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author | Guido van Rossum <guido@python.org> | 1991-01-01 18:10:40 (GMT) |
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committer | Guido van Rossum <guido@python.org> | 1991-01-01 18:10:40 (GMT) |
commit | b5e05e95c3d336ba1b5fde7a6a55e4c92e508da6 (patch) | |
tree | b6e97065092a2450e8eee7067632ce4391d402a7 | |
parent | 67c9b8cdad75aa0bbfa62de2ca678c32697d51bc (diff) | |
download | cpython-b5e05e95c3d336ba1b5fde7a6a55e4c92e508da6.zip cpython-b5e05e95c3d336ba1b5fde7a6a55e4c92e508da6.tar.gz cpython-b5e05e95c3d336ba1b5fde7a6a55e4c92e508da6.tar.bz2 |
Added explanatory comments.
-rw-r--r-- | Lib/macpath.py | 50 |
1 files changed, 44 insertions, 6 deletions
diff --git a/Lib/macpath.py b/Lib/macpath.py index 30d2f27..99254ab 100644 --- a/Lib/macpath.py +++ b/Lib/macpath.py @@ -1,14 +1,24 @@ -# module 'macpath' +# module 'macpath' -- pathname (or -related) operations for the Macintosh import mac -import string - from stat import * + +# 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] <> ':' + +# Concatenate two pathnames. +# The result is equivalent to what the second pathname would refer to +# if the first pathname were the current directory. + def cat(s, t): if (not s) or isabs(t): return t if t[:1] = ':': t = t[1:] @@ -18,9 +28,28 @@ def cat(s, t): s = s + ':' return s + t -norm_error = 'path cannot be normalized' + +# 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 cat(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], s[colon:] + + +# 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'. + +norm_error = 'macpath.norm_error: path cannot be normalized' def norm(s): + import string if ':' not in s: return ':' + s f = string.splitfields(s, ':') @@ -37,10 +66,10 @@ def norm(s): if seg: res.append(seg) else: - if not res: raise norm_error # starts with '::' + if not res: raise norm_error, 'path starts with ::' del res[len(res)-1] if not (pre or res): - raise norm_error # starts with 'vol::' + raise norm_error, 'path starts with volume::' if pre: res = pre + res if post: res = res + post s = res[0] @@ -48,6 +77,9 @@ def norm(s): s = s + ':' + seg return s + +# Return true if the pathname refers to an existing directory. + def isdir(s): try: st = mac.stat(s) @@ -55,6 +87,9 @@ def isdir(s): return 0 return S_ISDIR(st[ST_MODE]) + +# Return true if the pathname refers to an existing regular file. + def isfile(s): try: st = mac.stat(s) @@ -62,6 +97,9 @@ def isfile(s): 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) |