Add % current file register

Useful to open files relative to current file.

helix-core/src/register.rs

@@ -57,6 +57,10 @@ impl Registers {
         }
     }
 
+    pub fn clear(&mut self, name: char) {
+        self.inner.remove(&name);
+    }
+
     pub fn push(&mut self, name: char, value: String) {
         if name != '_' {
             if let Some(r) = self.inner.get_mut(&name) {

helix-term/src/commands.rs

@@ -4418,6 +4418,7 @@ fn wonly(cx: &mut Context) {
 }
 
 fn select_register(cx: &mut Context) {
+    cx.editor.update_registers();
     cx.editor.autoinfo = Some(Info::from_registers(&cx.editor.registers));
     cx.on_next_key(move |cx, event| {
         if let Some(ch) = event.char() {
@@ -4428,6 +4429,7 @@ fn select_register(cx: &mut Context) {
 }
 
 fn insert_register(cx: &mut Context) {
+    cx.editor.update_registers();
     cx.editor.autoinfo = Some(Info::from_registers(&cx.editor.registers));
     cx.on_next_key(move |cx, event| {
         if let Some(ch) = event.char() {

helix-term/src/ui/prompt.rs

@@ -592,6 +592,7 @@ impl Component for Prompt {
             }
             ctrl!('q') => self.exit_selection(),
             ctrl!('r') => {
+                cx.editor.update_registers();
                 self.completion = cx
                     .editor
                     .registers

helix-view/src/editor.rs

@@ -1469,6 +1469,17 @@ impl Editor {
             doc.restore_cursor = false;
         }
     }
+
+    /// Update read-only registers.
+    pub fn update_registers(&mut self) {
+        let doc = doc!(self);
+        if let Some(path) = doc.relative_path() {
+            self.registers
+                .write('%', vec![path.to_string_lossy().to_string()]);
+        } else {
+            self.registers.clear('%');
+        }
+    }
 }
 
 fn try_restore_indent(doc: &mut Document, view: &mut View) {