utils.py

#!/usr/bin/env python
"""
General Utilities
(part of web.py)
"""
from __future__ import print_function

import datetime
import os
import re
import subprocess
import sys
import threading
import time
import traceback
from threading import local as threadlocal

from .py3helpers import (
    PY2,
    imap,
    is_iter,
    iteritems,
    itervalues,
    string_types,
    text_type,
)

try:
    from StringIO import StringIO
except ImportError:
    from io import StringIO

__all__ = [
    "Storage",
    "storage",
    "storify",
    "Counter",
    "counter",
    "iters",
    "rstrips",
    "lstrips",
    "strips",
    "safeunicode",
    "safestr",
    "timelimit",
    "Memoize",
    "memoize",
    "re_compile",
    "re_subm",
    "group",
    "uniq",
    "iterview",
    "IterBetter",
    "iterbetter",
    "safeiter",
    "safewrite",
    "dictreverse",
    "dictfind",
    "dictfindall",
    "dictincr",
    "dictadd",
    "requeue",
    "restack",
    "listget",
    "intget",
    "datestr",
    "numify",
    "denumify",
    "commify",
    "dateify",
    "nthstr",
    "cond",
    "CaptureStdout",
    "capturestdout",
    "Profile",
    "profile",
    "tryall",
    "ThreadedDict",
    "threadeddict",
    "autoassign",
    "to36",
    "sendmail",
]


class Storage(dict):
    """
    A Storage object is like a dictionary except `obj.foo` can be used
    in addition to `obj['foo']`.

        >>> o = storage(a=1)
        >>> o.a
        1
        >>> o['a']
        1
        >>> o.a = 2
        >>> o['a']
        2
        >>> del o.a
        >>> o.a
        Traceback (most recent call last):
            ...
        AttributeError: 'a'

    """

    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError as k:
            raise AttributeError(k)

    def __setattr__(self, key, value):
        self[key] = value

    def __delattr__(self, key):
        try:
            del self[key]
        except KeyError as k:
            raise AttributeError(k)

    def __repr__(self):
        return "<Storage " + dict.__repr__(self) + ">"


storage = Storage


def storify(mapping, *requireds, **defaults):
    """
    Creates a `storage` object from dictionary `mapping`, raising `KeyError` if
    d doesn't have all of the keys in `requireds` and using the default
    values for keys found in `defaults`.

    For example, `storify({'a':1, 'c':3}, b=2, c=0)` will return the equivalent of
    `storage({'a':1, 'b':2, 'c':3})`.

    If a `storify` value is a list (e.g. multiple values in a form submission),
    `storify` returns the last element of the list, unless the key appears in
    `defaults` as a list. Thus:

        >>> storify({'a':[1, 2]}).a
        2
        >>> storify({'a':[1, 2]}, a=[]).a
        [1, 2]
        >>> storify({'a':1}, a=[]).a
        [1]
        >>> storify({}, a=[]).a
        []

    Similarly, if the value has a `value` attribute, `storify will return _its_
    value, unless the key appears in `defaults` as a dictionary.

        >>> storify({'a':storage(value=1)}).a
        1
        >>> storify({'a':storage(value=1)}, a={}).a
        <Storage {'value': 1}>
        >>> storify({}, a={}).a
        {}

    """
    _unicode = defaults.pop("_unicode", False)

    # if _unicode is callable object, use it convert a string to unicode.
    to_unicode = safeunicode
    if _unicode is not False and hasattr(_unicode, "__call__"):
        to_unicode = _unicode

    def unicodify(s):
        if _unicode and isinstance(s, str):
            return to_unicode(s)
        else:
            return s

    def getvalue(x):
        if hasattr(x, "file") and hasattr(x, "value"):
            return x.value
        elif hasattr(x, "value"):
            return unicodify(x.value)
        else:
            return unicodify(x)

    stor = Storage()
    for key in requireds + tuple(mapping.keys()):
        value = mapping[key]
        if isinstance(value, list):
            if isinstance(defaults.get(key), list):
                value = [getvalue(x) for x in value]
            else:
                value = value[-1]
        if not isinstance(defaults.get(key), dict):
            value = getvalue(value)
        if isinstance(defaults.get(key), list) and not isinstance(value, list):
            value = [value]

        setattr(stor, key, value)

    for (key, value) in iteritems(defaults):
        result = value
        if hasattr(stor, key):
            result = stor[key]
        if value == () and not isinstance(result, tuple):
            result = (result,)
        setattr(stor, key, result)

    return stor


class Counter(storage):
    """Keeps count of how many times something is added.

        >>> c = counter()
        >>> c.add('x')
        >>> c.add('x')
        >>> c.add('x')
        >>> c.add('x')
        >>> c.add('x')
        >>> c.add('y')
        >>> c['y']
        1
        >>> c['x']
        5
        >>> c.most()
        ['x']
    """

    def add(self, n):
        self.setdefault(n, 0)
        self[n] += 1

    def most(self):
        """Returns the keys with maximum count."""
        m = max(itervalues(self))
        return [k for k, v in iteritems(self) if v == m]

    def least(self):
        """Returns the keys with minimum count."""
        m = min(self.itervalues())
        return [k for k, v in iteritems(self) if v == m]

    def percent(self, key):
        """Returns what percentage a certain key is of all entries.

