Improve C vs C++ vs Objective-C language detection

Author: alanhamlett

tests/samples/codefiles/c_and_cpp/cpp.h

@@ -65,7 +65,7 @@ def test_c_language_detected_for_header_with_c_files_in_folder(self):
     def test_cpp_language_detected_for_header_with_c_and_cpp_files_in_folder(self):
         self.shared(
             expected_language='C++',
-            entity='c_and_cpp/empty.h',
+            entity='c_and_cpp/cpp.h',
         )
 
     def test_c_not_detected_for_non_header_with_c_files_in_folder(self):
@@ -80,12 +80,24 @@ def test_objectivec_language_detected_when_header_files_in_folder(self):
             entity='c_and_cpp/empty.m',
         )
 
+    def test_objectivec_language_detected_when_m_files_in_folder(self):
+        self.shared(
+            expected_language='Objective-C',
+            entity='c_and_cpp/objective-c.h',
+        )
+
     def test_objectivecpp_language_detected_when_header_files_in_folder(self):
         self.shared(
             expected_language='Objective-C++',
             entity='c_and_cpp/empty.mm',
         )
 
+    def test_objectivecpp_language_detected_when_m_files_in_folder(self):
+        self.shared(
+            expected_language='Objective-C++',
+            entity='c_and_cpp/objective-cpp.h',
+        )
+
     def test_guess_language(self):
         with utils.mock.patch('wakatime.stats.smart_guess_lexer') as mock_guess_lexer:
             mock_guess_lexer.return_value = None

tests/samples/codefiles/c_and_cpp/objective-c.h

@@ -177,18 +177,18 @@ def get_language_from_extension(file_name):
         if os.path.exists(u('{0}{1}').format(u(filepart), u('.c'))) or os.path.exists(u('{0}{1}').format(u(filepart), u('.C'))):
             return 'C'
 
-        available_extensions = extensions_in_same_folder(file_name)
-        if '.cpp' in available_extensions:
-            return 'C++'
-        if '.c' in available_extensions:
-            return 'C'
-
         if os.path.exists(u('{0}{1}').format(u(filepart), u('.m'))) or os.path.exists(u('{0}{1}').format(u(filepart), u('.M'))):
             return 'Objective-C'
 
         if os.path.exists(u('{0}{1}').format(u(filepart), u('.mm'))) or os.path.exists(u('{0}{1}').format(u(filepart), u('.MM'))):
             return 'Objective-C++'
 
+        available_extensions = extensions_in_same_folder(file_name)
+        if '.cpp' in available_extensions:
+            return 'C++'
+        if '.c' in available_extensions:
+            return 'C'
+
     if re.match(r'\.m$', extension, re.IGNORECASE) and (os.path.exists(u('{0}{1}').format(u(filepart), u('.h'))) or os.path.exists(u('{0}{1}').format(u(filepart), u('.H')))):
         return 'Objective-C'