Add help auto-complete, update readme

README.md

@@ -11,7 +11,8 @@ Currently:
 
 * Parsing of string command input into an argv array
 * Multi-line commands
-* Tab auto-complete for commands based on available commands
+* Tab auto-complete to choose command to run
+* Custom tab auto-complete implementation for command-specific arguments
 * API and Model for creating and loading your own commands
 * Flexible error handling
 * Custom PS1 and PS2 prompts
@@ -236,6 +237,12 @@ unknown$ iam branden
 branden$ quit
 ```
 
+### Custom Auto-complete
+
+It is possible to implement auto-complete for your custom commands. Provide an `autocomplete` function in your command implementation that takes a `session`, `args` array and `callback([err], [replacementsArray])`.
+
+See the [readline auto-complete explanation](https://github.com/mrvisser/node-readcommand#auto-complete) for more details, and the [help command](https://github.com/mrvisser/node-corporal/blob/master/commands/help.js) contains a reference implementation that returns auto-completions for command names for which to show help.
+
 ### Command Contexts
 
 It is possible to filter the commands available based on a custom context. For example, if your shell application requires authentication, you may want to provide some commands only to users when they are authenticated. Contexts allow you to accomplish this.

commands/help.js

@@ -85,6 +85,19 @@ module.exports = {
         }
 
         return callback();
+    },
+    'autocomplete': function(session, args, callback) {
+        if (args.length !== 1) {
+            return callback();
+        }
+
+        // Filter by command names
+        return callback(null, _.chain(session.commands().get())
+            .keys()
+            .filter(function(commandName) {
+                return (commandName.indexOf(args[0]) === 0);
+            })
+            .value());
     }
 };
 

lib/util.js

@@ -195,6 +195,9 @@ function _createPs(session, psVar) {
  */
 function _createAutocomplete(session) {
     return function(args, callback) {
+        args = args.slice();
+
+        // First handle the case where this is an auto-suggest based on finding the command name
         var allCommandNames = _.keys(session.commands().get());
         if (_.isEmpty(args)) {
             return callback(null, allCommandNames);
@@ -204,6 +207,14 @@ function _createAutocomplete(session) {
             }));
         }
 
+        // We presumably have a command argument already, feed the remaining arguments into the
+        // commands autocomplete implementation
+        var commandName = args.shift();
+        var command = session.commands().get(commandName);
+        if (command && _.isFunction(command.autocomplete)) {
+            return command.autocomplete(session, args, callback);
+        }
+
         return callback(null, []);
     };
 }