Move to using span slicing instead of string substrings (#135)

* Move to using span slicing instead of string substrings

* Adding unit test for JsonReaderExtensionsTests ReadValueAsTimeSpanDaprFormat method

src/Dapr.Actors/JsonReaderExtensions.cs

@@ -394,25 +394,32 @@ namespace Dapr.Actors
             {
                 case JsonToken.String:
                     var valueString = (string)reader.Value;
+                    var spanOfValue = valueString.AsSpan();
                     try
                     {
                         // Change the value returned by Dapr runtime, so that it can be parsed with TimeSpan.
                         // Format returned by Dapr runtime: 4h15m50s60ms. It doesnt have days.
                         // Dapr runtime should handle timespans in ISO 8601 format.
-                        // Replace ms before m & s. Also aappend 0 days for parsing correctly with TimeSpan
+                        // Replace ms before m & s. Also append 0 days for parsing correctly with TimeSpan
-                        int hIndex = valueString.IndexOf('h');
+                        int hIndex = spanOfValue.IndexOf('h');
-                        int mIndex = valueString.IndexOf('m');
+                        int mIndex = spanOfValue.IndexOf('m');
-                        int sIndex = valueString.IndexOf('s');
+                        int sIndex = spanOfValue.IndexOf('s');
-                        int msIndex = valueString.IndexOf("ms");
+                        int msIndex = spanOfValue.IndexOf("ms");
 
                         // handle days from hours.
-                        var hours = int.Parse(valueString.Substring(0, hIndex));
+                        var hoursSpan = spanOfValue.Slice(0, hIndex);
+                        var hours = int.Parse(hoursSpan);
                         var days = hours / 24;
                         hours = hours % 24;
 
-                        var minutes = int.Parse(valueString.Substring(hIndex + 1, mIndex - (hIndex + 1)));
+                        var minutesSpan = spanOfValue.Slice(hIndex + 1, mIndex - (hIndex + 1));
-                        var seconds = int.Parse(valueString.Substring(mIndex + 1, sIndex - (mIndex + 1)));
+                        var minutes = int.Parse(minutesSpan);
-                        var milliseconds = int.Parse(valueString.Substring(sIndex + 1, msIndex - (sIndex + 1)));
+
+                        var secondsSpan = spanOfValue.Slice(mIndex + 1, sIndex - (mIndex + 1));
+                        var seconds = int.Parse(secondsSpan);
+
+                        var millisecondsSpan = spanOfValue.Slice(sIndex + 1, msIndex - (sIndex + 1));
+                        var milliseconds = int.Parse(millisecondsSpan);
 
                         value = new TimeSpan(days, hours, minutes, seconds, milliseconds);
                     }

test/Dapr.Actors.Test/JsonReaderExtensionTests.cs

@@ -0,0 +1,47 @@
+// ------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+// ------------------------------------------------------------
+
+namespace Dapr.Actors.Test
+{
+    using System;
+    using System.Collections.Generic;
+    using System.IO;
+    using Newtonsoft.Json;
+    using Xunit;
+
+    public class JsonReaderExtensionTests
+    {
+        public static readonly IEnumerable<object[]> DaprFormatTimeSpanJsonStringsAndExpectedDeserializedValues = new List<object[]>
+        {
+            new object[]
+            {
+                "{\"dueTime\":\"4h15m50s60ms\"",
+                new TimeSpan(0, 4, 15, 50, 60),
+            },
+            new object[]
+            {
+                "{\"dueTime\":\"0h35m10s12ms\"",
+                new TimeSpan(0, 0, 35, 10, 12),
+            },
+        };
+
+        [Theory]
+        [MemberData(nameof(DaprFormatTimeSpanJsonStringsAndExpectedDeserializedValues))]
+        public void DaprFormat_TimeSpan_Parsing(string daprFormatTimeSpanJsonString, TimeSpan expectedDeserializedValue)
+        {
+            using var textReader = new StringReader(daprFormatTimeSpanJsonString);
+            using var jsonTextReader = new JsonTextReader(textReader);
+
+            while (jsonTextReader.TokenType != JsonToken.String)
+            {
+                jsonTextReader.Read();
+            }
+
+            var deserializedTimeSpan = jsonTextReader.ReadValueAsTimeSpanDaprFormat();
+
+            Assert.Equal(expectedDeserializedValue, deserializedTimeSpan);
+        }
+    }
+}