Add CommandMachine::add_alias to support custom command aliasing

crates/modalkit/src/commands.rs

@@ -113,6 +113,13 @@ impl<C: Command> CommandMachine<C> {
         self.names.insert(cmd.name(), cmd);
     }
 
+    /// Map a new alias to an existing command.
+    pub fn add_alias(&mut self, alias: &str, cmd: &str) -> Result<(), CommandError> {
+        let c = self.get(cmd)?;
+        self.aliases.insert(alias.to_owned(), c.clone());
+        Ok(())
+    }
+
     /// Generate a list of completion candidates for command names.
     pub fn complete_name(&self, prefix: &str) -> Vec<String> {
         completion_keys(&self.names, prefix)
@@ -123,11 +130,16 @@ impl<C: Command> CommandMachine<C> {
         completion_keys(&self.aliases, prefix)
     }
 
-    /// Get the previously executed command.
+    /// Get the specified command by alias or name.
+    ///
+    /// Aliases are checked first, so that [Command::add_alias] overrides can take precedence,
+    /// and then the actual command names.
+    ///
+    /// This returns [CommandError::InvalidCommand] if there is nothing mapped.
     pub fn get(&self, name: &str) -> Result<&C, CommandError> {
-        if let Some(m) = self.names.get(name) {
+        if let Some(m) = self.aliases.get(name) {
             Ok(m)
-        } else if let Some(m) = self.aliases.get(name) {
+        } else if let Some(m) = self.names.get(name) {
             Ok(m)
         } else {
             Err(CommandError::InvalidCommand(name.into()))

crates/modalkit/src/env/vim/command/mod.rs

@@ -1150,6 +1150,31 @@ mod tests {
         assert_eq!(res.unwrap(), vec![(act.clone(), ctx.clone())]);
     }
 
+    #[test]
+    fn test_alias_overrides() {
+        let (mut cmds, ctx) = mkcmd();
+
+        let exp = vec![(
+            WindowAction::Split(OpenTarget::Current, Horizontal, Previous, 1.into()).into(),
+            ctx.clone(),
+        )];
+
+        // Can overwrite an existing command name ("read") to instead map to an already
+        // existing alias name ("sp"):
+        cmds.add_alias("read", "sp").unwrap();
+        let res = cmds.input_cmd("read", ctx.clone());
+        assert_eq!(res.unwrap(), exp);
+
+        // Can overwrite an existing alias with another command name:
+        cmds.add_alias("r", "split").unwrap();
+        let res = cmds.input_cmd("r", ctx.clone());
+        assert_eq!(res.unwrap(), exp);
+
+        // Fails if the target command doesn't exist:
+        let res = cmds.add_alias("q", "foobar");
+        assert!(res.is_err());
+    }
+
     #[test]
     fn test_split_direction() {
         let (mut cmds, ctx) = mkcmd();