"""A copy of Python's rlcompleter module that removes all interaction with the readline module. This is a trivial modification of rlcompleter.py from Python 3.9, which is licensed under the Python Software Foundation License Version 2. This plainCompleter module is designed for use in Regina's GUI, which uses Python subinterpreters. The readline module does not play well with subinterpreters (due to the way it interacts with the GIL), and in some settings this results in a completely reproducible deadlock. Such settings include openSUSE Leap 15.2, and macOS 11.0 using the Python3 that is shipped with Xcode. This plainCompleter module still offers a Completer class (which is all that the GUI needs), but it does not offer full readline functionality at the command line. Crucially, importing this module will never attempt to import the readline module as a side-effect. Python's own rlcompleter documentation continues from here. 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 __main__ # The original rlcompleter simply imports the builtins module. # However, we need to maintain compatibility with python 2 also. try: import builtins except: import __builtin__ as builtins __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 # Regina's edits are here. # Instead of trying to import the readline module, we just ignore it # and treat this module as a standalone completion tool. _readline_available = False