angular-docs-cn/packages/core/src/util/noop.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
 */

export function noop(...args: any[]): any {
  // Do nothing.
}
build(ivy): support alternate compilation modes to enable Ivy testing (#24056) Bazel has a restriction that a single output (eg. a compiled version of //packages/common) can only be produced by a single rule. This precludes the Angular repo from having multiple rules that build the same code. And the complexity of having a single rule produce multiple outputs (eg. an ngc-compiled version of //packages/common and an Ivy-enabled version) is too high. Additionally, the Angular repo has lots of existing tests which could be executed as-is under Ivy. Such testing is very valuable, and it would be nice to share not only the code, but the dependency graph / build config as well. Thus, this change introduces a --define flag 'compile' with three potential values. When --define=compile=X is set, the entire build system runs in a particular mode - the behavior of all existing targets is controlled by the flag. This allows us to reuse our entire build structure for testing in a variety of different manners. The flag has three possible settings: * legacy (the default): the traditional View Engine (ngc) build * local: runs the prototype ngtsc compiler, which does not rely on global analysis * jit: runs ngtsc in a mode which executes tsickle, but excludes the Angular related transforms, which approximates the behavior of plain tsc. This allows the main packages such as common to be tested with the JIT compiler. Additionally, the ivy_ng_module() rule still exists and runs ngc in a mode where Ivy-compiled output is produced from global analysis information, as a stopgap while ngtsc is being developed. PR Close #24056 2018-05-21 15:48:00 -07:00			`/**`
			`* @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`
			`*/`

refactor(ivy): obviate the Bazel component of the ivy_switch (#26550) 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 2018-10-17 15:44:44 -07:00			`export function noop(...args: any[]): any {`
			`// Do nothing.`
			`}`