From e768bee388eca04682a9898ea53316c760f53988 Mon Sep 17 00:00:00 2001
From: Ram Rachum <ram@rachum.com>
Date: Tue, 12 Jan 2016 20:55:19 +0200
Subject: [PATCH] Chmod type

---
 source_py3/python_toolbox/file_tools.py | 93 +++++++++++++++++++++++++
 1 file changed, 93 insertions(+)

diff --git a/source_py3/python_toolbox/file_tools.py b/source_py3/python_toolbox/file_tools.py
index ac3e05ad0..76d560e57 100644
--- a/source_py3/python_toolbox/file_tools.py
+++ b/source_py3/python_toolbox/file_tools.py
@@ -7,7 +7,9 @@
     from python_toolbox.third_party import pathlib
 
 import os
+import functools
 import re
+import operator
 
 from python_toolbox import cute_iter_tools
 from python_toolbox import context_management
@@ -184,3 +186,94 @@ def atomic_create(path, binary=False):
             actual_temp_file_path.unlink()
             
 
+class Chmod:
+    # blocktodo test and doc, include testing __repr__. methods for setting on
+    # file. Say in docs it's static and modification returns a new object.
+    # explode fiel_tools to package and chmod-stuff to module.
+
+    @staticmethod
+    def _get_permissions_from_single_digit(digit):
+        assert 0 <= digit <= 7
+        permissions = set()
+        if digit & 4: permissions.add('r')
+        if digit & 1: permissions.add('w')
+        if digit & 2: permissions.add('x')
+        return frozenset(permissions)
+            
+    @staticmethod
+    def _get_nice_string_from_single_digit(digit):
+        permissions = Chmod._get_permissions_from_single_digit(digit)
+        return '%s%s%s' % (
+            'r' if 'r' in permissions else '-', 
+            'w' if 'w' in permissions else '-', 
+            'x' if 'x' in permissions else '-', 
+        )
+            
+    def __init__(self, path_or_number):
+        if isinstance(path_or_number, int):
+            self._number = path_or_number
+        else:
+            self._number = pathlib.Path(path).stat() & 0o777
+        self._dict = {
+            'u': Chmod._get_permissions_from_single_digit(self & 0o700),
+            'g': Chmod._get_permissions_from_single_digit(self & 0o070),
+            'o': Chmod._get_permissions_from_single_digit(self & 0o007),
+        }
+        self._dict['a'] = functools.reduce(operator.and_, self._dict.values())
+    
+        self.nice_string = ''.join(map(
+            Chmod._get_nice_string_from_single_digit,
+            (self & 0o700, self & 0o070, self & 0o007)
+        ))  
+            
+    __getitem__ = lambda self, key: self._dict[key]
+    
+    def __repr__(self):
+        return '<Chmod %s: %s>' % (oct(self), self.nice_string)
+    
+    def set_to_file(self, path):
+        pathlib.Path(path).chmod(self._number)
+        
+    _pattern = re.compile('^(?P<who>[ugoa]{0,4})(?P<operator>[-+=])(?P<what>['
+                         'rwx]{1,3)$')
+
+    def change(self, s):
+        from python_toolbox import sequence_tools
+        parts = ','.split(s)
+        matches = tuple(map(Chmod._pattern.match, parts))
+        if None in matches:
+            raise Exception('%s not valid.' % repr(s))
+        for match in matches:
+            who, operator, what = match.groups()
+            if sequence_tools.get_recurrences(who):
+                raise Exception('Can\'t repeat here: %s' % match.group(0))
+            if sequence_tools.get_recurrences(what):
+                raise Exception('Can\'t repeat here: %s' % match.group(0))
+        number = self._number
+        for match in matches:
+            who, operator, what = match.groups()
+            who_mask = 0o777 if 'a' in who else (
+                (0o700 * ('u' in who)) + (0o070 * ('g' in who)) +
+                (0o007 * ('o' in who))
+            )
+            what_mask = (0o444 * ('r' in what)) + (0o222 * ('w' in what)) + \
+                                                        (0o111 * ('x' in what))
+            t = who_mask & what_mask
+            
+            if operator == '+':
+                number |= t
+            elif operator == '-':
+                number &= ~t
+            else:
+                assert operator == '='
+                number = (number & (0o777 - who_mask)) | t
+                
+        return Chmod(number)
+        
+    __int__ = lambda self: self._number
+    __and__ = lambda self: self._number & other
+    __or__ = lambda self: self._number | other
+        
+        
+    
+            
\ No newline at end of file