Currently we have a `ParserError` that is used for the expression parser and a `ParseError` that is used everywhere else. These changes consolidate them into the `ParseError` to avoid confusion and make it easier to add more context in the future.
PR Close#62160
Currently our expression parser produces two different expressions for writes: `PropertyWrite` (e.g. `foo.bar = 123`) or `KeyedWrite` (e.g. `foo[0] = 123`). This is inconsistent with other ASTs, like TypeScript's, where writes are represented as binary expressions with a `=` operator and it makes it difficult to implement more write operators like `??=`, because we'd essentially have to duplicate them.
These changes switch the expression parser over to produce binary expressions instead.
PR Close#61682
When the expression parser consumes tokens inside a parenthesized expression, it looks for valid tokens until it hits and invalid one or a closing paren. If it finds an invalid token, it reports and error and tries to recover until it finds a closing paren. The problem is that in such cases, it would produce the `ParenthesizedExpression` and continue parsing **from** from the closing paren which would then produce more errors that add noise to the output and result in an incorrect representation of the user's code. E.g. `foo((event.target as HTMLElement).value)` would be recovered to `foo((event.target)).value` instead of `foo((event.target).value)`.
These changes resolve the issue by skipping over the closing paren at the recovery point.
Fixes#61792.
PR Close#61815
Currently we reuse the same binding parser for all expressions in the template. Under the hood, the parser has a single `errors` array that it passes into all ASTs which means that if there's one binding with an error, those errors will be propagated to all other ASTs in the template.
These changes switch to having a unique `errors` array for each AST so we only report errors once.
Relates to #61792.
PR Close#61793
These helpers are often imported by various tests throughout the
repository, but the helpers aren't exported/exposed from the public
entry-point; even though they confusingly reside in there.
This commit fixes this, and moves the helpers into
`packages/private/testing`. This is a preparation for the `ts_project`
migration where we don't want to leverage deep imports between packages.
PR Close#61472
This commit adds the support for the `in` keyword as a relational operator, with the same precedence as the other relational operators (<,>, <=, >=)
BREAKING CHANGE: 'in' in an expression now refers to the operator
PR Close#58432
Following up on #60127 which added the concept of a parenthesized
expression to the output AST, this does the same for the expression AST.
PR Close#60169
Add support for the `void` operator in templates and host bindings.
This is useful when binding a listener that may return `false` and
unintentionally prevent the default event behavior.
Ex:
```
@Directive({
host: { '(mousedown)': 'void handleMousedown()' }
})
```
BREAKING CHANGE: `void` in an expression now refers to the operator
Previously an expression in the template like `{{void}}` referred to a
property on the component class. After this change it now refers to the
`void` operator, which would make the above example invalid. If you have
existing expressions that need to refer to a property named `void`,
change the expression to use `this.void` instead: `{{this.void}}`.
PR Close#59894
Whenever we parse object property assignment shorthands in expression
ASTs, the AST will have no information about whether the property read
for the `LiteralMap` is built based on the shorthand or not.
Exposing this information in the AST is useful for migrations as those
might need to decompose the shorthand into its longer form to e.g.
invoke a signal read.
PR Close#56405
Currently the listener side two-way listeners are parsed by appending `=$event` to the raw expression. This is problematic, because:
1. It can interfere with other expressions (see #37809).
2. It can lead to confusing error messages because users will see code that they didn't write.
3. It doesn't allow us to further manipulate the expression.
These changes remove the logic that appends `=$event` to resolve the issue. There's also some new logic that checks the expression after it has been parsed to ensure that the result is an assignable expression.
Subsequent commits will update the code that emits the expression to add back the `$event` assignment where it's needed.
PR Close#54154
In #39004 some logic was introduced that tries to recover invalid expressions by treating the `=` token as a recovery point. It works by skipping ahead to the next recovery point inside the `skip` method which is called whenever an error is reported. This can lead to an infinite loop inside the `parseChain` method which assumes that reporting an error would've skipped over the token, but that won't happen since the `=` token is a recovery point. These changes resolve the infinite loop by breaking the loop if `error` didn't skip to a different token after the error was reported.
Fixes#47131.
