1 files changed, 61 insertions, 0 deletions
diff --git a/Mac/Lib/maccache.py b/Mac/Lib/maccache.py
new file mode 100644
index 0000000..dc6502b
--- /dev/null
+++ b/Mac/Lib/maccache.py
@@ -0,0 +1,61 @@
+# Module 'maccache'
+#
+# Maintain a cache of listdir(), isdir(), isfile() or exists() outcomes.
+
+import mac
+import macpath
+
+
+# The cache.
+# Keys are absolute pathnames;
+# values are 0 (nothing), 1 (file) or [...] (dir).
+#
+cache = {}
+
+
+# Current working directory.
+#
+cwd = mac.getcwd()
+
+
+# Constants.
+#
+NONE = 0
+FILE = 1
+LISTTYPE = type([])
+
+def _stat(name):
+	name = macpath.cat(cwd, name)
+	if cache.has_key(name):
+		return cache[name]
+	if macpath.isfile(name):
+		cache[name] = FILE
+		return FILE
+	try:
+		list = mac.listdir(name)
+	except:
+		cache[name] = NONE
+		return NONE
+	cache[name] = list
+	if name[-1:] = ':': cache[name[:-1]] = list
+	else: cache[name+':'] = list
+	return list
+
+def isdir(name):
+	st = _stat(name)
+	return type(st) = LISTTYPE
+
+def isfile(name):
+	st = _stat(name)
+	return st = FILE
+
+def exists(name):
+	st = _stat(name)
+	return st <> NONE
+
+def listdir(name):
+	st = _stat(name)
+	if type(st) = LISTTYPE:
+		return st
+	else:
+		raise RuntimeError, 'list non-directory'