookies, title,
 * location, and others.
 * - *Component Injectors*: Each component instance has its own {@link Injector}, and they follow
 * the same parent-child hierarchy
 *     as the component instances in the DOM.
 * - *Element Injectors*: Each component instance has a Shadow DOM. Within the Shadow DOM each
 * element has an `ElementInjector`
 *     which follow the same parent-child hierarchy as the DOM elements themselves.
 *
 * When a template is instantiated, it also must instantiate the corresponding directives in a
 * depth-first order. The
 * current `ElementInjector` resolves the constructor dependencies for each directive.
 *
 * Angular then resolves dependencies as follows, according to the order in which they appear in the
 * {@link ComponentMetadata}:
 *
 * 1. Dependencies on the current element
 * 2. Dependencies on element injectors and their parents until it encounters a Shadow DOM boundary
 * 3. Dependencies on component injectors and their parents until it encounters the root component
 * 4. Dependencies on pre-existing injectors
 *
 *
 * The `ElementInjector` can inject other directives, element-specific special objects, or it can
 * delegate to the parent
 * injector.
 *
 * To inject other directives, declare the constructor parameter as:
 * - `directive:DirectiveType`: a directive on the current element only
 * - `@Host() directive:DirectiveType`: any directive that matches the type between the current
 * element and the
 *    Shadow DOM root.
 * - `@Query(DirectiveType) query:QueryList<DirectiveType>`: A live collection of direct child
 * directives.
 * - `@QueryDescendants(DirectiveType) query:QueryList<DirectiveType>`: A live collection of any
 * child directives.
 *
 * To inject element-specific special objects, declare the constructor parameter as:
 * - `element: ElementRef` to obtain a reference to logical element in the view.
 * - `viewContainer: ViewContainerRef` to control child template instantiation, for
 * {@link DirectiveMetadata} directives only
 * - `bindingPropagation: BindingPropagation` to control change detection in a more granular way.
 *
 * ### Example
 *
 * The following example demonstrates how dependency injection resolves constructor arguments in
 * practice.
 *
 *
 * Assume this HTML template:
 *
 * ```
 * <div dependency="1">
 *   <div dependency="2">
 *     <div dependency="3" my-directive>
 *       <div dependency="4">
 *         <div dependency="5"></div>
 *       </div>
 *       <div dependency="6"></div>
 *     </div>
 *   </div>
 * </div>
 * ```
 *
 * With the following `dependency` decorator and `SomeService` injectable class.
 *
 * ```
 * @Injectable()
 * class SomeService {
 * }
 *
 * @Directive({
 *   selector: '[dependency]',
 *   inputs: [
 *     'id: dependency'
 *   ]
 * })
 * class Dependency {
 *   id:string;
 * }
 * ```
 *
 * Let's step through the different ways in which `MyDirective` could be declared...
 *
 *
 * ### No injection
 *
 * Here the constructor is declared with no arguments, therefore nothing is injected into
 * `MyDirective`.
 *
 * ```
 * @Directive({ selector: '[my-directive]' })
 * class MyDirective {
 *   constructor() {
 *   }
 * }
 * ```
 *
 * This directive would be instantiated with no dependencies.
 *
 *
 * ### Component-level injection
 *
 * Directives can inject any injectable instance from the closest component injector or any of its
 * parents.
 *
 * Here, the constructor declares a parameter, `someService`, and injects the `SomeService` type
 * from the parent
 * component's injector.
 * ```
 * @Directive({ selector: '[my-directive]' })
 * class MyDirective {
 *   constructor(someService: SomeService) {
 *   }
 * }
 * ```
 *
 * This directive would be instantiated with a dependency on `SomeService`.
 *
 *
 * ### Injecting a directive from the current element
 *
 * Directives can inject other directives declared on the current element.
 *
 * ```
 * @Directive({ selector: '[my-directive]' })
 * class MyDirective {
 *   constructor(dependency: Dependency) {
 *     expect(dependency.id).toEqual(3);
 *   }
 * }
 * ```
 * This directive would be instantiated with `Dependency` declared at the same element, in this case
 * `dependency="3"`.
 *
 * ### Injecting a directive from any ancestor elements
 *
 * Directives can inject other directives declared on any ancestor element (in the current Shadow
 * DOM), i.e. on the current element, the
 * parent element, or its parents.
 * ```
 * @Directive({ selector: '[my-directive]' })
 * class MyDirective {
 *   constructor(@Host() dependency: Dependency) {
 *     expect(dependency.id).toEqual(2);
 *   }
 * }
 * ```
 *
 * `@Host` checks the current element, the parent, as well as its parents recursively. If
 * `dependency="2"` didn't
 * exist on the direct parent, this injection would
 * have returned
 * `dependency="1"`.
