Prior to this change, the unary + and - operators would be parsed as `x - 0`
and `0 - x` respectively. The runtime semantics of these expressions are
equivalent, however they may introduce inaccurate template type checking
errors as the literal type is lost, for example:
```ts
@Component({
template: `<button [disabled]="isAdjacent(-1)"></button>`
})
export class Example {
isAdjacent(direction: -1 | 1): boolean { return false; }
}
```
would incorrectly report a type-check error:
> error TS2345: Argument of type 'number' is not assignable to parameter
of type '-1 | 1'.
Additionally, the translated expression for the unary + operator would be
considered as arithmetic expression with an incompatible left-hand side:
> error TS2362: The left-hand side of an arithmetic operation must be of
type 'any', 'number', 'bigint' or an enum type.
To resolve this issues, the implicit transformation should be avoided.
This commit adds a new unary AST node to represent these expressions,
allowing for more accurate type-checking.
Fixes#20845Fixes#36178
PR Close#37918
When using the safe navigation operator in a binding expression, a temporary
variable may be used for storing the result of a side-effectful call.
For example, the following template uses a pipe and a safe property access:
```html
<app-person-view [enabled]="enabled" [firstName]="(person$ | async)?.name"></app-person-view>
```
The result of the pipe evaluation is stored in a temporary to be able to check
whether it is present. The temporary variable needs to be declared in a separate
statement and this would also cause the full expression itself to be pulled out
into a separate statement. This would compile into the following
pseudo-code instructions:
```js
var temp = null;
var firstName = (temp = pipe('async', ctx.person$)) == null ? null : temp.name;
property('enabled', ctx.enabled)('firstName', firstName);
```
Notice that the pipe evaluation happens before evaluating the `enabled` binding,
such that the runtime's internal binding index would correspond with `enabled`,
not `firstName`. This introduces a problem when the pipe uses `WrappedValue` to
force a change to be detected, as the runtime would then mark the binding slot
corresponding with `enabled` as dirty, instead of `firstName`. This results
in the `enabled` binding to be updated, triggering setters and affecting how
`OnChanges` is called.
In the pseudo-code above, the intermediate `firstName` variable is not strictly
necessary---it only improved readability a bit---and emitting it inline with
the binding itself avoids the out-of-order execution of the pipe:
```js
var temp = null;
property('enabled', ctx.enabled)
('firstName', (temp = pipe('async', ctx.person$)) == null ? null : temp.name);
```
This commit introduces a new `BindingForm` that results in the above code to be
generated and adds compiler and acceptance tests to verify the proper behavior.
Fixes#37194
PR Close#37911
ASTs for property read and method calls contain information about
the entire span of the expression, including its receiver. Use cases
like a language service and compile error messages may be more
interested in the span of the direct identifier for which the
expression is constructed (i.e. an accessed property). To support this,
this commit adds a `nameSpan` property on
- `PropertyRead`s
- `SafePropertyRead`s
- `PropertyWrite`s
- `MethodCall`s
- `SafeMethodCall`s
The `nameSpan` property already existed for `BindingPipe`s.
This commit also updates usages of these expressions' `sourceSpan`s in
Ngtsc and the langauge service to use `nameSpan`s where appropriate.
PR Close#36826
Currently Ivy always generates the `$event` function argument, even if it isn't being used by the listener expressions. This can lead to unnecessary bytes being generated, because optimizers won't remove unused arguments by default. These changes add some logic to avoid adding the argument when it isn't required.
PR Close#35097
Currently, the spans of expressions are recorded only relative to the
template node that they reside in, not their source file.
Introduce a `sourceSpan` property on expression ASTs that records the
location of an expression relative to the entire source code file that
it is in. This may allow for reducing duplication of effort in
ngtsc/typecheck/src/diagnostics later on as well.
Child of #31898
PR Close#31897
To provide some context: The implicit receiver is part of the
parsed Angular template AST. Any property reads in bindings,
interpolations etc. read from a given object (usually the component
instance). In that case there is an _implicit_ receiver which can also
be specified explicitly by just using `this`.
e.g.
