Merge pull request #786 from liuyuyan2717/faster-chinese-hownetSwap

Use cache to achieve faster generation of Chinese HowNet replacement …

textattack/transformations/word_swaps/chn_transformations/chinese_word_swap_hownet.py

@@ -15,16 +15,20 @@ class ChineseWordSwapHowNet(WordSwap):
     def __init__(self, topk=5):
         self.hownet_dict = OpenHowNet.HowNetDict(init_sim=True)
         self.topk = topk
+        self.wordCache = {}
 
     def _get_replacement_words(self, word):
         """Returns a list containing all possible words with N characters
         replaced by a homoglyph."""
+        if word in self.wordCache:
+            return self.wordCache[word]
         results = self.hownet_dict.get_nearest_words(word, language="zh", K=self.topk)
         synonyms = []
         if results:
             for key, value in results.items():
-                for w in value:
-                    synonyms.append(w)
+                synonyms = synonyms + value[1:]
+                self.wordCache[word] = synonyms.copy()
+                break
             return synonyms
         else:
             return []