Commit Graph

6437 Commits

Author SHA1 Message Date
Joey Perrott 75610505c6 refactor(zone.js): remove usages of blacklist related to UNPATCHED_EVENTS (#38930)
Remove usages of blacklist around UNPATCHED_EVENTS configuration

PR Close #38930
2020-09-22 15:05:01 -07:00
Andrew Scott ba3f4c26bb refactor(compiler): make `keySpan` available for `BoundAttributes` (#38898)
Though we currently have the knowledge of where the `key` for an
attribute binding appears during parsing, we do not propagate this
information to the output AST. This means that once we produce the
template AST, we have no way of mapping a template position to the key
span alone. The best we can currently do is map back to the
`sourceSpan`. This presents problems downstream, specifically for the
language service, where we cannot provide correct information about a
position in a template because the AST is not granular enough.

PR Close #38898
2020-09-22 15:04:30 -07:00
Adrian Rutkowski c8f056beb6 fix(core): ensure TestBed is not instantiated before override provider (#38717)
There is an inconsistency in overrideProvider behaviour. Testing documentation says
(https://angular.io/guide/testing-components-basics#createcomponent) that all override...
methods throw error if TestBed is already instantiated. However overrideProvider doesn't throw any error, but (same as
other override... methods) doesn't replace providers if TestBed is instantiated. Add TestBed instantiation check to
overrideProvider method to make it consistent.

BREAKING CHANGE:

If you call `TestBed.overrideProvider` after TestBed initialization, provider overrides are not applied. This
behavior is consistent with other override methods (such as `TestBed.overrideDirective`, etc) but they
throw an error to indicate that, when the check was missing in the `TestBed.overrideProvider` function.
Now calling `TestBed.overrideProvider` after TestBed initialization also triggers an
error, thus there is a chance that some tests (where `TestBed.overrideProvider` is
called after TestBed initialization) will start to fail and require updates to move `TestBed.overrideProvider` calls
before TestBed initialization is completed.

Issue mentioned here: https://github.com/angular/angular/issues/13460#issuecomment-636005966
Documentation: https://angular.io/guide/testing-components-basics#createcomponent

PR Close #38717
2020-09-22 15:03:44 -07:00
klemenoslaj a2068523fd feat(service-worker): add the option to prefer network for navigation requests (#38565)
This commit introduces a new option for the service worker, called
`navigationRequestStrategy`, which adds the possibility to force the service worker
to always create a network request for navigation requests.
This enables the server redirects while retaining the offline behavior.

Fixes #38194

PR Close #38565
2020-09-22 09:29:20 -07:00
Pete Bacon Darwin 3082f7378b test(compiler-cli): make typescript_ast_factory_spec tests resilient to line-endings (#38925)
The tests were assuming that newlines were `\n` characters but this is not
the case on Windows.

PR Close #38925
2020-09-21 16:24:34 -07:00
Pete Bacon Darwin 297b123151 refactor(compiler-cli): make the output AST translator generic (#38775)
This commit refactors the `ExpressionTranslatorVisitor` so that it
is not tied directly to the TypeScript AST. Instead it uses generic
`TExpression` and `TStatement` types that are then converted
to concrete types by the `TypeScriptAstFactory`.

This paves the way for a `BabelAstFactory` that can be used to
generate Babel AST nodes instead of TypeScript, which will be
part of the new linker tool.

PR Close #38775
2020-09-21 12:27:27 -07:00
Pete Bacon Darwin a93605f2a4 refactor(compiler-cli): simplify imports from compiler to type translator (#38775)
Previously each identifier was being imported individually, which made for a
very long import statement, but also obscurred, in the code, which identifiers
came from the compiler.

PR Close #38775
2020-09-21 12:27:27 -07:00
Pete Bacon Darwin 15dfd3439a refactor(compiler-cli): split up translator file (#38775)
This file contains a number of classes making it long and hard to work with.
This commit splits the `ImportManager`, `Context` and `TypeTranslatorVisitor`
classes, along with associated functions and types into their own files.

