| [40094] | 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 | |
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| 40 | try: |
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| 41 | return updatecache(filename, module_globals) |
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| 42 | except MemoryError: |
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| 43 | clearcache() |
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| 44 | return [] |
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| 45 | |
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| 46 | |
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| 47 | def checkcache(filename=None): |
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| 48 | """Discard cache entries that are out of date. |
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| 49 | (This is not checked upon each call!)""" |
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| 50 | |
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| 51 | if filename is None: |
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| 52 | filenames = cache.keys() |
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| 53 | else: |
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| 54 | if filename in cache: |
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| 55 | filenames = [filename] |
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| 56 | else: |
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| 57 | return |
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| 58 | |
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| 59 | for filename in filenames: |
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| 60 | size, mtime, lines, fullname = cache[filename] |
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| 61 | if mtime is None: |
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| 62 | continue # no-op for files loaded via a __loader__ |
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| 63 | try: |
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| 64 | stat = os.stat(fullname) |
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| 65 | except os.error: |
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| 66 | del cache[filename] |
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| 67 | continue |
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| 68 | if size != stat.st_size or mtime != stat.st_mtime: |
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| 69 | del cache[filename] |
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| 70 | |
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| 71 | |
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| 72 | def updatecache(filename, module_globals=None): |
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| 73 | """Update a cache entry and return its list of lines. |
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| 74 | If something's wrong, print a message, discard the cache entry, |
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| 75 | and return an empty list.""" |
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| 76 | |
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| 77 | if filename in cache: |
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| 78 | del cache[filename] |
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| 79 | if not filename or (filename.startswith('<') and filename.endswith('>')): |
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| 80 | return [] |
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| 81 | |
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| 82 | fullname = filename |
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| 83 | try: |
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| 84 | stat = os.stat(fullname) |
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| 85 | except OSError: |
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| 86 | basename = filename |
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| 87 | |
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| 88 | # Try for a __loader__, if available |
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| 89 | if module_globals and '__loader__' in module_globals: |
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| 90 | name = module_globals.get('__name__') |
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| 91 | loader = module_globals['__loader__'] |
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| 92 | get_source = getattr(loader, 'get_source', None) |
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| 93 | |
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| 94 | if name and get_source: |
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| 95 | try: |
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| 96 | data = get_source(name) |
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| 97 | except (ImportError, IOError): |
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| 98 | pass |
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| 99 | else: |
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| 100 | if data is None: |
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| 101 | # No luck, the PEP302 loader cannot find the source |
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| 102 | # for this module. |
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| 103 | return [] |
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| 104 | cache[filename] = ( |
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| 105 | len(data), None, |
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| 106 | [line+'\n' for line in data.splitlines()], fullname |
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| 107 | ) |
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| 108 | return cache[filename][2] |
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| 109 | |
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| 110 | # Try looking through the module search path, which is only useful |
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| 111 | # when handling a relative filename. |
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| 112 | if os.path.isabs(filename): |
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| 113 | return [] |
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| 114 | |
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| 115 | for dirname in sys.path: |
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| 116 | # When using imputil, sys.path may contain things other than |
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| 117 | # strings; ignore them when it happens. |
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| 118 | try: |
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| 119 | fullname = os.path.join(dirname, basename) |
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| 120 | except (TypeError, AttributeError): |
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| 121 | # Not sufficiently string-like to do anything useful with. |
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| 122 | continue |
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| 123 | try: |
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| 124 | stat = os.stat(fullname) |
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| 125 | break |
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| 126 | except os.error: |
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| 127 | pass |
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| 128 | else: |
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| 129 | return [] |
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| 130 | try: |
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| 131 | with open(fullname, 'rU') as fp: |
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| 132 | lines = fp.readlines() |
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| 133 | except IOError: |
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| 134 | return [] |
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| 135 | if lines and not lines[-1].endswith('\n'): |
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| 136 | lines[-1] += '\n' |
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| 137 | size, mtime = stat.st_size, stat.st_mtime |
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| 138 | cache[filename] = size, mtime, lines, fullname |
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| 139 | return lines |
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