When the parser encounters a `<` after an expression, it must choose
whether to interpret it as a relational operator or a <typeArguments>
selector. The disambiguation rule is: if the `<` and the tokens
following it *can* be parsed as <typeArguments>, and the token that
follows is a member of a privileged set of tokens, then it is treated
as a <typeArguments> selector; otherwise it is treated as a relational
operator.
This change reduces the privileged set of tokens to the following:
- the "continuation tokens" `(`, `.`, `==`, and `!=`
- the "stop tokens" `)`, `]`, `}`, `;`, `:`, and `,`
The names "continuation tokens" and "stop tokens" reflect the
rationale for choosing these tokens:
- Continuation tokens are tokens that we can reasonably imagine a
programmer wanting to place after a type argument selector to
*continue* the expression. For example, `if (List<int> == T) ...`
is allowed.
- Stop tokens are tokens that can't possibly follow a `>` that is a
relational operator, because they *stop* the expression that's in
progress. For example, `var x = List<int>;` is allowed.
If a user wants to follow a <typeArguments> selector with a token
other than the ones above, they'll have to parenthesize the
expression. So for example, if they want to do `List<int> + 1` (which
could be meaningful if an extension method defined `operator +` for
the type `Type`), they will have to use parentheses, and instead write
`(List<int>) + 1`.
Bug: https://github.com/dart-lang/language/issues/1806
Change-Id: I2816cdac24e55eac3cb3e9920e276404c1228d46
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/210941
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Now that we have an AST and visitor support for the FunctionReference
structure (which represents `Expression<TypeArguments>` for various
kinds of expressions), we no longer need to error recover this as a
FunctionExpressionInvocation with synthetic arguments. The resolver
still doesn't resolve the syntax properly, but that's ok because it's
not permitted in valid code (for now we just treat it as having type
`dynamic`).
Fixes#46150.
Change-Id: I357175cc16bcf2f9027be2e1da66bb6ca70a9400
Bug: https://github.com/dart-lang/sdk/issues/46020
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/199682
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
This CL adds parser support for use of `<typeArguments>` as a
selector. This allows expressions like `List<int>` (type literal with
type arguments), `f<int>` (function tear-off with type arguments),
`C.m<int>` (static method tear-off with type arguments), `EXPR.m<int>`
(instance method tear-off with type arguments), and `EXPR<int>`
(tear-off of `.call` method with type arguments).
I will add parser support for `.new` as a constructor name in a
follow-up CL.
Change-Id: I157e732276421e8c3fd20c38c67ae9643993bd85
Bug: https://github.com/dart-lang/sdk/issues/46020, https://github.com/dart-lang/sdk/issues/46044.
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/197102
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Konstantin Shcheglov