pyrc-autocomplete

pyrc.py

#!/usr/bin/env python
#
"""Python startup script."""


class IndentOrCompleteMixin(object):

    u""" Mixin to add tab completion for inserting indents.

    The idea is that a (base10) natural number (e.g. 3, 45) has no sensible
    auto-complete value. This mixin, intended for use with rlcompleter, adds
    completion for numbers. When suggesting number completions, however, this
    mixin only returns one suggestion - which is a string containing that
    number of indents.

    """

    bind_backend = {'libedit': u'bind ^I rl_complete',
                    'readline': u'tab: complete', }
    u""" The command used to bind tab to completion with different
    python readline implementations. """

    def __init__(self, indent='    '):
        u""" Initialize completer.

        :param str indent: The intent string we want (default='    ')
        """
        self.__tab = indent
        super(IndentOrCompleteMixin, self).__init__()

    @classmethod
    def get_bind_command(cls, readline_module):
        u""" Get keybind command suggestion for `readline_module'.

        Parses the docstring of `readline_module', to decide which
        implementation it is.

        :param readline_module: The imported readline module.

        :return str:
            Returns a command string that can be passed to
            `readline_module.parse_and_bind()'
        """
        if 'GNU readline' in getattr(readline_module, '__doc__', ''):
            return cls.bind_backend['readline']
        elif 'libedit' in getattr(readline_module, '__doc__', ''):
            return cls.bind_backend['libedit']

        # No match, gamble that it will work with readline command
        return cls.bind_backend['readline']

    def complete(self, text, state):
        u""" Fetch next suggestion.

        :param str text: The actual text we're completing.
        :param int state: The suggestion number

        :ref: `readline documentation <python:readline>`

        :rtype: NoneType, basestring
        :return: Suggestion string, or None if no more suggestions exist.

        """
        if text.isdigit():
            if state == 0:
                num = int(text)
                return self.__tab * num
            return None
        else:
            return super(IndentOrCompleteMixin, self).complete(text, state)

    @classmethod
    def get_completer(cls, completer=type):
        u""" Prepare a completer class with this mixin.

        :type completer: type
        :param completer:
            Use `completer' as base class. If `completer' already have `cls' in
            its bases, we do nothing (just return `completer' as is).
            If `completer' is `type' or `cls', we try to use
            `rlcompleter.Completer' as base class (this is the default).

        :return type: Returns a completer class with this mixin.
        """
        if type(completer) is not type:
            raise TypeError(
                "`completer' must be of type 'type' (not %s)" %
                type(completer))
        if completer is type or completer == cls:
            from rlcompleter import Completer as completer
        if not issubclass(completer, cls):
            completer = type('_IndentOrComplete',
                             (cls, completer, object),
                             {})
        return completer

    @classmethod
    def register(cls, *args, **kwargs):
        u""" Register with readline.

        Performs the neccessay readline magic to enable this completer in
        an interactive session.
        """
        import readline
        completer_cls = cls.get_completer()
        readline.parse_and_bind(cls.get_bind_command(readline))
        readline.set_completer(completer_cls(*args, **kwargs).complete)

if __name__ == '__main__':
    try:
        IndentOrCompleteMixin.register()
    except ImportError:
        print(u"NOTE: Unable to set up tab completion")

To use from scripts that invoke an interactive session (e.g. with code.interact()), just do execfile('/path/to/thisfile') before the interactive session is set up.