PR Close #38775
2020-09-21 12:27:27 -07:00
Pete Bacon Darwin 123bff7cb6 fix(compiler-cli): generate `let` statements in ES2015+ mode (#38775)
When the target of the compiler is ES2015 or newer then we should
be generating `let` and `const` variable declarations rather than `var`.

PR Close #38775
2020-09-21 12:27:27 -07:00
Pete Bacon Darwin 6158dc16b4 refactor(compiler): use a named type for cooked/raw string objects (#38775)
Using an interface makes the code cleaner and more readable.
This change also adds the `range` property to the type to be used
for source-mapping.

PR Close #38775
2020-09-21 12:27:27 -07:00
Pete Bacon Darwin b0a43872a8 refactor(compiler-cli): remove unused imports (#38775)
These imports are not used and so are just bloating the code unnecessarily

PR Close #38775
2020-09-21 12:27:27 -07:00
Pete Bacon Darwin 856e74ac98 refactor(compiler-cli): remove undesirable cast in the type translator (#38775)
The cast to `ts.Identifier` was a hack that "just happened to work".
The new approach is more robust and doesn't have to undermine
the type checker.

PR Close #38775
2020-09-21 12:27:27 -07:00
Ayaz Hafiz 6ae3b68acf feat(compiler): Parse and recover on incomplete opening HTML tags (#38681)
Let's say we have a code like

```html
<div<span>123</span>
```

Currently this gets parsed into a tree with the element tag `div<span`.
This has at least two downsides:

- An incorrect diagnostic that `</span>` doesn't close an element is
  emitted.
- A consumer of the parse tree using it for editor services is unable to
  provide correct completions for the opening `<span>` tag.

This patch attempts to fix both issues by instead parsing the code into
the same tree that would be parsed for `<div></div><span>123</span>`.

In particular, we do this by optimistically scanning an open tag as
usual, but if we do not notice a terminating '>', we mark the tag as
"incomplete". A parser then emits an error for the incomplete tag and
adds a synthetic (recovered) element node to the tree with the
incomplete open tag's name.

What's the downside of this? For one, a breaking change.

<ol>
<li>

The first breaking change is that `<` symbols that are ambiguously text
or opening tags will be parsed as opening tags instead of text in
element bodies. Take the code

```html
<p>a<b</p>
```

Clearly we cannot have the best of both worlds, and this patch chooses
to swap the parsing strategy to support the new feature. Of course, `<`
can still be inserted as text via the `&lt;` entity.

</li>
</ol>

Part of #38596

PR Close #38681
2020-09-21 12:27:01 -07:00
JoostK 49f27e31ed test(compiler-cli): re-enable dynamic value diagnostic tests on Windows CI (#37782)
This commit re-enables some tests that were temporarily disabled on Windows,
as they failed on native Windows CI. The Windows filesystem emulation has
been corrected in an earlier commit, such that the original failure would
now also occur during emulation on Linux CI.

PR Close #37782
2020-09-21 12:26:33 -07:00
JoostK 1a62f74496 test(compiler-cli): fix drive letter casing in Windows filesystem emulation (#37782)
In native windows, the drive letter is a capital letter, while our Windows
filesystem emulation would use lowercase drive letters. This difference may
introduce tests to behave differently in native Windows versus emulated
Windows, potentially causing unexpected CI failures on Windows CI after a PR
has been merged.

Resolves FW-2267

PR Close #37782
2020-09-21 12:26:33 -07:00
Ingo Bürk 2b1b7180db fix(forms): type NG_VALUE_ACCESSOR injection token as array (#29723)
NG_VALUE_ACCESSOR is a multi injection token, users can and
should expect more than one ControlValueAccessor to be
available (and this is how it is used in @angular/forms).

