file system backed properties

Signed-off-by: Steven Armstrong <steven@icarus.ethz.ch>

lib/cdist/core/property.py

@@ -0,0 +1,119 @@
+# -*- coding: utf-8 -*-
+#
+# 2010-2011 Steven Armstrong (steven-cdist at armstrong.cc)
+#
+# This file is part of cdist.
+#
+# cdist 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.
+#
+# cdist 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 cdist. If not, see <http://www.gnu.org/licenses/>.
+#
+#
+
+import os
+import collections
+
+import cdist
+
+
+DOT_CDIST = '.cdist'
+
+
+class FileList(collections.MutableSequence):
+    """A list that stores it's state in a file.
+
+    """
+    def __init__(self, path, initial=None):
+        self._path = path
+        if initial:
+            for i in initial:
+                self.append(i)
+
+    def __read(self):
+        lines = []
+        try:
+            with open(self._path) as fd:
+                for line in fd:
+                    lines.append(line.strip())
+        except EnvironmentError as e:
+            # error ignored
+            pass
+        return lines
+
+    def __write(self, lines):
+        try:
+            with open(self._path, 'w') as fd:
+                for line in lines:
+                    fd.write(line + '\n')
+        except EnvironmentError as e:
+            # error ignored
+            raise
+
+    def __repr__(self):
+        return repr(list(self))
+
+    def __getitem__(self, index):
+        return self.__read()[index]
+        
+    def __setitem__(self, index, value):
+        lines = self.__read()
+        lines[index] = value
+        self.__write(lines)
+
+    def __delitem__(self, index):
+        lines = self.__read()
+        del lines[index]
+        self.__write(lines)
+
+    def __len__(self):
+        lines = self.__read()
+        return len(lines)
+
+    def insert(self, index, value):
+        lines = self.__read()
+        lines.insert(index, value)
+        self.__write(lines)
+
+
+class DirectoryDict(collections.MutableMapping):
+    """A dict that stores it's state in a directory.
+
+    """
+    def __init__(self, path, dict=None, **kwargs):
+        self._path = path
+        if dict is not None:
+            self.update(dict)
+        if len(kwargs):
+            self.update(kwargs)
+
+    def __repr__(self):
+        return repr(dict(self))
+
+    def __getitem__(self, key):
+        try:
+            with open(os.path.join(self._path, key), "r") as fd:
+                return fd.read()
+        except EnvironmentError:
+            raise KeyError(key)
+
+    def __setitem__(self, key, value):
+        with open(os.path.join(self._path, key), "w") as fd:
+            fd.write(value)        
+
+    def __delitem__(self, key):
+        os.remove(os.path.join(self._path, key))
+
+    def __iter__(self):
+        return iter(os.listdir(self._path))
+
+    def __len__(self):
+        return len(os.listdir(self._path))