Add an init method to KeyMaps

src/context.rs

@@ -110,7 +110,7 @@ impl Context {
             let mut ed = Editor::new_with_init_buffer(stdout, prompt, f, self, buffer)?;
             match self.key_bindings {
                 KeyBindings::Emacs => Self::handle_keys(keymap::Emacs::new(), ed, handler),
-                KeyBindings::Vi => Self::handle_keys(keymap::Vi::new(&mut ed), ed, handler),
+                KeyBindings::Vi => Self::handle_keys(keymap::Vi::new(), ed, handler),
             }
         };
 
@@ -123,6 +123,7 @@ impl Context {
         mut ed: Editor<'a, W>,
         handler: &mut C,
     ) -> io::Result<String> {
+        keymap.init(&mut ed);
         for c in stdin().keys() {
             if keymap.handle_key(c.unwrap(), &mut ed, handler)? {
                 break;

src/keymap/emacs.rs

@@ -12,15 +12,14 @@ use KeyMap;
 /// let mut context = Context::new();
 /// context.key_bindings = KeyBindings::Emacs;
 /// ```
+#[derive(Default)]
 pub struct Emacs {
     last_arg_fetch_index: Option<usize>,
 }
 
 impl Emacs {
     pub fn new() -> Self {
-        Emacs {
-            last_arg_fetch_index: None,
-        }
+        Self::default()
     }
 
     fn handle_ctrl_key<'a, W: Write>(&mut self, c: char, ed: &mut Editor<'a, W>) -> io::Result<()> {

src/keymap/mod.rs

@@ -4,13 +4,15 @@ use std::io::{self, ErrorKind, Write};
 use termion::event::Key;
 use Editor;
 
-pub trait KeyMap {
+pub trait KeyMap: Default {
     fn handle_key_core<'a, W: Write>(
         &mut self,
         key: Key,
         editor: &mut Editor<'a, W>,
     ) -> io::Result<()>;
 
+    fn init<'a, W: Write>(&mut self, _editor: &mut Editor<'a, W>) {}
+
     fn handle_key<'a, W: Write, C: Completer<W>>(
         &mut self,
         mut key: Key,
@@ -84,6 +86,7 @@ mod tests {
     use termion::event::Key::*;
     use Context;
 
+    #[derive(Default)]
     struct TestKeyMap;
 
     impl KeyMap for TestKeyMap {