98 lines
3.2 KiB
Python
98 lines
3.2 KiB
Python
# SPDX-FileCopyrightText: 2017 Yoch <https://github.com/yoch>
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#
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# SPDX-License-Identifier: EPL-1.0
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"""
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`matcher`
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====================================================================================
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MQTT topic filter matcher from the Eclipse Project's Paho.MQTT.Python
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https://github.com/eclipse/paho.mqtt.python/blob/master/src/paho/mqtt/matcher.py
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* Author(s): Yoch (https://github.com/yoch)
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"""
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class MQTTMatcher:
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"""Intended to manage topic filters including wildcards.
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Internally, MQTTMatcher use a prefix tree (trie) to store
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values associated with filters, and has an iter_match()
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method to iterate efficiently over all filters that match
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some topic name.
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"""
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# pylint: disable=too-few-public-methods
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class Node:
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"""Individual node on the MQTT prefix tree."""
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__slots__ = "children", "content"
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def __init__(self):
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self.children = {}
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self.content = None
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def __init__(self):
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self._root = self.Node()
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def __setitem__(self, key, value):
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"""Add a topic filter :key to the prefix tree
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and associate it to :value"""
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node = self._root
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for sym in key.split("/"):
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node = node.children.setdefault(sym, self.Node())
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node.content = value
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def __getitem__(self, key):
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"""Retrieve the value associated with some topic filter :key"""
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try:
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node = self._root
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for sym in key.split("/"):
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node = node.children[sym]
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if node.content is None:
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raise KeyError(key)
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return node.content
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except KeyError:
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raise KeyError(key) from None
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def __delitem__(self, key):
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"""Delete the value associated with some topic filter :key"""
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lst = []
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try:
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parent, node = None, self._root
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for k in key.split("/"):
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parent, node = node, node.children[k]
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lst.append((parent, k, node))
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node.content = None
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except KeyError:
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raise KeyError(key) from None
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else: # cleanup
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for parent, k, node in reversed(lst):
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if node.children or node.content is not None:
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break
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del parent.children[k]
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def iter_match(self, topic):
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"""Return an iterator on all values associated with filters
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that match the :topic"""
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lst = topic.split("/")
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normal = not topic.startswith("$")
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def rec(node, i=0):
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if i == len(lst):
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if node.content is not None:
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yield node.content
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else:
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part = lst[i]
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if part in node.children:
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for content in rec(node.children[part], i + 1):
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yield content
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if "+" in node.children and (normal or i > 0):
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for content in rec(node.children["+"], i + 1):
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yield content
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if "#" in node.children and (normal or i > 0):
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content = node.children["#"].content
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if content is not None:
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yield content
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return rec(self._root)
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