enable tabs for readline if tab completion is not enabled

documentation updates

add test

Author: Trott

doc/api/readline.markdown

@@ -41,6 +41,10 @@ the following values:
 
  - `historySize` - maximum number of history lines retained. Defaults to `30`.
 
+If a `completer` function is supplied, the user will not be able to enter tab
+characters as part of their input. If no `completer` function is supplied, tabs
+will be permitted in user input.
+
 The `completer` function is given the current line entered by the user, and
 is supposed to return an Array with 2 entries:
 

lib/readline.js

@@ -47,9 +47,9 @@ function Interface(input, output, completer, terminal) {
   }
   historySize = historySize || kHistorySize;
 
-  completer = completer || function() { return []; };
+  completer = completer || undefined;
 
-  if (typeof completer !== 'function') {
+  if (! typeof completer in ['function', 'undefined']) {
     throw new TypeError('Argument \'completer\' must be a function');
   }
 
@@ -72,9 +72,12 @@ function Interface(input, output, completer, terminal) {
   this.historySize = historySize;
 
   // Check arity, 2 - for async, 1 for sync
-  this.completer = completer.length === 2 ? completer : function(v, callback) {
-    callback(null, completer(v));
-  };
+  if (typeof completer === 'function') {
+    this.completer = completer.length === 2 ? 
+      completer : function(v, callback) {
+        callback(null, completer(v));
+      };
+  }
 
   this.setPrompt('> ');
 
@@ -344,9 +347,6 @@ Interface.prototype._normalWrite = function(b) {
 };
 
 Interface.prototype._insertString = function(c) {
-  //BUG: Problem when adding tabs with following content.
-  //     Perhaps the bug is in _refreshLine(). Not sure.
-  //     A hack would be to insert spaces instead of literal '\t'.
   if (this.cursor < this.line.length) {
     var beg = this.line.slice(0, this.cursor);
     var end = this.line.slice(this.cursor, this.line.length);
@@ -839,10 +839,6 @@ Interface.prototype._ttyWrite = function(s, key) {
         this._deleteRight();
         break;
 
-      case 'tab': // tab completion
-        this._tabComplete();
-        break;
-
       case 'left':
         this._moveCursor(-1);
         break;
@@ -868,6 +864,14 @@ Interface.prototype._ttyWrite = function(s, key) {
         break;
 
       default:
+        if (key.name === 'tab') {
+          // If tab completion enabled, do that...
+          if (typeof this.completer === 'function') {
+            this._tabComplete();
+            break;
+          }
+        }
+
         if (s instanceof Buffer)
           s = s.toString('utf-8');
 

test/parallel/test-readline-interface.js

@@ -175,6 +175,21 @@ function isWarned(emitter) {
   assert.equal(callCount, expectedLines.length);
   rli.close();
 
+  // \t when there is no completer function should behave like an ordinary 
+  //   character
+  fi = new FakeInput();
+  rli = new readline.Interface({ input: fi, output: fi, terminal: true });
+  expectedLines = ['\t'];
+  callCount = 0;
+  rli.on('line', function(line) {
+    assert.equal(line, expectedLines[callCount]);
+    callCount++;
+  });
+  fi.emit('data', '\t');
+  fi.emit('data', '\n');
+  assert.equal(callCount, expectedLines.length);
+  rli.close();
+
   // sending a multi-byte utf8 char over multiple writes
   var buf = Buffer('☮', 'utf8');
   fi = new FakeInput();