Source

Unipath / unipath / abstractpath.py

"""unipath.py - A two-class approach to file/directory operations in Python.

Full usage, documentation, changelog, and history are at
http://sluggo.scrapping.cc/python/unipath/

(c) 2007 by Mike Orr (and others listed in "History" section of doc page).
Permission is granted to redistribute, modify, and include in commercial and
noncommercial products under the terms of the Python license (i.e., the "Python
Software Foundation License version 2" at 
http://www.python.org/download/releases/2.5/license/).
"""

import os

from unipath.errors import UnsafePathError

__all__ = ["AbstractPath"]

# Use unicode strings if possible
_base = os.path.supports_unicode_filenames and unicode or str

class AbstractPath(_base):
    """An object-oriented approach to os.path functions."""
    pathlib = os.path
    auto_norm = False

    #### Special Python methods.
    def __new__(class_, *args, **kw):
        norm = kw.pop("norm", None)
        if norm is None:
            norm = class_.auto_norm
        if kw:
            kw_str = ", ".join(kw.iterkeys())
            raise TypeError("unrecognized keyword args: %s" % kw_str)
        newpath = class_._new_helper(args)
        if isinstance(newpath, class_):
            return newpath
        if norm:
            newpath = class_.pathlib.normpath(newpath)
            # Can't call .norm() because the path isn't instantiated yet.
        return _base.__new__(class_, newpath)

    def __add__(self, more):
        try:
            resultStr = _base.__add__(self, more)
        except TypeError:  #Python bug
            resultStr = NotImplemented
        if resultStr is NotImplemented:
            return resultStr
        return self.__class__(resultStr)
 
    @classmethod
    def _new_helper(class_, args):
        pathlib = class_.pathlib
        # If no args, return "." or platform equivalent.
        if not args:
            return pathlib.curdir
        # Avoid making duplicate instances of the same immutable path
        if len(args) == 1 and isinstance(args[0], class_) and \
            args[0].pathlib == pathlib:
            return args[0]
        legal_arg_types = (class_, basestring, list, int, long)
        args = list(args)
        for i, arg in enumerate(args):
            if not isinstance(arg, legal_arg_types):
                m = "arguments must be str, unicode, list, int, long, or %s"
                raise TypeError(m % class_.__name__)
            if isinstance(arg, (int, long)):
                args[i] = str(arg)
            elif isinstance(arg, class_) and arg.pathlib != pathlib:
                arg = getattr(arg, components)()   # Now a list.
                if arg[0]:
                    reason = ("must use a relative path when converting "
                              "from '%s' platform to '%s': %s")
                    tup = arg.pathlib.__name__, pathlib.__name__, arg
                    raise ValueError(reason % tup)
                # Fall through to convert list of components.
            if isinstance(arg, list):
                args[i] = pathlib.join(*arg)
        return pathlib.join(*args)
        
    def __repr__(self):
        return '%s(%r)' % (self.__class__.__name__, _base(self))

    def norm(self):
        return self.__class__(self.pathlib.normpath(self))

    def expand_user(self):
        return self.__class__(self.pathlib.expanduser(self))
    
    def expand_vars(self):
        return self.__class__(self.pathlib.expandvars(self))
    
    def expand(self):
        """ Clean up a filename by calling expandvars(),
        expanduser(), and norm() on it.

