Revert experimentation

sphinx/search/en.py

@@ -2,9 +2,8 @@
 
 from typing import Dict
 
-import snowballstemmer
-
 from sphinx.search import SearchLanguage
+from sphinx.util.stemmer import get_stemmer
 
 english_stopwords = set("""
 a  and  are  as  at
@@ -212,7 +211,7 @@ class SearchEnglish(SearchLanguage):
     stopwords = english_stopwords
 
     def init(self, options: Dict) -> None:
-        self.stemmer = snowballstemmer.stemmer('english')
+        self.stemmer = get_stemmer()
 
     def stem(self, word: str) -> str:
-        return self.stemmer.stemWord(word.lower())
+        return self.stemmer.stem(word.lower())

sphinx/util/stemmer/__init__.py

@@ -1,16 +1,37 @@
 """Word stemming utilities for Sphinx."""
 
-import snowballstemmer
-
 from sphinx.util.stemmer.porter import PorterStemmer
 
+try:
+    from Stemmer import Stemmer as _PyStemmer
+    PYSTEMMER = True
+except ImportError:
+    PYSTEMMER = False
+
 
 class BaseStemmer:
     def stem(self, word: str) -> str:
-        raise NotImplementedError
+        raise NotImplementedError()
 
 
-def get_stemmer() -> BaseStemmer:
-    stemmer = snowballstemmer.stemmer('english')
+class PyStemmer(BaseStemmer):
+    def __init__(self) -> None:
+        self.stemmer = _PyStemmer('porter')
+
+    def stem(self, word: str) -> str:
+        return self.stemmer.stemWord(word)
+
 
+class StandardStemmer(PorterStemmer, BaseStemmer):
+    """All those porter stemmer implementations look hideous;
+    make at least the stem method nicer.
+    """
+    def stem(self, word: str) -> str:  # type: ignore
+        return super().stem(word, 0, len(word) - 1)
 
+
+def get_stemmer() -> BaseStemmer:
+    if PYSTEMMER:
+        return PyStemmer()
+    else:
+        return StandardStemmer()