           >>> c = counter()
           >>> c.add('x')
           >>> c.add('x')
           >>> c.add('x')
           >>> c.add('y')
           >>> c.percent('x')
           0.75
           >>> c.percent('y')
           0.25
        """
        return float(self[key]) / sum(self.values())

    def sorted_keys(self):
        """Returns keys sorted by value.

             >>> c = counter()
             >>> c.add('x')
             >>> c.add('x')
             >>> c.add('y')
             >>> c.sorted_keys()
             ['x', 'y']
        """
        return sorted(self.keys(), key=lambda k: self[k], reverse=True)

    def sorted_values(self):
        """Returns values sorted by value.

            >>> c = counter()
            >>> c.add('x')
            >>> c.add('x')
            >>> c.add('y')
            >>> c.sorted_values()
            [2, 1]
        """
        return [self[k] for k in self.sorted_keys()]

    def sorted_items(self):
        """Returns items sorted by value.

            >>> c = counter()
            >>> c.add('x')
            >>> c.add('x')
            >>> c.add('y')
            >>> c.sorted_items()
            [('x', 2), ('y', 1)]
        """
        return [(k, self[k]) for k in self.sorted_keys()]

    def __repr__(self):
        return "<Counter " + dict.__repr__(self) + ">"


counter = Counter

iters = [list, tuple, set, frozenset]


class _hack(tuple):
    pass


iters = _hack(iters)
iters.__doc__ = """
A list of iterable items (like lists, but not strings). Includes whichever
of lists, tuples, sets, and Sets are available in this version of Python.
"""


def _strips(direction, text, remove):
    if isinstance(remove, iters):
        for subr in remove:
            text = _strips(direction, text, subr)
        return text

    if direction == "l":
        if text.startswith(remove):
            return text[len(remove) :]
    elif direction == "r":
        if text.endswith(remove):
            return text[: -len(remove)]
    else:
        raise ValueError("Direction needs to be r or l.")
    return text


def rstrips(text, remove):
    """
    removes the string `remove` from the right of `text`

        >>> rstrips("foobar", "bar")
        'foo'

    """
    return _strips("r", text, remove)


def lstrips(text, remove):
    """
    removes the string `remove` from the left of `text`

        >>> lstrips("foobar", "foo")
        'bar'
        >>> lstrips('http://foo.org/', ['http://', 'https://'])
        'foo.org/'
        >>> lstrips('FOOBARBAZ', ['FOO', 'BAR'])
        'BAZ'
        >>> lstrips('FOOBARBAZ', ['BAR', 'FOO'])
        'BARBAZ'

    """
    return _strips("l", text, remove)


def strips(text, remove):
    """
    removes the string `remove` from the both sides of `text`

        >>> strips("foobarfoo", "foo")
        'bar'

    """
    return rstrips(lstrips(text, remove), remove)


def safeunicode(obj, encoding="utf-8"):
    r"""
    Converts any given object to unicode string.

        >>> safeunicode('hello')
        u'hello'
        >>> safeunicode(2)
        u'2'
        >>> safeunicode('\xe1\x88\xb4')
        u'\u1234'
    """
    t = type(obj)
    if t is text_type:
        return obj
    elif t is bytes:
        return obj.decode(encoding)
    elif t in [int, float, bool]:
        return text_type(obj)
    # elif hasattr(obj, '__unicode__') or isinstance(obj, unicode):
    #    return unicode(obj)
    # else:
    #    return str(obj).decode(encoding)
    else:
        return text_type(obj)


def safestr(obj, encoding="utf-8"):
    r"""
    Converts any given object to utf-8 encoded string.

        >>> safestr('hello')
        'hello'
        >>> safestr(2)
        '2'
    """

    if PY2 and isinstance(obj, text_type):
        return obj.encode(encoding)
    elif is_iter(obj):
        return imap(safestr, obj)
    else:
        return str(obj)


if not PY2:
    # Since Python3, utf-8 encoded strings and unicode strings are the same thing
    safeunicode = safestr


def timelimit(timeout):
    """
    A decorator to limit a function to `timeout` seconds, raising `TimeoutError`
    if it takes longer.

        >>> import time
        >>> def meaningoflife():
        ...     time.sleep(.2)
        ...     return 42
        >>>
        >>> timelimit(.1)(meaningoflife)()
        Traceback (most recent call last):
            ...
        RuntimeError: took too long
        >>> timelimit(1)(meaningoflife)()
        42

    _Caveat:_ The function isn't stopped after `timeout` seconds but continues
    executing in a separate thread. (There seems to be no way to kill a thread.)

    inspired by <http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/473878>
    """

    def _1(function):
        def _2(*args, **kw):
            class Dispatch(threading.Thread):
                def __init__(self):
                    threading.Thread.__init__(self)
                    self.result = None
                    self.error = None

                    self.setDaemon(True)
                    self.start()

                def run(self):
                    try:
                        self.result = function(*args, **kw)
                    except:
                        self.error = sys.exc_info()

            c = Dispatch()
            c.join(timeout)
            if c.is_alive():
                raise RuntimeError("took too long")
            if c.error:
                raise c.error[1]
            return c.result

        return _2

    return _1


class Memoize:
    """
    'Memoizes' a function, caching its return values for each input.
    If `expires` is specified, values are recalculated after `expires` seconds.
    If `background` is specified, values are recalculated in a separate thread.