        This is commonly everything needed to clean up a filename
        read from a configuration file, for example.
        """
        newpath = self.pathlib.expanduser(self)
        newpath = self.pathlib.expandvars(newpath)
        newpath = self.pathlib.normpath(newpath)
        return self.__class__(newpath)

    #### Properies: parts of the path.

    @property
    def parent(self):
        """The path without the final component; akin to os.path.dirname().
           Example: Path('/usr/lib/libpython.so').parent => Path('/usr/lib')
        """
        return self.__class__(self.pathlib.dirname(self))
    
    @property
    def name(self):
        """The final component of the path.
           Example: path('/usr/lib/libpython.so').name => Path('libpython.so')
        """
        return self.__class__(self.pathlib.basename(self))
    
    @property
    def stem(self):
        """Same as path.name but with one file extension stripped off.
           Example: path('/home/guido/python.tar.gz').stem => Path('python.tar')
        """
        return self.__class__(self.pathlib.splitext(self.name)[0])
    
    @property
    def ext(self):
        """The file extension, for example '.py'."""
        return self.__class__(self.pathlib.splitext(self)[1])

    #### Methods to extract and add parts to the path.

    def split_root(self):
        """Split a path into root and remainder.  The root is always "/" for
           posixpath, or a backslash-root, drive-root, or UNC-root for ntpath.
           If the path begins with none of these, the root is returned as ""
           and the remainder is the entire path.
        """
        P = self.__class__
        if hasattr(self.pathlib, "splitunc"):
            root, rest = self.pathlib.splitunc(self)
            if root:
                if rest.startswith(self.pathlib.sep):
                    root += self.pathlib.sep
                    rest = rest[len(self.pathlib.sep):]
                return P(root), P(rest)
                # @@MO: Should test altsep too.
        root, rest = self.pathlib.splitdrive(self)
        if root:
            if rest.startswith(self.pathlib.sep):
                root += self.pathlib.sep
                rest = rest[len(self.pathlib.sep):]
            return P(root), P(rest)
            # @@MO: Should test altsep too.
        if self.startswith(self.pathlib.sep):
            return P(self.pathlib.sep), P(rest[len(self.pathlib.sep):])
        if self.pathlib.altsep and self.startswith(self.pathlib.altsep):
            return P(self.pathlib.altsep), P(rest[len(self.pathlib.altsep):])
        return P(""), self

    def components(self):
        # @@MO: Had to prevent "" components from being appended.  I don't
        # understand why Lindqvist didn't have this problem.
        # Also, doesn't this fail to get the beginning components if there's
        # a "." or ".." in the middle of the path?
        root, loc = self.split_root()
        components = []
        while loc != self.pathlib.curdir and loc != self.pathlib.pardir:
            prev = loc
            loc, child = self.pathlib.split(prev)
            #print "prev=%r, loc=%r, child=%r" % (prev, loc, child)
            if loc == prev:
                break
            if child != "":
                components.append(child)
            if loc == "":
                break
        if loc != "":
            components.append(loc)
        components.reverse()
        components.insert(0, root)
        return [self.__class__(x) for x in components]

    def ancestor(self, n):
        p = self
        for i in range(n):
            p = p.parent
        return p

    def child(self, *children):
        # @@MO: Compare against Glyph's method.
        for child in children:
            if self.pathlib.sep in child:
                msg = "arg '%s' contains path separator '%s'"
                tup = child, self.pathlib.sep
                raise UnsafePathError(msg % tup)
            if self.pathlib.altsep and self.pathlib.altsep in child:
                msg = "arg '%s' contains alternate path separator '%s'"
                tup = child, self.pathlib.altsep
                raise UnsafePathError(msg % tup)
            if child == self.pathlib.pardir:
                msg = "arg '%s' is parent directory specifier '%s'"
                tup = child, self.pathlib.pardir
                raise UnsafePathError(msg % tup)
            if child == self.pathlib.curdir:    
                msg = "arg '%s' is current directory specifier '%s'"
                tup = child, self.pathlib.curdir
                raise UnsafePathError(msg % tup)
        newpath = self.pathlib.join(self, *children)
        return self.__class__(newpath)

    def norm_case(self):
        return self.__class__(self.pathlib.normcase(self))
    
    def isabsolute(self):
        """True if the path is absolute.
           Note that we consider a Windows drive-relative path ("C:foo") 
           absolute even though ntpath.isabs() considers it relative.
        """
        return bool(self.split_root()[0])