refactor utils

utils.h

@@ -7,13 +7,27 @@
 #include <sstream>
 #include <string_view>
 
-constexpr std::string_view to_string_view(const std::ranges::subrange<const char *> cs) {
+namespace utils {
+
+template<typename T>
+concept StringLike = requires(const T &t)
+{
+    { std::string_view{t} } -> std::convertible_to<std::string_view>;
+    { t.size() } -> std::convertible_to<size_t>;
+};
+
+constexpr std::string_view to_string_view(const std::ranges::subrange<const char *>& cs) {
     return std::string_view{cs.data(), cs.size()};
 }
 
+constexpr bool non_empty(const std::string_view sv) {
+    return !sv.empty();
+}
+
 inline std::string read_file(std::string_view path) {
     std::ifstream input(path.data());
     std::stringstream buffer;
     buffer << input.rdbuf();
     return buffer.str();
 }
+}