1 """Word completion for GNU readline. 2 3 The completer completes keywords, built-ins and globals in a selectable 4 namespace (which defaults to __main__); when completing NAME.NAME..., it 5 evaluates (!) the expression up to the last dot and completes its attributes. 6 7 It's very cool to do "import sys" type "sys.", hit the completion key (twice), 8 and see the list of names defined by the sys module! 9 10 Tip: to use the tab key as the completion key, call 11 12 readline.parse_and_bind("tab: complete") 13 14 Notes: 15 16 - Exceptions raised by the completer function are *ignored* (and generally cause 17 the completion to fail). This is a feature -- since readline sets the tty 18 device in raw (or cbreak) mode, printing a traceback wouldn't work well 19 without some complicated hoopla to save, reset and restore the tty state. 20 21 - The evaluation of the NAME.NAME... form may cause arbitrary application 22 defined code to be executed if an object with a __getattr__ hook is found. 23 Since it is the responsibility of the application (or the user) to enable this 24 feature, I consider this an acceptable risk. More complicated expressions 25 (e.g. function calls or indexing operations) are *not* evaluated. 26 27 - GNU readline is also used by the built-in functions input() and 28 raw_input(), and thus these also benefit/suffer from the completer 29 features. Clearly an interactive application can benefit by 30 specifying its own completer function and using raw_input() for all 31 its input. 32 33 - When the original stdin is not a tty device, GNU readline is never 34 used, and this module (and the readline module) are silently inactive. 35 36 """ 37 38 import __builtin__ 39 import __main__ 40 41 __all__ = ["Completer"] 42 43 class Completer: 44 def __init__(self, namespace = None): 45 """Create a new completer for the command line. 46 47 Completer([namespace]) -> completer instance. 48 49 If unspecified, the default namespace where completions are performed 50 is __main__ (technically, __main__.__dict__). Namespaces should be 51 given as dictionaries. 52 53 Completer instances should be used as the completion mechanism of 54 readline via the set_completer() call: 55 56 readline.set_completer(Completer(my_namespace).complete) 57 """ 58 59 if namespace and not isinstance(namespace, dict): 60 raise TypeError,'namespace must be a dictionary' 61 62 # Don't bind to namespace quite yet, but flag whether the user wants a 63 # specific namespace or to use __main__.__dict__. This will allow us 64 # to bind to __main__.__dict__ at completion time, not now. 65 if namespace is None: 66 self.use_main_ns = 1 67 else: 68 self.use_main_ns = 0 69 self.namespace = namespace 70 71 def complete(self, text, state): 72 """Return the next possible completion for 'text'. 73 74 This is called successively with state == 0, 1, 2, ... until it 75 returns None. The completion should begin with 'text'. 76 77 """ 78 if self.use_main_ns: 79 self.namespace = __main__.__dict__ 80 81 if state == 0: 82 if "." in text: 83 self.matches = self.attr_matches(text) 84 else: 85 self.matches = self.global_matches(text) 86 try: 87 return self.matches[state] 88 except IndexError: 89 return None 90 91 def _callable_postfix(self, val, word): 92 if hasattr(val, '__call__'): 93 word = word + "(" 94 return word 95 96 def global_matches(self, text): 97 """Compute matches when text is a simple name. 98 99 Return a list of all keywords, built-in functions and names currently 100 defined in self.namespace that match. 101 102 """ 103 import keyword 104 matches = [] 105 seen = {"__builtins__"} 106 n = len(text) 107 for word in keyword.kwlist: 108 if word[:n] == text: 109 seen.add(word) 110 matches.append(word) 111 for nspace in [self.namespace, __builtin__.__dict__]: 112 for word, val in nspace.items(): 113 if word[:n] == text and word not in seen: 114 seen.add(word) 115 matches.append(self._callable_postfix(val, word)) 116 return matches 117 118 def attr_matches(self, text): 119 """Compute matches when text contains a dot. 120 121 Assuming the text is of the form NAME.NAME....[NAME], and is 122 evaluable in self.namespace, it will be evaluated and its attributes 123 (as revealed by dir()) are used as possible completions. (For class 124 instances, class members are also considered.) 125 126 WARNING: this can still invoke arbitrary C code, if an object 127 with a __getattr__ hook is evaluated. 128 129 """ 130 import re 131 m = re.match(r"(\w+(\.\w+)*)\.(\w*)", text) 132 if not m: 133 return [] 134 expr, attr = m.group(1, 3) 135 try: 136 thisobject = eval(expr, self.namespace) 137 except Exception: 138 return [] 139 140 # get the content of the object, except __builtins__ 141 words = set(dir(thisobject)) 142 words.discard("__builtins__") 143 144 if hasattr(thisobject, '__class__'): 145 words.add('__class__') 146 words.update(get_class_members(thisobject.__class__)) 147 matches = [] 148 n = len(attr) 149 for word in words: 150 if word[:n] == attr: 151 try: 152 val = getattr(thisobject, word) 153 except Exception: 154 continue # Exclude properties that are not set 155 word = self._callable_postfix(val, "%s.%s" % (expr, word)) 156 matches.append(word) 157 matches.sort() 158 return matches 159 160 def get_class_members(klass): 161 ret = dir(klass) 162 if hasattr(klass,'__bases__'): 163 for base in klass.__bases__: 164 ret = ret + get_class_members(base) 165 return ret 166 167 try: 168 import readline 169 except ImportError: 170 pass 171 else: 172 readline.set_completer(Completer().complete) 173
