1 files changed, 75 insertions, 0 deletions
diff --git a/genbackupdatalib/names.py b/genbackupdatalib/names.py
new file mode 100644
index 0000000..287112d
--- /dev/null
+++ b/genbackupdatalib/names.py
@@ -0,0 +1,75 @@
+# Copyright 2011  Lars Wirzenius
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+import os
+
+
+class NameGenerator(object):
+
+    '''Generate names for new output files.
+    
+    If the target directory is empty, the sequence of output files is
+    always the same for the same parameters.
+    
+    A directory structure is also generated. The shape of the tree is
+    defined by two parameters: 'max' and 'depth'. 'depth' is the number
+    of levels of subdirectories to create, and 'max' is the maximum
+    number of files/dirs to allow per output directory. Thus, if max is
+    3 and depth is 2, the output files are: 0/0/0, 0/0/1, 0/0/2,
+    0/1/0, 0/1/1, etc.
+    
+    If depth is zero, all output files go directly to the target
+    directory, and max is ignored.
+    
+    '''
+    
+    def __init__(self, dirname, depth, max):
+        self.dirname = dirname
+        self.depth = depth
+        self.max = max
+        self.counter = 0
+        
+    def _path_tuple(self, n):
+        '''Return tuple for dir/file numbers for nth output file.
+        
+        The last item in the tuple gives the file number, the precding
+        items the directory numbers. Thus, a tuple (1, 2, 3) would
+        mean path '1/2/3', but it is given as a tuple for easier
+        manipulation.
+        
+        '''
+        
+        if self.depth == 0:
+            return (n,)
+        else:
+            items = []
+            for i in range(self.depth):
+                items.append(n % self.max)
+                n /= self.max
+            items.append(n)
+            items.reverse()
+        return tuple(items)
+        
+    def _next_candidate_name(self):
+        items = self._path_tuple(self.counter)
+        self.counter += 1
+        return os.path.join(self.dirname, *[str(i) for i in items])
+        
+    def new(self):
+        while True:
+            name = self._next_candidate_name()
+            if not os.path.exists(name):
+                return name