path: root/compat.py

# pylint: disable-msg=E0601,W0622,W0611
"""Wrappers around some builtins introduced in python 2.3, 2.4 and
2.5, making them available in for earlier versions of python.

:copyright: 2000-2009 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: General Public License version 2 - http://www.gnu.org/licenses
"""
from __future__ import generators
__docformat__ = "restructuredtext en"

import os
from warnings import warn

import builtins

from logilab.common.deprecation import class_renamed

try:
    set = set
    frozenset = frozenset
except NameError:
    try:
        from sets import Set as set, ImmutableSet as frozenset
    except ImportError:
        class _baseset(object):
            def __init__(self, values=()):
                self._data = {}
                warn("This implementation of Set is not complete !",
                     stacklevel=2)
                for v in values:
                    self._data[v] = 1

            def __or__(self, other):
                result = self.__class__(self._data.keys())
                for val in other:
                    result.add(val)
                return result
            __add__ = __or__
            
            def __and__(self, other):
                result = self.__class__()
                for val in other:
                    if val in self._data:
                        result.add(val)
                return result
            
            def __sub__(self, other):
                result = self.__class__(self._data.keys())
                for val in other:
                    if val in self._data:
                        result.remove(val)
                return result
            
            def __cmp__(self, other):
                keys = self._data.keys()
                okeys = other._data.keys()
                keys.sort()
                okeys.sort()
                return cmp(keys, okeys)
            
            def __len__(self):
                return len(self._data)

            def __repr__(self):
                elements = self._data.keys()
                return 'lcc.%s(%r)' % (self.__class__.__name__, elements)
            __str__ = __repr__

            def __iter__(self):
                return iter(self._data)

        class frozenset(_baseset):
            """immutable set (can be set in dictionnaries)"""
            def __init__(self, values=()):
                super(frozenset, self).__init__(values)
                self._hashcode = None
                
            def _compute_hash(self):
                """taken from python stdlib (sets.py)"""
                # Calculate hash code for a set by xor'ing the hash codes of
                # the elements.  This ensures that the hash code does not depend
                # on the order in which elements are added to the set.  This is
                # not called __hash__ because a BaseSet should not be hashable;
                # only an ImmutableSet is hashable.
                result = 0
                for elt in self:
                    result ^= hash(elt)
                return result
            
            def __hash__(self):
                """taken from python stdlib (sets.py)"""
                if self._hashcode is None:
                    self._hashcode = self._compute_hash()
                return self._hashcode

            
        class set(_baseset):
            """mutable set"""
            def add(self, value):
                self._data[value] = 1

            def remove(self, element):
                """removes <element> from set"""
                del self._data[element]

            def pop(self):
                """pops an arbitrary element from set"""
                return self._data.popitem()[0]

            def __hash__(self):
                """mutable et cannot be hashed."""
                raise TypeError("set objects are not hashable")

        del _baseset # don't explicity provide this class

Set = class_renamed('Set', set, 'logilab.common.compat.Set is deprecated, '
                    'use logilab.common.compat.set instead')

try:
    from itertools import izip, chain, imap
except ImportError:
    # from itertools documentation ###
    def izip(*iterables):
        iterables = map(iter, iterables)
        while iterables:
            result = [i.next() for i in iterables]
            yield tuple(result)

    def chain(*iterables):
        for it in iterables:
            for element in it:
                yield element
                
    def imap(function, *iterables):
        iterables = map(iter, iterables)
        while True:
            args = [i.next() for i in iterables]
            if function is None:
                yield tuple(args)
            else:
                yield function(*args)                
try:
    sum = sum
    enumerate = enumerate
except NameError:
    # define the sum and enumerate functions (builtins introduced in py 2.3)
    import operator
    def sum(seq, start=0):
        """Returns the sum of all elements in the sequence"""
        return reduce(operator.add, seq, start)

    def enumerate(iterable):
        """emulates the python2.3 enumerate() function"""
        i = 0
        for val in iterable:
            yield i, val
            i += 1
        #return zip(range(len(iterable)), iterable)
try:
    sorted = sorted
    reversed = reversed
except NameError:
    
    def sorted(iterable, cmp=None, key=None, reverse=False):
        original = list(iterable)
        if key:
            l2 = [(key(elt), index) for index, elt in enumerate(original)]
        else:
            l2 = original
        l2.sort(cmp)
        if reverse:
            l2.reverse()
        if key:
            return [original[index] for elt, index in l2]
        return l2
    
    def reversed(l):
        l2 = list(l)
        l2.reverse()
        return l2

try: #
    max = max
    max(("ab","cde"),key=len)
except TypeError:
    def max( *args, **kargs):
        if len(args) == 0:
            raise TypeError("max expected at least 1 arguments, got 0")
        key= kargs.pop("key", None)
        #default implementation
        if key is None:
            return builtins.max(*args,**kargs)

        for karg in kargs:
            raise TypeError("unexpected keyword argument %s for function max") % karg

        if len(args) == 1:
            items = iter(args[0])
        else:
            items = iter(args)
        
        try:
            best_item = items.next()
            best_value = key(best_item)
        except StopIteration:
            raise ValueError("max() arg is an empty sequence")
        
        for item in items:
            value = key(item)
            if value > best_value:
                best_item = item
                best_value = value

        return best_item





# Python2.5 builtins
try:
    any = any
    all = all
except NameError:
    def any(iterable):
        """any(iterable) -> bool

        Return True if bool(x) is True for any x in the iterable.
        """
        for elt in iterable:
            if elt:
                return True
        return False
    
    def all(iterable):
        """all(iterable) -> bool

        Return True if bool(x) is True for all values x in the iterable.
        """
        for elt in iterable:
            if not elt:
                return False
        return True

# Python2.5 subprocess added functions and exceptions
from subprocess import Popen
class CalledProcessError(Exception):
    """This exception is raised when a process run by check_call() returns
    a non-zero exit status.  The exit status will be stored in the
    returncode attribute."""
    def __init__(self, returncode, cmd):
        self.returncode = returncode
        self.cmd = cmd
    def __str__(self):
        return "Command '%s' returned non-zero exit status %d" % (self.cmd,
self.returncode)

def call(*popenargs, **kwargs):
    """Run command with arguments.  Wait for command to complete, then
    return the returncode attribute.

    The arguments are the same as for the Popen constructor.  Example:

    retcode = call(["ls", "-l"])
    """
    # workaround: subprocess.Popen(cmd, stdout=sys.stdout) fails
    # see http://bugs.python.org/issue1531862
    if "stdout" in kwargs:
        fileno = kwargs.get("stdout").fileno()
        del kwargs['stdout']
        return Popen(stdout=os.dup(fileno), *popenargs, **kwargs).wait()
    return Popen(*popenargs, **kwargs).wait()

def check_call(*popenargs, **kwargs):
    """Run command with arguments.  Wait for command to complete.  If
    the exit code was zero then return, otherwise raise
    CalledProcessError.  The CalledProcessError object will have the
    return code in the returncode attribute.

    The arguments are the same as for the Popen constructor.  Example:

    check_call(["ls", "-l"])
    """
    retcode = call(*popenargs, **kwargs)
    cmd = kwargs.get("args")
    if cmd is None:
        cmd = popenargs[0]
    if retcode:
        raise CalledProcessError(retcode, cmd)
    return retcode