-Reduced allocations of JToken.Path

Src/Newtonsoft.Json.TestConsole/Program.cs

@@ -31,6 +31,7 @@ using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Web.Script.Serialization;
+using Newtonsoft.Json.Linq;
 using Newtonsoft.Json.Tests;
 using Newtonsoft.Json.Tests.Converters;
 
@@ -52,6 +53,7 @@ namespace Newtonsoft.Json.TestConsole
             //t.DeserializeLargeJson();
 
             //PerformanceTests t = new PerformanceTests();
+            LargeArrayJTokenPathPerformance();
             //t.Iterations = 50000;
             //t.BenchmarkDeserializeMethod<TestClass>(PerformanceTests.SerializeMethod.JsonNet, PerformanceTests.JsonText);
 
@@ -62,7 +64,7 @@ namespace Newtonsoft.Json.TestConsole
 
             //ReadLargeJson();
             //WriteLargeJson();
-            DeserializeJson();
+            //DeserializeJson();
             //ReadLargeJson();
             //ReadLargeJsonJavaScriptSerializer();
 
@@ -72,6 +74,28 @@ namespace Newtonsoft.Json.TestConsole
             Console.ReadKey();
         }
 
+        public static void LargeArrayJTokenPathPerformance()
+        {
+            JArray a = new JArray();
+            for (int i = 0; i < 100000; i++)
+            {
+                a.Add(i);
+            }
+
+            JToken last = a.Last;
+
+            int interations = 1000;
+
+            Console.WriteLine("Ready!!!");
+            Console.ReadKey();
+
+            string p = null;
+            for (int i = 0; i < interations; i++)
+            {
+                p = last.Path;
+            }
+        }
+
         public static void DeserializeJson()
         {
             PerformanceTests t = new PerformanceTests();

Src/Newtonsoft.Json/Linq/JContainer.cs

@@ -675,9 +675,10 @@ namespace Newtonsoft.Json.Linq
 
         internal static JToken CreateFromContent(object content)
         {
-            if (content is JToken)
+            JToken token = content as JToken;
+            if (token != null)
             {
-                return (JToken)content;
+                return token;
             }
 
             return new JValue(content);
@@ -759,7 +760,7 @@ namespace Newtonsoft.Json.Linq
 
             do
             {
-                if (parent is JProperty && ((JProperty)parent).Value != null)
+                if ((parent as JProperty)?.Value != null)
                 {
                     if (parent == this)
                     {
@@ -887,12 +888,7 @@ namespace Newtonsoft.Json.Linq
         PropertyDescriptorCollection ITypedList.GetItemProperties(PropertyDescriptor[] listAccessors)
         {
             ICustomTypeDescriptor d = First as ICustomTypeDescriptor;
-            if (d != null)
-            {
-                return d.GetProperties();
-            }
-
-            return null;
+            return d?.GetProperties();
         }
 #endif
 
@@ -958,9 +954,10 @@ namespace Newtonsoft.Json.Linq
                 return null;
             }
 
-            if (value is JToken)
+            JToken token = value as JToken;
+            if (token != null)
             {
-                return (JToken)value;
+                return token;
             }
 
             throw new ArgumentException("Argument is not a JToken.");
@@ -1169,7 +1166,7 @@ namespace Newtonsoft.Json.Linq
                         }
                     }
 #else
-                    IDictionary<JToken, bool> items = new Dictionary<JToken, bool>(EqualityComparer);
+                    Dictionary<JToken, bool> items = new Dictionary<JToken, bool>(EqualityComparer);
                     foreach (JToken t in target)
                     {
                         items[t] = true;

Src/Newtonsoft.Json/Linq/JToken.cs

@@ -190,9 +190,14 @@ namespace Newtonsoft.Json.Linq
                     return string.Empty;
                 }
 
-                IList<JToken> ancestors = AncestorsAndSelf().Reverse().ToList();
+                List<JToken> ancestors = new List<JToken>();
+                for (JToken current = this; current != null; current = current.Parent)
+                {
+                    ancestors.Add(current);
+                }
+                ancestors.Reverse();
 
-                List<JsonPosition> positions = new List<JsonPosition>();
+                List<JsonPosition> positions = new List<JsonPosition>(ancestors.Count);
                 for (int i = 0; i < ancestors.Count; i++)
                 {
                     JToken current = ancestors[i];