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linecache

Source code for linecache

"""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"]

[docs]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
[docs]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] try: return updatecache(filename, module_globals) except MemoryError: clearcache() return []
[docs]def checkcache(filename=None): """Discard cache entries that are out of date.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