Added MQTT library

sbapp/mqtt/matcher.py

@@ -0,0 +1,78 @@
+class MQTTMatcher:
+    """Intended to manage topic filters including wildcards.
+
+    Internally, MQTTMatcher use a prefix tree (trie) to store
+    values associated with filters, and has an iter_match()
+    method to iterate efficiently over all filters that match
+    some topic name."""
+
+    class Node:
+        __slots__ = '_children', '_content'
+
+        def __init__(self):
+            self._children = {}
+            self._content = None
+
+    def __init__(self):
+        self._root = self.Node()
+
+    def __setitem__(self, key, value):
+        """Add a topic filter :key to the prefix tree
+        and associate it to :value"""
+        node = self._root
+        for sym in key.split('/'):
+            node = node._children.setdefault(sym, self.Node())
+        node._content = value
+
+    def __getitem__(self, key):
+        """Retrieve the value associated with some topic filter :key"""
+        try:
+            node = self._root
+            for sym in key.split('/'):
+                node = node._children[sym]
+            if node._content is None:
+                raise KeyError(key)
+            return node._content
+        except KeyError as ke:
+            raise KeyError(key) from ke
+
+    def __delitem__(self, key):
+        """Delete the value associated with some topic filter :key"""
+        lst = []
+        try:
+            parent, node = None, self._root
+            for k in key.split('/'):
+                 parent, node = node, node._children[k]
+                 lst.append((parent, k, node))
+            # TODO
+            node._content = None
+        except KeyError as ke:
+            raise KeyError(key) from ke
+        else:  # cleanup
+            for parent, k, node in reversed(lst):
+                if node._children or node._content is not None:
+                     break
+                del parent._children[k]
+
+    def iter_match(self, topic):
+        """Return an iterator on all values associated with filters
+        that match the :topic"""
+        lst = topic.split('/')
+        normal = not topic.startswith('$')
+        def rec(node, i=0):
+            if i == len(lst):
+                if node._content is not None:
+                    yield node._content
+            else:
+                part = lst[i]
+                if part in node._children:
+                    for content in rec(node._children[part], i + 1):
+                        yield content
+                if '+' in node._children and (normal or i > 0):
+                    for content in rec(node._children['+'], i + 1):
+                        yield content
+            if '#' in node._children and (normal or i > 0):
+                content = node._children['#']._content
+                if content is not None:
+                    yield content
+        return rec(self._root)