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# Module 'ntpath' -- common operations on WinNT/Win95 pathnames

"""Common pathname manipulations, WindowsNT/95 version.

Instead of importing this module directly, import os and refer to this

module as os.path.

"""

import os

import stat

__all__ = ["normcase","isabs","join","splitdrive","split","splitext",

           "basename","dirname","commonprefix","getsize","getmtime",

           "getatime","islink","exists","isdir","isfile","ismount",

           "walk","expanduser","expandvars","normpath","abspath","splitunc"]

# Normalize the case of a pathname and map slashes to backslashes.

# Other normalizations (such as optimizing '../' away) are not done

# (this is done by normpath).

def normcase(s):

    """Normalize case of pathname.

    Makes all characters lowercase and all slashes into backslashes."""

    return s.replace("/", "\\").lower()

# Return whether a path is absolute.

# Trivial in Posix, harder on the Mac or MS-DOS.

# For DOS it is absolute if it starts with a slash or backslash (current

# volume), or if a pathname after the volume letter and colon / UNC resource

# starts with a slash or backslash.

def isabs(s):

    """Test whether a path is absolute"""

    s = splitdrive(s)[1]

    return s != '' and s[:1] in '/\\'

# Join two (or more) paths.

def join(a, *p):

    """Join two or more pathname components, inserting "\\" as needed"""

    path = a

    for b in p:

        if isabs(b):

            path = b

        elif path == '' or path[-1:] in '/\\:':

            path = path + b

        else:

            path = path + "\\" + b

    return path

# Split a path in a drive specification (a drive letter followed by a

# colon) and the path specification.

# It is always true that drivespec + pathspec == p

def splitdrive(p):

    """Split a pathname into drive and path specifiers. Returns a 2-tuple

"(drive,path)";  either part may be empty"""

    if p[1:2] == ':':

        return p[0:2], p[2:]

    return '', p

# Parse UNC paths

def splitunc(p):

    """Split a pathname into UNC mount point and relative path specifiers.

    Return a 2-tuple (unc, rest); either part may be empty.

    If unc is not empty, it has the form '//host/mount' (or similar

    using backslashes).  unc+rest is always the input path.

    Paths containing drive letters never have an UNC part.

    """

    if p[1:2] == ':':

        return '', p # Drive letter present

    firstTwo = p[0:2]

    if firstTwo == '//' or firstTwo == '\\\\':

        # is a UNC path:

        # vvvvvvvvvvvvvvvvvvvv equivalent to drive letter

        # \\machine\mountpoint\directories...

        #           directory ^^^^^^^^^^^^^^^

        normp = normcase(p)

        index = normp.find('\\', 2)

        if index == -1:

            ##raise RuntimeError, 'illegal UNC path: "' + p + '"'

            return ("", p)

        index = normp.find('\\', index + 1)

        if index == -1:

            index = len(p)

        return p[:index], p[index:]

    return '', p

# Split a path in head (everything up to the last '/') and tail (the

# rest).  After the trailing '/' is stripped, the invariant

# join(head, tail) == p holds.

# The resulting head won't end in '/' unless it is the root.

def split(p):

    """Split a pathname.

    Return tuple (head, tail) where tail is everything after the final slash.

    Either part may be empty."""

    d, p = splitdrive(p)

    # set i to index beyond p's last slash

    i = len(p)

    while i and p[i-1] not in '/\\':

        i = i - 1

    head, tail = p[:i], p[i:]  # now tail has no slashes

    # remove trailing slashes from head, unless it's all slashes

    head2 = head

    while head2 and head2[-1] in '/\\':

        head2 = head2[:-1]

    head = head2 or head

    return d + head, tail

# Split a path in root and extension.

# The extension is everything starting at the last dot in the last

# pathname component; the root is everything before that.

# It is always true that root + ext == p.

def splitext(p):

    """Split the extension from a pathname.

    Extension is everything from the last dot to the end.