PR Close#47151
When parsing interpolations, the input string is _decoded_ from what was
in the orginal template. This means that we cannot soley rely on the input
string to compute source spans because it does not necessarily reflect
the exact content of the original template. Specifically, when there is
an HTML entity (i.e. ` `), this will show up in its decoded form
when processing the interpolation (' '). We need to compute offsets
using the original _encoded_ string.
Note that this problem only surfaces in the splitting of interpolations.
The spans to this point have already been tracked accurately. For
example, given the template ` <div></div>`, the source span for the
`div` is already correctly determined to be 6. Only when we encounter
interpolations with many parts do we run into situations where we need
to compute new spans for the individual parts of the interpolation.
PR Close#44811
For two-way-bindings that use the banana-in-a-box syntax, the compiler
synthesizes an event assignment expression from the primary expression.
It is valid for the primary expression to be terminated by the non-null
operator, however naive string substitution is used for the synthesized
expression, such that the `!` would immediately precede the `=` token,
resulting in the valid `!=` operator token. The expression would still
parse correctly but it doesn't implement the proper semantics, resulting
in incorrect runtime behavior.
Changing the expression substitution to force a space between the
primary expression and the assignment avoids this mistake, but it
uncovers a new issue. The grammar does not allow for the LHS of an
assignment to be the non-null operator, so the synthesized expression
would fail to parse. To alleviate this, the synthesized expression is
parsed with a special parser flag to allow for this syntax.
Fixes#36551
PR Close#37809
So-called "Quote expressions" were added in b6ec2387b3
to support foreign syntax to be used in Angular templates, requiring a custom
template transform to convert them somehow during compilation. Support for template
transforms was originally implemented in a43ed79ee7 but
has since been dropped. Since the compiler is not public API the quote expressions
should not have any usages anymore. Removing support for them can improve error
reporting for expressions that contain a `:`, e.g. binding to a URL without quotes:
```html
<a [href]="http://google.com">Click me</a>
```
Here, `http` would be parsed as foreign "http" quote expression with `//google.com` as
value, later reporting the error "Quotes are not supported for evaluation!" because
there was no template transform to convert that code.
Closes#40398
PR Close#44915
Currently the compiler has three different classes to represent a "call to something":
1. `MethodCall` - `foo.bar()`
2. `SafeMethodCall` - `foo?.bar()`.
3. `FunctionCall` - Any calls that don't fit into the first two classes. E.g. `foo.bar()()`.
There are a few problems with this approach:
1. It is inconistent with the TypeScript AST which only has one node: `CallExpression`.
2. It means that we have to maintain more code, because the various parts of the compiler need to know about three node types.
3. It doesn't allow us to easily implement some new JS features like safe calls (e.g. `foo.bar?.())`).
These changes rework the compiler so that it produces only one node: `Call`. The new node behaves similarly to the TypeScript `CallExpression` whose `receiver` can be any expression.
There was a similar situation in the output AST where we had an `InvokeMethodExpression` and `InvokeFunctionExpression`. I've combined both of them into `InvokeFunctionExpression`.
PR Close#42882
Adds support for shorthand property declarations inside Angular templates. E.g. doing `{foo, bar}` instead of `{foo: foo, bar: bar}`.
Fixes#10277.
PR Close#42421
Currently we support safe property (`a?.b`) and method (`a?.b()`) accesses, but we don't handle safe keyed reads (`a?.[0]`) which is inconsistent. These changes expand the compiler in order to support safe key read expressions as well.
PR Close#41911
TypeScript supports ECMAScript private identifiers. It can happen that
developers intend to access such members from within an expression.
This currently results in an unclear error from the lexer. e.g.
```
'Parser Error: Unexpected token # at column 1 in [{{#myField}}] in C:/test.ts@5:2
```
We could improve such errors by tokenizing private identifiers similar to
how the TypeScript scanner processes them. Later we can report better
errors in the expression parser or in the typecheck block. This commit
causes all private identifier tokens to be disallowed, so it never
reaches the type checker. This is done intentionally as private
identifiers should not be considered valid Angular syntax, especially
because private fields are not guaranteed to be accessible from within
a component/directive definition (e.g. there cases where a template
function is generated outside of the class; which results in private
members not being accessible; and this results in mixed/confusing
behavior).
Fixes#36003.
