@drooms/ng-metadata
Version:
Angular 2 decorators and utils for Angular 1.x
47 lines • 1.51 kB
JavaScript
;
var lang_1 = require("../../facade/lang");
/**
* Allows to refer to references which are not yet defined.
*
* For instance, `forwardRef` is used when the `token` which we need to refer to for the purposes of
* DI is declared,
* but not yet defined. It is also used when the `token` which we use when creating a query is not
* yet defined.
*
* ### Example
* {@example core/di/ts/forward_ref/forward_ref.ts region='forward_ref'}
*/
function forwardRef(forwardRefFn) {
forwardRefFn.__forward_ref__ = forwardRef;
forwardRefFn.toString = function () { return lang_1.stringify(this()); };
return forwardRefFn;
}
exports.forwardRef = forwardRef;
/**
* Lazily retrieves the reference value from a forwardRef.
*
* Acts as the identity function when given a non-forward-ref value.
*
* ### Example ([live demo](http://plnkr.co/edit/GU72mJrk1fiodChcmiDR?p=preview))
*
* ```typescript
* var ref = forwardRef(() => "refValue");
* expect(resolveForwardRef(ref)).toEqual("refValue");
* expect(resolveForwardRef("regularValue")).toEqual("regularValue");
* ```
*
* See: {@link forwardRef}
*/
function resolveForwardRef(type) {
if (_isForwardRef(type)) {
return type();
}
else {
return type;
}
function _isForwardRef(type) {
return lang_1.isFunction(type) && type.hasOwnProperty('__forward_ref__') && type.__forward_ref__ === forwardRef;
}
}
exports.resolveForwardRef = resolveForwardRef;
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