This is now reflected in the definition of the injection token
by typing it as an array of ControlValueAccessor. The motivating
reason is that using the programmatic Injector api will now
type Injector#get correspondingly.

fixes #29351

BREAKING CHANGES

NG_VALUE_ACCESSOR is now typed as a readonly array rather than
a mutable scalar. It is used as a multi injection token and as
such it should always be expected that more than one accessor
may be returned.

PR Close #29723
2020-09-21 12:26:07 -07:00
Prashant Tholia 984ed39195 feat(common): Add ISO week-numbering year formats support to formatDate (#38828)
Add ISO 8601 week-numbering year formats ('r', 'rr', 'rrr', 'rrrr') support for formatDate function.

Issue:https://github.com/angular/angular/issues/38739

PR Close #38828
2020-09-21 12:24:43 -07:00
Andrew Scott 0c0c54d615 refactor(compiler): simplify visitor logic for attributes (#38899)
The logic for computing identifiers, specifically for bound attributes
can be simplified by using the value span of the binding rather than the
source span.

PR Close #38899
2020-09-21 12:23:58 -07:00
Marley Powell e498ea9b5a revert: feat(router): better warning message when a router outlet has not been instantiated (#38920)
This reverts commit [1609815].
The warning that was added created more confusion than it solved and also warned for valid use-cases.

PR Close #38920
2020-09-21 09:35:06 -07:00
Andrew Scott a91f0f6b82 refactor(compiler): refactor ast spans test to be more human readable (#38902)
The current tests print out the span numbers, which are really difficult to verify
since it requires manually going to the template string and looking at what
characters appear within those indexes. The better humanization would be
to use the toString method of the spans, which prints the span text itself

PR Close #38902
2020-09-18 16:55:52 -07:00
William Koza 88d7bb8386 fix(http): Fix error message when we call jsonp without importing HttpClientJsonpModule (#38756)
Currently, when we call jsonp method without importing HttpClientJsonpModule, an error message appears saying
'Attempted to construct Jsonp request without JsonpClientModule installed.' instance of 'Attempted to
construct Jsonp request without HttpClientJsonpModule installed.'

PR Close #38756
2020-09-18 11:20:36 -07:00
Andrew Kushnir 95b8a8706a refactor(core): reduce the number of circular deps (#38805)
This commit updates several import statements in the core package to decrease the number of
cycles detected by the dependency checker tool.

PR Close #38805
2020-09-18 11:20:08 -07:00
JiaLiPassion d92a0dd72f fix(zone.js): should invoke xhr send task when no response error occurs (#38836)
Close #38795

in the XMLHttpRequest patch, when get `readystatechange` event, zone.js try to
invoke `load` event listener first, then call `invokeTask` to finish the
`XMLHttpRequest::send` macroTask, but if the request failed because the
server can not be reached, the `load` event listener will not be invoked,
so the `invokeTask` of the `XMLHttpRequest::send` will not be triggered either,
so we will have a non finished macroTask there which will make the Zone
not stable, also memory leak.

So in this PR, if the `XMLHttpRequest.status = 0` when we get the `readystatechange`
event, that means something wents wrong before we reached the server, we need to
invoke the task to finish the macroTask.

PR Close #38836
2020-09-18 11:19:37 -07:00
Sonu Kapoor d3169c533e refactor(core): remove unused imports (#38818)
This commit removes some unused imports from the spec files.

PR Close #38818
2020-09-18 08:03:48 -07:00
JoostK e4424863c2 fix(ngcc): fix compilation of `ChangeDetectorRef` in pipe constructors (#38892)
In #38666 we changed how ngcc deals with type expressions, where it
would now always emit the original type expression into the generated
code as a "local" type value reference instead of synthesizing new
imports using an "imported" type value reference. This was done as a fix
to properly deal with renamed symbols, however it turns out that the
compiler has special handling for certain imported symbols, e.g.
`ChangeDetectorRef` from `@angular/core`. The "local" type value
reference prevented this special logic from being hit, resulting in
incorrect compilation of pipe factories.

This commit fixes the issue by manually inspecting the import of the
type expression, in order to return an "imported" type value reference.
By manually inspecting the import we continue to handle renamed symbols.

