1 files changed, 86 insertions, 0 deletions
diff --git a/cloudinit/mergers/m_dict.py b/cloudinit/mergers/m_dict.py
new file mode 100644
index 00000000..a16141fa
--- /dev/null
+++ b/cloudinit/mergers/m_dict.py
@@ -0,0 +1,86 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2012 Yahoo! Inc.
+#
+#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License version 3, as
+#    published by the Free Software Foundation.
+#
+#    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/>.
+
+DEF_MERGE_TYPE = 'no_replace'
+MERGE_TYPES = ('replace', DEF_MERGE_TYPE,)
+
+
+def _has_any(what, *keys):
+    for k in keys:
+        if k in what:
+            return True
+    return False
+
+
+class Merger(object):
+    def __init__(self, merger, opts):
+        self._merger = merger
+        # Affects merging behavior...
+        self._method = DEF_MERGE_TYPE
+        for m in MERGE_TYPES:
+            if m in opts:
+                self._method = m
+                break
+        # Affect how recursive merging is done on other primitives.
+        self._recurse_str = 'recurse_str' in opts
+        self._recurse_array = _has_any(opts, 'recurse_array', 'recurse_list')
+        self._allow_delete = 'allow_delete' in opts
+        # Backwards compat require this to be on.
+        self._recurse_dict = True
+
+    def __str__(self):
+        s = ('DictMerger: (method=%s,recurse_str=%s,'
+             'recurse_dict=%s,recurse_array=%s,allow_delete=%s)')
+        s = s % (self._method, self._recurse_str,
+                 self._recurse_dict, self._recurse_array, self._allow_delete)
+        return s
+
+    def _do_dict_replace(self, value, merge_with, do_replace):
+
+        def merge_same_key(old_v, new_v):
+            if do_replace:
+                return new_v
+            if isinstance(new_v, (list, tuple)) and self._recurse_array:
+                return self._merger.merge(old_v, new_v)
+            if isinstance(new_v, (basestring)) and self._recurse_str:
+                return self._merger.merge(old_v, new_v)
+            if isinstance(new_v, (dict)) and self._recurse_dict:
+                return self._merger.merge(old_v, new_v)
+            # Otherwise leave it be...
+            return old_v
+
+        for (k, v) in merge_with.items():
+            if k in value:
+                if v is None and self._allow_delete:
+                    value.pop(k)
+                else:
+                    value[k] = merge_same_key(value[k], v)
+            else:
+                value[k] = v
+        return value
+
+    def _on_dict(self, value, merge_with):
+        if not isinstance(merge_with, (dict)):
+            return value
+        if self._method == 'replace':
+            merged = self._do_dict_replace(dict(value), merge_with, True)
+        elif self._method == 'no_replace':
+            merged = self._do_dict_replace(dict(value), merge_with, False)
+        else:
+            raise NotImplementedError("Unknown merge type %s" % (self._method))
+        return merged