-Performance

Src/Newtonsoft.Json.Tests/JsonTextReaderTest.cs

@@ -1110,6 +1110,44 @@ bye", reader.Value);
       }
     }
 
+    [Test]
+    public void ParseIntegers()
+    {
+      JsonTextReader reader = null;
+
+      reader = new JsonTextReader(new StringReader("1"));
+      Assert.AreEqual(1, reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader("-1"));
+      Assert.AreEqual(-1, reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader("0"));
+      Assert.AreEqual(0, reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader("-0"));
+      Assert.AreEqual(0, reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader(int.MaxValue.ToString()));
+      Assert.AreEqual(int.MaxValue, reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader(int.MinValue.ToString()));
+      Assert.AreEqual(int.MinValue, reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader(long.MaxValue.ToString()));
+
+      reader = new JsonTextReader(new StringReader("1E-06"));
+      ExceptionAssert.Throws<FormatException>("Input string was not in a correct format.", () => reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader("1.1"));
+      ExceptionAssert.Throws<FormatException>("Input string was not in a correct format.", () => reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader(""));
+      Assert.AreEqual(null, reader.ReadAsInt32());
+
+      reader = new JsonTextReader(new StringReader("-"));
+      ExceptionAssert.Throws<FormatException>("Input string was not in a correct format.", () => reader.ReadAsInt32());
+    }
+
     [Test]
     public void WriteReadWrite()
     {

Src/Newtonsoft.Json/JsonTextReader.cs

@@ -1185,9 +1185,7 @@ namespace Newtonsoft.Json
         }
         else
         {
-          string number = _stringReference.ToString();
-
-          numberValue = Convert.ToInt32(number, CultureInfo.InvariantCulture);
+          numberValue = ConvertUtils.IntParseFast(_stringReference.Chars, _stringReference.StartIndex, _stringReference.Length);
         }
 
         numberType = JsonToken.Integer;

Src/Newtonsoft.Json/Utilities/ConvertUtils.cs

@@ -563,5 +563,40 @@ namespace Newtonsoft.Json.Utilities
           return false;
       }
     }
+
+    public static int IntParseFast(char[] value, int start, int length)
+    {
+      if (length == 0)
+        throw new FormatException("Input string was not in a correct format.");
+
+      bool isNegative = (value[start] == '-');
+
+      if (isNegative)
+      {
+        // just a negative sign
+        if (length == 1)
+          throw new FormatException("Input string was not in a correct format.");
+
+        start++;
+        length--;
+      }
+
+      int result = 0;
+      int end = start + length;
+      for (int i = start; i < end; i++)
+      {
+        char c = value[i];
+
+        if (!(c >= '0' && c <= '9'))
+          throw new FormatException("Input string was not in a correct format.");
+
+        result = 10 * result + (c - 48);
+      }
+
+      if (isNegative)
+        result = 0 - result;
+
+      return result;
+    }
   }
 }