Replace is-and-cast with as-and-nullcheck

Gives slightly better performance, so applying across the board
adds up.

Src/Newtonsoft.Json/Bson/BsonWriter.cs

@@ -203,9 +203,10 @@ namespace Newtonsoft.Json.Bson
         {
             if (_parent != null)
             {
-                if (_parent is BsonObject)
+                BsonObject bo = _parent as BsonObject;
+                if (bo != null)
                 {
-                    ((BsonObject)_parent).Add(_propertyName, token);
+                    bo.Add(_propertyName, token);
                     _propertyName = null;
                 }
                 else

Src/Newtonsoft.Json/Converters/XmlNodeConverter.cs

@@ -311,9 +311,8 @@ namespace Newtonsoft.Json.Converters
         {
             get
             {
-                XmlNode node = (_node is XmlAttribute)
-                    ? ((XmlAttribute)_node).OwnerElement
-                    : _node.ParentNode;
+                XmlAttribute attribute = _node as XmlAttribute;
+                XmlNode node = attribute != null ? attribute.OwnerElement : _node.ParentNode;
 
                 if (node == null)
                 {
@@ -727,42 +726,55 @@ namespace Newtonsoft.Json.Converters
 
         internal static IXmlNode WrapNode(XObject node)
         {
-            if (node is XDocument)
+            XDocument document = node as XDocument;
+            if (document != null)
             {
-                return new XDocumentWrapper((XDocument)node);
+                return new XDocumentWrapper(document);
             }
-            else if (node is XElement)
+
+            XElement element = node as XElement;
+            if (element != null)
             {
-                return new XElementWrapper((XElement)node);
+                return new XElementWrapper(element);
             }
-            else if (node is XContainer)
+
+            XContainer container = node as XContainer;
+            if (container != null)
             {
-                return new XContainerWrapper((XContainer)node);
+                return new XContainerWrapper(container);
             }
-            else if (node is XProcessingInstruction)
+
+            XProcessingInstruction pi = node as XProcessingInstruction;
+            if (pi != null)
             {
-                return new XProcessingInstructionWrapper((XProcessingInstruction)node);
+                return new XProcessingInstructionWrapper(pi);
             }
-            else if (node is XText)
+
+            XText text = node as XText;
+            if (text != null)
             {
-                return new XTextWrapper((XText)node);
+                return new XTextWrapper(text);
             }
-            else if (node is XComment)
+
+            XComment comment = node as XComment;
+            if (comment != null)
             {
-                return new XCommentWrapper((XComment)node);
+                return new XCommentWrapper(comment);
             }
-            else if (node is XAttribute)
+
+            XAttribute attribute = node as XAttribute;
+            if (attribute != null)
             {
-                return new XAttributeWrapper((XAttribute)node);
+                return new XAttributeWrapper(attribute);
             }
-            else if (node is XDocumentType)
+
+            XDocumentType type = node as XDocumentType;
+            if (type != null)
             {
-                return new XDocumentTypeWrapper((XDocumentType)node);
-            }
-            else
-            {
-                return new XObjectWrapper(node);
+                return new XDocumentTypeWrapper(type);
             }
+
+            return new XObjectWrapper(node);
         }
 
         public override IXmlNode AppendChild(IXmlNode newChild)
@@ -1034,15 +1046,17 @@ namespace Newtonsoft.Json.Converters
         private IXmlNode WrapXml(object value)
         {
 #if !NET20
-            if (value is XObject)
+            XObject xObject = value as XObject;
+            if (xObject != null)
             {
-                return XContainerWrapper.WrapNode((XObject)value);
+                return XContainerWrapper.WrapNode(xObject);
             }
 #endif
 #if !(DOTNET || PORTABLE)
-            if (value is XmlNode)
+            XmlNode node = value as XmlNode;
+            if (node != null)
             {
-                return XmlNodeWrapper.WrapNode((XmlNode)value);
+                return XmlNodeWrapper.WrapNode(node);
             }
 #endif
 

