termwiz: line editor: allow embedded app to override key map

termwiz/src/lineedit/actions.rs

@@ -23,4 +23,5 @@ pub enum Action {
     HistoryPrevious,
     HistoryNext,
     Complete,
+    NoAction,
 }

termwiz/src/lineedit/host.rs

@@ -1,4 +1,6 @@
 use crate::cell::{AttributeChange, CellAttributes};
+use crate::input::InputEvent;
+use crate::lineedit::actions::Action;
 use crate::lineedit::{BasicHistory, History};
 use crate::surface::Change;
 
@@ -72,6 +74,17 @@ pub trait LineEditorHost {
     fn complete(&self, _line: &str, _cursor_position: usize) -> Vec<CompletionCandidate> {
         vec![]
     }
+
+    /// Allows the embedding application an opportunity to override or
+    /// remap keys to alternative actions.
+    /// Return `None` to indicate that the default keymap processing
+    /// should occur.
+    /// Otherwise return an `Action` enum variant indicating the action
+    /// that should be taken.
+    /// Use `Action::NoAction` to indicate that no action should be taken.
+    fn resolve_action(&self, _event: &InputEvent) -> Option<Action> {
+        None
+    }
 }
 
 /// A candidate for tab completion.

termwiz/src/lineedit/mod.rs

@@ -245,8 +245,11 @@ impl<T: Terminal> LineEditor<T> {
         self.terminal.set_cooked_mode()?;
         res
     }
+    fn resolve_action(&self, event: &InputEvent, host: &mut dyn LineEditorHost) -> Option<Action> {
+        if let Some(action) = host.resolve_action(event) {
+            return Some(action);
+        }
 
-    fn resolve_action(&self, event: &InputEvent) -> Option<Action> {
         match event {
             InputEvent::Key(KeyEvent {
                 key: KeyCode::Char('C'),
@@ -534,8 +537,9 @@ impl<T: Terminal> LineEditor<T> {
 
         self.render(host)?;
         while let Some(event) = self.terminal.poll_input(None)? {
-            match self.resolve_action(&event) {
+            match self.resolve_action(&event, host) {
                 Some(Action::Cancel) => return Ok(None),
+                Some(Action::NoAction) => {}
                 Some(Action::AcceptLine) => break,
                 Some(Action::EndOfFile) => {
                     return Err(std::io::Error::new(