 *
 *
 * ### Injecting a live collection of direct child directives
 *
 *
 * A directive can also query for other child directives. Since parent directives are instantiated
 * before child directives, a directive can't simply inject the list of child directives. Instead,
 * the directive injects a {@link QueryList}, which updates its contents as children are added,
 * removed, or moved by a directive that uses a {@link ViewContainerRef} such as a `ngFor`, an
 * `ngIf`, or an `ngSwitch`.
 *
 * ```
 * @Directive({ selector: '[my-directive]' })
 * class MyDirective {
 *   constructor(@Query(Dependency) dependencies:QueryList<Dependency>) {
 *   }
 * }
 * ```
 *
 * This directive would be instantiated with a {@link QueryList} which contains `Dependency` 4 and
 * 6. Here, `Dependency` 5 would not be included, because it is not a direct child.
 *
 * ### Injecting a live collection of descendant directives
 *
 * By passing the descendant flag to `@Query` above, we can include the children of the child
 * elements.
 *
 * ```
 * @Directive({ selector: '[my-directive]' })
 * class MyDirective {
 *   constructor(@Query(Dependency, {descendants: true}) dependencies:QueryList<Dependency>) {
 *   }
 * }
 * ```
 *
 * This directive would be instantiated with a Query which would contain `Dependency` 4, 5 and 6.
 *
 * ### Optional injection
 *
 * The normal behavior of directives is to return an error when a specified dependency cannot be
 * resolved. If you
 * would like to inject `null` on unresolved dependency instead, you can annotate that dependency
 * with `@Optional()`.
 * This explicitly permits the author of a template to treat some of the surrounding directives as
 * optional.
 *
 * ```
 * @Directive({ selector: '[my-directive]' })
 * class MyDirective {
 *   constructor(@Optional() dependency:Dependency) {
 *   }
 * }
 * ```
 *
 * This directive would be instantiated with a `Dependency` directive found on the current element.
 * If none can be
 * found, the injector supplies `null` instead of throwing an error.
 *
 * ### Example
 *
 * Here we use a decorator directive to simply define basic tool-tip behavior.
 *
 * ```
 * @Directive({
 *   selector: '[tooltip]',
 *   inputs: [
 *     'text: tooltip'
 *   ],
 *   host: {
 *     '(mouseenter)': 'onMouseEnter()',
 *     '(mouseleave)': 'onMouseLeave()'
 *   }
 * })
 * class Tooltip{
 *   text:string;
 *   overlay:Overlay; // NOT YET IMPLEMENTED
 *   overlayManager:OverlayManager; // NOT YET IMPLEMENTED
 *
 *   constructor(overlayManager:OverlayManager) {
 *     this.overlayManager = overlayManager;
 *   }
 *
 *   onMouseEnter() {
 *     // exact signature to be determined
 *     this.overlay = this.overlayManager.open(text, ...);
 *   }
 *
 *   onMouseLeave() {
 *     this.overlay.close();
 *     this.overlay = null;
 *   }
 * }
 * ```
 * In our HTML template, we can then add this behavior to a `<div>` or any other element with the
 * `tooltip` selector,
 * like so:
 *
 * ```
 * <div tooltip="some text here"></div>
 * ```
 *
 * Directives can also control the instantiation, destruction, and positioning of inline template
 * elements:
 *
 * A directive uses a {@link ViewContainerRef} to instantiate, insert, move, and destroy views at
 * runtime.
 * The {@link ViewContainerRef} is created as a result of `<template>` element, and represents a
 * location in the current view
 * where these actions are performed.
 *
 * Views are always created as children of the current {@link ComponentMetadata}, and as siblings of
 * the
 * `<template>` element. Thus a
 * directive in a child view cannot inject the directive that created it.
 *
 * Since directives that create views via ViewContainers are common in Angular, and using the full
 * `<template>` element syntax is wordy, Angular
 * also supports a shorthand notation: `<li *foo="bar">` and `<li template="foo: bar">` are
 * equivalent.
 *
 * Thus,
 *
 * ```
 * <ul>
 *   <li *foo="bar" title="text"></li>
 * </ul>
 * ```
 *
 * Expands in use to:
 *
 * ```
 * <ul>
 *   <template [foo]="bar">
 *     <li title="text"></li>
 *   </template>
 * </ul>
 * ```
 *
 * Notice that although the shorthand places `*foo="bar"` within the `<li>` element, the binding for
 * the directive
 * controller is correctly instantiated on the `<template>` element rather than the `<li>` element.
