python/lib/Lib/macpath.py

"""Pathname and path-related operations for the Macintosh."""

import os
from stat import *

__all__ = ["normcase","isabs","join","splitdrive","split","splitext",
           "basename","dirname","commonprefix","getsize","getmtime",
           "getatime","getctime", "islink","exists","lexists","isdir","isfile",
           "walk","expanduser","expandvars","normpath","abspath",
           "curdir","pardir","sep","pathsep","defpath","altsep","extsep",
           "devnull","realpath","supports_unicode_filenames"]

# strings representing various path-related bits and pieces
curdir = ':'
pardir = '::'
extsep = '.'
sep = ':'
pathsep = '\n'
defpath = ':'
altsep = None
devnull = 'Dev:Null'

# Normalize the case of a pathname.  Dummy in Posix, but <s>.lower() here.

def normcase(path):
    return path.lower()


def isabs(s):
    """Return true if a path is absolute.
    On the Mac, relative paths begin with a colon,
    but as a special case, paths with no colons at all are also relative.
    Anything else is absolute (the string up to the first colon is the
    volume name)."""

    return ':' in s and s[0] != ':'


def join(s, *p):
    path = s
    for t in p:
        if (not s) or isabs(t):
            path = t
            continue
        if t[:1] == ':':
            t = t[1:]
        if ':' not in path:
            path = ':' + path
        if path[-1:] != ':':
            path = path + ':'
        path = path + t
    return path


def split(s):
    """Split a pathname into two parts: the directory leading up to the final
    bit, and the basename (the filename, without colons, in that directory).
    The result (s, t) is such that join(s, t) yields the original argument."""

    if ':' not in s: return '', s
    colon = 0
    for i in range(len(s)):
        if s[i] == ':': colon = i + 1
    path, file = s[:colon-1], s[colon:]
    if path and not ':' in path:
        path = path + ':'
    return path, file


def splitext(p):
    """Split a path into 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."""

    i = p.rfind('.')
    if i<=p.rfind(':'):
        return p, ''
    else:
        return p[:i], p[i:]


def splitdrive(p):
    """Split a pathname into a drive specification and the rest of the
    path.  Useful on DOS/Windows/NT; on the Mac, the drive is always
    empty (don't use the volume name -- it doesn't have the same
    syntactic and semantic oddities as DOS drive letters, such as there
    being a separate current directory per drive)."""

    return '', p


# Short interfaces to split()

def dirname(s): return split(s)[0]
def basename(s): return split(s)[1]

def ismount(s):
    if not isabs(s):
        return False
    components = split(s)
    return len(components) == 2 and components[1] == ''

def isdir(s):
    """Return true if the pathname refers to an existing directory."""

    try:
        st = os.stat(s)
    except os.error:
        return 0
    return S_ISDIR(st.st_mode)


# Get size, mtime, atime of files.

def getsize(filename):
    """Return the size of a file, reported by os.stat()."""
    return os.stat(filename).st_size

def getmtime(filename):
    """Return the last modification time of a file, reported by os.stat()."""
    return os.stat(filename).st_mtime

def getatime(filename):
    """Return the last access time of a file, reported by os.stat()."""
    return os.stat(filename).st_atime


def islink(s):
    """Return true if the pathname refers to a symbolic link."""

    try:
        import Carbon.File
        return Carbon.File.ResolveAliasFile(s, 0)[2]
    except:
        return False


def isfile(s):
    """Return true if the pathname refers to an existing regular file."""

    try:
        st = os.stat(s)
    except os.error:
        return False
    return S_ISREG(st.st_mode)

def getctime(filename):
    """Return the creation time of a file, reported by os.stat()."""
    return os.stat(filename).st_ctime

def exists(s):
    """Test whether a path exists.  Returns False for broken symbolic links"""

    try:
        st = os.stat(s)
    except os.error:
        return False
    return True

# Is `stat`/`lstat` a meaningful difference on the Mac?  This is safe in any
# case.

def lexists(path):
    """Test whether a path exists.  Returns True for broken symbolic links"""

    try:
        st = os.lstat(path)
    except os.error:
        return False
    return True

# 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 ''
    s1 = min(m)
    s2 = max(m)
    n = min(len(s1), len(s2))
    for i in xrange(n):
        if s1[i] != s2[i]:
            return s1[:i]
    return s1[:n]


def expandvars(path):
    """Dummy to retain interface-compatibility with other operating systems."""
    return path


def expanduser(path):
    """Dummy to retain interface-compatibility with other operating systems."""
    return path

class norm_error(Exception):
    """Path cannot be normalized"""

def normpath(s):
    """Normalize a pathname.  Will return the same result for
    equivalent paths."""

    if ":" not in s:
        return ":"+s

    comps = s.split(":")
    i = 1
    while i < len(comps)-1:
        if comps[i] == "" and comps[i-1] != "":
            if i > 1:
                del comps[i-1:i+1]
                i = i - 1
            else:
                # best way to handle this is to raise an exception
                raise norm_error, 'Cannot use :: immediately after volume name'
        else:
            i = i + 1

    s = ":".join(comps)

    # remove trailing ":" except for ":" and "Volume:"
    if s[-1] == ":" and len(comps) > 2 and s != ":"*len(s):
        s = s[:-1]
    return s


def walk(top, func, arg):
    """Directory tree walk with callback function.

    For each directory in the directory tree rooted at top (including top
    itself, but excluding '.' and '..'), call func(arg, dirname, fnames).
    dirname is the name of the directory, and fnames a list of the names of
    the files and subdirectories in dirname (excluding '.' and '..').  func
    may modify the fnames list in-place (e.g. via del or slice assignment),
    and walk will only recurse into the subdirectories whose names remain in
    fnames; this can be used to implement a filter, or to impose a specific
    order of visiting.  No semantics are defined for, or required of, arg,
    beyond that arg is always passed to func.  It can be used, e.g., to pass
    a filename pattern, or a mutable object designed to accumulate
    statistics.  Passing None for arg is common."""

    try:
        names = os.listdir(top)
    except os.error:
        return
    func(arg, top, names)
    for name in names:
        name = join(top, name)
        if isdir(name) and not islink(name):
            walk(name, func, arg)


def abspath(path):
    """Return an absolute path."""
    if not isabs(path):
        path = join(os.getcwd(), path)
    return normpath(path)

# realpath is a no-op on systems without islink support
def realpath(path):
    path = abspath(path)
    try:
        import Carbon.File
    except ImportError:
        return path
    if not path:
        return path
    components = path.split(':')
    path = components[0] + ':'
    for c in components[1:]:
        path = join(path, c)
        path = Carbon.File.FSResolveAliasFile(path, 1)[0].as_pathname()
    return path

supports_unicode_filenames = False