mirror of
https://github.com/angular/angular
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46 lines
1.4 KiB
TypeScript
46 lines
1.4 KiB
TypeScript
/**
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* @license
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* Copyright Google Inc. All Rights Reserved.
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*
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* Use of this source code is governed by an MIT-style license that can be
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* found in the LICENSE file at https://angular.io/license
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*/
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/**
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* Indicates that the result of a {@link Pipe} transformation has changed even though the
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* reference has not changed.
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*
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* Wrapped values are unwrapped automatically during the change detection, and the unwrapped value
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* is stored.
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*
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* Example:
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*
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* ```
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* if (this._latestValue === this._latestReturnedValue) {
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* return this._latestReturnedValue;
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* } else {
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* this._latestReturnedValue = this._latestValue;
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* return WrappedValue.wrap(this._latestValue); // this will force update
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* }
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* ```
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*
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* @publicApi
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*/
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export class WrappedValue {
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/** @deprecated from 5.3, use `unwrap()` instead - will switch to protected */
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wrapped: any;
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constructor(value: any) { this.wrapped = value; }
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/** Creates a wrapped value. */
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static wrap(value: any): WrappedValue { return new WrappedValue(value); }
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/**
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* Returns the underlying value of a wrapped value.
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* Returns the given `value` when it is not wrapped.
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**/
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static unwrap(value: any): any { return WrappedValue.isWrapped(value) ? value.wrapped : value; }
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/** Returns true if `value` is a wrapped value. */
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static isWrapped(value: any): value is WrappedValue { return value instanceof WrappedValue; }
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}
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