Add a way to persist the alternate screen on exit

Author: benbrittain

src/core/commands.rs

@@ -34,6 +34,7 @@ pub enum Command {
 
     // Configuration options
     SetExitStrategy(ExitStrategy),
+    PersistAlternate(bool),
     SetInputClassifier(Box<dyn InputClassifier + Send + Sync + 'static>),
     AddExitCallback(Box<dyn FnMut() + Send + Sync + 'static>),
     #[cfg(feature = "static_output")]
@@ -70,6 +71,7 @@ impl PartialEq for Command {
 impl Debug for Command {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
+            Self::PersistAlternate(persist) => write!(f, "PersistAlternate({persist})"),
             Self::SetData(text) => write!(f, "SetData({text:?})"),
             Self::AppendData(text) => write!(f, "AppendData({text:?})"),
             Self::SetPrompt(text) => write!(f, "SetPrompt({text:?})"),

src/core/ev_handler.rs

@@ -42,7 +42,7 @@ pub fn handle_event(
         Command::UserInput(InputEvent::Exit) => {
             p.exit();
             is_exited.store(true, std::sync::atomic::Ordering::SeqCst);
-            term::cleanup(&mut out, &p.exit_strategy, true)?;
+            term::cleanup(&mut out, &p.exit_strategy, true, p.persist_alternate)?;
         }
         Command::UserInput(InputEvent::UpdateUpperMark(mut um)) => {
             display::draw_for_change(out, p, &mut um)?;
@@ -274,6 +274,7 @@ pub fn handle_event(
             display::write_prompt(out, &p.displayed_prompt, p.rows.try_into().unwrap())?;
         }
         Command::SetExitStrategy(es) => p.exit_strategy = es,
+        Command::PersistAlternate(b) => p.persist_alternate = b,
         #[cfg(feature = "static_output")]
         Command::SetRunNoOverflow(val) => p.run_no_overflow = val,
         #[cfg(feature = "search")]
@@ -475,6 +476,26 @@ mod tests {
         assert_eq!(ps.exit_strategy, ExitStrategy::PagerQuit);
     }
 
+    #[test]
+    fn set_persist_screen() {
+        let mut ps = PagerState::new().unwrap();
+        let ev = Command::PersistAlternate(true);
+        let mut out = Vec::new();
+        let mut command_queue = CommandQueue::new_zero();
+
+        handle_event(
+            ev,
+            &mut out,
+            &mut ps,
+            &mut command_queue,
+            &Arc::new(AtomicBool::new(false)),
+            #[cfg(feature = "search")]
+            &UIA,
+        )
+        .unwrap();
+        assert_eq!(ps.persist_alternate, true);
+    }
+
     #[test]
     fn add_exit_callback() {
         let mut ps = PagerState::new().unwrap();

src/core/init.rs

@@ -133,6 +133,7 @@ pub fn init_core(pager: &Pager, rm: RunMode) -> std::result::Result<(), MinusErr
                 stdout(),
                 &crate::ExitStrategy::PagerQuit,
                 true,
+                false,
             ));
             panic_hook(pinfo);
         }));
@@ -169,7 +170,7 @@ pub fn init_core(pager: &Pager, rm: RunMode) -> std::result::Result<(), MinusErr
                 let mut rm = RUNMODE.lock();
                 *rm = RunMode::Uninitialized;
                 drop(rm);
-                term::cleanup(out.as_ref(), &crate::ExitStrategy::PagerQuit, true)?;
+                term::cleanup(out.as_ref(), &crate::ExitStrategy::PagerQuit, true, false)?;
             }
             res
         });
@@ -188,7 +189,12 @@ pub fn init_core(pager: &Pager, rm: RunMode) -> std::result::Result<(), MinusErr
                 let mut rm = RUNMODE.lock();
                 *rm = RunMode::Uninitialized;
                 drop(rm);
-                term::cleanup(out_copy.as_ref(), &crate::ExitStrategy::PagerQuit, true)?;
+                term::cleanup(
+                    out_copy.as_ref(),
+                    &crate::ExitStrategy::PagerQuit,
+                    true,
+                    false,
+                )?;
             }
             res
         });

src/core/utils/term.rs

@@ -60,15 +60,22 @@ pub fn cleanup(
     mut out: impl io::Write,
     es: &crate::ExitStrategy,
     cleanup_screen: bool,
+    persist_screen: bool,
 ) -> std::result::Result<(), CleanupError> {
     if cleanup_screen {
         // Reverse order of setup.
         execute!(out, cursor::Show).map_err(|e| CleanupError::ShowCursor(e.into()))?;
         terminal::disable_raw_mode().map_err(|e| CleanupError::DisableRawMode(e.into()))?;
         execute!(out, event::DisableMouseCapture)
             .map_err(|e| CleanupError::DisableMouseCapture(e.into()))?;
-        execute!(out, terminal::LeaveAlternateScreen)
-            .map_err(|e| CleanupError::LeaveAlternateScreen(e.into()))?;
+        if !persist_screen {
+            execute!(out, terminal::LeaveAlternateScreen)
+                .map_err(|e| CleanupError::LeaveAlternateScreen(e.into()))?;
+        } else {
+            // Clear out the pager line, it's not something you'd want to keep
+            queue!(out, Clear(terminal::ClearType::CurrentLine)).unwrap();
+            out.flush().unwrap();
+        }
     }
 
     if *es == crate::ExitStrategy::ProcessQuit {

src/pager.rs

@@ -186,6 +186,15 @@ impl Pager {
         Ok(self.tx.send(Command::SetExitStrategy(es))?)
     }
 
+    /// Set if minus persists the alternate screen buffer on exit.
+    ///
+    /// This controls how the pager will behave with regards to clearing the screen when
+    /// the user presses `q` or `Ctrl+C'. If it is set, instead of clearing the screen
+    /// when exited, it will continue to show.
+    pub fn persist_alternate_screen(&self, b: bool) -> Result<(), MinusError> {
+        Ok(self.tx.send(Command::PersistAlternate(b))?)
+    }
+
     /// Set whether to display pager if there's less data than
     /// available screen height
     ///

src/state.rs

@@ -143,6 +143,9 @@ pub struct PagerState {
     /// The behaviour to do when user quits the program using `q` or `Ctrl+C`
     /// See [`ExitStrategy`] for available options
     pub(crate) exit_strategy: ExitStrategy,
+    /// The behaviour to do when user quits the program using `q` or `Ctrl+C`
+    /// See [persist_alternate_screen](crate::pager::Pager::persist_alternate_screen) for more info.
+    pub(crate) persist_alternate: bool,
     /// The prompt that should be displayed to the user, formatted with the
     /// current search index and number of matches (if the search feature is enabled),
     /// and the current numbers inputted to scroll
@@ -194,6 +197,7 @@ impl PagerState {
             prompt,
             running: &minus_core::RUNMODE,
             exit_strategy: ExitStrategy::ProcessQuit,
+            persist_alternate: false,
             input_classifier: Box::<HashedEventRegister<RandomState>>::default(),
             exit_callbacks: Vec::with_capacity(5),
             message: None,