Add an AssetStream class to Barback.

Add an AssetStream class to Barback.

This makes it easier to create an asset from a stream of bytes.

R=rnystrom@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=26734

[Bob Nystrom, 2013-08-27 17:20:29]

https://codereview.chromium.org/23469003/diff/1/pkg/barback/lib/src/stream_re...
File pkg/barback/lib/src/stream_replayer.dart (right):

https://codereview.chromium.org/23469003/diff/1/pkg/barback/lib/src/stream_re...
pkg/barback/lib/src/stream_replayer.dart:28: /// The controllers are listening
for future events from [_stream].
"are" -> "that are".

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/stream...
File pkg/barback/lib/src/stream_replayer.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/stream...
pkg/barback/lib/src/stream_replayer.dart:61: controller.add(eventOrError.type2);
addError

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
File pkg/barback/lib/src/utils.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:27: class Union<E, F> {
In Haskell, this type is called "Either", which I think reads better. How about:

class Either<E, F> {
  bool get isFirst;
  bool get isSecond;
  E first;
  F second;
}

This isn't strictly a *union*, since it's valid and useful to use this with E
and F being the *same* type. Given that, I think "either" and "first" and
"second" make a bit more sense.

It might also be nice to add a higher-order function that basically does the
pattern match for you:

  match(whenFirst(E value), whenSecond(E value)) { ... }

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:41: final E _type1;
You can just use a single var _value for either value.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:50: final F _type2;
See above and remove this.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:62: String toString() => (isType1 ? type1 :
type2).toString();
You should include the value of isType1 in the output since the two types could
be the same and could even have the same value. A new Union.withType1("foo") is
different from a new Union.withType2("foo").

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/asset_tes...
File pkg/barback/test/asset_test.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/asset_tes...
pkg/barback/test/asset_test.dart:171: // TODO(nweiz): Test other encodings once
#6284 is fixed.
Add some tests for how it handles the source stream emitting values over time.
In particular:

- If a stream emits values before the asset is read, they are captured by the
asset.
- Reading the asset multiple times replays the stream.
- Reading doesn't complete until the source stream is closed.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/stream_re...
File pkg/barback/test/stream_replayer_test.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/stream_re...
pkg/barback/test/stream_replayer_test.dart:56: });
Add a test that the replayed stream doesn't close until the source stream does.

[nweiz, 2013-08-27 17:47:51]

https://codereview.chromium.org/23469003/diff/1/pkg/barback/lib/src/stream_re...
File pkg/barback/lib/src/stream_replayer.dart (right):

https://codereview.chromium.org/23469003/diff/1/pkg/barback/lib/src/stream_re...
pkg/barback/lib/src/stream_replayer.dart:28: /// The controllers are listening
for future events from [_stream].
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> "are" -> "that are".

Done.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/stream...
File pkg/barback/lib/src/stream_replayer.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/stream...
pkg/barback/lib/src/stream_replayer.dart:61: controller.add(eventOrError.type2);
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> addError

Done.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
File pkg/barback/lib/src/utils.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:27: class Union<E, F> {
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> In Haskell, this type is called "Either", which I think reads better. How
about:
> 
> class Either<E, F> {
>   bool get isFirst;
>   bool get isSecond;
>   E first;
>   F second;
> }
> 
> This isn't strictly a *union*, since it's valid and useful to use this with E
> and F being the *same* type. Given that, I think "either" and "first" and
> "second" make a bit more sense.
> 
> It might also be nice to add a higher-order function that basically does the
> pattern match for you:
> 
>   match(whenFirst(E value), whenSecond(E value)) { ... }

Done.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:41: final E _type1;
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> You can just use a single var _value for either value.

Done.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:50: final F _type2;
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> See above and remove this.

Done.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/lib/src/utils....
pkg/barback/lib/src/utils.dart:62: String toString() => (isType1 ? type1 :
type2).toString();
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> You should include the value of isType1 in the output since the two types
could
> be the same and could even have the same value. A new Union.withType1("foo")
is
> different from a new Union.withType2("foo").

Done.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/asset_tes...
File pkg/barback/test/asset_test.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/asset_tes...
pkg/barback/test/asset_test.dart:171: // TODO(nweiz): Test other encodings once
#6284 is fixed.
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> Add some tests for how it handles the source stream emitting values over time.
> In particular:
> 
> - If a stream emits values before the asset is read, they are captured by the
> asset.
> - Reading the asset multiple times replays the stream.
> - Reading doesn't complete until the source stream is closed.

These are essentially the tests we already have for StreamReplayer. I don't
think we'd get value from duplicating them here, any more than we'd get value
from testing basic Stream functionality here.

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/stream_re...
File pkg/barback/test/stream_replayer_test.dart (right):

https://codereview.chromium.org/23469003/diff/3001/pkg/barback/test/stream_re...
pkg/barback/test/stream_replayer_test.dart:56: });
On 2013/08/27 17:20:29, Bob Nystrom wrote:
> Add a test that the replayed stream doesn't close until the source stream
does.

Done.

[Bob Nystrom, 2013-08-27 17:59:56]

LGTM!

https://codereview.chromium.org/23469003/diff/7001/pkg/barback/lib/src/stream...
File pkg/barback/lib/src/stream_replayer.dart (right):

https://codereview.chromium.org/23469003/diff/7001/pkg/barback/lib/src/stream...
pkg/barback/lib/src/stream_replayer.dart:58: eventOrError.match(controller.add,
controller.addError);
Oh, that cleaned up nicely.

[nweiz, 2013-08-27 18:29:37]

Committed patchset #3 manually as r26734 (presubmit successful).