Src/Newtonsoft.Json/JsonReader.cs

@@ -483,17 +483,15 @@ namespace Newtonsoft.Json
                 if (Value != null)
                 {
                     string s;
-                    if (Value is IFormattable)
+                    IFormattable formattable = Value as IFormattable;
+                    if (formattable != null)
                     {
-                        s = ((IFormattable)Value).ToString(null, Culture);
-                    }
-                    else if (Value is Uri)
-                    {
-                        s = ((Uri)Value).OriginalString;
+                        s = formattable.ToString(null, Culture);
                     }
                     else
                     {
-                        s = Value.ToString();
+                        Uri uri = Value as Uri;
+                        s = uri != null ? uri.OriginalString : Value.ToString();
                     }
 
                     SetToken(JsonToken.String, s, false);

Src/Newtonsoft.Json/JsonWriter.cs

@@ -1576,28 +1576,25 @@ namespace Newtonsoft.Json
 #endif
                 default:
 #if !PORTABLE
-                    if (value is IConvertible)
+                    IConvertible convertible = value as IConvertible;
+                    if (convertible != null)
                     {
                         // the value is a non-standard IConvertible
                         // convert to the underlying value and retry
-                        IConvertible convertable = (IConvertible)value;
 
-                        TypeInformation typeInformation = ConvertUtils.GetTypeInformation(convertable);
+                        TypeInformation typeInformation = ConvertUtils.GetTypeInformation(convertible);
 
                         // if convertible has an underlying typecode of Object then attempt to convert it to a string
                         PrimitiveTypeCode resolvedTypeCode = (typeInformation.TypeCode == PrimitiveTypeCode.Object) ? PrimitiveTypeCode.String : typeInformation.TypeCode;
                         Type resolvedType = (typeInformation.TypeCode == PrimitiveTypeCode.Object) ? typeof(string) : typeInformation.Type;
 
-                        object convertedValue = convertable.ToType(resolvedType, CultureInfo.InvariantCulture);
+                        object convertedValue = convertible.ToType(resolvedType, CultureInfo.InvariantCulture);
 
                         WriteValue(writer, resolvedTypeCode, convertedValue);
                         break;
                     }
-                    else
 #endif
-                    {
-                        throw CreateUnsupportedTypeException(writer, value);
-                    }
+                    throw CreateUnsupportedTypeException(writer, value);
             }
         }
 

Src/Newtonsoft.Json/Linq/JPropertyDescriptor.cs

@@ -89,7 +89,7 @@ namespace Newtonsoft.Json.Linq
         /// <param name="value">The new value.</param>
         public override void SetValue(object component, object value)
         {
-            JToken token = (value is JToken) ? (JToken)value : new JValue(value);
+            JToken token = value as JToken ?? new JValue(value);
 
             CastInstance(component)[Name] = token;
         }

Src/Newtonsoft.Json/Linq/JToken.cs

@@ -520,9 +520,11 @@ namespace Newtonsoft.Json.Linq
             {
                 return (DateTimeOffset)v.Value;
             }
-            if (v.Value is string)
+
+            string s = v.Value as string;
+            if (s != null)
             {
-                return DateTimeOffset.Parse((string)v.Value, CultureInfo.InvariantCulture);
+                return DateTimeOffset.Parse(s, CultureInfo.InvariantCulture);
             }
             return new DateTimeOffset(Convert.ToDateTime(v.Value, CultureInfo.InvariantCulture));
         }
@@ -634,10 +636,13 @@ namespace Newtonsoft.Json.Linq
             {
                 return (DateTimeOffset?)v.Value;
             }
-            if (v.Value is string)
+
+            string s = v.Value as string;
+            if (s != null)
             {
-                return DateTimeOffset.Parse((string)v.Value, CultureInfo.InvariantCulture);
+                return DateTimeOffset.Parse(s, CultureInfo.InvariantCulture);
             }
+
             return new DateTimeOffset(Convert.ToDateTime(v.Value, CultureInfo.InvariantCulture));
         }
 #endif
@@ -1237,10 +1242,13 @@ namespace Newtonsoft.Json.Linq
             {
                 return null;
             }
-            if (v.Value is byte[])
+
+            byte[] bytes = v.Value as byte[];
+            if (bytes != null)
             {
-                return Convert.ToBase64String((byte[])v.Value);
+                return Convert.ToBase64String(bytes);
             }
+
 #if !(NET20 || NET35 || PORTABLE40 || PORTABLE) || NETSTANDARD1_1
             if (v.Value is BigInteger)
             {
@@ -1328,9 +1336,10 @@ namespace Newtonsoft.Json.Linq
             }
 #endif
 
