RFR: 8352693: Use a simpler console reader instead of JLine for System.console()

[Naoto Sato]

On Wed, 26 Mar 2025 07:54:48 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> The `java.io.Console` has several backends: a simple on in `java.base`, a more convenient one in `jdk.internal.le` (with line-reading based on JLine) and one for JShell.
> 
> The backend based on JLine is proving to be a somewhat problematic - JLine is very powerful, possibly too powerful and complex for the simple task of editing a line with no completion, no history, no variables, no commands, etc. As a consequence, there are inevitable sharp edges in this backend.
> 
> The idea in this PR is to replace the use of JLine in the `jdk.internal.le` backend with a simple escape code interpreter, that only handles a handful of keys/codes (left/right arrow, home, end, delete, backspace, enter), and ignores the rest. The goal is to have something simple with less surprising behavior.

I am not very familiar with those escape sequences/modes in the native console, but looks good to me. Sharing the common part as the base looks reasonable.

src/jdk.internal.le/share/classes/jdk/internal/console/SimpleConsoleReader.java line 69:

> 67:                 case 4: break READ; //EOF/Ctrl-D
> 68:                 case 127:
> 69:                     //backspace:

Is it `delete`?

src/jdk.internal.le/share/classes/jdk/internal/console/SimpleConsoleReader.java line 198:

> 196: 
> 197:             if (it.hasNext()) {
> 198:                 out.append("\n\r");

I understand this is a simple console, but do we want to CR/LF/CRLF based on the platform?

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PR Review: https://git.openjdk.org/jdk/pull/24242#pullrequestreview-2723057740
PR Review Comment: https://git.openjdk.org/jdk/pull/24242#discussion_r2017409982
PR Review Comment: https://git.openjdk.org/jdk/pull/24242#discussion_r2017488129