Move headers to include/fmt

include/fmt/time.h

@@ -0,0 +1,60 @@
+/*
+ Formatting library for C++ - time formatting
+
+ Copyright (c) 2012 - 2016, Victor Zverovich
+ All rights reserved.
+
+ For the license information refer to format.h.
+ */
+
+#ifndef FMT_TIME_H_
+#define FMT_TIME_H_
+
+#include "fmt/format.h"
+#include <ctime>
+
+namespace fmt {
+
+template <>
+struct formatter<std::tm> {
+  template <typename ParseContext>
+  auto parse(ParseContext &ctx) -> decltype(ctx.begin()) {
+    auto it = internal::null_terminating_iterator<char>(ctx);
+    if (*it == ':')
+      ++it;
+    auto end = it;
+    while (*end && *end != '}')
+      ++end;
+    tm_format.reserve(end - it + 1);
+    using internal::pointer_from;
+    tm_format.append(pointer_from(it), pointer_from(end));
+    tm_format.push_back('\0');
+    return pointer_from(end);
+  }
+
+  void format(buffer &buf, const std::tm &tm, context &ctx) {
+    std::size_t start = buf.size();
+    for (;;) {
+      std::size_t size = buf.capacity() - start;
+      std::size_t count = std::strftime(&buf[start], size, &tm_format[0], &tm);
+      if (count != 0) {
+        buf.resize(start + count);
+        break;
+      }
+      if (size >= tm_format.size() * 256) {
+        // If the buffer is 256 times larger than the format string, assume
+        // that `strftime` gives an empty result. There doesn't seem to be a
+        // better way to distinguish the two cases:
+        // https://github.com/fmtlib/fmt/issues/367
+        break;
+      }
+      const std::size_t MIN_GROWTH = 10;
+      buf.reserve(buf.capacity() + (size > MIN_GROWTH ? size : MIN_GROWTH));
+    }
+  }
+
+  memory_buffer tm_format;
+};
+}
+
+#endif  // FMT_TIME_H_