gh-102130: Support a tab completion for Libedit in cmd, site, and pdb.

Doc/library/cmd.rst

@@ -15,15 +15,15 @@ command interpreters.  These are often useful for test harnesses, administrative
 tools, and prototypes that will later be wrapped in a more sophisticated
 interface.
 
-.. class:: Cmd(completekey='tab', stdin=None, stdout=None)
+.. class:: Cmd(completekey=r'"\t"', stdin=None, stdout=None)
 
    A :class:`Cmd` instance or subclass instance is a line-oriented interpreter
    framework.  There is no good reason to instantiate :class:`Cmd` itself; rather,
    it's useful as a superclass of an interpreter class you define yourself in order
    to inherit :class:`Cmd`'s methods and encapsulate action methods.
 
    The optional argument *completekey* is the :mod:`readline` name of a completion
-   key; it defaults to :kbd:`Tab`. If *completekey* is not :const:`None` and
+   key; it defaults to "\\t"(:kbd:`tab`). If *completekey* is not :const:`None` and
    :mod:`readline` is available, command completion is done automatically.
 
    The optional arguments *stdin* and *stdout* specify the  input and output file

Doc/library/pdb.rst

@@ -183,7 +183,7 @@ The ``run*`` functions and :func:`set_trace` are aliases for instantiating the
 :class:`Pdb` class and calling the method of the same name.  If you want to
 access further features, you have to do this yourself:
 
-.. class:: Pdb(completekey='tab', stdin=None, stdout=None, skip=None, \
+.. class:: Pdb(completekey=r'"\t"', stdin=None, stdout=None, skip=None, \
                nosigint=False, readrc=True)
 
    :class:`Pdb` is the debugger class.

Doc/library/readline.rst

@@ -17,6 +17,21 @@ made using  this module affect the behaviour of both the interpreter's
 interactive prompt  and the prompts offered by the built-in :func:`input`
 function.
 
+Compatible keybindings
+----------------------
+
+To support compatible keybindings between GNU readline and Libedit, use the
+following backslashed escape sequences or octal escape sequences in quotes. ::
+
+  \a     bell
+  \b     backspace
+  \f     form feed
+  \n     newline
+  \r     carriage return
+  \t     horizontal tab
+  \v     vertical tab
+  \nnn   octal escape sequences
+
 Readline keybindings may be configured via an initialization file, typically
 ``.inputrc`` in your home directory.  See `Readline Init File
 <https://tiswww.cwru.edu/php/chet/readline/rluserman.html#Readline-Init-File>`_
@@ -39,10 +54,10 @@ Readline library in general.
   If you use *editline*/``libedit`` readline emulation on macOS, the
   initialization file located in your home directory is named
   ``.editrc``. For example, the following content in ``~/.editrc`` will
-  turn ON *vi* keybindings and TAB completion::
+  turn ON *vi* keybindings and "\\t"(:kbd:`tab`) completion::
 
     python:bind -v
-    python:bind ^I rl_complete
+    python:bind "\t" rl_complete
 
 
 Init file
@@ -56,6 +71,16 @@ The following functions relate to the init file and user configuration:
    Execute the init line provided in the *string* argument. This calls
    :c:func:`rl_parse_and_bind` in the underlying library.
 
+.. note::
+   The syntax and command of *string* argument may be different depends on the readline library.
+
+   For GNU readline::
+
+    readline.parse_and_bind(r'"\t": complete')
+
+   For Libedit::
+
+    readline.parse_and_bind(r'bind "\t" rl_complete')
 
 .. function:: read_init_file([filename])
 
@@ -348,7 +373,12 @@ support history save/restore. ::
            self.init_history(histfile)
 
        def init_history(self, histfile):
-           readline.parse_and_bind("tab: complete")
+
+            readline_doc = getattr(readline, '__doc__', '')
+            if readline_doc is not None and 'libedit' in readline_doc:
+                readline.parse_and_bind(r'bind "\t" rl_complete')
+            else:
+               readline.parse_and_bind(r'"\t": complete')
            if hasattr(readline, "read_history_file"):
                try:
                    readline.read_history_file(histfile)

Doc/library/rlcompleter.rst

@@ -21,7 +21,7 @@ Example::
 
    >>> import rlcompleter
    >>> import readline
-   >>> readline.parse_and_bind("tab: complete")
+   >>> readline.parse_and_bind(r'"\t": complete')
    >>> readline. <TAB PRESSED>
    readline.__doc__          readline.get_line_buffer(  readline.read_init_file(
    readline.__file__         readline.insert_text(      readline.set_completer(

Lib/cmd.py

@@ -73,7 +73,7 @@ class Cmd:
     nohelp = "*** No help on %s"
     use_rawinput = 1
 
-    def __init__(self, completekey='tab', stdin=None, stdout=None):
+    def __init__(self, completekey='"\t"', stdin=None, stdout=None):
         """Instantiate a line-oriented interpreter framework.
 
         The optional argument 'completekey' is the readline name of a
@@ -108,7 +108,11 @@ def cmdloop(self, intro=None):
                 import readline
                 self.old_completer = readline.get_completer()
                 readline.set_completer(self.complete)
-                readline.parse_and_bind(self.completekey+": complete")
+                readline_doc = getattr(readline, '__doc__', '')
+                if readline_doc is not None and 'libedit' in readline_doc:
+                    readline.parse_and_bind("bind "+self.completekey+" rl_complete")
+                else:
+                    readline.parse_and_bind(self.completekey+": complete")
             except ImportError:
                 pass
         try:

Lib/pdb.py

@@ -209,7 +209,7 @@ class Pdb(bdb.Bdb, cmd.Cmd):
 
     _previous_sigint_handler = None
 
-    def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None,
+    def __init__(self, completekey=r'"\t"', stdin=None, stdout=None, skip=None,
                  nosigint=False, readrc=True):
         bdb.Bdb.__init__(self, skip=skip)
         cmd.Cmd.__init__(self, completekey, stdin, stdout)

Lib/site.py

@@ -446,9 +446,9 @@ def register_readline():
         # completion key, so we set one first and then read the file.
         readline_doc = getattr(readline, '__doc__', '')
         if readline_doc is not None and 'libedit' in readline_doc:
-            readline.parse_and_bind('bind ^I rl_complete')
+            readline.parse_and_bind(r'bind "\t" rl_complete')
         else:
-            readline.parse_and_bind('tab: complete')
+            readline.parse_and_bind(r'"\t": complete')
 
         try:
             readline.read_init_file()

Misc/ACKS

@@ -784,6 +784,7 @@ Thomas Holmes
 Craig Holmquist
 Philip Homburg
 Naofumi Honda
+Constantin Hong
 Weipeng Hong
 Jeffrey Honig
 Rob Hooft

Misc/NEWS.d/next/Library/2023-08-07-19-57-34.gh-issue-102130._UyI5i.rst

@@ -0,0 +1 @@
+Support a tab completion for Libedit in :mod:`cmd `, :mod:`site`, and :mod:`pdb`.