ref: 486523bbc57b111d198432d2416e598c6d5c2d63
dir: /sys/lib/python/linecache.py/
"""Cache lines from files. This is intended to read lines from modules imported -- hence if a filename is not found, it will look down the module search path for a file by that name. """ import sys import os __all__ = ["getline", "clearcache", "checkcache"] def getline(filename, lineno, module_globals=None): lines = getlines(filename, module_globals) if 1 <= lineno <= len(lines): return lines[lineno-1] else: return '' # The cache cache = {} # The cache def clearcache(): """Clear the cache entirely.""" global cache cache = {} def getlines(filename, module_globals=None): """Get the lines for a file from the cache. Update the cache if it doesn't contain an entry for this file already.""" if filename in cache: return cache[filename][2] else: return updatecache(filename, module_globals) def checkcache(filename=None): """Discard cache entries that are out of date. (This is not checked upon each call!)""" if filename is None: filenames = cache.keys() else: if filename in cache: filenames = [filename] else: return for filename in filenames: size, mtime, lines, fullname = cache[filename] if mtime is None: continue # no-op for files loaded via a __loader__ try: stat = os.stat(fullname) except os.error: del cache[filename] continue if size != stat.st_size or mtime != stat.st_mtime: del cache[filename] def updatecache(filename, module_globals=None): """Update a cache entry and return its list of lines. If something's wrong, print a message, discard the cache entry, and return an empty list.""" if filename in cache: del cache[filename] if not filename or filename[0] + filename[-1] == '<>': return [] fullname = filename try: stat = os.stat(fullname) except os.error, msg: basename = os.path.split(filename)[1] # Try for a __loader__, if available if module_globals and '__loader__' in module_globals: name = module_globals.get('__name__') loader = module_globals['__loader__'] get_source = getattr(loader, 'get_source', None) if name and get_source: if basename.startswith(name.split('.')[-1]+'.'): try: data = get_source(name) except (ImportError, IOError): pass else: if data is None: # No luck, the PEP302 loader cannot find the source # for this module. return [] cache[filename] = ( len(data), None, [line+'\n' for line in data.splitlines()], fullname ) return cache[filename][2] # Try looking through the module search path. for dirname in sys.path: # When using imputil, sys.path may contain things other than # strings; ignore them when it happens. try: fullname = os.path.join(dirname, basename) except (TypeError, AttributeError): # Not sufficiently string-like to do anything useful with. pass else: try: stat = os.stat(fullname) break except os.error: pass else: # No luck ## print '*** Cannot stat', filename, ':', msg return [] try: fp = open(fullname, 'rU') lines = fp.readlines() fp.close() except IOError, msg: ## print '*** Cannot open', fullname, ':', msg return [] size, mtime = stat.st_size, stat.st_mtime cache[filename] = size, mtime, lines, fullname return lines