 *
 * ## Lifecycle hooks
 *
 * When the directive class implements some {@linkDocs guide/lifecycle-hooks} the
 * callbacks are called by the change detection at defined points in time during the life of the
 * directive.
 *
 * ### Example
 *
 * Let's suppose we want to implement the `unless` behavior, to conditionally include a template.
 *
 * Here is a simple directive that triggers on an `unless` selector:
 *
 * ```
 * @Directive({
 *   selector: '[unless]',
 *   inputs: ['unless']
 * })
 * export class Unless {
 *   viewContainer: ViewContainerRef;
 *   templateRef: TemplateRef;
 *   prevCondition: boolean;
 *
 *   constructor(viewContainer: ViewContainerRef, templateRef: TemplateRef) {
 *     this.viewContainer = viewContainer;
 *     this.templateRef = templateRef;
 *     this.prevCondition = null;
 *   }
 *
 *   set unless(newCondition) {
 *     if (newCondition && (isBlank(this.prevCondition) || !this.prevCondition)) {
 *       this.prevCondition = true;
 *       this.viewContainer.clear();
 *     } else if (!newCondition && (isBlank(this.prevCondition) || this.prevCondition)) {
 *       this.prevCondition = false;
 *       this.viewContainer.create(this.templateRef);
 *     }
 *   }
 * }
 * ```
 *
 * We can then use this `unless` selector in a template:
 * ```
 * <ul>
 *   <li *unless="expr"></li>
 * </ul>
 * ```
 *
 * Once the directive instantiates the child view, the shorthand notation for the template expands
 * and the result is:
 *
 * ```
 * <ul>
 *   <template [unless]="exp">
 *     <li></li>
 *   </template>
 *   <li></li>
 * </ul>
 * ```
 *
 * Note also that although the `<li></li>` template still exists inside the `<template></template>`,
 * the instantiated
 * view occurs on the second `<li></li>` which is a sibling to the `<template>` element.
 * @stable
 * @Annotation
 */
export var Directive: DirectiveMetadataFactory =
    <DirectiveMetadataFactory>makeDecorator(DirectiveMetadata);

/**
 * Specifies that a constant attribute value should be injected.
 *
 * The directive can inject constant string literals of host element attributes.
 *
 * ### Example
 *
 * Suppose we have an `<input>` element and want to know its `type`.
 *
 * ```html
 * <input type="text">
 * ```
 *
 * A decorator can inject string literal `text` like so:
 *
 * {@example core/ts/metadata/metadata.ts region='attributeMetadata'}
 * @stable
 * @Annotation
 */
export var Attribute: AttributeMetadataFactory = makeParamDecorator(AttributeMetadata);


// TODO(alexeagle): remove the duplication of this doc. It is copied from ContentChildrenMetadata.
/**
 * Configures a content query.
 *
 * Content queries are set before the `ngAfterContentInit` callback is called.
 *
 * ### Example
 *
 * ```
 * @Directive({
 *   selector: 'someDir'
 * })
 * class SomeDir {
 *   @ContentChildren(ChildDirective) contentChildren: QueryList<ChildDirective>;
 *
 *   ngAfterContentInit() {
 *     // contentChildren is set
 *   }
 * }
 * ```
 * @stable
 * @Annotation
 */
export var ContentChildren: ContentChildrenMetadataFactory =
    makePropDecorator(ContentChildrenMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from ContentChildMetadata.
/**
 * Configures a content query.
 *
 * Content queries are set before the `ngAfterContentInit` callback is called.
 *
 * ### Example
 *
 * ```
 * @Directive({
 *   selector: 'someDir'
 * })
 * class SomeDir {
 *   @ContentChild(ChildDirective) contentChild;
 *   @ContentChild('container_ref') containerChild
 *
 *   ngAfterContentInit() {
 *     // contentChild is set
 *     // containerChild is set
 *   }
 * }
 * ```
 *
 * ```html
 * <container #container_ref>
 *   <item>a</item>
 *   <item>b</item>
 * </container>
 * ```
 * @stable
 * @Annotation
 */
export var ContentChild: ContentChildMetadataFactory = makePropDecorator(ContentChildMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from ViewChildrenMetadata.
/**
 * Declares a list of child element references.
 *
 * Angular automatically updates the list when the DOM is updated.
 *
 * `ViewChildren` takes a argument to select elements.
 *
 * - If the argument is a type, directives or components with the type will be bound.
