I have implemented parse_roman() function

number_parser/__init__.py

@@ -1 +1 @@
-from number_parser.parser import parse, parse_number, parse_ordinal, parse_fraction
+from number_parser.parser import parse, parse_number, parse_ordinal, parse_fraction, NUMERAL_SYSTEMS

number_parser/parser.py

@@ -1,9 +1,11 @@
 import re
 from importlib import import_module
 import unicodedata
+
 SENTENCE_SEPARATORS = [".", ","]
 SUPPORTED_LANGUAGES = ['en', 'es', 'hi', 'ru']
 RE_BUG_LANGUAGES = ['hi']
+NUMERAL_SYSTEMS = ['decimal', 'roman']
 
 
 class LanguageData:
@@ -249,6 +251,9 @@ def parse_number(input_string, language=None):
     if input_string.strip().isnumeric():
         return int(input_string)
 
+    if re.search("^(m{0,3})(cm|cd|d?c{0,3})(xc|xl|l?x{0,3})(ix|iv|v?i{0,3})$", input_string.lower()):
+        return int(_parse_roman(input_string))
+
     if language is None:
         language = _valid_tokens_by_language(input_string)
 
@@ -298,14 +303,33 @@ def parse_fraction(input_string, language=None):
     return None
 
 
-def parse(input_string, language=None):
+def parse(input_string, language=None, numeral_systems=None):
     """
     Converts all the numbers in a sentence written in natural language to their numeric type while keeping
     the other words unchanged. Returns the transformed string.
     """
+    global complete_sentence
+
+    if numeral_systems is None:
+        numeral_systems = ['decimal', 'roman']
+
     if language is None:
         language = _valid_tokens_by_language(input_string)
 
+    for numeral_system in numeral_systems:
+
+        if numeral_system == 'decimal':
+            complete_sentence = _parse_decimal(input_string, language)
+            input_string = complete_sentence
+
+        if numeral_system == 'roman':
+            complete_sentence = _parse_roman(input_string)
+            input_string = complete_sentence
+
+    return complete_sentence
+
+
+def _parse_decimal(input_string, language):
     lang_data = LanguageData(language)
 
     tokens = _tokenize(input_string, language)
@@ -359,8 +383,33 @@ def _build_and_add_number(pop_last_space=False):
 
             _build_and_add_number()
             current_sentence.append(token)
-
     _build_and_add_number()
 
     final_sentence.extend(current_sentence)
     return ''.join(final_sentence).strip()
+
+
+def _parse_roman(input_string):
+    tokens = _tokenize(input_string, None)
+    for token in tokens:
+        if re.search("^(m{0,3})(cm|cd|d?c{0,3})(xc|xl|l?x{0,3})(ix|iv|v?i{0,3})$", token.lower()):
+            if _build_roman(token) != 0:
+                tokens[tokens.index(token)] = str(_build_roman(token))
+    final_sentence = ''.join(tokens)
+
+    return final_sentence
+
+
+def _build_roman(roman_number):
+    roman = {'i': 1, 'v': 5, 'x': 10, 'l': 50, 'c': 100, 'd': 500, 'm': 1000}
+    num_tokens = re.split("^(m{0,3})(cm|cd|d?c{0,3})(xc|xl|l?x{0,3})(ix|iv|v?i{0,3})$", roman_number.lower())
+    num_tokens = [item for item in num_tokens if item != '']
+    built_num = 0
+    for num_token in num_tokens:
+        if re.search('iv|ix|xl|xc|cd|cm', num_token):
+            built_num += roman[num_token[1]] - roman[num_token[0]]
+        elif re.search('[vld][ixc]{1,3}', num_token):
+            built_num += roman[num_token[0]] + (roman[num_token[1]] * (len(num_token) - 1))
+        else:
+            built_num += roman[num_token[0]] * len(num_token)
+    return built_num

test.py

@@ -0,0 +1,3 @@
+from number_parser import parse ,parse_number
+
+print(parse_number('built in CDXX', numeral_system='roman'))

tests/__init__.py

@@ -20,7 +20,7 @@ def get_test_files(path, prefix):
 def _test_files(path, language, is_ordinal=True):
     fnx = parse_ordinal if is_ordinal else parse_number
     for filename in get_test_files(path, f'{language}_'):
-        with open(filename, "r") as csv_file:
+        with open(filename, "r", encoding="utf8") as csv_file:
             csv_reader = csv.DictReader(csv_file)
             for row in csv_reader:
                 try: