Just realised that `BufferedReader.forEachLine` do...

# getting-started

[Rob Elliot]

Just realised that BufferedReader.forEachLine doesn’t distinguish between last line\nEOF and last lineEOF - in both cases the last line emitted is last line, whether it ends in a line feed or not.

This is frustrating if you need to capture the output of the Reader exactly, but would also like to buffer based on line feeds rather than an arbitrary number of characters.

Anyone know of a workaround?

(It’s nearly NOT KOTLIN I know, because it just delegates to `java.io.BufferedReader.readLine`… hope the fact that kotlin has extension methods calling it justifies asking?!)

[ephemient]

no, not really. this may not help you, but https://en.wikipedia.org/wiki/Text_file#Unix_text_files

POSIX defines a text file as a file that contains characters organized into zero or more lines, where lines are sequences of zero or more non-newline characters plus a terminating newline character

a file that ends in a non-newline character is not a "text" file, and most line-oriented processing tools (such as sed) don't preserve final lines without newlines either

[Rob Elliot]

I decided in the end just to use read() directly, it was for capturing a child process’s standard out in memory while also passing it to the current process’s standard out, and I realised that for e.g. progress bars it was going to be rubbish to only emit at line feed anyway.

[Rob Elliot]

(I want the captured output of echo 'hello world' and printf 'hello world' to contain the fact that the first has a newline and the second does not)

[ephemient]

you'd have an easier time passing through as a binary InputStream/OutputStream, I suspect

[ephemient]

(of course you can tee the bytestream through a CharsetDecoder or similar to get chars for your own use)

[Rob Elliot]

Good ideas, thanks. I want to store the in memory capture in some kind of ring buffer ideally so that it’s not unbounded, so I think it would need to be char rather than byte based otherwise if the encoding were UTF-8 dropping some early bytes might render the result undecodable.

[ephemient]

example that can pass process output directly, while also safely decoding UTF-8 for your own use, even if it contains binary garbage

err: "4+0 records in\n4+0 records out\n64 bytes transferred in 0.000016 secs (3947580 bytes/sec)\n"
out: "\r\uFFFD\uFFFD8\uFFFDd\uFFFD&\uFFFD\uFFFDA\uFFFD\u0580l\uFFFD\u0000\uFFFD\uFFFD\uFFFD\uFFFD\uFFFD\u0007\uFFFD`\uFFFD\uFFFDQB\u0000v\uFFFD\uFFFD\uFFFD\u491BD\uFFFD\uFFFDi\uFFFD\uFFFDe\uFFFD_\uFFFD)\uFFFD\uFFFD\u000Fy\u001C4\u0004\uFFFD\uFFFD\u0007Q\uFFFD\uFFFD#"
out: "\uFFFD"
exitCode: 0

(U+FFFD being the default replacement character)

Untitled.cpp

[Rob Elliot]

Wow, thanks