Remove Polyglot transliteration library

The model server for the Polyglot transliteration library is currently
down and the project looks unmaintained; this currently is breaking
LibreTranslate installs. This commit removes Polyglot for
transliteration but keeps using Polyglot for language detection.

- https://github.com/LibreTranslate/LibreTranslate/issues/344
- https://community.libretranslate.com/t/improving-transliteration-in-libretranslate/400

app/app.py

@@ -15,7 +15,7 @@ from translatehtml import translate_html
 from werkzeug.utils import secure_filename
 
 from app import flood, remove_translated_files, security
-from app.language import detect_languages, transliterate, improve_translation_formatting
+from app.language import detect_languages, improve_translation_formatting
 
 from .api_keys import Database, RemoteDatabase
 from .suggestions import Database as SuggestionsDatabase
@@ -489,8 +489,7 @@ def create_app(args):
                     if text_format == "html":
                         translated_text = str(translate_html(translator, text))
                     else:
-                        translated_text = improve_translation_formatting(text, translator.translate(
-                            transliterate(text, target_lang=source_langs[idx]["language"])))
+                        translated_text = improve_translation_formatting(text, translator.translate(text))
 
                     results.append(unescape(translated_text))
                 if source_lang == "auto":
@@ -512,8 +511,7 @@ def create_app(args):
                 if text_format == "html":
                     translated_text = str(translate_html(translator, q))
                 else:
-                    translated_text = improve_translation_formatting(q, translator.translate(
-                        transliterate(q, target_lang=source_langs[0]["language"])))
+                    translated_text = improve_translation_formatting(q, translator.translate(q))
 
                 if source_lang == "auto":
                     return jsonify(

app/init.py

@@ -1,6 +1,5 @@
 from pathlib import Path
 
-import polyglot
 from argostranslate import package, translate
 
 import app.language
@@ -9,7 +8,6 @@ import app.language
 def boot(load_only=None):
     try:
         check_and_install_models(load_only_lang_codes=load_only)
-        check_and_install_transliteration()
     except Exception as e:
         print("Cannot update models (normal if you're offline): %s" % str(e))
 
@@ -60,35 +58,3 @@ def check_and_install_models(force=False, load_only_lang_codes=None):
             "Loaded support for %s languages (%s models total)!"
             % (len(translate.get_installed_languages()), len(available_packages))
         )
-
-
-def check_and_install_transliteration(force=False):
-    # 'en' is not a supported transliteration language
-    transliteration_languages = [
-        l.code for l in app.language.load_languages() if l.code != "en"
-    ]
-
-    # check installed
-    install_needed = []
-    if not force:
-        t_packages_path = Path(polyglot.polyglot_path) / "transliteration2"
-        for lang in transliteration_languages:
-            if not (
-                t_packages_path / lang / f"transliteration.{lang}.tar.bz2"
-            ).exists():
-                install_needed.append(lang)
-    else:
-        install_needed = transliteration_languages
-
-    # install the needed transliteration packages
-    if install_needed:
-        print(
-            f"Installing transliteration models for the following languages: {', '.join(install_needed)}"
-        )
-
-        from polyglot.downloader import Downloader
-
-        downloader = Downloader()
-
-        for lang in install_needed:
-            downloader.download(f"transliteration2.{lang}")

app/language.py

@@ -2,7 +2,6 @@ import string
 
 from argostranslate import translate
 from polyglot.detect.base import Detector, UnknownLanguage
-from polyglot.transliteration.base import Transliterator
 
 __languages = None
 
@@ -113,52 +112,3 @@ def improve_translation_formatting(source, translation, improve_punctuation=True
 
     return translation
 
-
-def __transliterate_line(transliterator, line_text):
-    new_text = []
-
-    # transliteration is done word by word
-    for orig_word in line_text.split(" "):
-        # remove any punctuation on the right side
-        r_word = orig_word.rstrip(string.punctuation)
-        r_diff = set(char for char in orig_word) - set(char for char in r_word)
-        # and on the left side
-        l_word = orig_word.lstrip(string.punctuation)
-        l_diff = set(char for char in orig_word) - set(char for char in l_word)
-
-        # the actual transliteration of the word
-        t_word = transliterator.transliterate(orig_word.strip(string.punctuation))
-
-        # if transliteration fails, default back to the original word
-        if not t_word:
-            t_word = orig_word
-        else:
-            t_word = improve_translation_formatting(orig_word.strip(string.punctuation), t_word, improve_punctuation=False)
-
-            # add back any stripped punctuation
-            if r_diff:
-                t_word = t_word + "".join(r_diff)
-            if l_diff:
-                t_word = "".join(l_diff) + t_word
-
-        new_text.append(t_word)
-
-    # rebuild the text
-    return " ".join(new_text)
-
-
-def transliterate(text, target_lang="en"):
-    # initialize the transliterator from polyglot
-    transliterator = Transliterator(target_lang=target_lang)
-
-    # check for multiline string
-    if "\n" in text:
-        lines = []
-        # process each line separate
-        for line in text.split("\n"):
-            lines.append(__transliterate_line(transliterator, line))
-
-        # rejoin multiline string
-        return "\n".join(lines)
-    else:
-        return __transliterate_line(transliterator, text)

install_models.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 import argparse
-from app.init import check_and_install_models, check_and_install_transliteration
+from app.init import check_and_install_models
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()
@@ -10,4 +10,3 @@ if __name__ == "__main__":
     if len(lang_codes) == 0 or lang_codes[0] == '':
         lang_codes = None
     check_and_install_models(force=True, load_only_lang_codes=lang_codes)
-    check_and_install_transliteration(force=True)