cpython/Lib/macpath.py

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

import string
import os
from stat import *


# Normalize the case of a pathname.  Dummy in Posix, but string.lower here.

normcase = string.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."""

    root, ext = '', ''
    for c in p:
        if c == ':':
            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


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]


# Return the longest prefix of all list elements.
# XXX completely untested on Mac!!!

def commonprefix(m):
    "Given a list of pathnames, returns the longest common leading component"
    if not m: return ''
    n = m[:]
    for i in range(len(n)):
        n[i] = n[i].split(os.sep)
        # if os.sep didn't have any effect, try os.altsep
        if os.altsep and len(n[i]) == 1:
            n[i] = n[i].split(os.altsep)
            
    prefix = n[0]
    for item in n:
        for i in range(len(prefix)):
            if prefix[:i+1] <> item[:i+1]:
                prefix = prefix[:i]
                if i == 0: return ''
                break
    return os.sep.join(prefix)


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()."""
    st = os.stat(filename)
    return st[ST_SIZE]

def getmtime(filename):
    """Return the last modification time of a file, reported by os.stat()."""
    st = os.stat(filename)
    return st[ST_MTIME]

def getatime(filename):
    """Return the last access time of a file, reported by os.stat()."""
    st = os.stat(filename)
    return st[ST_ATIME]


def islink(s):
    """Return true if the pathname refers to a symbolic link.
    Always false on the Mac, until we understand Aliases.)"""

    return 0


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

    try:
        st = os.stat(s)
    except os.error:
        return 0
    return S_ISREG(st[ST_MODE])


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

    try:
        st = os.stat(s)
    except os.error:
        return 0
    return 1


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

norm_error = 'macpath.norm_error: path cannot be normalized'

def normpath(s):
    """Normalize a pathname: get rid of '::' sequences by backing up,
    e.g., 'foo:bar::bletch' becomes 'foo:bletch'.
    Raise the exception norm_error below if backing up is impossible,
    e.g., for '::foo'."""
    # XXX The Unix version doesn't raise an exception but simply
    # returns an unnormalized path.  Should do so here too.

    import string
    if ':' not in s:
        return ':' + s
    f = string.splitfields(s, ':')
    pre = []
    post = []
    if not f[0]:
        pre = f[:1]
        f = f[1:]
    if not f[len(f)-1]:
        post = f[-1:]
        f = f[:-1]
    res = []
    for seg in f:
        if seg:
            res.append(seg)
        else:
            if not res: raise norm_error, 'path starts with ::'
            del res[len(res)-1]
            if not (pre or res):
                raise norm_error, 'path starts with volume::'
    if pre: res = pre + res
    if post: res = res + post
    s = res[0]
    for seg in res[1:]:
        s = s + ':' + seg
    return s


def walk(top, func, arg):
    """Directory tree walk.
    For each directory under top (including top itself),
    func(arg, dirname, filenames) is called, where
    dirname is the name of the directory and filenames is the list
    of 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."""

    try:
        names = os.listdir(top)
    except os.error:
        return
    func(arg, top, names)
    for name in names:
        name = join(top, name)
        if isdir(name):
            walk(name, func, arg)


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