72 lines
1.5 KiB
Python
72 lines
1.5 KiB
Python
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# Cache lines from files.
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import os
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from stat import *
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def getline(filename, lineno):
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lines = getlines(filename)
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if 1 <= lineno <= len(lines):
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return lines[lineno-1]
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else:
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return ''
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# The cache
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cache = {} # The cache
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# Clear the cache entirely
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def clearcache():
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global cache
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cache = {}
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# Get the lines for a file from the cache.
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# Update the cache if it doesn't contain an entry for this file already.
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def getlines(filename):
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if cache.has_key(filename):
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return cache[filename][2]
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else:
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return updatecache(filename)
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# Discard cache entries that are out of date.
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# (This is not checked upon each call
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def checkcache():
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for filename in cache.keys():
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size, mtime, lines = cache[filename]
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try: stat = os.stat(filename)
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except os.error:
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del cache[filename]
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continue
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if size <> stat[ST_SIZE] or mtime <> stat[ST_MTIME]:
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del cache[filename]
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# Update a cache entry and return its list of lines.
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# If something's wrong, print a message, discard the cache entry,
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# and return an empty list.
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def updatecache(filename):
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try: del cache[filename]
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except KeyError: pass
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try: stat = os.stat(filename)
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except os.error, msg:
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if filename[0] + filename[-1] <> '<>':
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print '*** Cannot stat', filename, ':', msg
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return []
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try:
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fp = open(filename, 'r')
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lines = fp.readlines()
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fp.close()
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except IOError, msg:
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print '*** Cannot open', filename, ':', msg
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return []
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size, mtime = stat[ST_SIZE], stat[ST_MTIME]
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cache[filename] = size, mtime, lines
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return lines
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