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321 lines
10 KiB
Python
321 lines
10 KiB
Python
"""Utilities for comparing files and directories.
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Classes:
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dircmp
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Functions:
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cmp(f1, f2, shallow=True) -> int
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cmpfiles(a, b, common) -> ([], [], [])
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clear_cache()
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"""
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import os
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import stat
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from itertools import filterfalse
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from types import GenericAlias
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__all__ = ['clear_cache', 'cmp', 'dircmp', 'cmpfiles', 'DEFAULT_IGNORES']
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_cache = {}
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BUFSIZE = 8*1024
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DEFAULT_IGNORES = [
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'RCS', 'CVS', 'tags', '.git', '.hg', '.bzr', '_darcs', '__pycache__']
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def clear_cache():
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"""Clear the filecmp cache."""
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_cache.clear()
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def cmp(f1, f2, shallow=True):
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"""Compare two files.
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Arguments:
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f1 -- First file name
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f2 -- Second file name
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shallow -- treat files as identical if their stat signatures (type, size,
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mtime) are identical. Otherwise, files are considered different
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if their sizes or contents differ. [default: True]
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Return value:
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True if the files are the same, False otherwise.
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This function uses a cache for past comparisons and the results,
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with cache entries invalidated if their stat information
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changes. The cache may be cleared by calling clear_cache().
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"""
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s1 = _sig(os.stat(f1))
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s2 = _sig(os.stat(f2))
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if s1[0] != stat.S_IFREG or s2[0] != stat.S_IFREG:
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return False
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if shallow and s1 == s2:
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return True
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if s1[1] != s2[1]:
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return False
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outcome = _cache.get((f1, f2, s1, s2))
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if outcome is None:
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outcome = _do_cmp(f1, f2)
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if len(_cache) > 100: # limit the maximum size of the cache
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clear_cache()
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_cache[f1, f2, s1, s2] = outcome
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return outcome
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def _sig(st):
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return (stat.S_IFMT(st.st_mode),
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st.st_size,
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st.st_mtime)
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def _do_cmp(f1, f2):
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bufsize = BUFSIZE
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with open(f1, 'rb') as fp1, open(f2, 'rb') as fp2:
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while True:
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b1 = fp1.read(bufsize)
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b2 = fp2.read(bufsize)
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if b1 != b2:
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return False
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if not b1:
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return True
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# Directory comparison class.
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#
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class dircmp:
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"""A class that manages the comparison of 2 directories.
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dircmp(a, b, ignore=None, hide=None, *, shallow=True)
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A and B are directories.
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IGNORE is a list of names to ignore,
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defaults to DEFAULT_IGNORES.
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HIDE is a list of names to hide,
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defaults to [os.curdir, os.pardir].
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SHALLOW specifies whether to just check the stat signature (do not read
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the files).
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defaults to True.
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High level usage:
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x = dircmp(dir1, dir2)
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x.report() -> prints a report on the differences between dir1 and dir2
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or
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x.report_partial_closure() -> prints report on differences between dir1
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and dir2, and reports on common immediate subdirectories.
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x.report_full_closure() -> like report_partial_closure,
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but fully recursive.
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Attributes:
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left_list, right_list: The files in dir1 and dir2,
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filtered by hide and ignore.
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common: a list of names in both dir1 and dir2.
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left_only, right_only: names only in dir1, dir2.
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common_dirs: subdirectories in both dir1 and dir2.
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common_files: files in both dir1 and dir2.
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common_funny: names in both dir1 and dir2 where the type differs between
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dir1 and dir2, or the name is not stat-able.
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same_files: list of identical files.
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diff_files: list of filenames which differ.
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funny_files: list of files which could not be compared.
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subdirs: a dictionary of dircmp instances (or MyDirCmp instances if this
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object is of type MyDirCmp, a subclass of dircmp), keyed by names
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in common_dirs.
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"""
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def __init__(self, a, b, ignore=None, hide=None, *, shallow=True): # Initialize
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self.left = a
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self.right = b
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if hide is None:
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self.hide = [os.curdir, os.pardir] # Names never to be shown
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else:
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self.hide = hide
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if ignore is None:
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self.ignore = DEFAULT_IGNORES
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else:
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self.ignore = ignore
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self.shallow = shallow
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def phase0(self): # Compare everything except common subdirectories
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self.left_list = _filter(os.listdir(self.left),
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self.hide+self.ignore)
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self.right_list = _filter(os.listdir(self.right),
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self.hide+self.ignore)
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self.left_list.sort()
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self.right_list.sort()
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def phase1(self): # Compute common names
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a = dict(zip(map(os.path.normcase, self.left_list), self.left_list))
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b = dict(zip(map(os.path.normcase, self.right_list), self.right_list))
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self.common = list(map(a.__getitem__, filter(b.__contains__, a)))
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self.left_only = list(map(a.__getitem__, filterfalse(b.__contains__, a)))
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self.right_only = list(map(b.__getitem__, filterfalse(a.__contains__, b)))
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def phase2(self): # Distinguish files, directories, funnies
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self.common_dirs = []
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self.common_files = []
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self.common_funny = []
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for x in self.common:
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a_path = os.path.join(self.left, x)
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b_path = os.path.join(self.right, x)
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ok = True
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try:
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a_stat = os.stat(a_path)
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except (OSError, ValueError):
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# See https://github.com/python/cpython/issues/122400
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# for the rationale for protecting against ValueError.