        >>> calls = 0
        >>> def howmanytimeshaveibeencalled():
        ...     global calls
        ...     calls += 1
        ...     return calls
        >>> fastcalls = memoize(howmanytimeshaveibeencalled)
        >>> howmanytimeshaveibeencalled()
        1
        >>> howmanytimeshaveibeencalled()
        2
        >>> fastcalls()
        3
        >>> fastcalls()
        3
        >>> import time
        >>> fastcalls = memoize(howmanytimeshaveibeencalled, .1, background=False)
        >>> fastcalls()
        4
        >>> fastcalls()
        4
        >>> time.sleep(.2)
        >>> fastcalls()
        5
        >>> def slowfunc():
        ...     time.sleep(.1)
        ...     return howmanytimeshaveibeencalled()
        >>> fastcalls = memoize(slowfunc, .2, background=True)
        >>> fastcalls()
        6
        >>> timelimit(.05)(fastcalls)()
        6
        >>> time.sleep(.2)
        >>> timelimit(.05)(fastcalls)()
        6
        >>> timelimit(.05)(fastcalls)()
        6
        >>> time.sleep(.2)
        >>> timelimit(.05)(fastcalls)()
        7
        >>> fastcalls = memoize(slowfunc, None, background=True)
        >>> threading.Thread(target=fastcalls).start()
        >>> time.sleep(.01)
        >>> fastcalls()
        9
    """

    def __init__(self, func, expires=None, background=True):
        self.func = func
        self.cache = {}
        self.expires = expires
        self.background = background
        self.running = {}
        self.running_lock = threading.Lock()

    def __call__(self, *args, **keywords):
        key = (args, tuple(keywords.items()))
        with self.running_lock:
            if not self.running.get(key):
                self.running[key] = threading.Lock()

        def update(block=False):
            if self.running[key].acquire(block):
                try:
                    self.cache[key] = (self.func(*args, **keywords), time.time())
                finally:
                    self.running[key].release()

        if key not in self.cache:
            update(block=True)
        elif self.expires and (time.time() - self.cache[key][1]) > self.expires:
            if self.background:
                threading.Thread(target=update).start()
            else:
                update()
        return self.cache[key][0]


memoize = Memoize

re_compile = memoize(re.compile)
re_compile.__doc__ = """
A memoized version of re.compile.
"""


class _re_subm_proxy:
    def __init__(self):
        self.match = None

    def __call__(self, match):
        self.match = match
        return ""


def re_subm(pat, repl, string):
    """
    Like re.sub, but returns the replacement _and_ the match object.

        >>> t, m = re_subm('g(oo+)fball', r'f\\1lish', 'goooooofball')
        >>> t
        'foooooolish'
        >>> m.groups()
        ('oooooo',)
    """
    compiled_pat = re_compile(pat)
    proxy = _re_subm_proxy()
    compiled_pat.sub(proxy.__call__, string)
    return compiled_pat.sub(repl, string), proxy.match


def group(seq, size):
    """
    Returns an iterator over a series of lists of length size from iterable.

        >>> list(group([1,2,3,4], 2))
        [[1, 2], [3, 4]]
        >>> list(group([1,2,3,4,5], 2))
        [[1, 2], [3, 4], [5]]
    """
    return (seq[i : i + size] for i in range(0, len(seq), size))


def uniq(seq, key=None):
    """
    Removes duplicate elements from a list while preserving the order of the rest.

        >>> uniq([9,0,2,1,0])
        [9, 0, 2, 1]

    The value of the optional `key` parameter should be a function that
    takes a single argument and returns a key to test the uniqueness.

        >>> uniq(["Foo", "foo", "bar"], key=lambda s: s.lower())
        ['Foo', 'bar']
    """
    key = key or (lambda x: x)
    seen = set()
    result = []
    for v in seq:
        k = key(v)
        if k in seen:
            continue
        seen.add(k)
        result.append(v)
    return result


def iterview(x):
    """
    Takes an iterable `x` and returns an iterator over it
    which prints its progress to stderr as it iterates through.
    """
    WIDTH = 70

    def plainformat(n, lenx):
        return "%5.1f%% (%*d/%d)" % ((float(n) / lenx) * 100, len(str(lenx)), n, lenx)

    def bars(size, n, lenx):
        val = int((float(n) * size) / lenx + 0.5)
        if size - val:
            spacing = ">" + (" " * (size - val))[1:]
        else:
            spacing = ""
        return "[%s%s]" % ("=" * val, spacing)

