| 1 | """Word completion for GNU readline 2.0.
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| 2 |
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| 3 | This requires the latest extension to the readline module. The completer
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| 4 | completes keywords, built-ins and globals in a selectable namespace (which
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| 5 | defaults to __main__); when completing NAME.NAME..., it evaluates (!) the
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| 6 | expression up to the last dot and completes its attributes.
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| 7 |
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| 8 | It's very cool to do "import sys" type "sys.", hit the
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| 9 | completion key (twice), and see the list of names defined by the
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| 10 | sys module!
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| 11 |
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| 12 | Tip: to use the tab key as the completion key, call
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| 13 |
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| 14 | readline.parse_and_bind("tab: complete")
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| 15 |
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| 16 | Notes:
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| 17 |
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| 18 | - Exceptions raised by the completer function are *ignored* (and
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| 19 | generally cause the completion to fail). This is a feature -- since
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| 20 | readline sets the tty device in raw (or cbreak) mode, printing a
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| 21 | traceback wouldn't work well without some complicated hoopla to save,
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| 22 | reset and restore the tty state.
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| 23 |
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| 24 | - The evaluation of the NAME.NAME... form may cause arbitrary
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| 25 | application defined code to be executed if an object with a
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| 26 | __getattr__ hook is found. Since it is the responsibility of the
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| 27 | application (or the user) to enable this feature, I consider this an
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| 28 | acceptable risk. More complicated expressions (e.g. function calls or
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| 29 | indexing operations) are *not* evaluated.
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| 30 |
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| 31 | - GNU readline is also used by the built-in functions input() and
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| 32 | raw_input(), and thus these also benefit/suffer from the completer
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| 33 | features. Clearly an interactive application can benefit by
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| 34 | specifying its own completer function and using raw_input() for all
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| 35 | its input.
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| 36 |
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| 37 | - When the original stdin is not a tty device, GNU readline is never
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| 38 | used, and this module (and the readline module) are silently inactive.
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| 39 |
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| 40 | """
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| 41 |
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| 42 | import __builtin__
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| 43 | import __main__
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| 44 |
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| 45 | __all__ = ["Completer"]
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| 46 |
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| 47 | class Completer:
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| 48 | def __init__(self, namespace = None):
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| 49 | """Create a new completer for the command line.
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| 50 |
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| 51 | Completer([namespace]) -> completer instance.
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| 52 |
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| 53 | If unspecified, the default namespace where completions are performed
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| 54 | is __main__ (technically, __main__.__dict__). Namespaces should be
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| 55 | given as dictionaries.
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| 56 |
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| 57 | Completer instances should be used as the completion mechanism of
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| 58 | readline via the set_completer() call:
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| 59 |
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| 60 | readline.set_completer(Completer(my_namespace).complete)
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| 61 | """
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| 62 |
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| 63 | if namespace and not isinstance(namespace, dict):
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| 64 | raise TypeError,'namespace must be a dictionary'
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| 65 |
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| 66 | # Don't bind to namespace quite yet, but flag whether the user wants a
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| 67 | # specific namespace or to use __main__.__dict__. This will allow us
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| 68 | # to bind to __main__.__dict__ at completion time, not now.
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| 69 | if namespace is None:
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| 70 | self.use_main_ns = 1
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| 71 | else:
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| 72 | self.use_main_ns = 0
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| 73 | self.namespace = namespace
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| 74 |
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| 75 | def complete(self, text, state):
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| 76 | """Return the next possible completion for 'text'.
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| 77 |
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| 78 | This is called successively with state == 0, 1, 2, ... until it
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| 79 | returns None. The completion should begin with 'text'.
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| 80 |
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| 81 | """
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| 82 | if self.use_main_ns:
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| 83 | self.namespace = __main__.__dict__
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| 84 |
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| 85 | if state == 0:
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| 86 | if "." in text:
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| 87 | self.matches = self.attr_matches(text)
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| 88 | else:
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| 89 | self.matches = self.global_matches(text)
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| 90 | try:
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| 91 | return self.matches[state]
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| 92 | except IndexError:
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| 93 | return None
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| 94 |
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| 95 | def global_matches(self, text):
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| 96 | """Compute matches when text is a simple name.
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| 97 |
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| 98 | Return a list of all keywords, built-in functions and names currently
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| 99 | defined in self.namespace that match.
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| 100 |
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| 101 | """
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| 102 | import keyword
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| 103 | matches = []
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| 104 | n = len(text)
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| 105 | for list in [keyword.kwlist,
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| 106 | __builtin__.__dict__,
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| 107 | self.namespace]:
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| 108 | for word in list:
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| 109 | if word[:n] == text and word != "__builtins__":
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| 110 | matches.append(word)
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| 111 | return matches
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| 112 |
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| 113 | def attr_matches(self, text):
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| 114 | """Compute matches when text contains a dot.
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| 115 |
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| 116 | Assuming the text is of the form NAME.NAME....[NAME], and is
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| 117 | evaluatable in self.namespace, it will be evaluated and its attributes
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| 118 | (as revealed by dir()) are used as possible completions. (For class
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| 119 | instances, class members are also considered.)
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| 120 |
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| 121 | WARNING: this can still invoke arbitrary C code, if an object
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| 122 | with a __getattr__ hook is evaluated.
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| 123 |
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| 124 | """
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| 125 | import re
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| 126 | m = re.match(r"(\w+(\.\w+)*)\.(\w*)", text)
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| 127 | if not m:
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| 128 | return
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| 129 | expr, attr = m.group(1, 3)
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| 130 | object = eval(expr, self.namespace)
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| 131 | words = dir(object)
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| 132 | if hasattr(object,'__class__'):
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| 133 | words.append('__class__')
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| 134 | words = words + get_class_members(object.__class__)
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| 135 | matches = []
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| 136 | n = len(attr)
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| 137 | for word in words:
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| 138 | if word[:n] == attr and word != "__builtins__":
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| 139 | matches.append("%s.%s" % (expr, word))
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| 140 | return matches
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| 141 |
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| 142 | def get_class_members(klass):
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| 143 | ret = dir(klass)
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| 144 | if hasattr(klass,'__bases__'):
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| 145 | for base in klass.__bases__:
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| 146 | ret = ret + get_class_members(base)
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| 147 | return ret
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| 148 |
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| 149 | try:
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| 150 | import readline
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| 151 | except ImportError:
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| 152 | pass
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| 153 | else:
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| 154 | readline.set_completer(Completer().complete)
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