Fixes #38883

PR Close #38892
2020-09-18 08:02:46 -07:00
Pete Bacon Darwin d795a00137 refactor(compiler): replace Comment nodes with leadingComments property (#38811)
Common AST formats such as TS and Babel do not use a separate
node for comments, but instead attach comments to other AST nodes.
Previously this was worked around in TS by creating a `NotEmittedStatement`
AST node to attach the comment to. But Babel does not have this facility,
so it will not be a viable approach for the linker.

This commit refactors the output AST, to remove the `CommentStmt` and
`JSDocCommentStmt` nodes. Instead statements have a collection of
`leadingComments` that are rendered/attached to the final AST nodes
when being translated or printed.

PR Close #38811
2020-09-18 08:01:25 -07:00
JiaLiPassion a33d630a21 fix(zone.js): should have better backward compatibilities (#38797)
Close #38561, #38669

zone.js 0.11.1 introduces a breaking change to adpat Angular package format,
and it breaks the module loading order, before 0.11, in IE11, the `zone.js` es5
format bundle will be imported, but after 0.11, the `fesm2015` format bundle will
be imported, which causes error.

And since the only purpose of the `dist` folder of zone.js bundles is to keep backward
 compatibility, in the original commit, I use package redirect to implement that, but
it is not fully backward compatible, we should keep the same dist structure as `0.10.3`.

PR Close #38797
2020-09-17 09:32:19 -07:00
Ajit Singh dd8d8c8289 fix(common): add `params` and `reportProgress` options to `HttpClient.put()` overload (#37873)
When the response type is JSON, the `put()` overload signature did not have `reportProgress`
and  `params` options. This makes it difficult to type-check this overload.

This commit adds them to the overload signature.

Fixes #23600

PR Close #37873
2020-09-16 15:28:21 -07:00
Andrew Scott 129107191c refactor(compiler): always return a mutable clone from `Scope#resolve` (#38857)
This change prevents comments from a resolved node from appearing at
each location the resolved expression is used and also prevents callers
of `Scope#resolve` from accidentally modifying / adding comments to the
declaration site.

PR Close #38857
2020-09-16 15:27:22 -07:00
JiaLiPassion 5614258cc7 docs(zone.js): Add breaking changes info for zone.js v0.11.1 (#38821)
Before Zone.js `v0.11.1`, Zone.js provides two format of bundles under `dist` folder,
`ES5` bundle `zone.js` and `ES2015` bundle `zone-evergreen.js`, these bundles are used
for `differential loading` of Angular. By default, the following code

```
import 'zone.js';
```

loads the `ES5` bundle `zone.js`.

From `v0.11.1`, Zone.js follows the [Angular Package Format]
(https://docs.google.com/document/d/1CZC2rcpxffTDfRDs6p1cfbmKNLA6x5O-NtkJglDaBVs),
so the folder structure of the Zone.js bundles is updated to match `Angular Package Format`.

So the same code

```
import 'zone.js';
```
loads the `ES2015` bundle.

This is a breaking change, so if the apps import zone.js in this way,
the apps will not work in legacy browsers such as `IE11`.

Zone.js still provides the same bundles under `dist` folder to keep backward
compatibility after `v0.11.1`. So the following code in `polyfills.ts` generated
by `Angular CLI` still works.

```
import 'zone.js/dist/zone';
```

For details, please refer the [changelog](./CHANGELOG.md) and
the [PR](https://github.com/angular/angular/pull/36540).

PR Close #38821
2020-09-16 15:21:10 -07:00
Oscar Rosner e62a918542 docs(forms): fix grammar in first sentence of reset function docs (#38872)
PR Close #38872
2020-09-16 15:20:30 -07:00
pmartijena 49ee90b1b5 docs: fix typo in architecture.md guide (#38853)
PR Close #38853
2020-09-16 15:19:43 -07:00
Kristiyan Kostadinov 7849fdde09 feat(router): add migration to update calls to navigateByUrl and createUrlTree with invalid parameters (#38825)
In #38227 the signatures of `navigateByUrl` and `createUrlTree` were updated to exclude unsupported
properties from their `extras` parameter. This migration looks for the relevant method calls that
pass in an `extras` parameter and drops the unsupported properties.

