1"""Utilities for writing code that runs on Python 2 and 3"""
2
3#Copyright (c) 2010-2011 Benjamin Peterson
4
5#Permission is hereby granted, free of charge, to any person obtaining a copy of
6#this software and associated documentation files (the "Software"), to deal in
7#the Software without restriction, including without limitation the rights to
8#use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
9#the Software, and to permit persons to whom the Software is furnished to do so,
10#subject to the following conditions:
11
12#The above copyright notice and this permission notice shall be included in all
13#copies or substantial portions of the Software.
14
15#THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16#IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
17#FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
18#COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
19#IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
20#CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
21
22import operator
23import sys
24import types
25
26__author__ = "Benjamin Peterson <benjamin@python.org>"
27__version__ = "1.2.0"  # Revision 41c74fef2ded
28
29
30# True if we are running on Python 3.
31PY3 = sys.version_info[0] == 3
32
33if PY3:
34    string_types = str,
35    integer_types = int,
36    class_types = type,
37    text_type = str
38    binary_type = bytes
39
40    MAXSIZE = sys.maxsize
41else:
42    string_types = basestring,
43    integer_types = (int, long)
44    class_types = (type, types.ClassType)
45    text_type = unicode
46    binary_type = str
47
48    if sys.platform.startswith("java"):
49        # Jython always uses 32 bits.
50        MAXSIZE = int((1 << 31) - 1)
51    else:
52        # It's possible to have sizeof(long) != sizeof(Py_ssize_t).
53        class X(object):
54            def __len__(self):
55                return 1 << 31
56        try:
57            len(X())
58        except OverflowError:
59            # 32-bit
60            MAXSIZE = int((1 << 31) - 1)
61        else:
62            # 64-bit
63            MAXSIZE = int((1 << 63) - 1)
64            del X
65
66
67def _add_doc(func, doc):
68    """Add documentation to a function."""
69    func.__doc__ = doc
70
71
72def _import_module(name):
73    """Import module, returning the module after the last dot."""
74    __import__(name)
75    return sys.modules[name]
76
77
78class _LazyDescr(object):
79
80    def __init__(self, name):
81        self.name = name
82
83    def __get__(self, obj, tp):
84        result = self._resolve()
85        setattr(obj, self.name, result)
86        # This is a bit ugly, but it avoids running this again.
87        delattr(tp, self.name)
88        return result
89
90
91class MovedModule(_LazyDescr):
92
93    def __init__(self, name, old, new=None):
94        super(MovedModule, self).__init__(name)
95        if PY3:
96            if new is None:
97                new = name
98            self.mod = new
99        else:
100            self.mod = old
101
102    def _resolve(self):
103        return _import_module(self.mod)
104
105
106class MovedAttribute(_LazyDescr):
107
108    def __init__(self, name, old_mod, new_mod, old_attr=None, new_attr=None):
109        super(MovedAttribute, self).__init__(name)
110        if PY3:
111            if new_mod is None:
112                new_mod = name
113            self.mod = new_mod
114            if new_attr is None:
115                if old_attr is None:
116                    new_attr = name
117                else:
118                    new_attr = old_attr
119            self.attr = new_attr
120        else:
121            self.mod = old_mod
122            if old_attr is None:
123                old_attr = name
124            self.attr = old_attr
125
126    def _resolve(self):
127        module = _import_module(self.mod)
128        return getattr(module, self.attr)
129
130
131
132class _MovedItems(types.ModuleType):
133    """Lazy loading of moved objects"""
134
135
136_moved_attributes = [
137    MovedAttribute("cStringIO", "cStringIO", "io", "StringIO"),
138    MovedAttribute("filter", "itertools", "builtins", "ifilter", "filter"),
139    MovedAttribute("input", "__builtin__", "builtins", "raw_input", "input"),
140    MovedAttribute("map", "itertools", "builtins", "imap", "map"),
141    MovedAttribute("reload_module", "__builtin__", "imp", "reload"),
142    MovedAttribute("reduce", "__builtin__", "functools"),
