Implemented prefix-meta command.

2 files changed, 32 insertions, 1 deletions

diff --git a/prompt_toolkit/key_binding/bindings/named_commands.py b/prompt_toolkit/key_binding/bindings/named_commands.py
index c8588492..f72766c7 100644
--- a/prompt_toolkit/key_binding/bindings/named_commands.py
+++ b/prompt_toolkit/key_binding/bindings/named_commands.py
@@ -12,6 +12,8 @@ import six
 from .completion import generate_completions
 from prompt_toolkit.document import Document
 from prompt_toolkit.enums import EditingMode
+from prompt_toolkit.key_binding.input_processor import KeyPress
+from prompt_toolkit.keys import Keys
 
 __all__ = (
     'get_by_name',
@@ -466,3 +468,15 @@ def vi_editing_mode(event):
 def emacs_editing_mode(event):
     " Switch to Emacs editing mode. "
     event.cli.editing_mode = EditingMode.EMACS
+
+
+@register('prefix-meta')
+def prefix_meta(event):
+    """
+    Metafy the next character typed. This is for keyboards without a meta key.
+
+    Sometimes people also want to bind other keys to Meta, e.g. 'jj'::
+
+        registry.add_key_binding('j', 'j', filter=ViInsertMode())(prefix_meta)
+    """
+    event.cli.input_processor.feed(KeyPress(Keys.Escape))
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 33d55d20..ecab145d 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -28,7 +28,8 @@ def _history():
 
 
 def _feed_cli_with_input(text, editing_mode=EditingMode.EMACS, clipboard=None,
-                         history=None, multiline=False, check_line_ending=True):
+                         history=None, multiline=False, check_line_ending=True,
+                         pre_run_callback=None):
     """
     Create a CommandLineInterface, feed it with the given user input and return
     the CLI object.
@@ -54,6 +55,10 @@ def _feed_cli_with_input(text, editing_mode=EditingMode.EMACS, clipboard=None,
             eventloop=loop,
             input=inp,
             output=DummyOutput())
+
+        if pre_run_callback:
+            pre_run_callback(cli)
+
         result = cli.run()
         return result, cli
     finally:
@@ -423,6 +428,18 @@ def test_emacs_insert_comment():
     assert result.text == '#hello\n#world'
 
 
+def test_prefix_meta():
+    # Test the prefix-meta command.
+    def setup_keybindings(cli):
+        from prompt_toolkit.key_binding.bindings.named_commands import prefix_meta
+        from prompt_toolkit.filters import ViInsertMode
+        cli.application.key_bindings_registry.add_binding('j', 'j', filter=ViInsertMode())(prefix_meta)
+
+    result, cli = _feed_cli_with_input(
+        'hellojjIX\n', pre_run_callback=setup_keybindings, editing_mode=EditingMode.VI)
+    assert result.text == 'Xhello'
+
+
 def test_bracketed_paste():
     result, cli = _feed_cli_with_input('\x1b[200~hello world\x1b[201~\n')
     assert result.text == 'hello world'