d4cee514f6
Originally, the ivy_switch mechanism used Bazel genrules to conditionally compile one TS file or another depending on whether ngc or ngtsc was the selected compiler. This was done because we wanted to avoid importing certain modules (and thus pulling them into the build) if Ivy was on or off. This mechanism had a major drawback: ivy_switch became a bottleneck in the import graph, as it both imports from many places in the codebase and is imported by many modules in the codebase. This frequently resulted in cyclic imports which caused issues both with TS and Closure compilation. It turns out ngcc needs both code paths in the bundle to perform the switch during its operation anyway, so import switching was later abandoned. This means that there's no real reason why the ivy_switch mechanism needed to operate at the Bazel level, and for the ivy_switch file to be a bottleneck. This commit removes the Bazel-level ivy_switch mechanism, and introduces an additional TypeScript transform in ngtsc (and the pass-through tsc compiler used for testing JIT) to perform the same operation that ngcc does, and flip the switch during ngtsc compilation. This allows the ivy_switch file to be removed, and the individual switches to be located directly next to their consumers in the codebase, greatly mitigating the circular import issues and making the mechanism much easier to use. As part of this commit, the tag for marking switched variables was changed from __PRE_NGCC__ to __PRE_R3__, since it's no longer just ngcc which flips these tags. Most variables were renamed from R3_* to SWITCH_* as well, since they're referenced mostly in render2 code. Test strategy: existing test coverage is more than sufficient - if this didn't work correctly it would break the hello world and todo apps. PR Close #26550
64 lines
2.3 KiB
TypeScript
64 lines
2.3 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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import {injectTemplateRef as render3InjectTemplateRef} from '../render3/view_engine_compatibility';
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import {noop} from '../util/noop';
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import {ElementRef} from './element_ref';
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import {EmbeddedViewRef} from './view_ref';
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/**
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* Represents an embedded template that can be used to instantiate embedded views.
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* To instantiate embedded views based on a template, use the `ViewContainerRef`
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* method `createEmbeddedView()`.
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*
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* Access a `TemplateRef` instance by placing a directive on an `<ng-template>`
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* element (or directive prefixed with `*`). The `TemplateRef` for the embedded view
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* is injected into the constructor of the directive,
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* using the `TemplateRef` token.
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*
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* You can also use a `Query` to find a `TemplateRef` associated with
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* a component or a directive.
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*
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* @see `ViewContainerRef`
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* @see [Navigate the Component Tree with DI](guide/dependency-injection-navtree)
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*
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*/
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export abstract class TemplateRef<C> {
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/**
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* The anchor element in the parent view for this embedded view.
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*
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* The data-binding and injection contexts of embedded views created from this `TemplateRef`
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* inherit from the contexts of this location.
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*
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* Typically new embedded views are attached to the view container of this location, but in
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* advanced use-cases, the view can be attached to a different container while keeping the
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* data-binding and injection context from the original location.
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*
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*/
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// TODO(i): rename to anchor or location
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abstract get elementRef(): ElementRef;
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/**
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* Creates a view object and attaches it to the view container of the parent view.
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* @param context The context for the new view, inherited from the anchor element.
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* @returns The new view object.
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*/
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abstract createEmbeddedView(context: C): EmbeddedViewRef<C>;
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/** @internal */
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static __NG_ELEMENT_ID__:
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() => TemplateRef<any> = () => SWITCH_TEMPLATE_REF_FACTORY(TemplateRef, ElementRef)
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}
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export const SWITCH_TEMPLATE_REF_FACTORY__POST_R3__ = render3InjectTemplateRef;
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const SWITCH_TEMPLATE_REF_FACTORY__PRE_R3__ = noop;
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const SWITCH_TEMPLATE_REF_FACTORY: typeof render3InjectTemplateRef =
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SWITCH_TEMPLATE_REF_FACTORY__PRE_R3__;
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