143    MovedAttribute("StringIO", "StringIO", "io"),
144    MovedAttribute("xrange", "__builtin__", "builtins", "xrange", "range"),
145    MovedAttribute("zip", "itertools", "builtins", "izip", "zip"),
146
147    MovedModule("builtins", "__builtin__"),
148    MovedModule("configparser", "ConfigParser"),
149    MovedModule("copyreg", "copy_reg"),
150    MovedModule("http_cookiejar", "cookielib", "http.cookiejar"),
151    MovedModule("http_cookies", "Cookie", "http.cookies"),
152    MovedModule("html_entities", "htmlentitydefs", "html.entities"),
153    MovedModule("html_parser", "HTMLParser", "html.parser"),
154    MovedModule("http_client", "httplib", "http.client"),
155    MovedModule("BaseHTTPServer", "BaseHTTPServer", "http.server"),
156    MovedModule("CGIHTTPServer", "CGIHTTPServer", "http.server"),
157    MovedModule("SimpleHTTPServer", "SimpleHTTPServer", "http.server"),
158    MovedModule("cPickle", "cPickle", "pickle"),
159    MovedModule("queue", "Queue"),
160    MovedModule("reprlib", "repr"),
161    MovedModule("socketserver", "SocketServer"),
162    MovedModule("tkinter", "Tkinter"),
163    MovedModule("tkinter_dialog", "Dialog", "tkinter.dialog"),
164    MovedModule("tkinter_filedialog", "FileDialog", "tkinter.filedialog"),
165    MovedModule("tkinter_scrolledtext", "ScrolledText", "tkinter.scrolledtext"),
166    MovedModule("tkinter_simpledialog", "SimpleDialog", "tkinter.simpledialog"),
167    MovedModule("tkinter_tix", "Tix", "tkinter.tix"),
168    MovedModule("tkinter_constants", "Tkconstants", "tkinter.constants"),
169    MovedModule("tkinter_dnd", "Tkdnd", "tkinter.dnd"),
170    MovedModule("tkinter_colorchooser", "tkColorChooser",
171                "tkinter.colorchooser"),
172    MovedModule("tkinter_commondialog", "tkCommonDialog",
173                "tkinter.commondialog"),
174    MovedModule("tkinter_tkfiledialog", "tkFileDialog", "tkinter.filedialog"),
175    MovedModule("tkinter_font", "tkFont", "tkinter.font"),
176    MovedModule("tkinter_messagebox", "tkMessageBox", "tkinter.messagebox"),
177    MovedModule("tkinter_tksimpledialog", "tkSimpleDialog",
178                "tkinter.simpledialog"),
179    MovedModule("urllib_robotparser", "robotparser", "urllib.robotparser"),
180    MovedModule("winreg", "_winreg"),
181]
182for attr in _moved_attributes:
183    setattr(_MovedItems, attr.name, attr)
184del attr
185
186moves = sys.modules[__name__ + ".moves"] = _MovedItems("moves")
187
188
189def add_move(move):
190    """Add an item to six.moves."""
191    setattr(_MovedItems, move.name, move)
192
193
194def remove_move(name):
195    """Remove item from six.moves."""
196    try:
197        delattr(_MovedItems, name)
198    except AttributeError:
199        try:
200            del moves.__dict__[name]
201        except KeyError:
202            raise AttributeError("no such move, %r" % (name,))
203
204
205if PY3:
206    _meth_func = "__func__"
207    _meth_self = "__self__"
208
209    _func_code = "__code__"
210    _func_defaults = "__defaults__"
211
212    _iterkeys = "keys"
213    _itervalues = "values"
214    _iteritems = "items"
215else:
216    _meth_func = "im_func"
217    _meth_self = "im_self"
218
219    _func_code = "func_code"
220    _func_defaults = "func_defaults"
221
222    _iterkeys = "iterkeys"
223    _itervalues = "itervalues"
224    _iteritems = "iteritems"
225
226
227try:
228    advance_iterator = next
229except NameError:
230    def advance_iterator(it):
231        return it.next()
232next = advance_iterator
233
234
235if PY3:
236    def get_unbound_function(unbound):
237        return unbound
238
239    Iterator = object
240
241    def callable(obj):
242        return any("__call__" in klass.__dict__ for klass in type(obj).__mro__)
243else:
244    def get_unbound_function(unbound):
245        return unbound.im_func
246
247    class Iterator(object):
248
249        def next(self):
250            return type(self).__next__(self)
251
252    callable = callable
253_add_doc(get_unbound_function,
254         """Get the function out of a possibly unbound function""")
255
256
257get_method_function = operator.attrgetter(_meth_func)
258get_method_self = operator.attrgetter(_meth_self)
259get_function_code = operator.attrgetter(_func_code)
260get_function_defaults = operator.attrgetter(_func_defaults)
261
262
263def iterkeys(d):
264    """Return an iterator over the keys of a dictionary."""
