|
| 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, module_globals=None): |
| 14 | + lines = getlines(filename, module_globals) |
| 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, module_globals=None): |
| 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, module_globals) |
| 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| 44 | + """Discard cache entries that are out of date.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 | + if mtime is None: |
| 58 | + continue # no-op for files loaded via a __loader__ |
| 59 | + try: |
| 60 | + stat = os.stat(fullname) |
| 61 | + except os.error: |
| 62 | + del cache[filename] |
| 63 | + continue |
| 64 | + if size != stat.st_size or mtime != stat.st_mtime: |
| 65 | + del cache[filename] |
| 66 | + |
| 67 | + |
| 68 | +def updatecache(filename, module_globals=None): |
| 69 | + """Update a cache entry and return its list of lines. |
| 70 | + If something's wrong, print a message, discard the cache entry, |
| 71 | + and return an empty list.""" |
| 72 | + |
| 73 | + if filename in cache: |
| 74 | + del cache[filename] |
| 75 | + if not filename or (filename.startswith('<') and filename.endswith('>')): |
| 76 | + return [] |
| 77 | + |
| 78 | + fullname = filename |
| 79 | + try: |
| 80 | + stat = os.stat(fullname) |
| 81 | + except OSError: |
| 82 | + basename = filename |
| 83 | + |
| 84 | + # Try for a __loader__, if available |
| 85 | + if module_globals and '__loader__' in module_globals: |
| 86 | + name = module_globals.get('__name__') |
| 87 | + loader = module_globals['__loader__'] |
| 88 | + get_source = getattr(loader, 'get_source', None) |
| 89 | + |
| 90 | + if name and get_source: |
| 91 | + try: |
| 92 | + data = get_source(name) |
| 93 | + except (ImportError, IOError): |
| 94 | + pass |
| 95 | + else: |
| 96 | + if data is None: |
| 97 | + # No luck, the PEP302 loader cannot find the source |
| 98 | + # for this module. |
| 99 | + return [] |
| 100 | + cache[filename] = ( |
| 101 | + len(data), None, |
| 102 | + [line+'\n' for line in data.splitlines()], fullname |
| 103 | + ) |
| 104 | + return cache[filename][2] |
| 105 | + |
| 106 | + # Try looking through the module search path, which is only useful |
| 107 | + # when handling a relative filename. |
| 108 | + if os.path.isabs(filename): |
| 109 | + return [] |
| 110 | + |
| 111 | + for dirname in sys.path: |
| 112 | + # When using imputil, sys.path may contain things other than |
| 113 | + # strings; ignore them when it happens. |
| 114 | + try: |
| 115 | + fullname = os.path.join(dirname, basename) |
| 116 | + except (TypeError, AttributeError): |
| 117 | + # Not sufficiently string-like to do anything useful with. |
| 118 | + continue |
| 119 | + try: |
| 120 | + stat = os.stat(fullname) |
| 121 | + break |
| 122 | + except os.error: |
| 123 | + pass |
| 124 | + else: |
| 125 | + return [] |
| 126 | + try: |
| 127 | + with open(fullname, 'rU') as fp: |
| 128 | + lines = fp.readlines() |
| 129 | + except IOError: |
| 130 | + return [] |
| 131 | + if lines and not lines[-1].endswith('\n'): |
| 132 | + lines[-1] += '\n' |
| 133 | + size, mtime = stat.st_size, stat.st_mtime |
| 134 | + cache[filename] = size, mtime, lines, fullname |
| 135 | + return lines |
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