"""Cache lines from Python source 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
__all__ = ["getline", "clearcache", "checkcache", "lazycache"]
# The cache. Maps filenames to either a thunk which will provide source code,
# or a tuple (size, mtime, lines, fullname) once loaded.
"""Clear the cache entirely."""
def getline(filename, lineno, module_globals=None):
"""Get a line for a Python source file from the cache.
Update the cache if it doesn't contain an entry for this file already."""
lines = getlines(filename, module_globals)
if 1 <= lineno <= len(lines):
def getlines(filename, module_globals=None):
"""Get the lines for a Python source file from the cache.
Update the cache if it doesn't contain an entry for this file already."""
return cache[filename][2]
return updatecache(filename, module_globals)
def checkcache(filename=None):
"""Discard cache entries that are out of date.
(This is not checked upon each call!)"""
filenames = list(cache.keys())
for filename in filenames:
# lazy cache entry, leave it lazy.
size, mtime, lines, fullname = entry
continue # no-op for files loaded via a __loader__
cache.pop(filename, None)
if size != stat.st_size or mtime != stat.st_mtime:
cache.pop(filename, None)
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 len(cache[filename]) != 1:
cache.pop(filename, None)
if not filename or (filename.startswith('<') and filename.endswith('>')):
# Realise a lazy loader based lookup if there is one
# otherwise try to lookup right now.
if lazycache(filename, module_globals):
data = cache[filename][0]()
except (ImportError, OSError):
# No luck, the PEP302 loader cannot find the source
[line + '\n' for line in data.splitlines()],
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):
fullname = os.path.join(dirname, basename)
except (TypeError, AttributeError):
# Not sufficiently string-like to do anything useful with.
with tokenize.open(fullname) as fp:
if lines and not lines[-1].endswith('\n'):
size, mtime = stat.st_size, stat.st_mtime
cache[filename] = size, mtime, lines, fullname
def lazycache(filename, module_globals):
"""Seed the cache for filename with module_globals.
The module loader will be asked for the source only when getlines is
If there is an entry in the cache already, it is not altered.
:return: True if a lazy load is registered in the cache,
otherwise False. To register such a load a module loader with a
get_source method must be found, the filename must be a cachable
filename, and the filename must not be already cached.
if len(cache[filename]) == 1:
if not filename or (filename.startswith('<') and filename.endswith('>')):
# 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)
get_lines = functools.partial(get_source, name)
cache[filename] = (get_lines,)
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
