nu-explore/ A few fixes. (#7334)

close #7322
close #7323

Signed-off-by: Maxim Zhiburt <zhiburt@gmail.com>

crates/nu-explore/src/events.rs

@@ -48,4 +48,15 @@ impl UIEvents {
             Err(err) => Err(err),
         }
     }
+
+    pub fn try_next(&self) -> Result<Option<KeyEvent>> {
+        match poll(Duration::default()) {
+            Ok(true) => match read()? {
+                Event::Key(event) => Ok(Some(event)),
+                _ => Ok(None),
+            },
+            Ok(false) => Ok(None),
+            Err(err) => Err(err),
+        }
+    }
 }

crates/nu-explore/src/nu_common/command.rs

@@ -11,8 +11,8 @@ pub fn run_nu_command(
     cmd: &str,
     current: PipelineData,
 ) -> std::result::Result<PipelineData, ShellError> {
-    let engine_state = engine_state.clone();
-    eval_source2(&engine_state, stack, cmd.as_bytes(), "", current)
+    let mut engine_state = engine_state.clone();
+    eval_source2(&mut engine_state, stack, cmd.as_bytes(), "", current)
 }
 
 pub fn is_ignored_command(command: &str) -> bool {
@@ -20,13 +20,13 @@ pub fn is_ignored_command(command: &str) -> bool {
 }
 
 fn eval_source2(
-    engine_state: &EngineState,
+    engine_state: &mut EngineState,
     stack: &mut Stack,
     source: &[u8],
     fname: &str,
     input: PipelineData,
 ) -> Result<PipelineData, ShellError> {
-    let (mut block, _) = {
+    let (mut block, delta) = {
         let mut working_set = StateWorkingSet::new(engine_state);
         let (output, err) = parse(
             &mut working_set,
@@ -35,6 +35,7 @@ fn eval_source2(
             false,
             &[],
         );
+
         if let Some(err) = err {
             return Err(ShellError::IOError(err.to_string()));
         }
@@ -42,6 +43,11 @@ fn eval_source2(
         (output, working_set.render())
     };
 
+    // We need to merge different info other wise things like PIPEs etc will not work.
+    if let Err(err) = engine_state.merge_delta(delta) {
+        return Err(ShellError::IOError(err.to_string()));
+    }
+
     // eval_block outputs all expressions expept the last to STDOUT;
     // we don't wont that.
     //

crates/nu-explore/src/pager.rs

@@ -432,7 +432,7 @@ fn highlight_search_results(f: &mut Frame, pager: &Pager, layout: &Layout, style
 }
 
 #[allow(clippy::too_many_arguments)]
-fn handle_events<V>(
+fn handle_events<V: View>(
     engine_state: &EngineState,
     stack: &mut Stack,
     events: &UIEvents,
@@ -441,15 +441,64 @@ fn handle_events<V>(
     search: &mut SearchBuf,
     command: &mut CommandBuf,
     mut view: Option<&mut V>,
-) -> (bool, bool)
-where
-    V: View,
-{
+) -> (bool, bool) {
     let key = match events.next() {
         Ok(Some(key)) => key,
         _ => return (false, false),
     };
 
+    let result = handle_event(
+        engine_state,
+        stack,
+        layout,
+        info,
+        search,
+        command,
+        view.as_deref_mut(),
+        key,
+    );
+
+    if let (true, _) = result {
+        return result;
+    }
+
+    // Sometimes we get a BIG list of events;
+    // for example when someone scrolls via a mouse either UP or DOWN.
+    // This MIGHT causes freeses as we have a 400 delay for a next command read.
+    //
+    // To eliminate that we are trying ot read all possible commands which we should action upon.
+
+    while let Ok(Some(key)) = events.try_next() {
+        let result = handle_event(
+            engine_state,
+            stack,
+            layout,
+            info,
+            search,
+            command,
+            view.as_deref_mut(),
+            key,
+        );
+
+        if let (true, _) = result {
+            return result;
+        }
+    }
+
+    result
+}
+
+#[allow(clippy::too_many_arguments)]
+fn handle_event<V: View>(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    layout: &Layout,
+    info: &mut ViewInfo,
+    search: &mut SearchBuf,
+    command: &mut CommandBuf,
+    mut view: Option<&mut V>,
+    key: KeyEvent,
+) -> (bool, bool) {
     if handle_exit_key_event(&key) {
         return (true, true);
     }
@@ -472,7 +521,6 @@ where
     }
 
     // was not handled so we must check our default controlls
-
     handle_general_key_events2(&key, search, command, view, info);
 
     (false, false)

crates/nu-explore/src/views/preview.rs

@@ -84,6 +84,12 @@ impl View for Preview {
                 Some(Transition::Ok)
             }
             KeyCode::Up => {
+                let is_start = self.i_row == 0;
+                if is_start {
+                    // noop
+                    return Some(Transition::Ok);
+                }
+
                 let page_size = layout.data.len();
                 let max = self.lines.len().saturating_sub(page_size);
                 let was_end = self.i_row == max;
@@ -99,6 +105,13 @@ impl View for Preview {
             KeyCode::Down => {
                 let page_size = layout.data.len();
                 let max = self.lines.len().saturating_sub(page_size);
+
+                let is_end = self.i_row == max;
+                if is_end {
+                    // noop
+                    return Some(Transition::Ok);
+                }
+
                 self.i_row = min(self.i_row + 1, max);
 
                 let is_end = self.i_row == max;