    Return (root, ext), either part may be empty."""

    root, ext = '', ''

    for c in p:

        if c in ['/','\\']:

            root, ext = root + ext + c, ''

        elif c == '.':

            if ext:

                root, ext = root + ext, c

            else:

                ext = c

        elif ext:

            ext = ext + c

        else:

            root = root + c

    return root, ext

# Return the tail (basename) part of a path.

def basename(p):

    """Returns the final component of a pathname"""

    return split(p)[1]

# Return the head (dirname) part of a path.

def dirname(p):

    """Returns the directory component of a pathname"""

    return split(p)[0]

# Return the longest prefix of all list elements.

def commonprefix(m):

    "Given a list of pathnames, returns the longest common leading component"

    if not m: return ''

    prefix = m[0]

    for item in m:

        for i in range(len(prefix)):

            if prefix[:i+1] != item[:i+1]:

                prefix = prefix[:i]

                if i == 0: return ''

                break

    return prefix

# Get size, mtime, atime of files.

def getsize(filename):

    """Return the size of a file, reported by os.stat()"""

    st = os.stat(filename)

    return st[stat.ST_SIZE]

def getmtime(filename):

    """Return the last modification time of a file, reported by os.stat()"""

    st = os.stat(filename)

    return st[stat.ST_MTIME]

def getatime(filename):

    """Return the last access time of a file, reported by os.stat()"""

    st = os.stat(filename)

    return st[stat.ST_ATIME]

# Is a path a symbolic link?

# This will always return false on systems where posix.lstat doesn't exist.

def islink(path):

    """Test for symbolic link.  On WindowsNT/95 always returns false"""

    return 0

# Does a path exist?

# This is false for dangling symbolic links.

def exists(path):

    """Test whether a path exists"""

    try:

        st = os.stat(path)

    except os.error:

        return 0

    return 1

# Is a path a dos directory?

# This follows symbolic links, so both islink() and isdir() can be true

# for the same path.

def isdir(path):

    """Test whether a path is a directory"""

    try:

        st = os.stat(path)

    except os.error:

        return 0

    return stat.S_ISDIR(st[stat.ST_MODE])

# Is a path a regular file?

# This follows symbolic links, so both islink() and isdir() can be true

# for the same path.

def isfile(path):

    """Test whether a path is a regular file"""

    try:

        st = os.stat(path)

    except os.error:

        return 0

    return stat.S_ISREG(st[stat.ST_MODE])

# Is a path a mount point?  Either a root (with or without drive letter)

# or an UNC path with at most a / or \ after the mount point.

def ismount(path):

    """Test whether a path is a mount point (defined as root of drive)"""

    unc, rest = splitunc(path)

    if unc:

        return rest in ("", "/", "\\")

    p = splitdrive(path)[1]

    return len(p) == 1 and p[0] in '/\\'

# Directory tree walk.

# For each directory under top (including top itself, but excluding

# '.' and '..'), func(arg, dirname, filenames) is called, where

# dirname is the name of the directory and filenames is the list

# files files (and subdirectories etc.) in the directory.

# The func may modify the filenames list, to implement a filter,

# or to impose a different order of visiting.

def walk(top, func, arg):

    """Directory tree walk whth callback function.

    walk(top, func, arg) calls func(arg, d, files) for each directory d

    in the tree rooted at top (including top itself); files is a list

    of all the files and subdirs in directory d."""

    try:

        names = os.listdir(top)

    except os.error:

        return

    func(arg, top, names)

    exceptions = ('.', '..')

    for name in names:

        if name not in exceptions:

            name = join(top, name)

            if isdir(name):

                walk(name, func, arg)

# Expand paths beginning with '~' or '~user'.

# '~' means $HOME; '~user' means that user's home directory.

# If the path doesn't begin with '~', or if the user or $HOME is unknown,

# the path is returned unchanged (leaving error reporting to whatever

# function is called with the expanded path as argument).

# See also module 'glob' for expansion of *, ? and [...] in pathnames.

# (A function should also be defined to do full *sh-style environment

# variable expansion.)

def expanduser(path):

    """Expand ~ and ~user constructs.