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# print('Can\'t stat', a_path, ':', why.args[1])
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ok = False
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try:
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b_stat = os.stat(b_path)
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except (OSError, ValueError):
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# print('Can\'t stat', b_path, ':', why.args[1])
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ok = False
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if ok:
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a_type = stat.S_IFMT(a_stat.st_mode)
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b_type = stat.S_IFMT(b_stat.st_mode)
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if a_type != b_type:
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self.common_funny.append(x)
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elif stat.S_ISDIR(a_type):
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self.common_dirs.append(x)
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elif stat.S_ISREG(a_type):
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self.common_files.append(x)
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else:
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self.common_funny.append(x)
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else:
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self.common_funny.append(x)
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def phase3(self): # Find out differences between common files
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xx = cmpfiles(self.left, self.right, self.common_files, self.shallow)
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self.same_files, self.diff_files, self.funny_files = xx
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def phase4(self): # Find out differences between common subdirectories
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# A new dircmp (or MyDirCmp if dircmp was subclassed) object is created
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# for each common subdirectory,
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# these are stored in a dictionary indexed by filename.
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# The hide and ignore properties are inherited from the parent
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self.subdirs = {}
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for x in self.common_dirs:
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a_x = os.path.join(self.left, x)
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b_x = os.path.join(self.right, x)
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self.subdirs[x] = self.__class__(a_x, b_x, self.ignore, self.hide,
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shallow=self.shallow)
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def phase4_closure(self): # Recursively call phase4() on subdirectories
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self.phase4()
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for sd in self.subdirs.values():
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sd.phase4_closure()
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def report(self): # Print a report on the differences between a and b
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# Output format is purposely lousy
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print('diff', self.left, self.right)
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if self.left_only:
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self.left_only.sort()
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print('Only in', self.left, ':', self.left_only)
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if self.right_only:
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self.right_only.sort()
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print('Only in', self.right, ':', self.right_only)
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if self.same_files:
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self.same_files.sort()
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print('Identical files :', self.same_files)
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if self.diff_files:
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self.diff_files.sort()
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print('Differing files :', self.diff_files)
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if self.funny_files:
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self.funny_files.sort()
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print('Trouble with common files :', self.funny_files)
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if self.common_dirs:
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self.common_dirs.sort()
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print('Common subdirectories :', self.common_dirs)
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if self.common_funny:
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self.common_funny.sort()
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print('Common funny cases :', self.common_funny)
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def report_partial_closure(self): # Print reports on self and on subdirs
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self.report()
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for sd in self.subdirs.values():
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print()
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sd.report()
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def report_full_closure(self): # Report on self and subdirs recursively
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self.report()
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for sd in self.subdirs.values():
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print()
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sd.report_full_closure()
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methodmap = dict(subdirs=phase4,
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same_files=phase3, diff_files=phase3, funny_files=phase3,
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common_dirs=phase2, common_files=phase2, common_funny=phase2,
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common=phase1, left_only=phase1, right_only=phase1,
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left_list=phase0, right_list=phase0)
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def __getattr__(self, attr):
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if attr not in self.methodmap:
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raise AttributeError(attr)
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self.methodmap[attr](self)
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return getattr(self, attr)
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__class_getitem__ = classmethod(GenericAlias)
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def cmpfiles(a, b, common, shallow=True):
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"""Compare common files in two directories.
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a, b -- directory names
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common -- list of file names found in both directories
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shallow -- if true, do comparison based solely on stat() information
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Returns a tuple of three lists:
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files that compare equal
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files that are different
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filenames that aren't regular files.
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"""
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res = ([], [], [])
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for x in common:
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ax = os.path.join(a, x)
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bx = os.path.join(b, x)
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res[_cmp(ax, bx, shallow)].append(x)
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return res
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# Compare two files.
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# Return:
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# 0 for equal
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# 1 for different
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# 2 for funny cases (can't stat, NUL bytes, etc.)
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#
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def _cmp(a, b, sh, abs=abs, cmp=cmp):
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try:
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return not abs(cmp(a, b, sh))
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except (OSError, ValueError):
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return 2
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# Return a copy with items that occur in skip removed.
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#
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def _filter(flist, skip):
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return list(filterfalse(skip.__contains__, flist))
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# Demonstration and testing.
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#
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def demo():
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import sys
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import getopt
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options, args = getopt.getopt(sys.argv[1:], 'r')
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if len(args) != 2:
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raise getopt.GetoptError('need exactly two args', None)
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dd = dircmp(args[0], args[1])
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if ('-r', '') in options:
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dd.report_full_closure()
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else:
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dd.report()
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if __name__ == '__main__':
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demo()
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