Currently it is impossible to determine the source of a binding that
generates `BoundAttribute` because all bound attributes generated from a
microsyntax expression share the same source span.
For example, in
```html
<div *ngFor="let item of items; trackBy: trackByFn"></div>
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
source span for all `BoundAttribute`s generated from microsyntax
```
the `BoundAttribute` for both `ngForOf` and `ngForTrackBy`
share the same source span.
A lot of hacks were necessary in View Engine language service to work
around this limitation. It was done by inspecting the whole source span
then figuring out the relative position of the cursor.
With this change, we introduce a flag to set the binding span as the
source span of the `ParsedProperty` in Ivy AST.
This flag is needed so that we don't have to change VE ASTs.
Note that in the binding parser, we already set `bindingSpan` as the
source span for a `ParsedVariable`, and `keySpan` as the source span for
a literal attribute. This change makes the Ivy AST more consistent by
propagating the binding span to `ParsedProperty` as well.
PR Close#39036
Now that we have `keySpan` for `BoundAttribute` (implemented in
https://github.com/angular/angular/pull/38898) we could do the same
for `Variable`.
This would allow us to distinguish the LHS and RHS from the whole source
span.
PR Close#38965
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
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
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
Previously, the `sourceSpan` and `startSourceSpan` were the same
object, which meant that you had the following situation:
```
element = <div>some content</div>
sourceSpan = <div>
startSourceSpan = <div>
endSourceSpan = </div>
```
This made `sourceSpan` redundant and meant that if you
wanted a span for the whole element including its content
and closing tag, it had to be computed.
Now `sourceSpan` is separated from `startSourceSpan`
resulting in:
```
element = <div>some content</div>
sourceSpan = <div>some content</div>
startSourceSpan = <div>
endSourceSpan = </div>
```
PR Close#38581
This commit propagates the correct value span in an ExpressionBinding of
a microsyntax expression to ParsedProperty, which in turn porpagates the
span to the template ASTs (both VE and Ivy).
PR Close#36133
This commit propagates the `sourceSpan` and `valueSpan` of a `VariableBinding`
in a microsyntax expression to `ParsedVariable`, and subsequently to
View Engine Variable AST and Ivy Variable AST.
Note that this commit does not propagate the `keySpan`, because it involves
significant changes to the template AST.
PR Close#36047
The only test case for `ngFor` exercises an incorrect usage which causes
two bound attributes to be generated . This commit adds a canonical and
correct usage to show the difference between the two.
PR Close#35671
Template AST nodes for (bound) attributes, variables and references will
now retain a reference to the source span of their value, which allows
for more accurate type check diagnostics.
PR Close#30181
Keen Yee Liau
Keen Yee Liau
Andrew Scott
Pete Bacon Darwin
Joey Perrott
Alex Rickabaugh
JoostK