 *
 * - If the argument is a string, the string is interpreted as a list of comma-separated selectors.
 * For each selector, an element containing the matching template variable (e.g. `#child`) will be
 * bound.
 *
 * View children are set before the `ngAfterViewInit` callback is called.
 *
 * ### Example
 *
 * With type selector:
 *
 * ```
 * @Component({
 *   selector: 'child-cmp',
 *   template: '<p>child</p>'
 * })
 * class ChildCmp {
 *   doSomething() {}
 * }
 *
 * @Component({
 *   selector: 'some-cmp',
 *   template: `
 *     <child-cmp></child-cmp>
 *     <child-cmp></child-cmp>
 *     <child-cmp></child-cmp>
 *   `
 * })
 * class SomeCmp {
 *   @ViewChildren(ChildCmp) children:QueryList<ChildCmp>;
 *
 *   ngAfterViewInit() {
 *     // children are set
 *     this.children.toArray().forEach((child)=>child.doSomething());
 *   }
 * }
 * ```
 *
 * With string selector:
 *
 * ```
 * @Component({
 *   selector: 'child-cmp',
 *   template: '<p>child</p>'
 * })
 * class ChildCmp {
 *   doSomething() {}
 * }
 *
 * @Component({
 *   selector: 'some-cmp',
 *   template: `
 *     <child-cmp #child1></child-cmp>
 *     <child-cmp #child2></child-cmp>
 *     <child-cmp #child3></child-cmp>
 *   `
 * })
 * class SomeCmp {
 *   @ViewChildren('child1,child2,child3') children:QueryList<ChildCmp>;
 *
 *   ngAfterViewInit() {
 *     // children are set
 *     this.children.toArray().forEach((child)=>child.doSomething());
 *   }
 * }
 * ```
 *
 * See also: [ViewChildrenMetadata]
 * @stable
 * @Annotation
 */
export var ViewChildren: ViewChildrenMetadataFactory = makePropDecorator(ViewChildrenMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from ViewChildMetadata.
/**
 * Declares a reference to a child element.
 *
 * `ViewChildren` takes a argument to select elements.
 *
 * - If the argument is a type, a directive or a component with the type will be bound.
 *
 * - If the argument is a string, the string is interpreted as a selector. An element containing the
 * matching template variable (e.g. `#child`) will be bound.
 *
 * In either case, `@ViewChild()` assigns the first (looking from above) element if there are
 * multiple matches.
 *
 * View child is set before the `ngAfterViewInit` callback is called.
 *
 * ### Example
 *
 * With type selector:
 *
 * ```
 * @Component({
 *   selector: 'child-cmp',
 *   template: '<p>child</p>'
 * })
 * class ChildCmp {
 *   doSomething() {}
 * }
 *
 * @Component({
 *   selector: 'some-cmp',
 *   template: '<child-cmp></child-cmp>'
 * })
 * class SomeCmp {
 *   @ViewChild(ChildCmp) child:ChildCmp;
 *
 *   ngAfterViewInit() {
 *     // child is set
 *     this.child.doSomething();
 *   }
 * }
 * ```
 *
 * With string selector:
 *
 * ```
 * @Component({
 *   selector: 'child-cmp',
 *   template: '<p>child</p>'
 * })
 * class ChildCmp {
 *   doSomething() {}
 * }
 *
 * @Component({
 *   selector: 'some-cmp',
 *   template: '<child-cmp #child></child-cmp>'
 * })
 * class SomeCmp {
 *   @ViewChild('child') child:ChildCmp;
 *
 *   ngAfterViewInit() {
 *     // child is set
 *     this.child.doSomething();
 *   }
 * }
 * ```
 * See also: [ViewChildMetadata]
 * @stable
 * @Annotation
 */
export var ViewChild: ViewChildMetadataFactory = makePropDecorator(ViewChildMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from PipeMetadata.
/**
 * Declare reusable pipe function.
 *
 * ### Example
 *
 * {@example core/ts/metadata/metadata.ts region='pipe'}
 * @stable
 * @Annotation
 */
export var Pipe: PipeMetadataFactory = <PipeMetadataFactory>makeDecorator(PipeMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from InputMetadata.
/**
 * Declares a data-bound input property.
 *
 * Angular automatically updates data-bound properties during change detection.
 *
 * `InputMetadata` takes an optional parameter that specifies the name
 * used when instantiating a component in the template. When not provided,
 * the name of the decorated property is used.
 *
 * ### Example
 *
 * The following example creates a component with two input properties.
