Function to remove surrounding punctuation

src/calibre/utils/hyphenation/hyphenate.py

@@ -6,3 +6,28 @@ from __future__ import absolute_import, division, print_function, unicode_litera
 
 # TODO: lower case word? remove trailing punctuation. abort early if contains = or length < 4 or length > 99
 # TODO: test with replacement words
+
+
+import regex
+REGEX_FLAGS = regex.VERSION1 | regex.WORD | regex.FULLCASE | regex.UNICODE
+
+
+def pats():
+    ans = getattr(pats, 'ans', None)
+    if ans is None:
+        pats.ans = ans = regex.compile(r'^\p{P}+', REGEX_FLAGS), regex.compile(r'\p{P}+$', REGEX_FLAGS)
+    return ans
+
+
+def remove_punctuation(word):
+    leading, trailing = pats()
+    prefix = suffix = ''
+    nword, n = leading.subn('', word)
+    if n > 0:
+        count = len(word) - len(nword)
+        prefix, word = word[:count], nword
+    nword, n = trailing.subn('', word)
+    if n > 0:
+        count = len(word) - len(nword)
+        suffix, word = word[-count:], nword
+    return prefix, word, suffix

src/calibre/utils/hyphenation/test_hyphenation.py

@@ -4,13 +4,15 @@
 
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-import shutil, os
+import os
+import shutil
 import unittest
 
 from calibre.ptempfile import PersistentTemporaryDirectory
 from calibre.utils.hyphenation.dictionaries import (
     dictionary_name_for_locale, path_to_dictionary
 )
+from calibre.utils.hyphenation.hyphenate import remove_punctuation
 
 
 class TestHyphenation(unittest.TestCase):
@@ -61,6 +63,11 @@ class TestHyphenation(unittest.TestCase):
         )
         self.assertFalse(cache[0])
 
+    def test_remove_punctuation(self):
+        self.ae(remove_punctuation('word'), ('', 'word', ''))
+        self.ae(remove_punctuation('wo.rd.'), ('', 'wo.rd', '.'))
+        self.ae(remove_punctuation('"«word!!'), ('"«', 'word', '!!'))
+
 
 def find_tests():
     return unittest.defaultTestLoader.loadTestsFromTestCase(TestHyphenation)