    def eta(elapsed, n, lenx):
        if n == 0:
            return "--:--:--"
        if n == lenx:
            secs = int(elapsed)
        else:
            secs = int((elapsed / n) * (lenx - n))
        mins, secs = divmod(secs, 60)
        hrs, mins = divmod(mins, 60)

        return "%02d:%02d:%02d" % (hrs, mins, secs)

    def format(starttime, n, lenx):
        out = plainformat(n, lenx) + " "
        if n == lenx:
            end = "     "
        else:
            end = " ETA "
        end += eta(time.time() - starttime, n, lenx)
        out += bars(WIDTH - len(out) - len(end), n, lenx)
        out += end
        return out

    starttime = time.time()
    lenx = len(x)
    for n, y in enumerate(x):
        sys.stderr.write("\r" + format(starttime, n, lenx))
        yield y
    sys.stderr.write("\r" + format(starttime, n + 1, lenx) + "\n")


class IterBetter:
    """
    Returns an object that can be used as an iterator
    but can also be used via __getitem__ (although it
    cannot go backwards -- that is, you cannot request
    `iterbetter[0]` after requesting `iterbetter[1]`).

        >>> import itertools
        >>> c = iterbetter(itertools.count())
        >>> c[1]
        1
        >>> c[5]
        5
        >>> c[3]
        Traceback (most recent call last):
            ...
        IndexError: already passed 3

    It is also possible to get the first value of the iterator or None.

        >>> c = iterbetter(iter([3, 4, 5]))
        >>> print(c.first())
        3
        >>> c = iterbetter(iter([]))
        >>> print(c.first())
        None

    For boolean test, IterBetter peeps at first value in the itertor without effecting the iteration.

        >>> c = iterbetter(iter(range(5)))
        >>> bool(c)
        True
        >>> list(c)
        [0, 1, 2, 3, 4]
        >>> c = iterbetter(iter([]))
        >>> bool(c)
        False
        >>> list(c)
        []
    """

    def __init__(self, iterator):
        self.i, self.c = iterator, 0

    def first(self, default=None):
        """Returns the first element of the iterator or None when there are no
        elements.

        If the optional argument default is specified, that is returned instead
        of None when there are no elements.
        """
        try:
            return next(iter(self))
        except StopIteration:
            return default

    def __iter__(self):
        if hasattr(self, "_head"):
            yield self._head

        while 1:
            try:
                yield next(self.i)
            except StopIteration:
                return
            self.c += 1

    def __getitem__(self, i):
        # todo: slices
        if i < self.c:
            raise IndexError("already passed " + str(i))
        try:
            while i > self.c:
                next(self.i)
                self.c += 1
            # now self.c == i
            self.c += 1
            return next(self.i)
        except StopIteration:
            raise IndexError(str(i))

    def __nonzero__(self):
        if hasattr(self, "__len__"):
            return self.__len__() != 0
        elif hasattr(self, "_head"):
            return True
        else:
            try:
                self._head = next(self.i)
            except StopIteration:
                return False
            else:
                return True

    __bool__ = __nonzero__


iterbetter = IterBetter


def safeiter(it, cleanup=None, ignore_errors=True):
    """Makes an iterator safe by ignoring the exceptions occurred during the iteration.
    """

    def next():
        while True:
            try:
                return next(it)
            except StopIteration:
                raise
            except:
                traceback.print_exc()

    it = iter(it)
    while True:
        yield next()


def safewrite(filename, content):
    """Writes the content to a temp file and then moves the temp file to
    given filename to avoid overwriting the existing file in case of errors.
    """
    with open(filename + ".tmp", "w") as f:
        f.write(content)
    os.rename(f.name, filename)


def dictreverse(mapping):
    """
    Returns a new dictionary with keys and values swapped.

        >>> dictreverse({1: 2, 3: 4})
        {2: 1, 4: 3}
    """
    return dict([(value, key) for (key, value) in iteritems(mapping)])


def dictfind(dictionary, element):
    """
    Returns a key whose value in `dictionary` is `element`
    or, if none exists, None.

        >>> d = {1:2, 3:4}
        >>> dictfind(d, 4)
        3
        >>> dictfind(d, 5)
    """
    for (key, value) in iteritems(dictionary):
        if element is value:
            return key


def dictfindall(dictionary, element):
    """
    Returns the keys whose values in `dictionary` are `element`
    or, if none exists, [].

        >>> d = {1:4, 3:4}
        >>> dictfindall(d, 4)
        [1, 3]
        >>> dictfindall(d, 5)
        []
    """
    res = []
    for (key, value) in iteritems(dictionary):
        if element is value:
            res.append(key)
    return res


def dictincr(dictionary, element):
    """
    Increments `element` in `dictionary`,
    setting it to one if it doesn't exist.

        >>> d = {1:2, 3:4}
        >>> dictincr(d, 1)
        3
        >>> d[1]
        3
        >>> dictincr(d, 5)
        1
        >>> d[5]
        1
    """
    dictionary.setdefault(element, 0)
    dictionary[element] += 1
    return dictionary[element]


def dictadd(*dicts):
    """
    Returns a dictionary consisting of the keys in the argument dictionaries.
    If they share a key, the value from the last argument is used.

