Slight improvement to last commit

They are detected as Octave, but *.m is also used for Objective-C.

src/source.cpp

@@ -83,6 +83,8 @@ Glib::RefPtr<Gsv::Language> Source::guess_language(const boost::filesystem::path
       language = language_manager->get_language("glsl");
     else if(extension == ".in" || extension == ".bak")
       return guess_language(boost::filesystem::path(file_path).replace_extension());
+    else if(extension == ".mm")
+      language = language_manager->get_language("objc");
     else if(!file_path.has_extension() && std::any_of(file_path.begin(), file_path.end(),
                                                       [](const boost::filesystem::path &path) { return path == "include"; }))
       language = language_manager->get_language("cpphdr");
@@ -101,6 +103,14 @@ Glib::RefPtr<Gsv::Language> Source::guess_language(const boost::filesystem::path
   }
   else if(language->get_id() == "opencl")
     language = language_manager->get_language("cpp");
+  else if(language->get_id() == "octave" && extension == ".m") {
+    // .m is used for both Octave and Objective-C, so try to differentiate
+    std::ifstream input(file_path.string(), std::ios::binary);
+    std::string line;
+    if(input && std::getline(input, line) &&
+       (starts_with(line, "#import ") || starts_with(line, "@interface ") || starts_with(line, "/*") || starts_with(line, "//")))
+      language = language_manager->get_language("objc");
+  }
   return language;
 }