    If user or $HOME is unknown, do nothing."""

    if path[:1] != '~':

        return path

    i, n = 1, len(path)

    while i < n and path[i] not in '/\\':

        i = i + 1

    if i == 1:

        if os.environ.has_key('HOME'):

            userhome = os.environ['HOME']

        elif not os.environ.has_key('HOMEPATH'):

            return path

        else:

            try:

                drive = os.environ['HOMEDRIVE']

            except KeyError:

                drive = ''

            userhome = join(drive, os.environ['HOMEPATH'])

    else:

        return path

    return userhome + path[i:]

# Expand paths containing shell variable substitutions.

# The following rules apply:

#       - no expansion within single quotes

#       - no escape character, except for '$$' which is translated into '$'

#       - ${varname} is accepted.

#       - varnames can be made out of letters, digits and the character '_'

# XXX With COMMAND.COM you can use any characters in a variable name,

# XXX except '^|<>='.

def expandvars(path):

    """Expand shell variables of form $var and ${var}.

    Unknown variables are left unchanged."""

    if '$' not in path:

        return path

    import string

    varchars = string.letters + string.digits + '_-'

    res = ''

    index = 0

    pathlen = len(path)

    while index < pathlen:

        c = path[index]

        if c == '\'':   # no expansion within single quotes

            path = path[index + 1:]

            pathlen = len(path)

            try:

                index = path.index('\'')

                res = res + '\'' + path[:index + 1]

            except ValueError:

                res = res + path

                index = pathlen - 1

        elif c == '$':  # variable or '$$'

            if path[index + 1:index + 2] == '$':

                res = res + c

                index = index + 1

            elif path[index + 1:index + 2] == '{':

                path = path[index+2:]

                pathlen = len(path)

                try:

                    index = path.index('}')

                    var = path[:index]

                    if os.environ.has_key(var):

                        res = res + os.environ[var]

                except ValueError:

                    res = res + path

                    index = pathlen - 1

            else:

                var = ''

                index = index + 1

                c = path[index:index + 1]

                while c != '' and c in varchars:

                    var = var + c

                    index = index + 1

                    c = path[index:index + 1]

                if os.environ.has_key(var):

                    res = res + os.environ[var]

                if c != '':

                    res = res + c

        else:

            res = res + c

        index = index + 1

    return res

# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.

# Previously, this function also truncated pathnames to 8+3 format,

# but as this module is called "ntpath", that's obviously wrong!

def normpath(path):

    """Normalize path, eliminating double slashes, etc."""

    path = path.replace("/", "\\")

    prefix, path = splitdrive(path)

    while path[:1] == "\\":

        prefix = prefix + "\\"

        path = path[1:]

    comps = path.split("\\")

    i = 0

    while i < len(comps):

        if comps[i] == '.':

            del comps[i]

        elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'):

            del comps[i-1:i+1]

            i = i - 1

        elif comps[i] == '' and i > 0 and comps[i-1] != '':

            del comps[i]

        else:

            i = i + 1

    # If the path is now empty, substitute '.'

    if not prefix and not comps:

        comps.append('.')

    return prefix + "\\".join(comps)

# Return an absolute path.

def abspath(path):

    """Return the absolute version of a path"""

    try:

        import win32api

    except ImportError:

        global abspath

        def _abspath(path):

            if not isabs(path):

                path = join(os.getcwd(), path)

            return normpath(path)

        abspath = _abspath

        return _abspath(path)

    if path: # Empty path must return current working directory.

        try:

            path = win32api.GetFullPathName(path)

        except win32api.error:

            pass # Bad path - return unchanged.

    else:

        path = os.getcwd()

    return normpath(path)