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# squarelibraries
j

jw

06/18/2022, 8:37 PM
That's pretty standard for InputStream, at least
j

Jeff Lockhart

06/20/2022, 4:30 PM
That should be acceptable, copying bytes as they're read. I'm similarly copying
ByteArray
to
NSData
with other platform type conversions. I'd be happy to take a stab at implementing a solution. Just need to familiarize myself with the code first. Feel free to share any guidance or suggestions.
Here's a quick pass at
java.io.InputStream
.
j

jw

06/20/2022, 9:20 PM
Okio has that built in
It's only the NS one we don't have
j

Jeff Lockhart

06/20/2022, 9:27 PM
I only see an API for
BufferedSource.inputStream()
, but not
Source.inputStream()
. Is that what you're referring to? Perhaps
BufferedSource
is the appropriate unifying API for
java.io.InputStream
and
NSInputStream
.
j

jw

06/20/2022, 9:45 PM
If you only have a Source you can trivially get a BufferedSource by calling buffer()
j

Jeff Lockhart

06/20/2022, 9:54 PM
Ok, so it seems it would make sense for the API to accept any
Source
, then in the platform implementations, call
buffer().inputStream()
to convert to
java.io.InputStream
or
NSInputStream
. Since the appleMain source set inherits
BufferedSource
from the nonJvmMain source set, would it make sense to implement
BufferedSource.inputStream(): NSInputStream
as an extension function?
j

jw

06/20/2022, 10:10 PM
Buffering should never be an implementation detail of calling a function. We always want to promote that to the caller
You can write it as an extension function but it will not be available to call from Swift or Objective-C then. See https://github.com/square/okio/issues/1113 for another example gone awry
j

Jeff Lockhart

06/20/2022, 10:20 PM
Ah, that answers some of my next line of thought. I'm assuming decoupling the appleMain source set from the nonJvmMain actual declaration of
BufferedSource
would be non-trivial, which is what would allow it to work similar to the jvmMain implementation, adding the additional
inputStream()
function to the interface. Besides the default implementation route, I was also thinking how it could be nice for source sets to override an inherited actual declaration with their own more granular version.
For my use case, I only need the extension in Kotlin though. The code I'm working on is a KMM wrapper API for a database, which mirrors the JVM database API with Kotlin expect declarations. The actual implementations for android either typealias to the underlying SDK or call through to the underlying, when typealias is inadequate. The ios actual implementation similarly calls through to the ObjC SDK, massaging the underlying API to align with the Kotlin definition and converting between platform types.
Although, I could see how an extension could be useful when utilizing the database API in Swift/ObjC if the user wished to use an Apple native
NSInputStream
instead of okio's
Source
API. But it wouldn't be a strict requirement to provide such an API.
For the most part, users would be consuming the API in a KMM module in Kotlin though.
Would also want to avoid actually converting between streams multiple times anyway, considering the data copying required.
Here's a crack at
BufferedSource.inputStream(): NSInputStream
.
And here's
NSInputStream.source(): Source
. In this direction, you can actually avoid the data copy, as
ByteArray
can be written to as a
CPointer
.
I added some tests with these
NSInputStream
additions on this branch. Let me know what you think. I can make a PR.
j

jw

06/22/2022, 3:13 PM
I'm definitely not experienced enough in the semantics of the darwin APIs, but it looks good from a cursory glance.
j

Jeff Lockhart

06/22/2022, 8:37 PM
Cool, here's the PR. I appreciate your help.
🎉 1
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