Add support for vocab.writing_system property (#3390)

* Add xfail test for vocab.writing_system

* Add vocab.writing_system property

* Set Language.Defaults.writing_system

* Set default writing system

* Remove xfail on test_vocab_writing_system

spacy/lang/fa/__init__.py

@@ -27,6 +27,7 @@ class PersianDefaults(Language.Defaults):
     stop_words = STOP_WORDS
     tag_map = TAG_MAP
     suffixes = TOKENIZER_SUFFIXES
+    writing_system = {"direction": "rtl", "has_case": False, "has_letters": True}
 
 
 class Persian(Language):

spacy/lang/he/__init__.py

@@ -14,7 +14,7 @@ class HebrewDefaults(Language.Defaults):
     lex_attr_getters[LANG] = lambda text: "he"
     tokenizer_exceptions = update_exc(BASE_EXCEPTIONS)
     stop_words = STOP_WORDS
-
+    writing_system = {"direction": "rtl", "has_case": False, "has_letters": True}
 
 class Hebrew(Language):
     lang = "he"

spacy/lang/ja/__init__.py

@@ -94,6 +94,7 @@ class JapaneseDefaults(Language.Defaults):
     lex_attr_getters[LANG] = lambda _text: "ja"
     stop_words = STOP_WORDS
     tag_map = TAG_MAP
+    writing_system = {"direction": "ltr", "has_case": False, "has_letters": False}
 
     @classmethod
     def create_tokenizer(cls, nlp=None):

spacy/lang/zh/__init__.py

@@ -14,7 +14,7 @@ class ChineseDefaults(Language.Defaults):
     use_jieba = True
     tokenizer_exceptions = BASE_EXCEPTIONS
     stop_words = STOP_WORDS
-
+    writing_system = {"direction": "ltr", "has_case": False, "has_letters": False}
 
 class Chinese(Language):
     lang = "zh"

spacy/language.py

@@ -94,6 +94,7 @@ class BaseDefaults(object):
     morph_rules = {}
     lex_attr_getters = LEX_ATTRS
     syntax_iterators = {}
+    writing_system = {"direction": "ltr", "has_case": True, "has_letters": True}
 
 
 class Language(object):

spacy/tests/vocab_vectors/test_vocab_api.py

@@ -45,3 +45,8 @@ def test_vocab_api_contains(en_vocab, text):
     _ = en_vocab[text]  # noqa: F841
     assert text in en_vocab
     assert "LKsdjvlsakdvlaksdvlkasjdvljasdlkfvm" not in en_vocab
+
+
+def test_vocab_writing_system(en_vocab):
+    assert en_vocab.writing_system["direction"] == "ltr"
+    assert en_vocab.writing_system["has_case"] == True

spacy/util.py

@@ -38,6 +38,18 @@ def set_env_log(value):
     _PRINT_ENV = value
 
 
+def lang_class_is_loaded(lang):
+    """Check whether a Language class is already loaded. Language classes are
+    loaded lazily, to avoid expensive setup code associated with the language
+    data.
+
+    lang (unicode): Two-letter language code, e.g. 'en'.
+    RETURNS (bool): Whether a Language class has been loaded.
+    """
+    global LANGUAGES
+    return lang in LANGUAGES
+ 
+
 def get_lang_class(lang):
     """Import and load a Language class.
 

spacy/vocab.pyx

@@ -67,6 +67,17 @@ cdef class Vocab:
                 langfunc = self.lex_attr_getters.get(LANG, None)
             return langfunc("_") if langfunc else ""
 
+    property writing_system:
+        """A dict with information about the language's writing system. To get
+        the data, we use the vocab.lang property to fetch the Language class.
+        If the Language class is not loaded, an empty dict is returned.
+        """
+        def __get__(self):
+            if not util.lang_class_is_loaded(self.lang):
+                return {}
+            lang_class = util.get_lang_class(self.lang)
+            return dict(lang_class.Defaults.writing_system)
+
     def __len__(self):
         """The current number of lexemes stored.