1 files changed, 116 insertions, 0 deletions
diff --git a/include/spdlog/details/fmt_helper.h b/include/spdlog/details/fmt_helper.h
new file mode 100644
index 00000000..5dc311a0
--- /dev/null
+++ b/include/spdlog/details/fmt_helper.h
@@ -0,0 +1,116 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+#pragma once
+
+#include <chrono>
+#include <type_traits>
+#include <spdlog/fmt/fmt.h>
+#include <spdlog/common.h>
+
+// Some fmt helpers to efficiently format and pad ints and strings
+namespace spdlog {
+namespace details {
+namespace fmt_helper {
+
+inline spdlog::string_view_t to_string_view(const memory_buf_t &buf) SPDLOG_NOEXCEPT
+{
+    return spdlog::string_view_t{buf.data(), buf.size()};
+}
+
+inline void append_string_view(spdlog::string_view_t view, memory_buf_t &dest)
+{
+    auto *buf_ptr = view.data();
+    dest.append(buf_ptr, buf_ptr + view.size());
+}
+
+template<typename T>
+inline void append_int(T n, memory_buf_t &dest)
+{
+    fmt::format_int i(n);
+    dest.append(i.data(), i.data() + i.size());
+}
+
+template<typename T>
+inline unsigned int count_digits(T n)
+{
+    using count_type = typename std::conditional<(sizeof(T) > sizeof(uint32_t)), uint64_t, uint32_t>::type;
+    return static_cast<unsigned int>(fmt::
+// fmt 7.0.0 renamed the internal namespace to detail.
+// See: https://github.com/fmtlib/fmt/issues/1538
+#if FMT_VERSION < 70000
+            internal
+#else
+            detail
+#endif
+        ::count_digits(static_cast<count_type>(n)));
+}
+
+inline void pad2(int n, memory_buf_t &dest)
+{
+    if (n >= 0 && n < 100) // 0-99
+    {
+        dest.push_back(static_cast<char>('0' + n / 10));
+        dest.push_back(static_cast<char>('0' + n % 10));
+    }
+    else // unlikely, but just in case, let fmt deal with it
+    {
+        fmt::format_to(dest, "{:02}", n);
+    }
+}
+
+template<typename T>
+inline void pad_uint(T n, unsigned int width, memory_buf_t &dest)
+{
+    static_assert(std::is_unsigned<T>::value, "pad_uint must get unsigned T");
+    for (auto digits = count_digits(n); digits < width; digits++)
+    {
+        dest.push_back('0');
+    }
+    append_int(n, dest);
+}
+
+template<typename T>
+inline void pad3(T n, memory_buf_t &dest)
+{
+    static_assert(std::is_unsigned<T>::value, "pad3 must get unsigned T");
+    if (n < 1000)
+    {
+        dest.push_back(static_cast<char>(n / 100 + '0'));
+        n = n % 100;
+        dest.push_back(static_cast<char>((n / 10) + '0'));
+        dest.push_back(static_cast<char>((n % 10) + '0'));
+    }
+    else
+    {
+        append_int(n, dest);
+    }
+}
+
+template<typename T>
+inline void pad6(T n, memory_buf_t &dest)
+{
+    pad_uint(n, 6, dest);
+}
+
+template<typename T>
+inline void pad9(T n, memory_buf_t &dest)
+{
+    pad_uint(n, 9, dest);
+}
+
+// return fraction of a second of the given time_point.
+// e.g.
+// fraction<std::milliseconds>(tp) -> will return the millis part of the second
+template<typename ToDuration>
+inline ToDuration time_fraction(log_clock::time_point tp)
+{
+    using std::chrono::duration_cast;
+    using std::chrono::seconds;
+    auto duration = tp.time_since_epoch();
+    auto secs = duration_cast<seconds>(duration);
+    return duration_cast<ToDuration>(duration) - duration_cast<ToDuration>(secs);
+}
+
+} // namespace fmt_helper
+} // namespace details
+} // namespace spdlog