From cb5249db7316112b835c95e1166c18d91294d2a1 Mon Sep 17 00:00:00 2001
From: Morten Nielsen <mn@iter.dk>
Date: Tue, 25 Aug 2020 15:39:40 -0700
Subject: [PATCH] Implemement `NmeaMessage : IEquatable<NmeaMessage>`

Also avoid processing identical messages in GnssMonitor
---
 src/NmeaParser/Gnss/GnssMonitor.cs |  4 ++++
 src/NmeaParser/Nmea/NmeaMessage.cs | 17 ++++++++++++++++-
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/NmeaParser/Gnss/GnssMonitor.cs b/src/NmeaParser/Gnss/GnssMonitor.cs
index 669f2a9..af5fcbe 100644
--- a/src/NmeaParser/Gnss/GnssMonitor.cs
+++ b/src/NmeaParser/Gnss/GnssMonitor.cs
@@ -75,7 +75,11 @@ namespace NmeaParser.Gnss
             double lon = 0;
             List<string> properties = new List<string>();
             lock (m_lock)
+            {
+                if(m_allMessages.ContainsKey(message.MessageType) && m_allMessages[message.MessageType].Equals(message))
+                        return; // Nothing to update/notify
                 m_allMessages[message.MessageType] = message;
+            }
             properties.Add(nameof(AllMessages));
             if (message.TalkerId == NmeaParser.Talker.GlobalNavigationSatelliteSystem)
                 m_supportGNMessages = true; // Support for GN* messages detected
diff --git a/src/NmeaParser/Nmea/NmeaMessage.cs b/src/NmeaParser/Nmea/NmeaMessage.cs
index 14db334..fbed360 100644
--- a/src/NmeaParser/Nmea/NmeaMessage.cs
+++ b/src/NmeaParser/Nmea/NmeaMessage.cs
@@ -52,7 +52,7 @@ namespace NmeaParser.Messages
     /// <summary>
     /// NMEA Message base class.
     /// </summary>
-    public abstract class NmeaMessage
+    public abstract class NmeaMessage : IEquatable<NmeaMessage>
     {
         private readonly static Dictionary<string, ConstructorInfo> messageTypes;
 
@@ -301,6 +301,21 @@ namespace NmeaParser.Messages
             return TimeSpan.Zero;
         }
 
+        /// <inheritdoc />
+        public bool Equals(NmeaMessage other)
+        {
+            if (other.MessageType != MessageType)
+                return false;
+            if (other.MessageParts.Count != MessageParts.Count)
+                return false;
+            for (int i = 0; i < MessageParts.Count; i++)
+            {
+                if (other.MessageParts[i] != MessageParts[i])
+                    return false;
+            }
+            return true;
+        }
+
         /// <summary>
         /// Gets a relative timestamp in milliseconds indicating the time the message was created.
         /// </summary>