Detect some common script languages via shebang

src/source_base.cpp

@@ -38,6 +38,24 @@ Glib::RefPtr<Gsv::StyleSchemeManager> Source::StyleSchemeManager::get_default()
   return instance;
 }
 
+static Glib::RefPtr<Gsv::Language> guess_shebang(const boost::filesystem::path &file_path, Glib::RefPtr<Gsv::LanguageManager> &language_manager) {
+  std::ifstream input(file_path.string(), std::ios::binary);
+  std::string line;
+  if(!std::getline(input, line) || line.empty() || line == "#!")
+    return {};
+
+  if(line.find("perl") < line.size())
+    return language_manager->get_language("perl");
+  else if(line.find("python3") < line.size())
+    return language_manager->get_language("python3");
+  else if(line.find("python") < line.size())
+    return language_manager->get_language("python");
+  else if(line.find("sh") < line.size())
+    return language_manager->get_language("sh");
+
+  return {};
+}
+
 Glib::RefPtr<Gsv::Language> Source::guess_language(const boost::filesystem::path &file_path) {
   auto language_manager = LanguageManager::get_default();
   bool result_uncertain = false;
@@ -81,6 +99,8 @@ Glib::RefPtr<Gsv::Language> Source::guess_language(const boost::filesystem::path
       std::string tag(5, '\0');
       if(input && input.read(&tag[0], static_cast<std::streamsize>(tag.size())) && tag == "<?xml")
         language = language_manager->get_language("xml");
+      else if(input && starts_with(tag, "#!"))
+        language = guess_shebang(file_path, language_manager);
     }
   }
   else if(language->get_id() == "cuda") {