        >>> dictadd({1: 0, 2: 0}, {2: 1, 3: 1})
        {1: 0, 2: 1, 3: 1}
    """
    result = {}
    for dct in dicts:
        result.update(dct)
    return result


def requeue(queue, index=-1):
    """Returns the element at index after moving it to the beginning of the queue.

        >>> x = [1, 2, 3, 4]
        >>> requeue(x)
        4
        >>> x
        [4, 1, 2, 3]
    """
    x = queue.pop(index)
    queue.insert(0, x)
    return x


def restack(stack, index=0):
    """Returns the element at index after moving it to the top of stack.

           >>> x = [1, 2, 3, 4]
           >>> restack(x)
           1
           >>> x
           [2, 3, 4, 1]
    """
    x = stack.pop(index)
    stack.append(x)
    return x


def listget(lst, ind, default=None):
    """
    Returns `lst[ind]` if it exists, `default` otherwise.

        >>> listget(['a'], 0)
        'a'
        >>> listget(['a'], 1)
        >>> listget(['a'], 1, 'b')
        'b'
    """
    if len(lst) - 1 < ind:
        return default
    return lst[ind]


def intget(integer, default=None):
    """
    Returns `integer` as an int or `default` if it can't.

        >>> intget('3')
        3
        >>> intget('3a')
        >>> intget('3a', 0)
        0
    """
    try:
        return int(integer)
    except (TypeError, ValueError):
        return default


def datestr(then, now=None):
    """
    Converts a (UTC) datetime object to a nice string representation.

        >>> from datetime import datetime, timedelta
        >>> d = datetime(1970, 5, 1)
        >>> datestr(d, now=d)
        '0 microseconds ago'
        >>> for t, v in iteritems({
        ...   timedelta(microseconds=1): '1 microsecond ago',
        ...   timedelta(microseconds=2): '2 microseconds ago',
        ...   -timedelta(microseconds=1): '1 microsecond from now',
        ...   -timedelta(microseconds=2): '2 microseconds from now',
        ...   timedelta(microseconds=2000): '2 milliseconds ago',
        ...   timedelta(seconds=2): '2 seconds ago',
        ...   timedelta(seconds=2*60): '2 minutes ago',
        ...   timedelta(seconds=2*60*60): '2 hours ago',
        ...   timedelta(days=2): '2 days ago',
        ... }):
        ...     assert datestr(d, now=d+t) == v
        >>> datestr(datetime(1970, 1, 1), now=d)
        'January  1'
        >>> datestr(datetime(1969, 1, 1), now=d)
        'January  1, 1969'
        >>> datestr(datetime(1970, 6, 1), now=d)
        'June  1, 1970'
        >>> datestr(None)
        ''
    """

    def agohence(n, what, divisor=None):
        if divisor:
            n = n // divisor

        out = str(abs(n)) + " " + what  # '2 days'
        if abs(n) != 1:
            out += "s"  # '2 days'

        out += " "  # '2 days '
        if n < 0:
            out += "from now"
        else:
            out += "ago"
        return out  # '2 days ago'

    oneday = 24 * 60 * 60

    if not then:
        return ""

    if not now:
        now = datetime.datetime.utcnow()

    if type(now).__name__ == "DateTime":
        now = datetime.datetime.fromtimestamp(now)

    if type(then).__name__ == "DateTime":
        then = datetime.datetime.fromtimestamp(then)
    elif type(then).__name__ == "date":
        then = datetime.datetime(then.year, then.month, then.day)

    delta = now - then
    deltaseconds = int(delta.days * oneday + delta.seconds + delta.microseconds * 1e-06)
    deltadays = abs(deltaseconds) // oneday
    if deltaseconds < 0:
        deltadays *= -1  # fix for oddity of floor

    if deltadays:
        if abs(deltadays) < 4:
            return agohence(deltadays, "day")

        # Trick to display 'June 3' instead of 'June 03'
        # Even though the %e format in strftime does that, it doesn't work on Windows.
        out = then.strftime("%B %d").replace(" 0", "  ")

        if then.year != now.year or deltadays < 0:
            out += ", %s" % then.year
        return out

    if int(deltaseconds):
        if abs(deltaseconds) > (60 * 60):
            return agohence(deltaseconds, "hour", 60 * 60)
        elif abs(deltaseconds) > 60:
            return agohence(deltaseconds, "minute", 60)
        else:
            return agohence(deltaseconds, "second")

    deltamicroseconds = delta.microseconds
    if delta.days:
        deltamicroseconds = int(delta.microseconds - 1e6)  # datetime oddity

    if abs(deltamicroseconds) > 1000:
        return agohence(deltamicroseconds, "millisecond", 1000)

    return agohence(deltamicroseconds, "microsecond")


def numify(string):
    """
    Removes all non-digit characters from `string`.

