utils.py

## Copyright (C) 2008, 2009, 2010 APC LPNHE CNRS Universite Paris Diderot <lejeune@apc.univ-paris7.fr>  <betoule@apc.univ-paris7.fr>
## 
## 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; either version 3 of the License, or
## (at your option) any later version.
##
## 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, see http://www.gnu.org/licenses/gpl.html

""" Define various tools used by the pipe engine.
"""

import os.path as path
import re
import subprocess

import tempfile
import base64
import zlib
import datetime

def flatten(seq):
    """
    this generator flattens nested containers such as

    >>> l=( ('John', 'Hunter'), (1,23), [[[[42,(5,23)]]]])

    so that

    >>> for i in flatten(l): print i,
    John Hunter 1 23 42 5 23

    By: Composite of Holger Krekel and Luther Blissett
    From: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/121294
    and Recipe 1.12 in cookbook
    """
    for item in seq:
        if isinstance(item,str): yield item
        else:
            try:
                iter(item)
                for subitem in flatten(item):
                    yield subitem
            except:
                yield item

_sup = re.compile(r"""[\(\)\{\}\[\]"']""")
_rep = re.compile(r"""\W+""")
def str_file(obj):
    """ String representation with all special caracters supressed or replaced by underscores.
    
    Parameters
    ----------
    obj: a python object.

    Returns
    -------
    string

    Examples
    --------
    >>> str_file((1,))
    '1_'
    """
    s = ''
    if isinstance(obj, str):
        s = _sup.sub('',obj)
        s = _rep.sub('_',s)
    else:
        try:
            s = '_'.join([str_file(o) for o in obj])
        except TypeError:
            s = str_file(str(obj))
    return s

def str_web(a):
    """String representation without the quotes and spaces that
    disturbs the web interface.

    Parameters
    ----------
    a: a python object.

    Returns
    -------
    string

    Examples
    --------
    >>> print(str_web(['a', ' b']))
    [a,b]
    """
    s = str(a)
    s = s.replace('"','')
    s = s.replace("'",'')
    s = s.replace(' ','')
    return s


def str_date():
    """ Return a string representation of the date time now. 
    
    Returns:
    --------
    string %y/%m/%d %H:%M:%s

    """
    d = datetime.datetime.now()
    return (d.strftime("%Y-%m-%d %H:%M:%S"))


def is_code_file(s):
    """Check wether the file is a python code file based an the file
    extension.

    Parameters
    ----------
    s: string, file name.

    Returns
    -------
    boolean
    """
    return path.splitext(s)[1] in ['.py']
class crc32:
    """ Hash object using the crc32 algorithm.
    """
    def __init__(self, s=""):
        """ Initialize the hash object. 
        
        Parameters
        ----------
        s: string.
        """
        
        ## string, checksum given by the crc32 algorithm
        self.checksum = 0
        if s:
            self.checksum = zlib.crc32(s)

    def base32_digest(self):
        """Return a base32 digest of the checksum
        
        Checksum is computed using the crc32 algorithm.
 
        Returns
        -------
        string
       
        Examples
        --------
        >>> print crc32('test').base32_digest()
        3B7X4DA
        """
        return base64.b32encode(base64.b16decode("%08X"%(self.checksum & 0xffffffff))).replace('=','')
    
    def update(self, s):
        """Update this hash object's state with the provided string.
        
        Parameters
        ----------
        s: string.
        """
        self.checksum = zlib.crc32(s, self.checksum)

_rm_comment = re.compile(r'^[ \t]*#.*')
_rm_endline_comments = re.compile(r'#.*')
_rm_blank_lines = re.compile(r'^\s*$')
_rm_double_space= re.compile(r'(\S+)\s+')
_rm_endline_space = re.compile(r'\s+$')
_rm_useless_space = re.compile(r'\s*([^A-Za-z0-9 \t\n\r\f\v])\s*')

def reduced_code_formatting(s, unsafe=False):
    """ Return a code string with some part of the non syntactic
    information removed.

    Parameters
    ----------
    s: string
    unsafe: boolean (optional), if True remove some syntactic information like spaces in string literals.

    Returns
    -------
    string

    Examples
    --------
    >>> reduced_code_formatting(r'def pouet():\n    #lets try it\n    a,  b = foo ( bar )  \n')
    """
    min_code=""
    for l in s.splitlines():
        if _rm_comment.match(l):
            continue
        if _rm_blank_lines.match(l):
            continue
        l = _rm_endline_comments.sub('',l)
        l = _rm_endline_space.sub(r'',l)
        if unsafe:
            l = _rm_double_space.sub(r'\1 ',l)
            l = _rm_useless_space.sub(r'\1',l)
        min_code += l+'\n'
    return min_code

def hash_file(codefile):
    """Use cheksum algorithm to return a unique key for file.
    
    DEPRECATED: use crc32

    Parameters
    ----------
    codefile: string. 

    Returns
    -------
    string

    Examples
    --------
    >>> print(hash_file('../test/codesample.py'))
    3DDAAEC1
    """
    if not path.exists(codefile):
        print('Try to compute checksum of non existing file %s.'%codefile)
        return None
    
    sum_binary = "cksum"
    # Computes checksum
    sp = subprocess.Popen([sum_binary, codefile], stdout=subprocess.PIPE)
    res = sp.communicate()[0]
    key = "%X" % int(res.split(' ')[0])
    if sp.returncode != 0:
        print('Error while computing checksum of file %s.'%codefile)
    return key


def get_hashkey(s, starthash):
    """Return a unique key which identify code string
    using cheksum algorithm.
    
    Comment lines and blanks are not taken into account in code string.

    Parameters
    ----------
    s: string 
    starthash: an Hash instance

    Returns
    -------
    string
    
    Examples
    --------
    >>> print(get_hashkey("a = 5"))
    B6EB81FE
    """
    if not starthash:
        starthash = crc32()
    
    starthash.update(reduced_code_formatting(s))
    
    return starthash


if __name__ == "__main__":
    import doctest
    doctest.testmod()