New C# CharStreams static factory class

[bhamiltoncx]

Based on the discussion at #1771 (comment) , this brings the Java runtime's CharStreams factory API to C#.

I updated BaseCSharpTest to make use of the new API to illustrate how it works.

[parrt]

@ericvergnaud Can you comment on this new API?

[ericvergnaud]

Overall looks good except FromStream which unlike other APIs should NOT 'ReadToEnd'.
If you're parsing from a socket, or stdin, EOF could be far away, or even unreachable.

[bhamiltoncx]

Makes sense. But how do we know how much to parse? Add length args?

…

On Tue, Mar 21, 2017, 10:15 AM ericvergnaud ***@***.***> wrote: Overall looks good except FromStream which unlike other APIs should NOT 'ReadToEnd'. If you're parsing from a socket, or stdin, EOF could be far away, or even unreachable. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#1775 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AApAU9cf7ZaJy0ED5LPhYACWaDrqCWU4ks5rn_eXgaJpZM4Mi2kc> .

[ericvergnaud]

You don't need to know.
You let the grammar author deal with it.
i.e. with stdin they can decide to stop when encountering 'exit' token
with socket they can detect a pattern to reset

[parrt]

I've added important comments here

[bhamiltoncx]

You don't need to know.
You let the grammar author deal with it.
i.e. with stdin they can decide to stop when encountering 'exit' token
with socket they can detect a pattern to reset

Hmm. Currently, the design of ICharStream doesn't really allow for reading less than the entire input; all known implementations read the entire contents before constructing ICharStream.

Could you give me an example of what you mean?

[parrt]

@bhamiltoncx are these consistent now with our tweaks to the Java stream API?

[bhamiltoncx]

Yes, everything is consistent, although I didn't do any optimization passes yet, so we don't have a version that takes a size.

[parrt]

Ok, we can probably worry about optimizing the other targets after 4.7.