Implement time formatting

fmt/CMakeLists.txt

@@ -1,6 +1,6 @@
 # Define the fmt library, its includes and the needed defines.
 # format.cc is added to FMT_HEADERS for the header-only configuration.
-set(FMT_HEADERS format.h format.cc)
+set(FMT_HEADERS format.h format.cc time.h)
 if (HAVE_OPEN)
   set(FMT_HEADERS ${FMT_HEADERS} posix.h)
   set(FMT_SOURCES ${FMT_SOURCES} posix.cc)

fmt/format.h

@@ -2626,6 +2626,8 @@ class BasicWriter {
   }
 
   void clear() FMT_NOEXCEPT { buffer_.clear(); }
+
+  Buffer<Char> &buffer() FMT_NOEXCEPT { return buffer_; }
 };
 
 template <typename Char>

fmt/time.h

@@ -0,0 +1,57 @@
+/*
+ Formatting library for C++ - time formatting
+
+ Copyright (c) 2012 - 2016, Victor Zverovich
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice, this
+    list of conditions and the following disclaimer.
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FMT_TIME_H_
+#define FMT_TIME_H_
+
+#include "fmt/format.h"
+#include <ctime>
+
+namespace fmt {
+template <typename ArgFormatter>
+void format(BasicFormatter<char, ArgFormatter> &f,
+            const char *&format_str, const std::tm &tm) {
+  if (*format_str == ':')
+    ++format_str;
+  const char *end = format_str;
+  while (*end && *end != '}')
+    ++end;
+  if (*end != '}')
+    FMT_THROW(FormatError("missing '}' in format string"));
+  Buffer<char> &buffer = f.writer().buffer();
+  std::size_t start = buffer.size();
+  internal::MemoryBuffer<char, internal::INLINE_BUFFER_SIZE> format;
+  format.append(format_str, end + 1);
+  format[format.size() - 1] = '\0';
+  std::size_t size = std::strftime(&buffer[start], buffer.capacity() - start,
+                                   &format[0], &tm);
+  buffer.resize(start + size);
+  format_str = end + 1;
+}
+}
+
+#endif  // FMT_TIME_H_

test/format-test.cc

@@ -47,6 +47,8 @@
 #define None 0
 
 #include "fmt/format.h"
+#include "fmt/time.h"
+
 #include "util.h"
 #include "mock-allocator.h"
 #include "gtest-extra.h"
@@ -1578,6 +1580,15 @@ TEST(FormatTest, Variadic) {
   EXPECT_EQ(L"abc1", format(L"{}c{}", L"ab", 1));
 }
 
+TEST(FormatTest, Time) {
+  std::tm tm = std::tm();
+  tm.tm_year = 116;
+  tm.tm_mon  = 3;
+  tm.tm_mday = 25;
+  EXPECT_EQ("The date is 2016-04-25.",
+            fmt::format("The date is {:%Y-%m-%d}.", tm));
+}
+
 template <typename T>
 std::string str(const T &value) {
   return fmt::format("{}", value);