add fallback onNextKey

adds a variant of on_next_key callbacks that are only called when no other
mapping matches a key

helix-term/src/commands.rs

@@ -78,6 +78,11 @@ use grep_searcher::{sinks, BinaryDetection, SearcherBuilder};
 use ignore::{DirEntry, WalkBuilder, WalkState};
 
 pub type OnKeyCallback = Box<dyn FnOnce(&mut Context, KeyEvent)>;
+#[derive(PartialEq, Eq, Clone, Copy, Debug)]
+pub enum OnKeyCallbackKind {
+    PseudoPending,
+    Fallback,
+}
 
 pub struct Context<'a> {
     pub register: Option<char>,
@@ -85,7 +90,7 @@ pub struct Context<'a> {
     pub editor: &'a mut Editor,
 
     pub callback: Vec<crate::compositor::Callback>,
-    pub on_next_key_callback: Option<OnKeyCallback>,
+    pub on_next_key_callback: Option<(OnKeyCallback, OnKeyCallbackKind)>,
     pub jobs: &'a mut Jobs,
 }
 
@@ -111,7 +116,19 @@ impl<'a> Context<'a> {
         &mut self,
         on_next_key_callback: impl FnOnce(&mut Context, KeyEvent) + 'static,
     ) {
-        self.on_next_key_callback = Some(Box::new(on_next_key_callback));
+        self.on_next_key_callback = Some((
+            Box::new(on_next_key_callback),
+            OnKeyCallbackKind::PseudoPending,
+        ));
+    }
+
+    #[inline]
+    pub fn on_next_key_fallback(
+        &mut self,
+        on_next_key_callback: impl FnOnce(&mut Context, KeyEvent) + 'static,
+    ) {
+        self.on_next_key_callback =
+            Some((Box::new(on_next_key_callback), OnKeyCallbackKind::Fallback));
     }
 
     #[inline]

helix-term/src/ui/editor.rs

@@ -1,5 +1,5 @@
 use crate::{
-    commands::{self, OnKeyCallback},
+    commands::{self, OnKeyCallback, OnKeyCallbackKind},
     compositor::{Component, Context, Event, EventResult},
     events::{OnModeSwitch, PostCommand},
     key,
@@ -38,7 +38,7 @@ use super::{completion::CompletionItem, statusline};
 
 pub struct EditorView {
     pub keymaps: Keymaps,
-    on_next_key: Option<OnKeyCallback>,
+    on_next_key: Option<(OnKeyCallback, OnKeyCallbackKind)>,
     pseudo_pending: Vec<KeyEvent>,
     pub(crate) last_insert: (commands::MappableCommand, Vec<InsertEvent>),
     pub(crate) completion: Option<Completion>,
@@ -891,8 +891,10 @@ impl EditorView {
         if let Some(keyresult) = self.handle_keymap_event(Mode::Insert, cx, event) {
             match keyresult {
                 KeymapResult::NotFound => {
-                    if let Some(ch) = event.char() {
-                        commands::insert::insert_char(cx, ch)
+                    if !self.on_next_key(OnKeyCallbackKind::Fallback, cx, event) {
+                        if let Some(ch) = event.char() {
+                            commands::insert::insert_char(cx, ch)
+                        }
                     }
                 }
                 KeymapResult::Cancelled(pending) => {
@@ -982,7 +984,10 @@ impl EditorView {
                 // set the register
                 cxt.register = cxt.editor.selected_register.take();
 
-                self.handle_keymap_event(mode, cxt, event);
+                let res = self.handle_keymap_event(mode, cxt, event);
+                if matches!(&res, Some(KeymapResult::NotFound)) {
+                    self.on_next_key(OnKeyCallbackKind::Fallback, cxt, event);
+                }
                 if self.keymaps.pending().is_empty() {
                     cxt.editor.count = None
                 } else {
@@ -1258,6 +1263,24 @@ impl EditorView {
             _ => EventResult::Ignored(None),
         }
     }
+    fn on_next_key(
+        &mut self,
+        kind: OnKeyCallbackKind,
+        ctx: &mut commands::Context,
+        event: KeyEvent,
+    ) -> bool {
+        if let Some((on_next_key, kind_)) = self.on_next_key.take() {
+            if kind == kind_ {
+                on_next_key(ctx, event);
+                true
+            } else {
+                self.on_next_key = Some((on_next_key, kind_));
+                false
+            }
+        } else {
+            false
+        }
+    }
 }
 
 impl Component for EditorView {
@@ -1308,10 +1331,7 @@ impl Component for EditorView {
 
                 let mode = cx.editor.mode();
 
-                if let Some(on_next_key) = self.on_next_key.take() {
-                    // if there's a command waiting input, do that first
-                    on_next_key(&mut cx, key);
-                } else {
+                if !self.on_next_key(OnKeyCallbackKind::PseudoPending, &mut cx, key) {
                     match mode {
                         Mode::Insert => {
                             // let completion swallow the event if necessary
@@ -1361,8 +1381,8 @@ impl Component for EditorView {
 
                 self.on_next_key = cx.on_next_key_callback.take();
                 match self.on_next_key {
-                    Some(_) => self.pseudo_pending.push(key),
-                    None => self.pseudo_pending.clear(),
+                    Some((_, OnKeyCallbackKind::PseudoPending)) => self.pseudo_pending.push(key),
+                    _ => self.pseudo_pending.clear(),
                 }
 
                 // appease borrowck