PR Close#42027
`EmptyExpr` is somewhat unique, in that it's constructed in a circumstance
where the parser has been looking for a particular token or string of tokens
and has failed to find any. This means the parser state when constructing
`EmptyExpr` is fairly unique.
This gives rise to a bug where the parser constructs `EmptyExpr` with a
backwards span - a `start` value that's beyond the `end` value. This likely
happens because of the strange state the parser is in when recovering with
`EmptyExpr`.
This commit adds a backstop/workaround to avoid constructing such broken
`EmptyExpr` spans (or any other kind of span). Eventually, the parser state
should be fixed such that this does not occur, but that requires a
significant change to the parser's functionality, so a simple fix in th
interim is in order.
PR Close#41581
This commit adds a separate span to `MethodCall` and `SafeMethodCall` which
tracks the text span between the `(` and `)` tokens of the call. Tools like
the Language Service can use this span to more accurately understand a
cursor position within a method call expression.
PR Close#41581
The parser does not include parenthesis in the AST, so if a LHS
expression would be parenthesized then its start span would start
after the opening parenthesis. Previously, some parent AST nodes would
be created with the start span of its LHS as its own start, so this
resulted in the parent AST node not encompassing the opening parenthesis
in its source span. This commit fixes the issue by capturing the start
index prior to parsing a child AST tree, which is then used as the
start of the source span of the the parent AST node that is parsed.
Fixes#40721
PR Close#40740
When parsing interpolations, if we encounter an empty interpolation
(`{{}}`), the current code uses a "pretend" value of `$implicit` for the
name as if the interplotion were really `{{$implicit}}`. This is
problematic because the spans are then incorrect downstream since they
are based off of the `$implicit` text.
This commit changes the interpretation of empty interpolations so that
the text is simply an empty string.
Fixes https://github.com/angular/vscode-ng-language-service/issues/1077
Fixes https://github.com/angular/vscode-ng-language-service/issues/1078
PR Close#40583
The Language Service uses the source span of AST nodes to recognize which
node a user has selected, given their cursor position in a template. This is
used to trigger autocompletion.
The previous source span of BindingPipe nodes created a problem when:
1) the pipe binding had no identifier (incomplete or in-progress expression)
2) the user typed trailing whitespace after the pipe character ('|')
For example, the expression `{{foo | }}`. If the cursor preceded the '}' in
that expression, the Language Service was unable to detect that the user was
autocompleting the BindingPipe expression, since the span of the BindingPipe
ended after the '|'.
This commit changes the expression parser to expand the span of BindingPipe
expressions with a missing identifier, to include any trailing whitespace.
This allows the Language Service to correctly recognize this case as
targeting the BindingPipe and complete it successfully. The `nameSpan` of
the BindingPipe is also moved to be right-aligned with the end of any
whitespace present in the pipe binding expression.
This change allows for the disabled test in the Language Service for pipe
completion in this case to be re-enabled.
PR Close#40346
Currently we check whether a property binding contains an interpolation using a regex so
that we can throw an error. The problem is that the regex doesn't account for quotes
which means that something like `[prop]="'{{ foo }}'"` will be considered an error, even
though it's not actually an interpolation.
These changes build on top of the logic from #39826 to account for interpolation
characters inside quotes.
Fixes#39601.
PR Close#40267
Currently the compiler treats something like `{{ '{{a}}' }}` as a nested
binding and throws an error, because it doesn't account for quotes
when it looks for binding characters. These changes add a bit of
logic to skip over text inside quotes when parsing.
Fixes#39601.
PR Close#39826
When parsing for i18n messages, interpolated strings are
split into `Text` and `Placeholder` pieces. The method that
does this `_visitTextWithInterpolation()` was becoming too
complex. This commit refactors that method along with some
associated functions that it uses.
PR Close#39717
This commit handles the following cases:
- incomplete pipes in a pipe chain
- incomplete arguments in a pipe chain
- incomplete arguments provided to a pipe
- nested pipes
The idea is to unconditionally recover on the presence of a pipe, which
should be okay because expression parsing can be independently between
pipes.
PR Close#39437
There is no actionable change in this commit other than to pretty-print
EOF tokens. Actual parsing of unterminated pipes is already supported,
this just adds a test for it.
Part of #38596
PR Close#39113
