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110 lines
3.6 KiB
Python
110 lines
3.6 KiB
Python
"""Word completion for GNU readline 2.0.
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This requires the latest extension to the readline module (the
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set_completer() function). When completing a simple identifier, it
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completes keywords, built-ins and globals in __main__; when completing
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NAME.NAME..., it evaluates (!) the expression up to the last dot and
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completes its attributes.
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It's very cool to do "import string" type "string.", hit the
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completion key (twice), and see the list of names defined by the
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string module!
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Tip: to use the tab key as the completion key, call
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readline.parse_and_bind("tab: complete")
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Notes:
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- Exceptions raised by the completer function are *ignored* (and
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generally cause the completion to fail). This is a feature -- since
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readline sets the tty device in raw (or cbreak) mode, printing a
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traceback wouldn't work well without some complicated hoopla to save,
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reset and restore the tty state.
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- The evaluation of the NAME.NAME... form may cause arbitrary
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application defined code to be executed if an object with a
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__getattr__ hook is found. Since it is the responsibility of the
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application (or the user) to enable this feature, I consider this an
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acceptable risk. More complicated expressions (e.g. function calls or
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indexing operations) are *not* evaluated.
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- GNU readline is also used by the built-in functions input() and
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raw_input(), and thus these also benefit/suffer from the completer
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features. Clearly an interactive application can benefit by
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specifying its own completer function and using raw_input() for all
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its input.
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- When the original stdin is not a tty device, GNU readline is never
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used, and this module (and the readline module) are silently inactive.
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"""
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import readline
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import __builtin__
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import __main__
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class Completer:
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def complete(self, text, state):
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"""Return the next possible completion for 'text'.
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This is called successively with state == 0, 1, 2, ... until it
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returns None. The completion should begin with 'text'.
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"""
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if state == 0:
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if "." in text:
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self.matches = self.attr_matches(text)
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else:
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self.matches = self.global_matches(text)
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try:
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return self.matches[state]
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except IndexError:
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return None
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def global_matches(self, text):
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"""Compute matches when text is a simple name.
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Return a list of all keywords, built-in functions and names
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currently defines in __main__ that match.
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"""
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import keyword
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matches = []
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n = len(text)
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for list in [keyword.kwlist,
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__builtin__.__dict__.keys(),
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__main__.__dict__.keys()]:
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for word in list:
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if word[:n] == text:
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matches.append(word)
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return matches
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def attr_matches(self, text):
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"""Compute matches when text contains a dot.
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Assuming the text is of the form NAME.NAME....[NAME], and is
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evaluabable in the globals of __main__, it will be evaluated
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and its attributes (as revealed by dir()) are used as possible
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completions.
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WARNING: this can still invoke arbitrary C code, if an object
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with a __getattr__ hook is evaluated.
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"""
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import re
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m = re.match(r"(\w+(\.\w+)*)\.(\w*)", text)
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if not m:
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return
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expr, attr = m.group(1, 3)
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words = dir(eval(expr, __main__.__dict__))
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matches = []
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n = len(attr)
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for word in words:
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if word[:n] == attr:
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matches.append("%s.%s" % (expr, word))
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return matches
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readline.set_completer(Completer().complete)
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