Corectly convert from %PATH%=c:\\X; "c:\\a; b" TO ['c:\\X', 'c:\\a; b']

[chirayuk]

Michael Spencer wrote:
> chirayuk wrote:
> > Hi,
> >
> > I am trying to treat an environment variable as a python list - and
I'm
> > sure there must be a standard and simple way to do so. I know that
the
> > interpreter itself must use it (to process $PATH / %PATH%, etc) but
I
> > am not able to find a simple function to do so.
> >
> > os.environ['PATH'].split(os.sep) is wrong on Windows for the case
when
> > PATH="c:\\A;B";c:\\D;
> > where there is a ';' embedded in the quoted path.
> >
> > Does anyone know of a simple way (addons ok) which would do it in a
> > cross platform way? If not - I will roll my own. My search has
shown
> > that generally people just use the simple split menthod as above
and
> > leave it there but it seemed like such a common operation that I
> > believe there must be a way out for it which I am not seeing.
> >
> > Thanks,
> > Chirayu.
> >
> You may be able to bend the csv module to your purpose:
>
>
>   >>> test = """\"c:\\A;B";c:\\D;"""
>   >>> test1 = os.environ['PATH']
>   >>> import csv
>   >>> class path(csv.excel):
>   ...     delimiter = ';'
>   ...     quotechar = '"'
>   ...
>   >>> csv.reader([test],path).next()
>   ['c:\\A;B', 'c:\\D', '']
>   >>> csv.reader([test1],path).next()
>   ['C:\\WINDOWS\\system32', 'C:\\WINDOWS',
'C:\\WINDOWS\\System32\\Wbem',
> 'C:\\Program Files\\ATI Technologies\\ATI Control Panel',
> 'C:\\PROGRA~1\\ATT\\Graphviz\\bin',
'C:\\PROGRA~1\\ATT\\Graphviz\\bin\\tools',
> 'C:\\WINDOWS\\system32', 'C:\\WINDOWS',
'C:\\WINDOWS\\System32\\Wbem',
> 'C:\\Program Files\\ATI Technologies\\ATI Control Panel',
> 'C:\\PROGRA~1\\ATT\\Graphviz\\bin',
'C:\\PROGRA~1\\ATT\\Graphviz\\bin\\tools',
> 'c:\\python24', 'c:\\python24\\scripts',
'G:\\cabs\\python\\pypy\\py\\bin']
>   >>>
>
> HTH
> Michael

That is a cool use of the csv module.

However, I just realized that the following is also a valid PATH in
windows.

PATH=c:\A"\B;C"\D;c:\program files\xyz"
(The quotes do not need to cover the entire path)

So here is my handcrafted solution.

def WinPathList_to_PyList (pathList):
    pIter = iter(pathList.split(';'))
    OddNumOfQuotes = lambda x: x.count('"') % 2 == 1
    def Accumulate (p):
        bAcc, acc = OddNumOfQuotes(p), [p]
        while bAcc:
            p = pIter.next ()
            acc.append (p)
            bAcc = not OddNumOfQuotes (p)
        return "".join (acc).replace('"','')
    return [q for q in [Accumulate (p) for p in pIter] if q]


So now I need to check if the os is windows.

Wishful thinking: It would be nice if something like this (taking care
of the cases for other OS's) made it into the standard library - the
interpreter must already be doing it.

Thanks,
Chirayu.