tui: Refactor Config type handling in backends

The `Config` can be passed when creating the backend (for example
`CrosstermBackend::new`) and is already updated in the
`Backend::reconfigure` callback. Recreating the tui `Config` during
`claim` and `restore` is unnecessary and causes a clone of the editor's
Config which is a fairly large type. This change drops the `Config`
parameter from those callbacks and updates the callers. Instead it is
passed to `CrosstermBackend` which then owns it.

I've also moved the override from the `editor.undercurl` key onto the
tui `Config` type - I believe it was just an oversight that this was not
done originally. And I've updated the `From<EditorConfig> for Config`
to take a reference to the editor's `Config` to avoid the unnecessary
clone during `CrosstermBackend::new` and `Backend::reconfigure`.

Author: the-mikedavis

helix-term/src/application.rs

@@ -104,7 +104,7 @@ impl Application {
         let theme_loader = theme::Loader::new(&theme_parent_dirs);
 
         #[cfg(not(feature = "integration"))]
-        let backend = CrosstermBackend::new(stdout(), &config.editor);
+        let backend = CrosstermBackend::new(stdout(), (&config.editor).into());
 
         #[cfg(feature = "integration")]
         let backend = TestBackend::new(120, 150);
@@ -367,7 +367,7 @@ impl Application {
             ConfigEvent::Update(editor_config) => {
                 let mut app_config = (*self.config.load().clone()).clone();
                 app_config.editor = *editor_config;
-                if let Err(err) = self.terminal.reconfigure(app_config.editor.clone().into()) {
+                if let Err(err) = self.terminal.reconfigure((&app_config.editor).into()) {
                     self.editor.set_error(err.to_string());
                 };
                 self.config.store(Arc::new(app_config));
@@ -412,8 +412,7 @@ impl Application {
                 document.replace_diagnostics(diagnostics, &[], None);
             }
 
-            self.terminal
-                .reconfigure(default_config.editor.clone().into())?;
+            self.terminal.reconfigure((&default_config.editor).into())?;
             // Store new config
             self.config.store(Arc::new(default_config));
             Ok(())
@@ -503,7 +502,7 @@ impl Application {
                 // https://github.com/neovim/neovim/issues/12322
                 // https://github.com/neovim/neovim/pull/13084
                 for retries in 1..=10 {
-                    match self.claim_term().await {
+                    match self.terminal.claim() {
                         Ok(()) => break,
                         Err(err) if retries == 10 => panic!("Failed to claim terminal: {}", err),
                         Err(_) => continue,
@@ -1099,26 +1098,20 @@ impl Application {
         lsp::ShowDocumentResult { success: true }
     }
 
-    async fn claim_term(&mut self) -> std::io::Result<()> {
-        let terminal_config = self.config.load().editor.clone().into();
-        self.terminal.claim(terminal_config)
-    }
-
     fn restore_term(&mut self) -> std::io::Result<()> {
-        let terminal_config = self.config.load().editor.clone().into();
         use helix_view::graphics::CursorKind;
         self.terminal
             .backend_mut()
             .show_cursor(CursorKind::Block)
             .ok();
-        self.terminal.restore(terminal_config)
+        self.terminal.restore()
     }
 
     pub async fn run<S>(&mut self, input_stream: &mut S) -> Result<i32, Error>
     where
         S: Stream<Item = std::io::Result<crossterm::event::Event>> + Unpin,
     {
-        self.claim_term().await?;
+        self.terminal.claim()?;
 
         // Exit the alternate screen and disable raw mode before panicking
         let hook = std::panic::take_hook();