        >>> numify('800-555-1212')
        '8005551212'
        >>> numify('800.555.1212')
        '8005551212'

    """
    return "".join([c for c in str(string) if c.isdigit()])


def denumify(string, pattern):
    """
    Formats `string` according to `pattern`, where the letter X gets replaced
    by characters from `string`.

        >>> denumify("8005551212", "(XXX) XXX-XXXX")
        '(800) 555-1212'

    """
    out = []
    for c in pattern:
        if c == "X":
            out.append(string[0])
            string = string[1:]
        else:
            out.append(c)
    return "".join(out)


def commify(n):
    """
    Add commas to an integer `n`.

        >>> commify(1)
        '1'
        >>> commify(123)
        '123'
        >>> commify(-123)
        '-123'
        >>> commify(1234)
        '1,234'
        >>> commify(1234567890)
        '1,234,567,890'
        >>> commify(123.0)
        '123.0'
        >>> commify(1234.5)
        '1,234.5'
        >>> commify(1234.56789)
        '1,234.56789'
        >>> commify(' %.2f ' % -1234.5)
        '-1,234.50'
        >>> commify(None)
        >>>

    """
    if n is None:
        return None

    n = str(n).strip()

    if n.startswith("-"):
        prefix = "-"
        n = n[1:].strip()
    else:
        prefix = ""

    if "." in n:
        dollars, cents = n.split(".")
    else:
        dollars, cents = n, None

    r = []
    for i, c in enumerate(str(dollars)[::-1]):
        if i and (not (i % 3)):
            r.insert(0, ",")
        r.insert(0, c)
    out = "".join(r)
    if cents:
        out += "." + cents
    return prefix + out


def dateify(datestring):
    """
    Formats a numified `datestring` properly.
    """
    return denumify(datestring, "XXXX-XX-XX XX:XX:XX")


def nthstr(n):
    """
    Formats an ordinal.
    Doesn't handle negative numbers.

        >>> nthstr(1)
        '1st'
        >>> nthstr(0)
        '0th'
        >>> [nthstr(x) for x in [2, 3, 4, 5, 10, 11, 12, 13, 14, 15]]
        ['2nd', '3rd', '4th', '5th', '10th', '11th', '12th', '13th', '14th', '15th']
        >>> [nthstr(x) for x in [91, 92, 93, 94, 99, 100, 101, 102]]
        ['91st', '92nd', '93rd', '94th', '99th', '100th', '101st', '102nd']
        >>> [nthstr(x) for x in [111, 112, 113, 114, 115]]
        ['111th', '112th', '113th', '114th', '115th']

    """

    assert n >= 0
    if n % 100 in [11, 12, 13]:
        return "%sth" % n
    return {1: "%sst", 2: "%snd", 3: "%srd"}.get(n % 10, "%sth") % n


def cond(predicate, consequence, alternative=None):
    """
    Function replacement for if-else to use in expressions.

        >>> x = 2
        >>> cond(x % 2 == 0, "even", "odd")
        'even'
        >>> cond(x % 2 == 0, "even", "odd") + '_row'
        'even_row'
    """
    if predicate:
        return consequence
    else:
        return alternative


class CaptureStdout:
    """
    Captures everything `func` prints to stdout and returns it instead.

        >>> def idiot():
        ...     print("foo")
        >>> capturestdout(idiot)()
        'foo\\n'

    **WARNING:** Not threadsafe!
    """

    def __init__(self, func):
        self.func = func

    def __call__(self, *args, **keywords):
        out = StringIO()
        oldstdout = sys.stdout
        sys.stdout = out
        try:
            self.func(*args, **keywords)
        finally:
            sys.stdout = oldstdout
        return out.getvalue()


capturestdout = CaptureStdout


class Profile:
    """
    Profiles `func` and returns a tuple containing its output
    and a string with human-readable profiling information.

        >>> import time
        >>> out, inf = profile(time.sleep)(.001)
        >>> out
        >>> inf[:10].strip()
        'took 0.0'
    """

    def __init__(self, func):
        self.func = func

    def __call__(self, *args):  # , **kw):   kw unused
        import cProfile
        import pstats
        import os
        import tempfile

        f, filename = tempfile.mkstemp()
        os.close(f)

        prof = cProfile.Profile()

        stime = time.time()
        result = prof.runcall(self.func, *args)
        stime = time.time() - stime

        out = StringIO()
        stats = pstats.Stats(prof, stream=out)
        stats.strip_dirs()
        stats.sort_stats("time", "calls")
        stats.print_stats(40)
        stats.print_callers()

        x = "\n\ntook " + str(stime) + " seconds\n"
        x += out.getvalue()

        # remove the tempfile
        try:
            os.remove(filename)
        except IOError:
            pass

        return result, x


profile = Profile


def tryall(context, prefix=None):
    """
    Tries a series of functions and prints their results.
    `context` is a dictionary mapping names to values;
    the value will only be tried if it's callable.