265    return iter(getattr(d, _iterkeys)())
266
267def itervalues(d):
268    """Return an iterator over the values of a dictionary."""
269    return iter(getattr(d, _itervalues)())
270
271def iteritems(d):
272    """Return an iterator over the (key, value) pairs of a dictionary."""
273    return iter(getattr(d, _iteritems)())
274
275
276if PY3:
277    def b(s):
278        return s.encode("latin-1")
279    def u(s):
280        return s
281    if sys.version_info[1] <= 1:
282        def int2byte(i):
283            return bytes((i,))
284    else:
285        # This is about 2x faster than the implementation above on 3.2+
286        int2byte = operator.methodcaller("to_bytes", 1, "big")
287    import io
288    StringIO = io.StringIO
289    BytesIO = io.BytesIO
290else:
291    def b(s):
292        return s
293    def u(s):
294        return unicode(s, "unicode_escape")
295    int2byte = chr
296    import StringIO
297    StringIO = BytesIO = StringIO.StringIO
298_add_doc(b, """Byte literal""")
299_add_doc(u, """Text literal""")
300
301
302if PY3:
303    import builtins
304    exec_ = getattr(builtins, "exec")
305
306
307    def reraise(tp, value, tb=None):
308        if value.__traceback__ is not tb:
309            raise value.with_traceback(tb)
310        raise value
311
312
313    print_ = getattr(builtins, "print")
314    del builtins
315
316else:
317    def exec_(code, globs=None, locs=None):
318        """Execute code in a namespace."""
319        if globs is None:
320            frame = sys._getframe(1)
321            globs = frame.f_globals
322            if locs is None:
323                locs = frame.f_locals
324            del frame
325        elif locs is None:
326            locs = globs
327        exec("""exec code in globs, locs""")
328
329
330    exec_("""def reraise(tp, value, tb=None):
331    raise tp, value, tb
332""")
333
334
335    def print_(*args, **kwargs):
336        """The new-style print function."""
337        fp = kwargs.pop("file", sys.stdout)
338        if fp is None:
339            return
340        def write(data):
341            if not isinstance(data, basestring):
342                data = str(data)
343            fp.write(data)
344        want_unicode = False
345        sep = kwargs.pop("sep", None)
346        if sep is not None:
347            if isinstance(sep, unicode):
348                want_unicode = True
349            elif not isinstance(sep, str):
350                raise TypeError("sep must be None or a string")
351        end = kwargs.pop("end", None)
352        if end is not None:
353            if isinstance(end, unicode):
354                want_unicode = True
355            elif not isinstance(end, str):
356                raise TypeError("end must be None or a string")
357        if kwargs:
358            raise TypeError("invalid keyword arguments to print()")
359        if not want_unicode:
360            for arg in args:
361                if isinstance(arg, unicode):
362                    want_unicode = True
363                    break
364        if want_unicode:
365            newline = unicode("\n")
366            space = unicode(" ")
367        else:
368            newline = "\n"
369            space = " "
370        if sep is None:
371            sep = space
372        if end is None:
373            end = newline
374        for i, arg in enumerate(args):
375            if i:
376                write(sep)
377            write(arg)
378        write(end)
379
380_add_doc(reraise, """Reraise an exception.""")
381
382
383def with_metaclass(meta, base=object):
384    """Create a base class with a metaclass."""
385    return meta("NewBase", (base,), {})
386