Optimize format string compilation

phprus · Jun 15, 2023 · 1daae55 · 1daae55
1 parent 6ad3012
commit 1daae55
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/include/fmt/compile.h b/include/fmt/compile.h
@@ -221,7 +221,12 @@ template <typename Char, typename T, int N> struct field {
 
   template <typename OutputIt, typename... Args>
   constexpr OutputIt format(OutputIt out, const Args&... args) const {
-    return write<Char>(out, get_arg_checked<T, N>(args...));
+    const T& arg = get_arg_checked<T, N>(args...);
+    if constexpr (std::is_convertible_v<T, basic_string_view<Char>>) {
+      auto s = basic_string_view<Char>(arg);
+      return copy_str<Char>(s.begin(), s.end(), out);
+    }
+    return write<Char>(out, arg);
   }
 };
 

diff --git a/include/fmt/core.h b/include/fmt/core.h
@@ -1486,6 +1486,13 @@ auto copy_str(InputIt begin, InputIt end, appender out) -> appender {
   get_container(out).append(begin, end);
   return out;
 }
+template <typename Char, typename InputIt>
+auto copy_str(InputIt begin, InputIt end,
+              std::back_insert_iterator<std::string> out)
+    -> std::back_insert_iterator<std::string> {
+  get_container(out).append(begin, end);
+  return out;
+}
 
 template <typename Char, typename R, typename OutputIt>
 FMT_CONSTEXPR auto copy_str(R&& rng, OutputIt out) -> OutputIt {