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- """Word completion for GNU readline.
- The completer completes keywords, built-ins and globals in a selectable
- namespace (which defaults to __main__); when completing NAME.NAME..., it
- evaluates (!) the expression up to the last dot and completes its attributes.
- It's very cool to do "import sys" type "sys.", hit the completion key (twice),
- and see the list of names defined by the sys module!
- Tip: to use the tab key as the completion key, call
- readline.parse_and_bind("tab: complete")
- Notes:
- - Exceptions raised by the completer function are *ignored* (and generally cause
- the completion to fail). This is a feature -- since readline sets the tty
- device in raw (or cbreak) mode, printing a traceback wouldn't work well
- without some complicated hoopla to save, reset and restore the tty state.
- - The evaluation of the NAME.NAME... form may cause arbitrary application
- defined code to be executed if an object with a __getattr__ hook is found.
- Since it is the responsibility of the application (or the user) to enable this
- feature, I consider this an acceptable risk. More complicated expressions
- (e.g. function calls or indexing operations) are *not* evaluated.
- - When the original stdin is not a tty device, GNU readline is never
- used, and this module (and the readline module) are silently inactive.
- """
- import atexit
- import builtins
- import __main__
- __all__ = ["Completer"]
- class Completer:
- def __init__(self, namespace = None):
- """Create a new completer for the command line.
- Completer([namespace]) -> completer instance.
- If unspecified, the default namespace where completions are performed
- is __main__ (technically, __main__.__dict__). Namespaces should be
- given as dictionaries.
- Completer instances should be used as the completion mechanism of
- readline via the set_completer() call:
- readline.set_completer(Completer(my_namespace).complete)
- """
- if namespace and not isinstance(namespace, dict):
- raise TypeError('namespace must be a dictionary')
- # Don't bind to namespace quite yet, but flag whether the user wants a
- # specific namespace or to use __main__.__dict__. This will allow us
- # to bind to __main__.__dict__ at completion time, not now.
- if namespace is None:
- self.use_main_ns = 1
- else:
- self.use_main_ns = 0
- self.namespace = namespace
- def complete(self, text, state):
- """Return the next possible completion for 'text'.
- This is called successively with state == 0, 1, 2, ... until it
- returns None. The completion should begin with 'text'.
- """
- if self.use_main_ns:
- self.namespace = __main__.__dict__
- if not text.strip():
- if state == 0:
- if _readline_available:
- readline.insert_text('\t')
- readline.redisplay()
- return ''
- else:
- return '\t'
- else:
- return None
- if state == 0:
- if "." in text:
- self.matches = self.attr_matches(text)
- else:
- self.matches = self.global_matches(text)
- try:
- return self.matches[state]
- except IndexError:
- return None
- def _callable_postfix(self, val, word):
- if callable(val):
- word = word + "("
- return word
- def global_matches(self, text):
- """Compute matches when text is a simple name.
- Return a list of all keywords, built-in functions and names currently
- defined in self.namespace that match.
- """
- import keyword
- matches = []
- seen = {"__builtins__"}
- n = len(text)
- for word in keyword.kwlist:
- if word[:n] == text:
- seen.add(word)
- if word in {'finally', 'try'}:
- word = word + ':'
- elif word not in {'False', 'None', 'True',
- 'break', 'continue', 'pass',
- 'else'}:
- word = word + ' '
- matches.append(word)
- for nspace in [self.namespace, builtins.__dict__]:
- for word, val in nspace.items():
- if word[:n] == text and word not in seen:
- seen.add(word)
- matches.append(self._callable_postfix(val, word))
- return matches
- def attr_matches(self, text):
- """Compute matches when text contains a dot.
- Assuming the text is of the form NAME.NAME....[NAME], and is
- evaluable in self.namespace, it will be evaluated and its attributes
- (as revealed by dir()) are used as possible completions. (For class
- instances, class members are also considered.)
- WARNING: this can still invoke arbitrary C code, if an object
- with a __getattr__ hook is evaluated.
- """
- import re
- m = re.match(r"(\w+(\.\w+)*)\.(\w*)", text)
- if not m:
- return []
- expr, attr = m.group(1, 3)
- try:
- thisobject = eval(expr, self.namespace)
- except Exception:
- return []
- # get the content of the object, except __builtins__
- words = set(dir(thisobject))
- words.discard("__builtins__")
- if hasattr(thisobject, '__class__'):
- words.add('__class__')
- words.update(get_class_members(thisobject.__class__))
- matches = []
- n = len(attr)
- if attr == '':
- noprefix = '_'
- elif attr == '_':
- noprefix = '__'
- else:
- noprefix = None
- while True:
- for word in words:
- if (word[:n] == attr and
- not (noprefix and word[:n+1] == noprefix)):
- match = "%s.%s" % (expr, word)
- try:
- val = getattr(thisobject, word)
- except Exception:
- pass # Include even if attribute not set
- else:
- match = self._callable_postfix(val, match)
- matches.append(match)
- if matches or not noprefix:
- break
- if noprefix == '_':
- noprefix = '__'
- else:
- noprefix = None
- matches.sort()
- return matches
- def get_class_members(klass):
- ret = dir(klass)
- if hasattr(klass,'__bases__'):
- for base in klass.__bases__:
- ret = ret + get_class_members(base)
- return ret
- try:
- import readline
- except ImportError:
- _readline_available = False
- else:
- readline.set_completer(Completer().complete)
- # Release references early at shutdown (the readline module's
- # contents are quasi-immortal, and the completer function holds a
- # reference to globals).
- atexit.register(lambda: readline.set_completer(None))
- _readline_available = True
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