core (tools): new tools.common module with tools used by backend and frontends. dict2iter and iter2dict method to serialise iterable in a dict (for bridge)

src/tools/common.py

@@ -0,0 +1,81 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# SAT: a jabber client
+# Copyright (C) 2009, 2010, 2011, 2012, 2013, 2014, 2015 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 """
+
+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 mb_data (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 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