rprompt implementation

CHANGELOG.rst

@@ -23,6 +23,8 @@ Current Developments
 * ``?`` and ``??`` operator output now has colored titles, like in IPython.
 * ``??`` will syntax highlight source code if pygments is available.
 * Python mode output is now syntax highlighted if pygments is available.
+* New ``$RIGHT_PROMPT`` environment variable for displaying right-aligned
+  text in prompt-toolkit shell.
 
 **Changed:**
 

xonsh/environ.py

@@ -79,6 +79,7 @@ DEFAULT_ENSURERS = {
     re.compile('\w*PATH$'): (is_env_path, str_to_env_path, env_path_to_str),
     'PATHEXT': (is_env_path, str_to_env_path, env_path_to_str),
     'RAISE_SUBPROC_ERROR': (is_bool, to_bool, bool_to_str),
+    'RIGHT_PROMPT': (is_string, ensure_string, ensure_string),
     'TEEPTY_PIPE_DELAY': (is_float, float, str),
     'XONSHRC': (is_env_path, str_to_env_path, env_path_to_str),
     'XONSH_COLOR_STYLE': (is_string, ensure_string, ensure_string),
@@ -181,6 +182,7 @@ DEFAULT_VALUES = {
     'PUSHD_MINUS': False,
     'PUSHD_SILENT': False,
     'RAISE_SUBPROC_ERROR': False,
+    'RIGHT_PROMPT': '', 
     'SHELL_TYPE': 'best',
     'SUGGEST_COMMANDS': True,
     'SUGGEST_MAX_NUM': 5,
@@ -349,6 +351,10 @@ DEFAULT_DOCS = {
         'This is most useful in xonsh scripts or modules where failures '
         'should cause an end to execution. This is less useful at a terminal.'
         'The error that is raised is a subprocess.CalledProcessError.'),
+    'RIGHT_PROMPT': VarDocs('Template string for right-aligned text '
+        'at the prompt. This may be parameterized in the same way as '
+        'the $PROMPT variable. Currently, this is only available in the '
+        'prompt-toolkit shell.'),
     'SHELL_TYPE': VarDocs(
         'Which shell is used. Currently two base shell types are supported:\n\n'
         "    - 'readline' that is backed by Python's readline module\n"

xonsh/ptk/shell.py

@@ -63,6 +63,7 @@ class PromptToolkitShell(BaseShell):
                     mouse_support=mouse_support,
                     auto_suggest=auto_suggest,
                     get_prompt_tokens=self.prompt_tokens,
+                    get_rprompt_tokens=self.rprompt_tokens,
                     style=PygmentsStyle(xonsh_style_proxy(self.styler)),
                     completer=completer,
                     lexer=PygmentsLexer(XonshLexer),
@@ -127,6 +128,20 @@ class PromptToolkitShell(BaseShell):
         self.settitle()
         return toks
 
+    def rprompt_tokens(self, cli):
+        """Returns a list of (token, str) tuples for the current right 
+        prompt.
+        """
+        p = builtins.__xonsh_env__.get('RIGHT_PROMPT')
+        if len(p) == 0:
+            return []
+        try:
+            p = partial_format_prompt(p)
+        except Exception:  # pylint: disable=broad-except
+            print_exception()
+        toks = partial_color_tokenize(p)
+        return toks
+
     def format_color(self, string, **kwargs):
         """Formats a color string using Pygments. This, therefore, returns
         a list of (Token, str) tuples.

xonsh/ptk/shortcuts.py

@@ -4,6 +4,8 @@ from prompt_toolkit.utils import DummyContext
 from prompt_toolkit.shortcuts import (create_prompt_application, 
     create_eventloop, create_asyncio_eventloop, create_output)
 
+from xonsh.shell import prompt_toolkit_version_info
+
 class Prompter(object):
 
     def __init__(self, cli=None, *args, **kwargs):
@@ -18,6 +20,7 @@ class Prompter(object):
             will be created when the prompt() method is called.
         """
         self.cli = cli
+        self.major_minor = prompt_toolkit_version_info()[:2]
 
     def __enter__(self):
         self.reset()
@@ -61,6 +64,8 @@ class Prompter(object):
 
         # Create CommandLineInterface.
         if self.cli is None:
+            if self.major_minor <= (0, 57):
+                kwargs.pop('get_rprompt_tokens', None)
             cli = CommandLineInterface(
                 application=create_prompt_application(message, **kwargs),
                 eventloop=eventloop,

xonsh/shell.py

@@ -33,6 +33,12 @@ def prompt_toolkit_version():
     return getattr(prompt_toolkit, '__version__', '<0.57')
 
 
+def prompt_toolkit_version_info():
+    """Gets the prompt toolkit version info tuple."""
+    v = prompt_toolkit_version().strip('<>+-=.')
+    return tuple(map(int, v.split('.')))
+
+
 def best_shell_type():
     """Gets the best shell type that is available"""
     if ON_WINDOWS or is_prompt_toolkit_available():