"""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"""Discard cache entries that are out of date.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.startswith('<') and filename.endswith('>')): | |
return [] | |
fullname = filename | |
try: | |
stat = os.stat(fullname) | |
except OSError: | |
basename = filename | |
# 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: | |
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, which is only useful | |
# when handling a relative filename. | |
if os.path.isabs(filename): | |
return [] | |
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. | |
continue | |
try: | |
stat = os.stat(fullname) | |
break | |
except os.error: | |
pass | |
else: | |
return [] | |
try: | |
with open(fullname, 'rU') as fp: | |
lines = fp.readlines() | |
except IOError: | |
return [] | |
if lines and not lines[-1].endswith('\n'): | |
lines[-1] += '\n' | |
size, mtime = stat.st_size, stat.st_mtime | |
cache[filename] = size, mtime, lines, fullname | |
return lines |