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Update StreamIterator docs for null safety.

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Bug: https://github.com/dart-lang/sdk/issues/43380
Change-Id: I12984d15961c1950a5b6bb1d087b43cba8960e43
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/170142
Reviewed-by: Lasse R.H. Nielsen <lrn@google.com>
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Auto-Submit: Bob Nystrom <rnystrom@google.com>
This commit is contained in:
Robert Nystrom 2020-11-11 12:06:09 +00:00 committed by commit-bot@chromium.org
parent ea9a4b1a78
commit adbc3cdad7
1 changed files with 14 additions and 10 deletions
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24
sdk/lib/async/stream.dart
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@ -2212,20 +2212,22 @@ abstract class StreamTransformerBase<S, T> implements StreamTransformer<S, T> {
}
/**
* An [Iterator] like interface for the values of a [Stream].
* An [Iterator]-like interface for the values of a [Stream].
*
* This wraps a [Stream] and a subscription on the stream. It listens
* on the stream, and completes the future returned by [moveNext] when the
* next value becomes available.
*
* The stream may be paused between calls to [moveNext].
*
* The [current] value must only be used after a future returned by [moveNext]
* has completed with `true`, and only until [moveNext] is called again.
*/
abstract class StreamIterator<T> {
/** Create a [StreamIterator] on [stream]. */
factory StreamIterator(Stream<T> stream)
factory StreamIterator(Stream<T> stream) =>
// TODO(lrn): use redirecting factory constructor when type
// arguments are supported.
=>
new _StreamIterator<T>(stream);
/**
@ -2247,14 +2249,16 @@ abstract class StreamIterator<T> {
/**
* The current value of the stream.
*
* Is `null` before the first call to [moveNext] and after a call to
* `moveNext` completes with a `false` result or an error.
*
* When a `moveNext` call completes with `true`, the `current` field holds
* When a [moveNext] call completes with `true`, the [current] field holds
* the most recent event of the stream, and it stays like that until the next
* call to `moveNext`.
* Between a call to `moveNext` and when its returned future completes,
* the value is unspecified.
* call to [moveNext]. This value must only be read after a call to [moveNext]
* has completed with `true`, and only until the [moveNext] is called again.
*
* If the StreamIterator has not yet been moved to the first element
* ([moveNext] has not been called and completed yet), or if the
* StreamIterator has been moved past the last element ([moveNext] has
* returned `false`), then [current] is unspecified. A [StreamIterator] may
* either throw or return an iterator-specific default value in that case.
*/
T get current;