 *
 * ```typescript
 * @Component({
 *   selector: 'bank-account',
 *   template: `
 *     Bank Name: {{bankName}}
 *     Account Id: {{id}}
 *   `
 * })
 * class BankAccount {
 *   @Input() bankName: string;
 *   @Input('account-id') id: string;
 *
 *   // this property is not bound, and won't be automatically updated by Angular
 *   normalizedBankName: string;
 * }
 *
 * @Component({
 *   selector: 'app',
 *   template: `
 *     <bank-account bank-name="RBC" account-id="4747"></bank-account>
 *   `,
 *   directives: [BankAccount]
 * })
 * class App {}
 * ```
 * @stable
 * @Annotation
 */
export var Input: InputMetadataFactory = makePropDecorator(InputMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from OutputMetadata.
/**
 * Declares an event-bound output property.
 *
 * When an output property emits an event, an event handler attached to that event
 * the template is invoked.
 *
 * `OutputMetadata` takes an optional parameter that specifies the name
 * used when instantiating a component in the template. When not provided,
 * the name of the decorated property is used.
 *
 * ### Example
 *
 * ```typescript
 * @Directive({
 *   selector: 'interval-dir',
 * })
 * class IntervalDir {
 *   @Output() everySecond = new EventEmitter();
 *   @Output('everyFiveSeconds') five5Secs = new EventEmitter();
 *
 *   constructor() {
 *     setInterval(() => this.everySecond.emit("event"), 1000);
 *     setInterval(() => this.five5Secs.emit("event"), 5000);
 *   }
 * }
 *
 * @Component({
 *   selector: 'app',
 *   template: `
 *     <interval-dir (everySecond)="everySecond()" (everyFiveSeconds)="everyFiveSeconds()">
 *     </interval-dir>
 *   `,
 *   directives: [IntervalDir]
 * })
 * class App {
 *   everySecond() { console.log('second'); }
 *   everyFiveSeconds() { console.log('five seconds'); }
 * }
 * ```
 * @stable
 * @Annotation
 */
export var Output: OutputMetadataFactory = makePropDecorator(OutputMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from HostBindingMetadata.
/**
 * Declares a host property binding.
 *
 * Angular automatically checks host property bindings during change detection.
 * If a binding changes, it will update the host element of the directive.
 *
 * `HostBindingMetadata` takes an optional parameter that specifies the property
 * name of the host element that will be updated. When not provided,
 * the class property name is used.
 *
 * ### Example
 *
 * The following example creates a directive that sets the `valid` and `invalid` classes
 * on the DOM element that has ngModel directive on it.
 *
 * ```typescript
 * @Directive({selector: '[ngModel]'})
 * class NgModelStatus {
 *   constructor(public control:NgModel) {}
 *   @HostBinding('class.valid') get valid() { return this.control.valid; }
 *   @HostBinding('class.invalid') get invalid() { return this.control.invalid; }
 * }
 *
 * @Component({
 *   selector: 'app',
 *   template: `<input [(ngModel)]="prop">`,
 *   directives: [FORM_DIRECTIVES, NgModelStatus]
 * })
 * class App {
 *   prop;
 * }
 * ```
 * @stable
 * @Annotation
 */
export var HostBinding: HostBindingMetadataFactory = makePropDecorator(HostBindingMetadata);

// TODO(alexeagle): remove the duplication of this doc. It is copied from HostListenerMetadata.
/**
 * Declares a host listener.
 *
 * Angular will invoke the decorated method when the host element emits the specified event.
 *
 * If the decorated method returns `false`, then `preventDefault` is applied on the DOM
 * event.
 *
 * ### Example
 *
 * The following example declares a directive that attaches a click listener to the button and
 * counts clicks.
 *
 * ```typescript
 * @Directive({selector: 'button[counting]'})
 * class CountClicks {
 *   numberOfClicks = 0;
 *
 *   @HostListener('click', ['$event.target'])
 *   onClick(btn) {
 *     console.log("button", btn, "number of clicks:", this.numberOfClicks++);
 *   }
 * }
 *
 * @Component({
 *   selector: 'app',
 *   template: `<button counting>Increment</button>`,
 *   directives: [CountClicks]
 * })
 * class App {}
 * ```
 * @stable
 * @Annotation
 */
export var HostListener: HostListenerMetadataFactory = makePropDecorator(HostListenerMetadata);

/**
 * Declares an ng module.
 * @stable
 * @Annotation
 */
export var NgModule: NgModuleMetadataFactory =
    <NgModuleMetadataFactory>makeDecorator(NgModuleMetadata);