cpython/Lib/macpath.py

# module 'macpath' -- pathname (or -related) operations for the Macintosh

import string
import mac
from stat import *


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

normcase = string.lower


# 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).

def isabs(s):
	return ':' in s and s[0] <> ':'


# Join two pathnames.
# The result is equivalent to what the second pathname would refer to
# if the first pathname were the current directory.

def join(s, t):
	if (not s) or isabs(t): return t
	if t[:1] == ':': t = t[1:]
	if ':' not in s:
		s = ':' + s
	if s[-1:] <> ':':
		s = s + ':'
	return s + t


# Split a pathname in 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.

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


# 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):
	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


# 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).

def splitdrive(p):
	return '', p


# Short interfaces to split()

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


# Return true if the pathname refers to an existing directory.

def isdir(s):
	try:
		st = mac.stat(s)
	except mac.error:
		return 0
	return S_ISDIR(st[ST_MODE])


# Return true if the pathname refers to a symbolic link.
# (Always false on the Mac, until we understand Aliases.)

def islink(s):
	return 0


# Return true if the pathname refers to an existing regular file.

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


# Return true if the pathname refers to an existing file or directory.

def exists(s):
	try:
		st = mac.stat(s)
	except mac.error:
		return 0
	return 1

#
# dummy expandvars to retain interface-compatability with other
# operating systems.
def expandvars(path):
	return path

#
# dummy expanduser to retain interface-compatability with other
# operating systems.
def expanduser(path):
	return path

# 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.

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

def normpath(s):
	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


# 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.

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