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# Cache lines from files.
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# Discard cache entries that are out of date.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 = cache[filename]
try: stat = os.stat(filename)
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):
try: del cache[filename]
except KeyError: pass
try: stat = os.stat(filename)
except os.error, msg:
if filename[0] + filename[-1] <> '<>':
print '*** Cannot stat', filename, ':', msg
return []
try:
fp = open(filename, 'r')
lines = fp.readlines()
fp.close()
except IOError, msg:
print '*** Cannot open', filename, ':', msg
return []
size, mtime = stat[ST_SIZE], stat[ST_MTIME]
cache[filename] = size, mtime, lines
return lines
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