```html
<ng-template>{{this.myProperty}}</ng-template>
```
This works as expected in Ivy and View Engine, but breaks in case the
implicit receiver is not used for property reads. For example:
```html
<my-dir [myFn]="greetFn.bind(this)"></my-dir>
```
In that case the `this` will not be properly translated into the generated
template function code because the Ivy compiler currently always treats
the `ctx` variable as the implicit receiver. This is **not correct** and breaks
compatibility with View Engine. Rather we need to ensure that we retrieve
the root context for the standalone implicit receiver similar to how it works
for property reads (as seen in the example above with `this.myProperty`)
Note that this requires some small changes to the `expression_converter`
because we only want to generate the `eenextContent()` instruction if the
implicit receiver is _actually_ used/needed. View Engine determines if that is the case by recursively walking through the converted output AST and
checking for usages of the `o.variable('_co')` variable ([see here][ve_check]). This would work too for Ivy, but involves most likely more code duplication
since templates are isolated in different functions and it another pass
through the output AST for every template expression.
[ve_check]: 0d6c9d36a1/packages/compiler/src/view_compiler/view_compiler.ts (L206-L208)
Resolves FW-1366.
PR Close#30897
- Extracts and documents code that will be common to interpolation instructions
- Ensures that binding indices are updated at the proper time during compilation
- Adds additional tests
Related #30011
PR Close#30129
The `convertActionBinding()` now accepts an optional `baseSourceSpan`,
which is the start point of the action expression being converted in the
original source code. This is used to compute the original position of
the output AST nodes.
PR Close#28055
Inside of a nested template, an attempt to generate code for a banana-
in-a-box expression would cause a crash in the _AstToIrVisitor, as it
was not handling the case where a write would be generated to a local
variable.
This change supports such a mode of operation.
PR Close#25321
When compiling templates the compiler would often bind to
closest context rather than the component context.
The only time one should be binding to the cont component is
in explicit cases where the inner template declares local variable.
PR Close#23168
The "enableIvy" compiler option is the initial implementation
of the Render3 (or Ivy) code generation. This commit enables
generation generating "Hello, World" (example in the test)
but not much else. It is currenly only useful for internal Ivy
testing as Ivy is in development.
PR Close#21427
Allows a directive to use the expression passed directly to a property
as a guard instead of filtering the type through a type expression.
This more accurately matches the intent of the ngIf usage of its template
enabling better type inference.
Moved NgIf to using this type of guard instead of a function guard.
Closes: #20967
`$any()` can now be used in a binding expression to disable type
checking for the rest of the expression. This similar to `as any` in
TypeScript and allows expression that work at runtime but do not
type-check.
PR Close#20876
Structural directives can now specify a type guard that describes
what types can be inferred for an input expression inside the
directive's template.
NgIf was modified to declare an input guard on ngIf.
After this change, `fullTemplateTypeCheck` will infer that
usage of `ngIf` expression inside it's template is truthy.
For example, if a component has a property `person?: Person`
and a template of `<div *ngIf="person"> {{person.name}} </div>`
the compiler will no longer report that `person` might be null or
undefined.
The template compiler will generate code similar to,
```
if (NgIf.ngIfTypeGuard(instance.person)) {
instance.person.name
}
```
to validate the template's use of the interpolation expression.
Calling the type guard in this fashion allows TypeScript to infer
that `person` is non-null.
Fixes: #19756?
PR Close#20702
Template expressions can now use a post-fix `!` operator
that asserts the target of the operator is not null. This is
similar to the TypeScript non-null assert operator. Expressions
generated in factories will be generated with the non-null assert
operator.
Closes: #10855
JoostK
Joey Perrott
Ayaz Hafiz
Alex Rickabaugh
Kristiyan Kostadinov
arturovt
mohax
Paul Gschwendtner
diyews
Ben Lesh
Pete Bacon Darwin
Miško Hevery
Chuck Jazdzewski
Victor Berchet
Tobias Bosch
Randall Koutnik
Aliaksei Kuncevič
Jason Aden