Add kitty protocol config to nushell (#10540)

# Description

Support keyboard enhancement protocol as implemented by Kitty console,
hence Kitty protocol.

This PR enables Nushell to use keybinding that is not available before,
such as Ctrl+i (that alias to Tab) or Ctrl+e (that alias to Esc, likely
I mistaken). After this PR merged and you set `use_kitty_protocol`
enabled, if your console app support Kitty protocol (WezTerm, Kitty,
etc.) you will be able to set more fine-grained keybinding.

For Colemak users, this feature is a blessing, because some Ctrl+[hjkl]
that previously unmap-able to Ctlr+[hnei] now it is.

# User-Facing Changes

This adds `use_kitty_protocol` config which defaults to false. When set
to `true`, it enables kitty protocol on the line editor when supported,
or else it warns.


---------

Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>

crates/nu-cli/src/commands/keybindings_listen.rs

@@ -1,3 +1,4 @@
+use crossterm::execute;
 use crossterm::QueueableCommand;
 use crossterm::{event::Event, event::KeyCode, event::KeyEvent, terminal};
 use nu_protocol::ast::Call;
@@ -69,6 +70,32 @@ pub fn print_events(engine_state: &EngineState) -> Result<Value, ShellError> {
 
     stdout().flush()?;
     terminal::enable_raw_mode()?;
+
+    if config.use_kitty_protocol {
+        if let Ok(false) = crossterm::terminal::supports_keyboard_enhancement() {
+            println!("WARN: The terminal doesn't support use_kitty_protocol config.\r");
+        }
+
+        // enable kitty protocol
+        //
+        // Note that, currently, only the following support this protocol:
+        // * [kitty terminal](https://sw.kovidgoyal.net/kitty/)
+        // * [foot terminal](https://codeberg.org/dnkl/foot/issues/319)
+        // * [WezTerm terminal](https://wezfurlong.org/wezterm/config/lua/config/enable_kitty_keyboard.html)
+        // * [notcurses library](https://github.com/dankamongmen/notcurses/issues/2131)
+        // * [neovim text editor](https://github.com/neovim/neovim/pull/18181)
+        // * [kakoune text editor](https://github.com/mawww/kakoune/issues/4103)
+        // * [dte text editor](https://gitlab.com/craigbarnes/dte/-/issues/138)
+        //
+        // Refer to https://sw.kovidgoyal.net/kitty/keyboard-protocol/ if you're curious.
+        let _ = execute!(
+            stdout(),
+            crossterm::event::PushKeyboardEnhancementFlags(
+                crossterm::event::KeyboardEnhancementFlags::DISAMBIGUATE_ESCAPE_CODES
+            )
+        );
+    }
+
     let mut stdout = std::io::BufWriter::new(std::io::stderr());
 
     loop {
@@ -95,6 +122,14 @@ pub fn print_events(engine_state: &EngineState) -> Result<Value, ShellError> {
         stdout.queue(crossterm::style::Print("\r\n"))?;
         stdout.flush()?;
     }
+
+    if config.use_kitty_protocol {
+        let _ = execute!(
+            std::io::stdout(),
+            crossterm::event::PopKeyboardEnhancementFlags
+        );
+    }
+
     terminal::disable_raw_mode()?;
 
     Ok(Value::nothing(Span::unknown()))

crates/nu-cli/src/repl.rs

@@ -180,6 +180,14 @@ pub fn evaluate_repl(
         );
     }
 
+    if engine_state.get_config().use_kitty_protocol {
+        if line_editor.can_use_kitty_protocol() {
+            line_editor.enable_kitty_protocol();
+        } else {
+            warn!("Terminal doesn't support use_kitty_protocol config");
+        }
+    }
+
     loop {
         let loop_start_time = std::time::Instant::now();
 

crates/nu-protocol/src/config.rs

@@ -115,6 +115,7 @@ pub struct Config {
     pub datetime_normal_format: Option<String>,
     pub datetime_table_format: Option<String>,
     pub error_style: String,
+    pub use_kitty_protocol: bool,
 }
 
 impl Default for Config {
@@ -180,6 +181,8 @@ impl Default for Config {
             keybindings: Vec::new(),
 
             error_style: "fancy".into(),
+
+            use_kitty_protocol: false,
         }
     }
 }
@@ -1200,6 +1203,9 @@ impl Value {
                     "bracketed_paste" => {
                         try_bool!(cols, vals, index, span, bracketed_paste);
                     }
+                    "use_kitty_protocol" => {
+                        try_bool!(cols, vals, index, span, use_kitty_protocol);
+                    }
                     // Menus
                     "menus" => match create_menus(value) {
                         Ok(map) => config.menus = map,

crates/nu-utils/src/sample_config/default_config.nu

@@ -239,6 +239,7 @@ $env.config = {
     edit_mode: emacs # emacs, vi
     shell_integration: false # enables terminal shell integration. Off by default, as some terminals have issues with this.
     render_right_prompt_on_last_line: false # true or false to enable or disable right prompt to be rendered on last line of the prompt.
+    use_kitty_protocol: false # enables keyboard enhancement protocol implemented by kitty console, only if your terminal support this
 
     hooks: {
         pre_prompt: [{ null }] # run before the prompt is shown