-            if (v.Value is byte[])
+            byte[] bytes = v.Value as byte[];
+            if (bytes != null)
             {
-                return (byte[])v.Value;
+                return bytes;
             }
 
             throw new ArgumentException("Can not convert {0} to byte array.".FormatWith(CultureInfo.InvariantCulture, GetType(value)));
@@ -1349,9 +1358,10 @@ namespace Newtonsoft.Json.Linq
                 throw new ArgumentException("Can not convert {0} to Guid.".FormatWith(CultureInfo.InvariantCulture, GetType(value)));
             }
 
-            if (v.Value is byte[])
+            byte[] bytes = v.Value as byte[];
+            if (bytes != null)
             {
-                return new Guid((byte[])v.Value);
+                return new Guid(bytes);
             }
 
             return (v.Value is Guid) ? (Guid)v.Value : new Guid(Convert.ToString(v.Value, CultureInfo.InvariantCulture));
@@ -1380,9 +1390,10 @@ namespace Newtonsoft.Json.Linq
                 return null;
             }
 
-            if (v.Value is byte[])
+            byte[] bytes = v.Value as byte[];
+            if (bytes != null)
             {
-                return new Guid((byte[])v.Value);
+                return new Guid(bytes);
             }
 
             return (v.Value is Guid) ? (Guid)v.Value : new Guid(Convert.ToString(v.Value, CultureInfo.InvariantCulture));

Src/Newtonsoft.Json/Linq/JTokenReader.cs

@@ -227,14 +227,8 @@ namespace Newtonsoft.Json.Linq
                     break;
                 case JTokenType.Uri:
                     object v = ((JValue)token).Value;
-                    if (v is Uri)
-                    {
-                        SetToken(JsonToken.String, ((Uri)v).OriginalString);
-                    }
-                    else
-                    {
-                        SetToken(JsonToken.String, SafeToString(v));
-                    }
+                    Uri uri = v as Uri;
+                    SetToken(JsonToken.String, uri != null ? uri.OriginalString : SafeToString(v));
                     break;
                 case JTokenType.TimeSpan:
                     SetToken(JsonToken.String, SafeToString(((JValue)token).Value));

Src/Newtonsoft.Json/Linq/JValue.cs

@@ -1004,7 +1004,8 @@ namespace Newtonsoft.Json.Linq
 
             public override bool TryBinaryOperation(JValue instance, BinaryOperationBinder binder, object arg, out object result)
             {
-                object compareValue = (arg is JValue) ? ((JValue)arg).Value : arg;
+                JValue value = arg as JValue;
+                object compareValue = value != null ? value.Value : arg;
 
                 switch (binder.Operation)
                 {
@@ -1055,7 +1056,8 @@ namespace Newtonsoft.Json.Linq
                 return 1;
             }
 
-            object otherValue = (obj is JValue) ? ((JValue)obj).Value : obj;
+            JValue value = obj as JValue;
+            object otherValue = value != null ? value.Value : obj;
 
             return Compare(_valueType, _value, otherValue);
         }

Src/Newtonsoft.Json/Serialization/DefaultReferenceResolver.cs

@@ -35,19 +35,18 @@ namespace Newtonsoft.Json.Serialization
 
         private BidirectionalDictionary<string, object> GetMappings(object context)
         {
-            JsonSerializerInternalBase internalSerializer;
-
-            if (context is JsonSerializerInternalBase)
+            JsonSerializerInternalBase internalSerializer = context as JsonSerializerInternalBase;
+            if (internalSerializer == null)
             {
-                internalSerializer = (JsonSerializerInternalBase)context;
-            }
-            else if (context is JsonSerializerProxy)
-            {
-                internalSerializer = ((JsonSerializerProxy)context).GetInternalSerializer();
-            }
-            else
-            {
-                throw new JsonException("The DefaultReferenceResolver can only be used internally.");
+                JsonSerializerProxy proxy = context as JsonSerializerProxy;
+                if (proxy != null)
+                {
+                    internalSerializer = proxy.GetInternalSerializer();
+                }
+                else
+                {
+                    throw new JsonException("The DefaultReferenceResolver can only be used internally.");
+                }
             }
 
             return internalSerializer.DefaultReferenceMappings;

Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs

@@ -1320,7 +1320,8 @@ namespace Newtonsoft.Json.Serialization
             }
 
             JsonConverter dictionaryValueConverter = contract.ItemConverter ?? GetConverter(contract.ItemContract, null, contract, containerProperty);
-            PrimitiveTypeCode keyTypeCode = (contract.KeyContract is JsonPrimitiveContract) ? ((JsonPrimitiveContract)contract.KeyContract).TypeCode : PrimitiveTypeCode.Empty;
+            JsonPrimitiveContract keyContract = contract.KeyContract as JsonPrimitiveContract;
+            PrimitiveTypeCode keyTypeCode = (keyContract != null) ? keyContract.TypeCode : PrimitiveTypeCode.Empty;
 
             bool finished = false;
             do

Src/Newtonsoft.Json/Serialization/JsonSerializerInternalWriter.cs

@@ -403,9 +403,10 @@ namespace Newtonsoft.Json.Serialization
             }
 #endif
 
-            if (value is Type)
+            type = value as Type;
+            if (type != null)
             {
-                s = ((Type)value).AssemblyQualifiedName;
+                s = type.AssemblyQualifiedName;
                 return true;
             }
 

Src/Newtonsoft.Json/Utilities/CollectionUtils.cs

@@ -268,9 +268,10 @@ namespace Newtonsoft.Json.Utilities
                 }
 
                 object v = currentArray[0];
-                if (v is IList)
+                IList list = v as IList;
+                if (list != null)
                 {
-                    currentArray = (IList)v;
+                    currentArray = list;
                 }
                 else
                 {

Src/Newtonsoft.Json/Utilities/CollectionWrapper.cs

@@ -52,9 +52,10 @@ namespace Newtonsoft.Json.Utilities
         {
             ValidationUtils.ArgumentNotNull(list, nameof(list));
 
-            if (list is ICollection<T>)
+            ICollection<T> collection = list as ICollection<T>;
+            if (collection != null)
             {
-                _genericCollection = (ICollection<T>)list;
+                _genericCollection = collection;
             }
             else
             {

Src/Newtonsoft.Json/Utilities/ConvertUtils.cs

@@ -318,10 +318,13 @@ namespace Newtonsoft.Json.Utilities
             {
                 return (BigInteger)value;
             }
-            if (value is string)
+
+            string s = value as string;
+            if (s != null)
             {
-                return BigInteger.Parse((string)value, CultureInfo.InvariantCulture);
+                return BigInteger.Parse(s, CultureInfo.InvariantCulture);
             }
+
             if (value is float)
             {
                 return new BigInteger((float)value);
@@ -350,9 +353,11 @@ namespace Newtonsoft.Json.Utilities
             {
                 return new BigInteger((ulong)value);
             }
-            if (value is byte[])
+
+            byte[] bytes = value as byte[];
+            if (bytes != null)
             {
-                return new BigInteger((byte[])value);
+                return new BigInteger(bytes);
             }
 
             throw new InvalidCastException("Cannot convert {0} to BigInteger.".FormatWith(CultureInfo.InvariantCulture, value.GetType()));
@@ -487,9 +492,10 @@ namespace Newtonsoft.Json.Utilities
             }
 #endif
 