**Before:**
```
this._router.navigateByUrl('/', {skipLocationChange: false, fragment: 'foo'});
```

**After:**
```
this._router.navigateByUrl('/', {
  /* Removed unsupported properties by Angular migration: fragment. */
  skipLocationChange: false
});
```

These changes also move the method call detection logic out of the `Renderer2` migration and into
a common place so that it can be reused in other migrations.

PR Close #38825
2020-09-16 15:16:18 -07:00
Mathieu Lemoine 3817e5f1df fix(router): Fix arguments order for call to shouldReuseRoute (#26949)
The `createOrReuseChildren` function calls shouldReuseRoute with the
previous child values use as the future and the future child value used
as the current argument. This is incosistent with the argument order in
`createNode`. This inconsistent order can make it difficult/impossible
to correctly implement the `shouldReuseRoute` function. Usually this
order doesn't matter because simple equality checks are made on the
args and it doesn't matter which is which.

More detail can be found in the bug report: #16192.

Fix #16192

BREAKING CHANGE: This change corrects the argument order when calling
RouteReuseStrategy#shouldReuseRoute. Previously, when evaluating child
routes, they would be called with the future and current arguments would
be swapped. If your RouteReuseStrategy relies specifically on only the future
or current snapshot state, you may need to update the shouldReuseRoute
implementation's use of "future" and "current" ActivateRouteSnapshots.

PR Close #26949
2020-09-15 11:33:52 -07:00
JoostK a1c1c450dc test(ngcc): load standard files only once (#38840)
In the integration test suite of ngcc, we load a set of files from
`node_modules` into memory. This includes the `typescript` package and
`@angular` scoped packages, which account for a large number of large
files that needs to be loaded from disk. This commit moves this work
to the top-level, such that it doesn't have to be repeated in all tests.

PR Close #38840
2020-09-15 11:23:13 -07:00
JoostK fd44d84a33 perf(ngcc): reduce maximum worker count (#38840)
Recent optimizations to ngcc have significantly reduced the total time
it takes to process `node_modules`, to such extend that sharding across
multiple processes has become less effective. Previously, running
ngcc asynchronously would allow for up to 8 workers to be allocated,
however these workers have to repeat work that could otherwise be shared.
Because ngcc is now able to reuse more shared computations, the overhead
of multiple workers is increased and therefore becomes less effective.
As an additional benefit, having fewer workers requires less memory and
less startup time.

To give an idea, using the following test setup:

```bash
npx @angular/cli new perf-test
cd perf-test
yarn ng add @angular/material
./node_modules/.bin/ngcc --properties es2015 module main \
  --first-only --create-ivy-entry-points
```

We observe the following figures on CI:

|                   | 10.1.1    | PR #38840 |
| ----------------- | --------- | --------- |
| Sync              | 85s       | 25s       |
| Async (8 workers) | 22s       | 16s       |
| Async (4 workers) | -         | 11s       |

In addition to changing the default number of workers, ngcc will now
use the environment variable `NGCC_MAX_WORKERS` that may be configured
to either reduce or increase the number of workers.

PR Close #38840
2020-09-15 11:23:09 -07:00
JoostK f0688b4d18 perf(ngcc): introduce cache for sharing data across entry-points (#38840)
ngcc creates typically two `ts.Program` instances for each entry-point,
one for processing sources and another one for processing the typings.
The creation of these programs is somewhat expensive, as it concerns
module resolution and parsing of source files.

