| 1 | """Cache lines from files.
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| 2 |
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| 3 | This is intended to read lines from modules imported -- hence if a filename
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| 4 | is not found, it will look down the module search path for a file by
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| 5 | that name.
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| 6 | """
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| 7 |
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| 8 | import sys
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| 9 | import os
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| 10 |
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| 11 | __all__ = ["getline", "clearcache", "checkcache"]
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| 12 |
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| 13 | def getline(filename, lineno, module_globals=None):
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| 14 | lines = getlines(filename, module_globals)
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| 15 | if 1 <= lineno <= len(lines):
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| 16 | return lines[lineno-1]
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| 17 | else:
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| 18 | return ''
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| 19 |
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| 20 |
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| 21 | # The cache
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| 22 |
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| 23 | cache = {} # The cache
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| 24 |
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| 25 |
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| 26 | def clearcache():
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| 27 | """Clear the cache entirely."""
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| 28 |
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| 29 | global cache
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| 30 | cache = {}
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| 31 |
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| 32 |
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| 33 | def getlines(filename, module_globals=None):
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| 34 | """Get the lines for a file from the cache.
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| 35 | Update the cache if it doesn't contain an entry for this file already."""
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| 36 |
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| 37 | if filename in cache:
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| 38 | return cache[filename][2]
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| 39 | else:
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| 40 | return updatecache(filename, module_globals)
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| 41 |
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| 42 |
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| 43 | def checkcache(filename=None):
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| 44 | """Discard cache entries that are out of date.
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| 45 | (This is not checked upon each call!)"""
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| 46 |
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| 47 | if filename is None:
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| 48 | filenames = cache.keys()
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| 49 | else:
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| 50 | if filename in cache:
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| 51 | filenames = [filename]
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| 52 | else:
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| 53 | return
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| 54 |
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| 55 | for filename in filenames:
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| 56 | size, mtime, lines, fullname = cache[filename]
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| 57 | if mtime is None:
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| 58 | continue # no-op for files loaded via a __loader__
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| 59 | try:
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| 60 | stat = os.stat(fullname)
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| 61 | except os.error:
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| 62 | del cache[filename]
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| 63 | continue
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| 64 | if size != stat.st_size or mtime != stat.st_mtime:
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| 65 | del cache[filename]
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| 66 |
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| 67 |
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| 68 | def updatecache(filename, module_globals=None):
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| 69 | """Update a cache entry and return its list of lines.
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| 70 | If something's wrong, print a message, discard the cache entry,
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| 71 | and return an empty list."""
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| 72 |
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| 73 | if filename in cache:
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| 74 | del cache[filename]
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| 75 | if not filename or (filename.startswith('<') and filename.endswith('>')):
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| 76 | return []
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| 77 |
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| 78 | fullname = filename
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| 79 | try:
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| 80 | stat = os.stat(fullname)
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| 81 | except OSError:
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| 82 | basename = filename
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| 83 |
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| 84 | # Try for a __loader__, if available
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| 85 | if module_globals and '__loader__' in module_globals:
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| 86 | name = module_globals.get('__name__')
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| 87 | loader = module_globals['__loader__']
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| 88 | get_source = getattr(loader, 'get_source', None)
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| 89 |
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| 90 | if name and get_source:
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| 91 | try:
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| 92 | data = get_source(name)
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| 93 | except (ImportError, IOError):
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| 94 | pass
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| 95 | else:
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| 96 | if data is None:
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| 97 | # No luck, the PEP302 loader cannot find the source
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| 98 | # for this module.
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| 99 | return []
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| 100 | cache[filename] = (
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| 101 | len(data), None,
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| 102 | [line+'\n' for line in data.splitlines()], fullname
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| 103 | )
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| 104 | return cache[filename][2]
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| 105 |
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| 106 | # Try looking through the module search path, which is only useful
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| 107 | # when handling a relative filename.
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| 108 | if os.path.isabs(filename):
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| 109 | return []
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| 110 |
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| 111 | for dirname in sys.path:
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| 112 | # When using imputil, sys.path may contain things other than
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| 113 | # strings; ignore them when it happens.
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| 114 | try:
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| 115 | fullname = os.path.join(dirname, basename)
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| 116 | except (TypeError, AttributeError):
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| 117 | # Not sufficiently string-like to do anything useful with.
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| 118 | continue
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| 119 | try:
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| 120 | stat = os.stat(fullname)
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| 121 | break
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| 122 | except os.error:
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| 123 | pass
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| 124 | else:
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| 125 | return []
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| 126 | try:
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| 127 | with open(fullname, 'rU') as fp:
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| 128 | lines = fp.readlines()
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| 129 | except IOError:
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| 130 | return []
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| 131 | if lines and not lines[-1].endswith('\n'):
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| 132 | lines[-1] += '\n'
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| 133 | size, mtime = stat.st_size, stat.st_mtime
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| 134 | cache[filename] = size, mtime, lines, fullname
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| 135 | return lines
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