From b3917aaadf02dce193c58ebd4bcde05a73a42eb4 Mon Sep 17 00:00:00 2001
From: ToruNiina <niina.toru.68u@gmail.com>
Date: Tue, 16 Apr 2019 20:54:29 +0900
Subject: [PATCH] refactor: use snprintf to show char in hex

instead of std::ostringstream.
---
 toml/combinator.hpp | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/toml/combinator.hpp b/toml/combinator.hpp
index ac8dd14..52aaaae 100644
--- a/toml/combinator.hpp
+++ b/toml/combinator.hpp
@@ -9,7 +9,10 @@
 #include <type_traits>
 #include <iterator>
 #include <limits>
+#include <array>
 #include <iomanip>
+#include <cstdio>
+#include <cassert>
 #include <cctype>
 
 // they scans characters and returns region if it matches to the condition.
@@ -38,10 +41,12 @@ inline std::string show_char(const char c)
     }
     else
     {
-        std::ostringstream oss;
-        oss << "0x" << std::hex << std::setfill('0') << std::setw(2)
-            << static_cast<int>(c);
-        return oss.str();
+        std::array<char, 5> buf;
+        buf.fill('\0');
+        const auto r = std::snprintf(
+                buf.data(), buf.size(), "0x%02x", static_cast<int>(c) & 0xFF);
+        assert(r == buf.size() - 1);
+        return std::string(buf.data());
     }
 }