This commit implements several layers of caching to optimize the
creation of programs:

1. A shared module resolution cache across all entry-points within a
   single invocation of ngcc. Both the sources and typings program
   benefit from this cache.
2. Sharing the parsed `ts.SourceFile` for a single entry-point between
   the sources and typings program.
3. Sharing parsed `ts.SourceFile`s of TypeScript's default libraries
   across all entry-points within a single invocation. Some of these
   default library typings are large and therefore expensive to parse,
   so sharing the parsed source files across all entry-points offers
   a significant performance improvement.

Using a bare CLI app created using `ng new` + `ng add @angular/material`,
the above changes offer a 3-4x improvement in ngcc's processing time
when running synchronously and ~2x improvement for asynchronous runs.

PR Close #38840
2020-09-15 11:23:04 -07:00
Joey Perrott 593bd594e3 build: create temporary script for symbol extractor tests (#38819)
Creates a temporary script to running all symbol extractor tests.

PR Close #38819
2020-09-14 16:54:39 -07:00
JoostK 297c060ae7 perf(compiler-cli): optimize computation of type-check scope information (#38539)
When type-checking a component, the declaring NgModule scope is used
to create a directive matcher that contains flattened directive metadata,
i.e. the metadata of a directive and its base classes. This computation
is done for all components, whereas the type-check scope is constant per
NgModule. Additionally, the flattening of metadata is constant per
directive instance so doesn't necessarily have to be recomputed for
each component.

This commit introduces a `TypeCheckScopes` class that is responsible
for flattening directives and computing the scope per NgModule. It
caches the computed results as appropriate to avoid repeated computation.

PR Close #38539
2020-09-14 11:54:40 -07:00
JoostK 077f51685a perf(compiler-cli): only emit directive/pipe references that are used (#38539)
For the compilation of a component, the compiler has to prepare some
information about the directives and pipes that are used in the template.
This information includes an expression for directives/pipes, for usage
within the compilation output. For large NgModule compilation scopes
this has shown to introduce a performance hotspot, as the generation of
expressions is quite expensive. This commit reduces the performance
overhead by only generating expressions for the directives/pipes that
are actually used within the template, significantly cutting down on
the compiler's resolve phase.

PR Close #38539
2020-09-14 11:54:37 -07:00
Sonu Kapoor 57c442f930 build(router): update symbols for routing app (#38817)
This commit updates the golden symbol files for the routing app.

PR Close #38817
2020-09-11 13:20:34 -07:00
Sonu Kapoor f667e374a9 build: create sample router app (#38714)
This commit creates a sample router test application to introduce the
symbol tests. It serves as a guard to ensure that any future work on the
router package does not unintentionally increase the payload size.

PR Close #38714
2020-09-11 12:10:46 -07:00
JoostK 15207e3c9c fix(compiler): detect pipes in ICUs in template binder (#38810)
Recent work on compiler internals in #38539 led to an unexpected failure,
where a pipe used exclusively inside of an ICU would no longer be
emitted into the compilation output. This caused runtime errors due to
missing pipes.

The issue occurred because the change in #38539 would determine the set
of used pipes up-front, independent from the template compilation using
the `R3TargetBinder`. However, `R3TargetBinder` did not consider
expressions within ICUs, so any pipe usages within those expressions
would not be detected. This fix unblocks #38539 and also concerns
upcoming linker work, given that prelink compilations would not go
through full template compilation but only `R3TargetBinder`.

PR Close #38810
2020-09-11 12:07:40 -07:00
JiaLiPassion 27cc56b359 fix(zone.js): add missing types field in package.json (#38585)
Close #38584

In zone.js 0.11.1, the `types` field is missing in the `package.json`,
the reason is in zone.js 0.11.0, the `files` field is used to specify the
types, but it cause the npm package not contain any bundles issue, so zone.js
0.11.1 remove the `files` field, which cause the `type` definition gone.

This PR concat the `zone.js.d.ts`, `zone.configurations.api.ts`, `zone.api.extensions.ts`
types into a single `zone.d.ts` file.

