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################ 待整理
from cppy.cp_util import *
'''
订阅者 = 注册者 = 观察者
注册回调的一个变体
要点是:中心化、统一化
为了简化消息订阅可能形成的复杂性,
提供一个中心消息管理器统一负责消息的订阅和回调
各个功能组件只是完成自己的功能,
在中心管理器上订阅消息挂到自己响应的处理函数上
总结,相比较的改变:
- 注册的时候,通过提供一个类型字段标识不同消息
- 其它实体不做注册和做回调,统一这两个功能到一个中心单元
这是一个示例性质的原型,具体分布式环境下需要调整
'''
from collections import defaultdict
#################################################
# Event Manager
#################################################
class EventManager:
def __init__(self):
self._subs = defaultdict(list)
def subscribe(self, event_type, handler):
self._subs[event_type].append(handler)
def publish(self, event):
event_type = event[0]
for handle in self._subs.get(event_type, []):
handle(event)
#################################################
# Application Entities
#################################################
class DataStorage:
def __init__(self, event_manager):
self._event_manager = event_manager
self._event_manager.subscribe('load', self._load)
self._event_manager.subscribe('start', self.produce_words)
def _load(self, event):
self._data = extract_file_words( event[1] )
def produce_words(self, _):
for word in self._data:
self._event_manager.publish(('word', word ))
self._event_manager.publish(('eof', None))
class StopWordFilter:
def __init__(self, event_manager):
self._event_manager = event_manager
self._event_manager.subscribe('load', self.load_stop_words)
self._event_manager.subscribe('word', self.filter_word)
self._stop_words = set()
def load_stop_words(self, _ ):
self._stop_words = set( get_stopwords() )
def filter_word(self, event):
word = event[1]
if word not in self._stop_words:
self._event_manager.publish(('valid_word', word))
class WordFrequencyCounter:
def __init__(self, event_manager):
self._event_manager = event_manager
self._event_manager.subscribe('valid_word', self.count_word)
self._event_manager.subscribe('print', self.print_freqs)
self._word_freqs = {}
def count_word(self, event):
word = event[1]
self._word_freqs[word] = self._word_freqs.get(word, 0) + 1
def print_freqs(self, _ ):
print_word_freqs ( sort_dict (self._word_freqs) )
class WordFrequencyApp:
def __init__(self, event_manager):
self._event_manager = event_manager
self._event_manager.subscribe('run', self.start_application)
self._event_manager.subscribe('eof', self.stop_application)
def start_application(self, event):
path_to_file = event[1]
self._event_manager.publish(('load', path_to_file))
self._event_manager.publish(('start', ))
def stop_application(self, _ ):
self._event_manager.publish(('print', ))
def main():
event_manager = EventManager()
DataStorage( event_manager )
StopWordFilter( event_manager )
WordFrequencyCounter( event_manager )
WordFrequencyApp( event_manager )
event_manager.publish(('run', testfilepath ))
if __name__ == "__main__":
main()