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refactor(ivy): obviate the Bazel component of the ivy_switch (#26550)

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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
This commit is contained in:
Alex Rickabaugh
2018-10-17 15:44:44 -07:00
committed by Alex Rickabaugh
parent 331989cea3
commit d4cee514f6
44 changed files with 507 additions and 437 deletions
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11
packages/core/src/change_detection/change_detector_ref.ts
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@ -6,7 +6,7 @@
* found in the LICENSE file at https://angular.io/license
*/
import {R3_CHANGE_DETECTOR_REF_FACTORY} from '../ivy_switch/runtime/index';
import {injectChangeDetectorRef as render3InjectChangeDetectorRef} from '../render3/view_engine_compatibility';
/**
* Base class for Angular Views, provides change detection functionality.
@ -107,5 +107,12 @@ export abstract class ChangeDetectorRef {
abstract reattach(): void;
/** @internal */
static __NG_ELEMENT_ID__: () => ChangeDetectorRef = () => R3_CHANGE_DETECTOR_REF_FACTORY();
static __NG_ELEMENT_ID__: () => ChangeDetectorRef = () => SWITCH_CHANGE_DETECTOR_REF_FACTORY();
}
export const SWITCH_CHANGE_DETECTOR_REF_FACTORY__POST_R3__ = render3InjectChangeDetectorRef;
const SWITCH_CHANGE_DETECTOR_REF_FACTORY__PRE_R3__ = (...args: any[]): any => {};
const SWITCH_CHANGE_DETECTOR_REF_FACTORY: typeof render3InjectChangeDetectorRef =
SWITCH_CHANGE_DETECTOR_REF_FACTORY__PRE_R3__;