Well-known type operations for Timestamp and Duration (but not JSON formatting).

While I've provided operators, I haven't yet provided the method equivalents. It's not clear to me that
they're actually a good idea, while we're really targeting C# developers who definitely *can* use the user-defined operators.

1 files changed, 164 insertions, 0 deletions

diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/TimestampPartial.cs b/csharp/src/Google.Protobuf/WellKnownTypes/TimestampPartial.cs
new file mode 100644
index 00000000..f682d093
--- /dev/null
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/TimestampPartial.cs
@@ -0,0 +1,164 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * 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.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// 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.
+#endregion
+
+using System;
+
+namespace Google.Protobuf.WellKnownTypes
+{
+    public partial class Timestamp
+    {
+        private static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        private static readonly long BclSecondsAtUnixEpoch = UnixEpoch.Ticks / TimeSpan.TicksPerSecond;
+
+        /// <summary>
+        /// Returns the difference between one <see cref="Timestamp"/> and another, as a <see cref="Duration"/>.
+        /// </summary>
+        /// <param name="lhs">The timestamp to subtract from. Must not be null.</param>
+        /// <param name="rhs">The timestamp to subtract. Must not be null.</param>
+        /// <returns>The difference between the two specified timestamps.</returns>
+        public static Duration operator -(Timestamp lhs, Timestamp rhs)
+        {
+            Preconditions.CheckNotNull(lhs, "lhs");
+            Preconditions.CheckNotNull(rhs, "rhs");
+            checked
+            {
+                return Duration.Normalize(lhs.Seconds - rhs.Seconds, lhs.Nanos - rhs.Nanos);
+            }
+        }
+
+        /// <summary>
+        /// Adds a <see cref="Duration"/> to a <see cref="Timestamp"/>, to obtain another <c>Timestamp</c>.
+        /// </summary>
+        /// <param name="lhs">The timestamp to add the duration to. Must not be null.</param>
+        /// <param name="rhs">The duration to add. Must not be null.</param>
+        /// <returns>The result of adding the duration to the timestamp.</returns>
+        public static Timestamp operator +(Timestamp lhs, Duration rhs)
+        {
+            Preconditions.CheckNotNull(lhs, "lhs");
+            Preconditions.CheckNotNull(rhs, "rhs");
+            checked
+            {
+                return Normalize(lhs.Seconds + rhs.Seconds, lhs.Nanos + rhs.Nanos);
+            }
+        }
+
+        /// <summary>
+        /// Subtracts a <see cref="Duration"/> from a <see cref="Timestamp"/>, to obtain another <c>Timestamp</c>.
+        /// </summary>
+        /// <param name="lhs">The timestamp to subtract the duration from. Must not be null.</param>
+        /// <param name="rhs">The duration to subtract.</param>
+        /// <returns>The result of subtracting the duration from the timestamp.</returns>
+        public static Timestamp operator -(Timestamp lhs, Duration rhs)
+        {
+            Preconditions.CheckNotNull(lhs, "lhs");
+            Preconditions.CheckNotNull(rhs, "rhs");
+            checked
+            {
+                return Normalize(lhs.Seconds - rhs.Seconds, lhs.Nanos - rhs.Nanos);
+            }
+        }
+
+        /// <summary>
+        /// Converts this timestamp into a <see cref="DateTime"/>.
+        /// </summary>
+        /// <remarks>
+        /// The resulting <c>DateTime</c> will always have a <c>Kind</c> of <c>Utc</c>.
+        /// If the timestamp is not a precise number of ticks, it will be truncated towards the start
+        /// of time. For example, a timestamp with a <see cref="Nanos"/> value of 99 will result in a
+        /// <see cref="DateTime"/> value precisely on a second.
+        /// </remarks>
+        /// <returns>This timestamp as a <c>DateTime</c>.</returns>
+        public DateTime ToDateTime()
+        {
+            return UnixEpoch.AddSeconds(Seconds).AddTicks(Nanos / Duration.NanosecondsPerTick);
+        }
+
+        /// <summary>
+        /// Converts this timestamp into a <see cref="DateTimeOffset"/>.
+        /// </summary>
+        /// <remarks>
+        /// The resulting <c>DateTimeOffset</c> will always have an <c>Offset</c> of zero.
+        /// If the timestamp is not a precise number of ticks, it will be truncated towards the start
+        /// of time. For example, a timestamp with a <see cref="Nanos"/> value of 99 will result in a
+        /// <see cref="DateTimeOffset"/> value precisely on a second.
+        /// </remarks>
+        /// <returns>This timestamp as a <c>DateTimeOffset</c>.</returns>
+        public DateTimeOffset ToDateTimeOffset()
+        {
+            return new DateTimeOffset(ToDateTime(), TimeSpan.Zero);
+        }
+
+        /// <summary>
+        /// Converts the specified <see cref="DateTime"/> to a <see cref="Timestamp"/>.
+        /// </summary>
+        /// <param name="dateTime"></param>
+        /// <exception cref="ArgumentException">The <c>Kind</c> of <paramref name="dateTime"/> is not <c>DateTimeKind.Utc</c>.</exception>
+        /// <returns>The converted timestamp.</returns>
+        public static Timestamp FromDateTime(DateTime dateTime)
+        {
+            if (dateTime.Kind != DateTimeKind.Utc)
+            {
+                throw new ArgumentException("Conversion from DateTime to Timestamp requires the DateTime kind to be Utc", "dateTime");
+            }
+            // Do the arithmetic using DateTime.Ticks, which is always non-negative, making things simpler.
+            long secondsSinceBclEpoch = dateTime.Ticks / TimeSpan.TicksPerSecond;
+            int nanoseconds = (int)  (dateTime.Ticks % TimeSpan.TicksPerSecond) * Duration.NanosecondsPerTick;
+            return new Timestamp { Seconds = secondsSinceBclEpoch - BclSecondsAtUnixEpoch, Nanos = nanoseconds };
+        }
+
+        /// <summary>
+        /// Converts the specified <see cref="DateTimeOffset"/> to a <see cref="Timestamp"/>.
+        /// </summary>
+        /// <param name="dateTime"></param>
+        /// <returns>The converted timestamp.</returns>
+        public static Timestamp FromDateTimeOffset(DateTimeOffset dateTimeOffset)
+        {
+            // We don't need to worry about this having negative ticks: DateTimeOffset is constrained to handle
+            // values whose *UTC* value is in the range of DateTime.
+            return FromDateTime(dateTimeOffset.UtcDateTime);
+        }
+
+        private static Timestamp Normalize(long seconds, int nanoseconds)
+        {
+            int extraSeconds = nanoseconds / Duration.NanosecondsPerSecond;
+            seconds += extraSeconds;
+            nanoseconds -= extraSeconds * Duration.NanosecondsPerSecond;
+
+            if (nanoseconds < 0)
+            {
+                nanoseconds += Duration.NanosecondsPerSecond;
+                seconds--;
+            }
+            return new Timestamp { Seconds = seconds, Nanos = nanoseconds };
+        }
+    }
+}