Mini Shell

# Authors: Karl MacMillan <kmacmillan@mentalrootkit.com>
#
# Copyright (C) 2006 Red Hat 
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; version 2 only
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
import locale
import sys


PY3 = sys.version_info[0] == 3

if PY3:
    bytes_type=bytes
    string_type=str
else:
    bytes_type=str
    string_type=unicode


class ConsoleProgressBar:
    def __init__(self, out, steps=100, indicator='#'):
        self.blocks = 0
        self.current = 0
        self.steps = steps
        self.indicator = indicator
        self.out = out
        self.done = False

    def start(self, message=None):
        self.done = False
        if message:
            self.out.write('\n%s:\n' % message)
        self.out.write('%--10---20---30---40---50---60---70---80---90--100\n')

    def step(self, n=1):
        self.current += n

        old = self.blocks
        self.blocks = int(round(self.current / float(self.steps) * 100) / 2)

        if self.blocks > 50:
            self.blocks = 50

        new = self.blocks - old

        self.out.write(self.indicator * new)
        self.out.flush()

        if self.blocks == 50 and not self.done:
            self.done = True
            self.out.write("\n")

def set_to_list(s):
    l = []
    l.extend(s)
    return l

def first(s, sorted=False):
    """
    Return the first element of a set.

    It sometimes useful to return the first element from a set but,
    because sets are not indexable, this is rather hard. This function
    will return the first element from a set. If sorted is True, then
    the set will first be sorted (making this an expensive operation).
    Otherwise a random element will be returned (as sets are not ordered).
    """
    if not len(s):
        raise IndexError("empty containter")
    
    if sorted:
        l = set_to_list(s)
        l.sort()
        return l[0]
    else:
        for x in s:
            return x

def encode_input(text):
    """Encode given text via preferred system encoding"""
    # locale will often find out the correct encoding
    encoding = locale.getpreferredencoding()
    try:
        encoded_text = text.encode(encoding)
    except UnicodeError:
    # if it fails to find correct encoding then ascii is used
    # which may lead to UnicodeError if `text` contains non ascii signs
    # utf-8 is our guess to fix the situation
        encoded_text = text.encode('utf-8')
    return encoded_text

def decode_input(text):
    """Decode given text via preferred system encoding"""
    # locale will often find out the correct encoding
    encoding = locale.getpreferredencoding()
    try:
        decoded_text = text.decode(encoding)
    except UnicodeError:
    # if it fails to find correct encoding then ascii is used
    # which may lead to UnicodeError if `text` contains non ascii signs
    # utf-8 is our guess to fix the situation
        decoded_text = text.decode('utf-8')
    return decoded_text

class Comparison():
    """Class used when implementing rich comparison.

    Inherit from this class if you want to have a rich
    comparison withing the class, afterwards implement
    _compare function within your class."""

    def _compare(self, other, method):
        return NotImplemented

    def __eq__(self, other):
        return self._compare(other, lambda a, b: a == b)

    def __lt__(self, other):
        return self._compare(other, lambda a, b: a < b)

    def __le__(self, other):
        return self._compare(other, lambda a, b: a <= b)

    def __ge__(self, other):
        return self._compare(other, lambda a, b: a >= b)

    def __gt__(self, other):
        return self._compare(other, lambda a, b: a > b)

    def __ne__(self, other):
        return self._compare(other, lambda a, b: a != b)

if sys.version_info < (2,7):
    # cmp_to_key function is missing in python2.6
    def cmp_to_key(mycmp):
        'Convert a cmp= function into a key= function'
        class K:
            def __init__(self, obj, *args):
                self.obj = obj
            def __lt__(self, other):
                return mycmp(self.obj, other.obj) < 0
            def __gt__(self, other):
                return mycmp(self.obj, other.obj) > 0
            def __eq__(self, other):
                return mycmp(self.obj, other.obj) == 0
            def __le__(self, other):
                return mycmp(self.obj, other.obj) <= 0
            def __ge__(self, other):
                return mycmp(self.obj, other.obj) >= 0
            def __ne__(self, other):
                return mycmp(self.obj, other.obj) != 0
        return K
else:
    from functools import cmp_to_key

def cmp(first, second):
    return (first > second) - (second > first)

if __name__ == "__main__":
    import time
    p = ConsoleProgressBar(sys.stdout, steps=999)
    p.start("computing pi")
    for i in range(999):
        p.step()
        time.sleep(0.001)