--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sat/tools/common/data_format.py	Mon Apr 02 19:44:50 2018 +0200
@@ -0,0 +1,120 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# SAT: a jabber client
+# Copyright (C) 2009-2018 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+""" tools common to backend and frontends """
+# FIXME: json may be more appropriate than manual serialising like done here
+
+from sat.core import exceptions
+
+def dict2iter(name, dict_, pop=False):
+    """iterate into a list serialised in a dict
+
+    name is the name of the key.
+    Serialisation is done with [name] [name#1] [name#2] and so on
+    e.g.: if name is 'group', keys are group, group#1, group#2, ...
+    iteration stop at first missing increment
+    Empty values are possible
+    @param name(unicode): name of the key
+    @param dict_(dict): dictionary with the serialised list
+    @param pop(bool): if True, remove the value from dict
+    @return iter: iterate through the deserialised list
+    """
+    if pop:
+        get=lambda d,k: d.pop(k)
+    else:
+        get=lambda d,k: d[k]
+
+    try:
+        yield get(dict_,name)
+    except KeyError:
+        return
+    else:
+        idx = 1
+        while True:
+            try:
+                yield get(dict_,u'{}#{}'.format(name, idx))
+            except KeyError:
+                return
+            else:
+                idx += 1
+
+def dict2iterdict(name, dict_, extra_keys, pop=False):
+    """like dict2iter but yield dictionaries
+
+    params are like in [dict2iter], extra_keys is used for extra dict keys.
+    e.g. dict2iterdict(comments, mb_data, ('node', 'service')) will yield dicts like:
+        {u'comments': u'value1', u'node': u'value2', u'service': u'value3'}
+    """
+    # FIXME: this format seem overcomplicated, it may be more appropriate to use json here
+    if pop:
+        get=lambda d,k: d.pop(k)
+    else:
+        get=lambda d,k: d[k]
+    for idx, main_value in enumerate(dict2iter(name, dict_, pop=pop)):
+        ret = {name: main_value}
+        for k in extra_keys:
+            ret[k] = get(dict_, u'{}{}_{}'.format(name, (u'#' + unicode(idx)) if idx else u'', k))
+        yield ret
+
+def iter2dict(name, iter_, dict_=None, check_conflict=True):
+    """Fill a dict with values from an iterable
+
+    name is used to serialise iter_, in the same way as in [dict2iter]
+    Build from the tags a dict using the microblog data format.
+
+    @param name(unicode): key to use for serialisation
+        e.g. "group" to have keys "group", "group#1", "group#2", ...
+    @param iter_(iterable): values to store
+    @param dict_(None, dict): dictionary to fill, or None to create one
+    @param check_conflict(bool): if True, raise an exception in case of existing key
+    @return (dict): filled dict, or newly created one
+    @raise exceptions.ConflictError: a needed key already exists
+    """
+    if dict_ is None:
+        dict_ = {}
+    for idx, value in enumerate(iter_):
+        if idx == 0:
+            key = name
+        else:
+            key = u'{}#{}'.format(name, idx)
+        if check_conflict and key in dict_:
+            raise exceptions.ConflictError
+        dict_[key] = value
+    return dict
+
+def getSubDict(name, dict_, sep=u'_'):
+    """get a sub dictionary from a serialised dictionary
+
+    look for keys starting with name, and create a dict with it
+    eg.: if "key" is looked for, {'html': 1, 'key_toto': 2, 'key_titi': 3} will return:
+        {None: 1, toto: 2, titi: 3}
+    @param name(unicode): name of the key
+    @param dict_(dict): dictionary with the serialised list
+    @param sep(unicode): separator used between name and subkey
+    @return iter: iterate through the deserialised items
+    """
+    for k,v in dict_.iteritems():
+        if k.startswith(name):
+            if k == name:
+                yield None, v
+            else:
+                if k[len(name)] != sep:
+                    continue
+                else:
+                    yield k[len(name)+1:], v