        >>> tryall(dict(j=lambda: True))
        j: True
        ----------------------------------------
        results:
           True: 1

    For example, you might have a file `test/stuff.py`
    with a series of functions testing various things in it.
    At the bottom, have a line:

        if __name__ == "__main__": tryall(globals())

    Then you can run `python test/stuff.py` and get the results of
    all the tests.
    """
    context = context.copy()  # vars() would update
    results = {}
    for (key, value) in iteritems(context):
        if not hasattr(value, "__call__"):
            continue
        if prefix and not key.startswith(prefix):
            continue
        print(key + ":", end=" ")
        try:
            r = value()
            dictincr(results, r)
            print(r)
        except:
            print("ERROR")
            dictincr(results, "ERROR")
            print("   " + "\n   ".join(traceback.format_exc().split("\n")))

    print("-" * 40)
    print("results:")
    for (key, value) in iteritems(results):
        print(" " * 2, str(key) + ":", value)


class ThreadedDict(threadlocal):
    """
    Thread local storage.

        >>> d = ThreadedDict()
        >>> d.x = 1
        >>> d.x
        1
        >>> import threading
        >>> def f(): d.x = 2
        ...
        >>> t = threading.Thread(target=f)
        >>> t.start()
        >>> t.join()
        >>> d.x
        1
    """

    _instances = set()

    def __init__(self):
        ThreadedDict._instances.add(self)

    def __del__(self):
        ThreadedDict._instances.remove(self)

    def __hash__(self):
        return id(self)

    def clear_all():
        """Clears all ThreadedDict instances.
        """
        for t in list(ThreadedDict._instances):
            t.clear()

    clear_all = staticmethod(clear_all)

    # Define all these methods to more or less fully emulate dict -- attribute access
    # is built into threading.local.

    def __getitem__(self, key):
        return self.__dict__[key]

    def __setitem__(self, key, value):
        self.__dict__[key] = value

    def __delitem__(self, key):
        del self.__dict__[key]

    def __contains__(self, key):
        return key in self.__dict__

    has_key = __contains__

    def clear(self):
        self.__dict__.clear()

    def copy(self):
        return self.__dict__.copy()

    def get(self, key, default=None):
        return self.__dict__.get(key, default)

    def items(self):
        return self.__dict__.items()

    def iteritems(self):
        return iteritems(self.__dict__)

    def keys(self):
        return self.__dict__.keys()

    def iterkeys(self):
        try:
            return iterkeys(self.__dict__)
        except NameError:
            return self.__dict__.keys()

    iter = iterkeys

    def values(self):
        return self.__dict__.values()

    def itervalues(self):
        return itervalues(self.__dict__)

    def pop(self, key, *args):
        return self.__dict__.pop(key, *args)

    def popitem(self):
        return self.__dict__.popitem()

    def setdefault(self, key, default=None):
        return self.__dict__.setdefault(key, default)

    def update(self, *args, **kwargs):
        self.__dict__.update(*args, **kwargs)

    def __repr__(self):
        return "<ThreadedDict %r>" % self.__dict__

    __str__ = __repr__


threadeddict = ThreadedDict


def autoassign(self, locals):
    """
    Automatically assigns local variables to `self`.

        >>> self = storage()
        >>> autoassign(self, dict(a=1, b=2))
        >>> self.a
        1
        >>> self.b
        2

    Generally used in `__init__` methods, as in:

        def __init__(self, foo, bar, baz=1): autoassign(self, locals())
    """
    for (key, value) in iteritems(locals):
        if key == "self":
            continue
        setattr(self, key, value)


def to36(q):
    """
    Converts an integer to base 36 (a useful scheme for human-sayable IDs).

        >>> to36(35)
        'z'
        >>> to36(119292)
        '2k1o'
        >>> int(to36(939387374), 36)
        939387374
        >>> to36(0)
        '0'
        >>> to36(-393)
        Traceback (most recent call last):
            ...
        ValueError: must supply a positive integer

    """
    if q < 0:
        raise ValueError("must supply a positive integer")

    letters = "0123456789abcdefghijklmnopqrstuvwxyz"
    converted = []
    while q != 0:
        q, r = divmod(q, 36)
        converted.insert(0, letters[r])
    return "".join(converted) or "0"


r_url = re_compile(r"(?<!\()(http://(\S+))")


def sendmail(from_address, to_address, subject, message, headers=None, **kw):
    """
    Sends the email message `message` with mail and envelope headers
    for from `from_address_` to `to_address` with `subject`.
    Additional email headers can be specified with the dictionary
    `headers.

    Optionally cc, bcc and attachments can be specified as keyword arguments.
    Attachments must be an iterable and each attachment can be either a
    filename or a file object or a dictionary with filename, content and
    optionally content_type keys.

