| 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 | |
| 11 | __all__ = ["getline", "clearcache", "checkcache"] |
| 12 | |
| 13 | def getline(filename, lineno): |
| 14 | lines = getlines(filename) |
| 15 | if 1 <= lineno <= len(lines): |
| 16 | return lines[lineno-1] |
| 17 | else: |
| 18 | return '' |
| 19 | |
| 20 | |
| 21 | # The cache |
| 22 | |
| 23 | cache = {} # The cache |
| 24 | |
| 25 | |
| 26 | def clearcache(): |
| 27 | """Clear the cache entirely.""" |
| 28 | |
| 29 | global cache |
| 30 | cache = {} |
| 31 | |
| 32 | |
| 33 | def getlines(filename): |
| 34 | """Get the lines for a file from the cache. |
| 35 | Update the cache if it doesn't contain an entry for this file already.""" |
| 36 | |
| 37 | if filename in cache: |
| 38 | return cache[filename][2] |
| 39 | else: |
| 40 | return updatecache(filename) |
| 41 | |
| 42 | |
| 43 | def checkcache(filename=None): |
| 44 | """Discard cache entries that are out of date. |
| 45 | (This is not checked upon each call!)""" |
| 46 | |
| 47 | if filename is None: |
| 48 | filenames = cache.keys() |
| 49 | else: |
| 50 | if filename in cache: |
| 51 | filenames = [filename] |
| 52 | else: |
| 53 | return |
| 54 | |
| 55 | for filename in filenames: |
| 56 | size, mtime, lines, fullname = cache[filename] |
| 57 | try: |
| 58 | stat = os.stat(fullname) |
| 59 | except os.error: |
| 60 | del cache[filename] |
| 61 | continue |
| 62 | if size != stat.st_size or mtime != stat.st_mtime: |
| 63 | del cache[filename] |
| 64 | |
| 65 | |
| 66 | def updatecache(filename): |
| 67 | """Update a cache entry and return its list of lines. |
| 68 | If something's wrong, print a message, discard the cache entry, |
| 69 | and return an empty list.""" |
| 70 | |
| 71 | if filename in cache: |
| 72 | del cache[filename] |
| 73 | if not filename or filename[0] + filename[-1] == '<>': |
| 74 | return [] |
| 75 | fullname = filename |
| 76 | try: |
| 77 | stat = os.stat(fullname) |
| 78 | except os.error, msg: |
| 79 | # Try looking through the module search path. |
| 80 | basename = os.path.split(filename)[1] |
| 81 | for dirname in sys.path: |
| 82 | # When using imputil, sys.path may contain things other than |
| 83 | # strings; ignore them when it happens. |
| 84 | try: |
| 85 | fullname = os.path.join(dirname, basename) |
| 86 | except (TypeError, AttributeError): |
| 87 | # Not sufficiently string-like to do anything useful with. |
| 88 | pass |
| 89 | else: |
| 90 | try: |
| 91 | stat = os.stat(fullname) |
| 92 | break |
| 93 | except os.error: |
| 94 | pass |
| 95 | else: |
| 96 | # No luck |
| 97 | ## print '*** Cannot stat', filename, ':', msg |
| 98 | return [] |
| 99 | try: |
| 100 | fp = open(fullname, 'rU') |
| 101 | lines = fp.readlines() |
| 102 | fp.close() |
| 103 | except IOError, msg: |
| 104 | ## print '*** Cannot open', fullname, ':', msg |
| 105 | return [] |
| 106 | size, mtime = stat.st_size, stat.st_mtime |
| 107 | cache[filename] = size, mtime, lines, fullname |
| 108 | return lines |