helix-tui/src/backend/crossterm.rs

@@ -14,10 +14,7 @@ use crossterm::{
     terminal::{self, Clear, ClearType},
     Command,
 };
-use helix_view::{
-    editor::Config as EditorConfig,
-    graphics::{Color, CursorKind, Modifier, Rect, UnderlineStyle},
-};
+use helix_view::graphics::{Color, CursorKind, Modifier, Rect, UnderlineStyle};
 use once_cell::sync::OnceCell;
 use std::{
     fmt,
@@ -74,17 +71,17 @@ impl Capabilities {
     /// on the $TERM environment variable. If detection fails, returns
     /// a default value where no capability is supported, or just undercurl
     /// if config.undercurl is set.
-    pub fn from_env_or_default(config: &EditorConfig) -> Self {
+    pub fn from_env_or_default(config: &Config) -> Self {
         match termini::TermInfo::from_env() {
             Err(_) => Capabilities {
-                has_extended_underlines: config.undercurl,
+                has_extended_underlines: config.force_enable_extended_underlines,
                 ..Capabilities::default()
             },
             Ok(t) => Capabilities {
                 // Smulx, VTE: https://unix.stackexchange.com/a/696253/246284
                 // Su (used by kitty): https://sw.kovidgoyal.net/kitty/underlines
                 // WezTerm supports underlines but a lot of distros don't properly install its terminfo
-                has_extended_underlines: config.undercurl
+                has_extended_underlines: config.force_enable_extended_underlines
                     || t.extended_cap("Smulx").is_some()
                     || t.extended_cap("Su").is_some()
                     || vte_version() >= Some(5102)
@@ -98,6 +95,7 @@ impl Capabilities {
 /// Terminal backend supporting a wide variety of terminals
 pub struct CrosstermBackend<W: Write> {
     buffer: W,
+    config: Config,
     capabilities: Capabilities,
     supports_keyboard_enhancement_protocol: OnceCell<bool>,
     mouse_capture_enabled: bool,
@@ -108,14 +106,15 @@ impl<W> CrosstermBackend<W>
 where
     W: Write,
 {
-    pub fn new(buffer: W, config: &EditorConfig) -> CrosstermBackend<W> {
+    pub fn new(buffer: W, config: Config) -> CrosstermBackend<W> {
         // helix is not usable without colors, but crossterm will disable
         // them by default if NO_COLOR is set in the environment. Override
         // this behaviour.
         crossterm::style::force_color_output(true);
         CrosstermBackend {
             buffer,
-            capabilities: Capabilities::from_env_or_default(config),
+            capabilities: Capabilities::from_env_or_default(&config),
+            config,
             supports_keyboard_enhancement_protocol: OnceCell::new(),
             mouse_capture_enabled: false,
             supports_bracketed_paste: true,
@@ -157,7 +156,7 @@ impl<W> Backend for CrosstermBackend<W>
 where
     W: Write,
 {
-    fn claim(&mut self, config: Config) -> io::Result<()> {
+    fn claim(&mut self) -> io::Result<()> {
         terminal::enable_raw_mode()?;
         execute!(
             self.buffer,
@@ -173,7 +172,7 @@ where
             Ok(_) => (),
         };
         execute!(self.buffer, terminal::Clear(terminal::ClearType::All))?;
-        if config.enable_mouse_capture {
+        if self.config.enable_mouse_capture {
             execute!(self.buffer, EnableMouseCapture)?;
             self.mouse_capture_enabled = true;
         }
@@ -198,15 +197,16 @@ where
             }
             self.mouse_capture_enabled = config.enable_mouse_capture;
         }
+        self.config = config;
 
         Ok(())
     }
 
-    fn restore(&mut self, config: Config) -> io::Result<()> {
+    fn restore(&mut self) -> io::Result<()> {
         // reset cursor shape
         self.buffer
             .write_all(self.capabilities.reset_cursor_command.as_bytes())?;
-        if config.enable_mouse_capture {
+        if self.config.enable_mouse_capture {
             execute!(self.buffer, DisableMouseCapture)?;
         }
         if self.supports_keyboard_enhancement_protocol() {

helix-tui/src/backend/mod.rs

@@ -17,11 +17,11 @@ pub use self::test::TestBackend;
 /// Representation of a terminal backend.
 pub trait Backend {
     /// Claims the terminal for TUI use.
-    fn claim(&mut self, config: Config) -> Result<(), io::Error>;
+    fn claim(&mut self) -> Result<(), io::Error>;
     /// Update terminal configuration.
     fn reconfigure(&mut self, config: Config) -> Result<(), io::Error>;
     /// Restores the terminal to a normal state, undoes `claim`
-    fn restore(&mut self, config: Config) -> Result<(), io::Error>;
+    fn restore(&mut self) -> Result<(), io::Error>;
     /// Forcibly resets the terminal, ignoring errors and configuration
     fn force_restore() -> Result<(), io::Error>;
     /// Draws styled text to the terminal

helix-tui/src/backend/test.rs

@@ -107,15 +107,15 @@ impl TestBackend {
 }
 
 impl Backend for TestBackend {
-    fn claim(&mut self, _config: Config) -> Result<(), io::Error> {
+    fn claim(&mut self) -> Result<(), io::Error> {
         Ok(())
     }
 
     fn reconfigure(&mut self, _config: Config) -> Result<(), io::Error> {
         Ok(())
     }
 
-    fn restore(&mut self, _config: Config) -> Result<(), io::Error> {
+    fn restore(&mut self) -> Result<(), io::Error> {
         Ok(())
     }
 

helix-tui/src/terminal.rs

@@ -24,12 +24,14 @@ pub struct Viewport {
 #[derive(Debug)]
 pub struct Config {
     pub enable_mouse_capture: bool,
+    pub force_enable_extended_underlines: bool,
 }
 
-impl From<EditorConfig> for Config {
-    fn from(config: EditorConfig) -> Self {
+impl From<&EditorConfig> for Config {
+    fn from(config: &EditorConfig) -> Self {
         Self {
             enable_mouse_capture: config.mouse,
+            force_enable_extended_underlines: config.undercurl,
         }
     }
 }
@@ -102,16 +104,16 @@ where
         })
     }
 
-    pub fn claim(&mut self, config: Config) -> io::Result<()> {
-        self.backend.claim(config)
+    pub fn claim(&mut self) -> io::Result<()> {
+        self.backend.claim()
     }
 
     pub fn reconfigure(&mut self, config: Config) -> io::Result<()> {
         self.backend.reconfigure(config)
     }
 
-    pub fn restore(&mut self, config: Config) -> io::Result<()> {
-        self.backend.restore(config)
+    pub fn restore(&mut self) -> io::Result<()> {
+        self.backend.restore()
     }
 
     // /// Get a Frame object which provides a consistent view into the terminal state for rendering.