PR Close #38585
2020-09-11 08:43:53 -07:00
Artem Halas 6acea54f62 fix(common): mark locale data arrays as readonly (#30397)
To discourage developers from mutating the arrays returned
from the following methods, their return types have been marked
as readonly.

* `getLocaleDayPeriods()`
* `getLocaleDayNames()`
* `getLocaleMonthNames()`
* `getLocaleEraNames()`

Fixes #27003

BREAKING CHANGE:
The locale data API has been marked as returning readonly arrays, rather
than mutable arrays, since these arrays are shared across calls to the
API. If you were mutating them (e.g. calling `sort()`, `push()`, `splice()`, etc)
then your code will not longer compile. If you need to mutate the array, you
should now take a copy (e.g. by calling `slice()`) and mutate the copy.

PR Close #30397
2020-09-10 15:35:30 -07:00
Andrew Scott 2d52c80332 test(compiler): Add back tests for renamed inputs and outputs (#38798)
#38685 corrected the confusion between field and property names so the consumer can
now be determined correctly.

PR Close #38798
2020-09-10 14:33:10 -07:00
Keen Yee Liau 8f349b2375 fix(compiler): source span for microsyntax text att should be key span (#38766)
In a microsyntax expressions, some attributes are not bound after
desugaring. For example,
```html
<div *ngFor="let item of items">
</div>
```
gets desugared to
```html
<ng-template ngFor let-items [ngForOf]="items">
</ngtemplate>
```
In this case, `ngFor` should be a literal attribute with no RHS value.
Therefore, its source span should be just the `keySpan` and not the
source span of the original template node.
This allows language service to precisely pinpoint different spans in a
microsyntax to provide accurate information.

PR Close #38766
2020-09-10 14:31:23 -07:00
Andrew Scott 19598b47ca feat(compiler-cli): add ability to get symbol of reference or variable (#38618)
Adds `TemplateTypeChecker` operation to retrieve the `Symbol` of a
`TmplAstVariable` or `TmplAstReference` in a template.

Sometimes we need to traverse an intermediate variable declaration to arrive at
the correct `ts.Symbol`. For example, loop variables are declared using an intermediate:
```
<div *ngFor="let user of users">
  {{user.name}}
</div>
```
Getting the symbol of user here (from the expression) is tricky, because the TCB looks like:

```
var _t0 = ...; // type of NgForOf
var _t1: any; // context of embedded view for NgForOf structural directive
if (NgForOf.ngTemplateContextGuard(_t0, _t1)) {
  // _t1 is now NgForOfContext<...>
  var _t2 = _t1.$implicit; // let user = '$implicit'
  _t2.name; // user.name expression
}
```
Just getting the `ts.Expression` for the `AST` node `PropRead(ImplicitReceiver, 'user')`
via the sourcemaps will yield the `_t2` expression.  This function recognizes that `_t2`
is a variable declared locally in the TCB, and actually fetch the `ts.Symbol` of its initializer.

These special handlings show the versatility of the `Symbol`
interface defined in the API. With this, when we encounter a template variable,
we can provide the declaration node, as well as specific information
about the variable instance, such as the `ts.Type` and `ts.Symbol`.

PR Close #38618
2020-09-10 12:40:50 -07:00
Andrew Scott f56ece4fdc feat(compiler-cli): Add ability to get `Symbol` of AST expression in component template (#38618)
Adds support to the `TemplateTypeChecker` to get a `Symbol` of an AST
expression in a component template.
Not all expressions will have `ts.Symbol`s (e.g. there is no `ts.Symbol`
associated with the expression `a + b`, but there are for both the a and b
nodes individually).

PR Close #38618
2020-09-10 12:40:47 -07:00
Andrew Scott cf2e8b99a8 feat(compiler-cli): Add ability to get `Symbol` of `Template`s and `Element`s in component template (#38618)
Adds support to the `TemplateTypeChecker` for retrieving a `Symbol` for
`TmplAstTemplate` and `TmplAstElement` nodes in a component template.

PR Close #38618
2020-09-10 12:40:44 -07:00