    If `web.config.smtp_server` is set, it will send the message
    to that SMTP server. Otherwise it will look for
    `/usr/sbin/sendmail`, the typical location for the sendmail-style
    binary. To use sendmail from a different path, set `web.config.sendmail_path`.
    """
    attachments = kw.pop("attachments", [])
    mail = _EmailMessage(from_address, to_address, subject, message, headers, **kw)

    for a in attachments:
        if isinstance(a, dict):
            mail.attach(a["filename"], a["content"], a.get("content_type"))
        elif hasattr(a, "read"):  # file
            filename = os.path.basename(getattr(a, "name", ""))
            content_type = getattr(a, "content_type", None)
            mail.attach(filename, a.read(), content_type)
        elif isinstance(a, string_types):
            f = open(a, "rb")
            content = f.read()
            f.close()
            filename = os.path.basename(a)
            mail.attach(filename, content, None)
        else:
            raise ValueError("Invalid attachment: %s" % repr(a))

    mail.send()


class _EmailMessage:
    def __init__(self, from_address, to_address, subject, message, headers=None, **kw):
        def listify(x):
            if not isinstance(x, list):
                return [safestr(x)]
            else:
                return [safestr(a) for a in x]

        subject = safestr(subject)
        message = safestr(message)

        from_address = safestr(from_address)
        to_address = listify(to_address)
        cc = listify(kw.get("cc", []))
        bcc = listify(kw.get("bcc", []))
        recipients = to_address + cc + bcc

        import email.utils

        self.from_address = email.utils.parseaddr(from_address)[1]
        self.recipients = [email.utils.parseaddr(r)[1] for r in recipients]

        self.headers = dictadd(
            {"From": from_address, "To": ", ".join(to_address), "Subject": subject},
            headers or {},
        )

        if cc:
            self.headers["Cc"] = ", ".join(cc)

        self.message = self.new_message()
        self.message.add_header("Content-Transfer-Encoding", "7bit")
        self.message.add_header("Content-Disposition", "inline")
        self.message.add_header("MIME-Version", "1.0")
        self.message.set_payload(message, "utf-8")
        self.multipart = False

    def new_message(self):
        from email.message import Message

        return Message()

    def attach(self, filename, content, content_type=None):
        if not self.multipart:
            msg = self.new_message()
            msg.add_header("Content-Type", "multipart/mixed")
            msg.attach(self.message)
            self.message = msg
            self.multipart = True

        import mimetypes

        try:
            from email import encoders
        except:
            from email import Encoders as encoders

        content_type = (
            content_type
            or mimetypes.guess_type(filename)[0]
            or "application/octet-stream"
        )

        msg = self.new_message()
        msg.set_payload(content)
        msg.add_header("Content-Type", content_type)
        msg.add_header("Content-Disposition", "attachment", filename=filename)

        if not content_type.startswith("text/"):
            encoders.encode_base64(msg)

        self.message.attach(msg)

    def prepare_message(self):
        for k, v in iteritems(self.headers):
            if k.lower() == "content-type":
                self.message.set_type(v)
            else:
                self.message.add_header(k, v)

        self.headers = {}

    def send(self):
        self.prepare_message()
        message_text = self.message.as_string()

        try:
            from . import webapi
        except ImportError:
            webapi = Storage(config=Storage())

        if webapi.config.get("smtp_server"):
            self.send_with_smtp(message_text)
        elif webapi.config.get("email_engine") == "aws":
            self.send_with_aws(message_text)
        else:
            self.default_email_sender(message_text)

    def send_with_aws(self, message_text):
        try:
            from . import webapi
        except ImportError:
            webapi = Storage(config=Storage())

        import boto.ses

        c = boto.ses.SESConnection(
            aws_access_key_id=webapi.config.get("aws_access_key_id"),
            aws_secret_access_key=webapi.config.get("aws_secret_access_key"),
        )
        c.send_raw_email(message_text, self.from_address, self.recipients)

    def send_with_smtp(self, message_text):
        try:
            from . import webapi
        except ImportError:
            webapi = Storage(config=Storage())

        server = webapi.config.get("smtp_server")
        port = webapi.config.get("smtp_port", 0)
        username = webapi.config.get("smtp_username")
        password = webapi.config.get("smtp_password")
        debug_level = webapi.config.get("smtp_debuglevel", None)
        starttls = webapi.config.get("smtp_starttls", False)

        import smtplib

        smtpserver = smtplib.SMTP(server, port)

        if debug_level:
            smtpserver.set_debuglevel(debug_level)

        if starttls:
            smtpserver.ehlo()
            smtpserver.starttls()
            smtpserver.ehlo()

        if username and password:
            smtpserver.login(username, password)

        smtpserver.sendmail(self.from_address, self.recipients, message_text)
        smtpserver.quit()

    def default_email_sender(self, message_text):
        try:
            from . import webapi
        except ImportError:
            webapi = Storage(config=Storage())

        sendmail = webapi.config.get("sendmail_path", "/usr/sbin/sendmail")

        assert not self.from_address.startswith("-"), "security"

        for r in self.recipients:
            assert not r.startswith("-"), "security"

        cmd = [sendmail, "-f", self.from_address] + self.recipients

        p = subprocess.Popen(cmd, stdin=subprocess.PIPE)
        p.stdin.write(message_text.encode("utf-8"))
        p.stdin.close()
        p.wait()

    def __repr__(self):
        return "<EmailMessage>"

    def __str__(self):
        return self.message.as_string()


if __name__ == "__main__":
    import doctest

    doctest.testmod()