1 files changed, 90 insertions, 0 deletions
diff --git a/Lib/dos_8x3/linecach.py b/Lib/dos_8x3/linecach.py
new file mode 100755
index 0000000..7de373f
--- /dev/null
+++ b/Lib/dos_8x3/linecach.py
@@ -0,0 +1,90 @@
+# Cache lines from files.
+# This is intended to read lines from modules imported -- hence if a filename
+# is not found, it will look down the module search path for a file by
+# that name.
+
+import sys
+import os
+from stat import *
+
+def getline(filename, lineno):
+	lines = getlines(filename)
+	if 1 <= lineno <= len(lines):
+		return lines[lineno-1]
+	else:
+		return ''
+
+
+# The cache
+
+cache = {} # The cache
+
+
+# Clear the cache entirely
+
+def clearcache():
+	global cache
+	cache = {}
+
+
+# Get the lines for a file from the cache.
+# Update the cache if it doesn't contain an entry for this file already.
+
+def getlines(filename):
+	if cache.has_key(filename):
+		return cache[filename][2]
+	else:
+		return updatecache(filename)
+
+
+# Discard cache entries that are out of date.
+# (This is not checked upon each call!)
+
+def checkcache():
+	for filename in cache.keys():
+		size, mtime, lines, fullname = cache[filename]
+		try:
+			stat = os.stat(fullname)
+		except os.error:
+			del cache[filename]
+			continue
+		if size <> stat[ST_SIZE] or mtime <> stat[ST_MTIME]:
+			del cache[filename]
+
+
+# Update a cache entry and return its list of lines.
+# If something's wrong, print a message, discard the cache entry,
+# and return an empty list.
+
+def updatecache(filename):
+	if cache.has_key(filename):
+		del cache[filename]
+	if not filename or filename[0] + filename[-1] == '<>':
+		return []
+	fullname = filename
+	try:
+		stat = os.stat(fullname)
+	except os.error, msg:
+		# Try looking through the module search path
+		basename = os.path.split(filename)[1]
+		for dirname in sys.path:
+			fullname = os.path.join(dirname, basename)
+			try:
+				stat = os.stat(fullname)
+				break
+			except os.error:
+				pass
+		else:
+			# No luck
+##			print '*** Cannot stat', filename, ':', msg
+			return []
+	try:
+		fp = open(fullname, 'r')
+		lines = fp.readlines()
+		fp.close()
+	except IOError, msg:
+##		print '*** Cannot open', fullname, ':', msg
+		return []
+	size, mtime = stat[ST_SIZE], stat[ST_MTIME]
+	cache[filename] = size, mtime, lines, fullname
+	return lines