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376658fa13
Use a Python source file (linecache.__file__) instead of /etc/passwd. Modify also linecache docstrings to clarify the linecache is written to cache Python source files, not any text files.
134 lines
3.8 KiB
Python
134 lines
3.8 KiB
Python
"""Cache lines from Python source files.
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This is intended to read lines from modules imported -- hence if a filename
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is not found, it will look down the module search path for a file by
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that name.
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"""
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import sys
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import os
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import tokenize
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__all__ = ["getline", "clearcache", "checkcache"]
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def getline(filename, lineno, module_globals=None):
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lines = getlines(filename, module_globals)
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if 1 <= lineno <= len(lines):
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return lines[lineno-1]
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else:
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return ''
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# The cache
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cache = {} # The cache
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def clearcache():
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"""Clear the cache entirely."""
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global cache
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cache = {}
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def getlines(filename, module_globals=None):
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"""Get the lines for a Python source file from the cache.
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Update the cache if it doesn't contain an entry for this file already."""
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if filename in cache:
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return cache[filename][2]
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else:
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return updatecache(filename, module_globals)
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def checkcache(filename=None):
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"""Discard cache entries that are out of date.
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(This is not checked upon each call!)"""
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if filename is None:
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filenames = list(cache.keys())
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else:
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if filename in cache:
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filenames = [filename]
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else:
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return
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for filename in filenames:
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size, mtime, lines, fullname = cache[filename]
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if mtime is None:
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continue # no-op for files loaded via a __loader__
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try:
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stat = os.stat(fullname)
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except OSError:
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del cache[filename]
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continue
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if size != stat.st_size or mtime != stat.st_mtime:
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del cache[filename]
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def updatecache(filename, module_globals=None):
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"""Update a cache entry and return its list of lines.
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If something's wrong, print a message, discard the cache entry,
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and return an empty list."""
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if filename in cache:
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del cache[filename]
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if not filename or (filename.startswith('<') and filename.endswith('>')):
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return []
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fullname = filename
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try:
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stat = os.stat(fullname)
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except OSError:
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basename = filename
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# Try for a __loader__, if available
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if module_globals and '__loader__' in module_globals:
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name = module_globals.get('__name__')
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loader = module_globals['__loader__']
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get_source = getattr(loader, 'get_source', None)
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if name and get_source:
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try:
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data = get_source(name)
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except (ImportError, OSError):
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pass
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else:
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if data is None:
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# No luck, the PEP302 loader cannot find the source
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# for this module.
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return []
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cache[filename] = (
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len(data), None,
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[line+'\n' for line in data.splitlines()], fullname
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)
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return cache[filename][2]
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# Try looking through the module search path, which is only useful
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# when handling a relative filename.
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if os.path.isabs(filename):
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return []
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for dirname in sys.path:
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try:
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fullname = os.path.join(dirname, basename)
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except (TypeError, AttributeError):
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# Not sufficiently string-like to do anything useful with.
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continue
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try:
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stat = os.stat(fullname)
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break
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except OSError:
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pass
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else:
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return []
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try:
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with tokenize.open(fullname) as fp:
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lines = fp.readlines()
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except OSError:
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return []
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if lines and not lines[-1].endswith('\n'):
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lines[-1] += '\n'
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size, mtime = stat.st_size, stat.st_mtime
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cache[filename] = size, mtime, lines, fullname
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return lines
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