The source code of linecache.py from python 2.0 is here.
from stat import *
Get file information
>>> filestat = os.stat(‘README.TXT‘) >>> filestat nt.stat_result(st_mode=33206, st_ino=0L, st_dev=0, st_nlink=0, st_uid=0, st_gid=0, st_size=2623L, st_atime=1450607830L, st_mtime=1398844440L, st_ctime=1398844440L) >>> filestat.st_mtime 1398844440.0 >>> import stat >>> from stat import * >>> filestat[ST_MTIME] 1398844440L
Notice filesta.st_mtime is a float number while filestat[ST_MTIME] is a long number which is strange.
Each cache is a entry is a dictionary with key=filename value=(size, mtime, lines, fullnames) (line 91)
Cache is only updated when a cache miss occurs. (line 39)
Function checkcache() is NOT called automatically and it seems that the user should call this function manually.
Source Code
1 """Cache lines from files. 2 3 This is intended to read lines from modules imported -- hence if a filename 4 is not found, it will look down the module search path for a file by 5 that name. 6 """ 7 8 import sys 9 import os 10 from stat import * 11 12 def getline(filename, lineno): 13 lines = getlines(filename) 14 if 1 <= lineno <= len(lines): 15 return lines[lineno-1] 16 else: 17 return ‘‘ 18 19 20 # The cache 21 22 cache = {} # The cache 23 24 25 def clearcache(): 26 """Clear the cache entirely.""" 27 28 global cache 29 cache = {} 30 31 32 def getlines(filename): 33 """Get the lines for a file from the cache. 34 Update the cache if it doesn‘t contain an entry for this file already.""" 35 36 if cache.has_key(filename): 37 return cache[filename][2] 38 else: 39 return updatecache(filename) 40 41 42 def checkcache(): 43 """Discard cache entries that are out of date. 44 (This is not checked upon each call!)""" 45 46 for filename in cache.keys(): 47 size, mtime, lines, fullname = cache[filename] 48 try: 49 stat = os.stat(fullname) 50 except os.error: 51 del cache[filename] 52 continue 53 if size <> stat[ST_SIZE] or mtime <> stat[ST_MTIME]: 54 del cache[filename] 55 56 57 def updatecache(filename): 58 """Update a cache entry and return its list of lines. 59 If something‘s wrong, print a message, discard the cache entry, 60 and return an empty list.""" 61 62 if cache.has_key(filename): 63 del cache[filename] 64 if not filename or filename[0] + filename[-1] == ‘<>‘: 65 return [] 66 fullname = filename 67 try: 68 stat = os.stat(fullname) 69 except os.error, msg: 70 # Try looking through the module search path 71 basename = os.path.split(filename)[1] 72 for dirname in sys.path: 73 fullname = os.path.join(dirname, basename) 74 try: 75 stat = os.stat(fullname) 76 break 77 except os.error: 78 pass 79 else: 80 # No luck 81 ## print ‘*** Cannot stat‘, filename, ‘:‘, msg 82 return [] 83 try: 84 fp = open(fullname, ‘r‘) 85 lines = fp.readlines() 86 fp.close() 87 except IOError, msg: 88 ## print ‘*** Cannot open‘, fullname, ‘:‘, msg 89 return [] 90 size, mtime = stat[ST_SIZE], stat[ST_MTIME] 91 cache[filename] = size, mtime, lines, fullname 92 return lines
时间: 2024-10-20 01:17:30