-            if (initialValue is byte[] && targetType == typeof(Guid))
+            byte[] bytes = initialValue as byte[];
+            if (bytes != null && targetType == typeof(Guid))
             {
-                value = new Guid((byte[])initialValue);
+                value = new Guid(bytes);
                 return ConvertResult.Success;
             }
 
@@ -587,9 +593,10 @@ namespace Newtonsoft.Json.Utilities
             }
 #endif
 #if !(DOTNET || PORTABLE40 || PORTABLE)
-            if (initialValue is INullable)
+            INullable nullable = initialValue as INullable;
+            if (nullable != null)
             {
-                value = EnsureTypeAssignable(ToValue((INullable)initialValue), initialType, targetType);
+                value = EnsureTypeAssignable(ToValue(nullable), initialType, targetType);
                 return ConvertResult.Success;
             }
 #endif

Src/Newtonsoft.Json/Utilities/ExpressionReflectionDelegateFactory.cs

@@ -139,9 +139,9 @@ namespace Newtonsoft.Json.Utilities
                 callExpression = Expression.Call(readParameter, (MethodInfo)method, argsExpression);
             }
 
-            if (method is MethodInfo)
+            MethodInfo m = method as MethodInfo;
+            if (m != null)
             {
-                MethodInfo m = (MethodInfo)method;
                 if (m.ReturnType != typeof(void))
                 {
                     callExpression = EnsureCastExpression(callExpression, type);

Src/Newtonsoft.Json/Utilities/ReflectionUtils.cs

@@ -762,11 +762,11 @@ namespace Newtonsoft.Json.Utilities
             // http://hyperthink.net/blog/getcustomattributes-gotcha/
             // ICustomAttributeProvider doesn't do inheritance
 
-            if (provider is Type)
+            Type t = provider as Type;
+            if (t != null)
             {
-                Type t = (Type)provider;
-                object[] a = (attributeType != null) ? t.GetCustomAttributes(attributeType, inherit) : t.GetCustomAttributes(inherit);
-                Attribute[] attributes = a.Cast<Attribute>().ToArray();
+                object[] array = attributeType != null ? t.GetCustomAttributes(attributeType, inherit) : t.GetCustomAttributes(inherit);
+                Attribute[] attributes = array.Cast<Attribute>().ToArray();
 
 #if (NET20 || NET35)
                 // ye olde .NET GetCustomAttributes doesn't respect the inherit argument
@@ -779,29 +779,29 @@ namespace Newtonsoft.Json.Utilities
                 return attributes;
             }
 
-            if (provider is Assembly)
+            Assembly a = provider as Assembly;
+            if (a != null)
             {
-                Assembly a = (Assembly)provider;
                 return (attributeType != null) ? Attribute.GetCustomAttributes(a, attributeType) : Attribute.GetCustomAttributes(a);
             }
 
-            if (provider is MemberInfo)
+            MemberInfo mi = provider as MemberInfo;
+            if (mi != null)
             {
-                MemberInfo m = (MemberInfo)provider;
-                return (attributeType != null) ? Attribute.GetCustomAttributes(m, attributeType, inherit) : Attribute.GetCustomAttributes(m, inherit);
+                return (attributeType != null) ? Attribute.GetCustomAttributes(mi, attributeType, inherit) : Attribute.GetCustomAttributes(mi, inherit);
             }
 
 #if !PORTABLE40
-            if (provider is Module)
+            Module m = provider as Module;
+            if (m != null)
             {
-                Module m = (Module)provider;
                 return (attributeType != null) ? Attribute.GetCustomAttributes(m, attributeType, inherit) : Attribute.GetCustomAttributes(m, inherit);
             }
 #endif
 
-            if (provider is ParameterInfo)
+            ParameterInfo p = provider as ParameterInfo;
+            if (p != null)
             {
-                ParameterInfo p = (ParameterInfo)provider;
                 return (attributeType != null) ? Attribute.GetCustomAttributes(p, attributeType, inherit) : Attribute.GetCustomAttributes(p, inherit);
             }