Add JsonNumberHandling(Attribute) & support for (de)serializing numbers from/to string

src/libraries/System.Text.Json/ref/System.Text.Json.cs

@@ -244,6 +244,7 @@ public JsonSerializerOptions(System.Text.Json.JsonSerializerDefaults defaults) {
         public bool IgnoreReadOnlyFields { get { throw null; } set { } }
         public bool IncludeFields { get { throw null; } set { } }
         public int MaxDepth { get { throw null; } set { } }
+        public System.Text.Json.Serialization.JsonNumberHandling NumberHandling { get { throw null; } set { } }
         public bool PropertyNameCaseInsensitive { get { throw null; } set { } }
         public System.Text.Json.JsonNamingPolicy? PropertyNamingPolicy { get { throw null; } set { } }
         public System.Text.Json.JsonCommentHandling ReadCommentHandling { get { throw null; } set { } }
@@ -496,6 +497,14 @@ public enum JsonIgnoreCondition
         WhenWritingDefault = 2,
         WhenWritingNull = 3,
     }
+    [System.FlagsAttribute]
+    public enum JsonNumberHandling
+    {
+        Strict = 0,
+        AllowReadingFromString = 1,
+        WriteAsString = 2,
+        AllowNamedFloatingPointLiterals = 4,
+    }
     public abstract partial class JsonAttribute : System.Attribute
     {
         protected JsonAttribute() { }
@@ -533,6 +542,12 @@ protected internal JsonConverter() { }
         public abstract T Read(ref System.Text.Json.Utf8JsonReader reader, System.Type typeToConvert, System.Text.Json.JsonSerializerOptions options);
         public abstract void Write(System.Text.Json.Utf8JsonWriter writer, T value, System.Text.Json.JsonSerializerOptions options);
     }
+    [System.AttributeUsageAttribute(System.AttributeTargets.Class | System.AttributeTargets.Struct | System.AttributeTargets.Property | System.AttributeTargets.Field, AllowMultiple = false)]
+    public sealed partial class JsonNumberHandlingAttribute : System.Text.Json.Serialization.JsonAttribute
+    {
+        public JsonNumberHandlingAttribute(System.Text.Json.Serialization.JsonNumberHandling handling) { }
+        public System.Text.Json.Serialization.JsonNumberHandling Handling { get { throw null; } }
+    }
     [System.AttributeUsageAttribute(System.AttributeTargets.Constructor, AllowMultiple = false)]
     public sealed partial class JsonConstructorAttribute : System.Text.Json.Serialization.JsonAttribute
     {

src/libraries/System.Text.Json/src/Resources/Strings.resx

@@ -536,4 +536,10 @@
   <data name="IgnoreConditionOnValueTypeInvalid" xml:space="preserve">
     <value>The ignore condition 'JsonIgnoreCondition.WhenWritingNull' is not valid on value-type member '{0}' on type '{1}'. Consider using 'JsonIgnoreCondition.WhenWritingDefault'.</value>
   </data>
+  <data name="NumberHandlingConverterMustBeBuiltIn" xml:space="preserve">
+    <value>'JsonNumberHandlingAttribute' cannot be placed on a property, field, or type that is handled by a custom converter. See usage(s) of converter '{0}' on type '{1}'.</value>
+  </data>
+  <data name="NumberHandlingOnPropertyTypeMustBeNumberOrCollection" xml:space="preserve">
+    <value>When 'JsonNumberHandlingAttribute' is placed on a property or field, the property or field must be a number or a collection. See member '{0}' on type '{1}'.</value>
+  </data>
 </root>

src/libraries/System.Text.Json/src/System.Text.Json.csproj

@@ -60,6 +60,7 @@
     <Compile Include="System\Text\Json\Serialization\Attributes\JsonExtensionDataAttribute.cs" />
     <Compile Include="System\Text\Json\Serialization\Attributes\JsonIgnoreAttribute.cs" />
     <Compile Include="System\Text\Json\Serialization\Attributes\JsonIncludeAttribute.cs" />
+    <Compile Include="System\Text\Json\Serialization\Attributes\JsonNumberHandlingAttribute.cs" />
     <Compile Include="System\Text\Json\Serialization\Attributes\JsonPropertyNameAttribute.cs" />
     <Compile Include="System\Text\Json\Serialization\ClassType.cs" />
     <Compile Include="System\Text\Json\Serialization\ConverterList.cs" />
@@ -135,6 +136,7 @@
     <Compile Include="System\Text\Json\Serialization\JsonDefaultNamingPolicy.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonIgnoreCondition.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonNamingPolicy.cs" />
+    <Compile Include="System\Text\Json\Serialization\JsonNumberHandling.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonParameterInfo.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonParameterInfoOfT.cs" />
     <Compile Include="System\Text\Json\Serialization\JsonPropertyInfo.cs" />

src/libraries/System.Text.Json/src/System/Text/Json/JsonConstants.cs

@@ -37,6 +37,10 @@ internal static class JsonConstants
         public static ReadOnlySpan<byte> FalseValue => new byte[] { (byte)'f', (byte)'a', (byte)'l', (byte)'s', (byte)'e' };
         public static ReadOnlySpan<byte> NullValue => new byte[] { (byte)'n', (byte)'u', (byte)'l', (byte)'l' };
 
+        public static ReadOnlySpan<byte> NaNValue => new byte[] { (byte)'N', (byte)'a', (byte)'N' };
+        public static ReadOnlySpan<byte> PositiveInfinityValue => new byte[] { (byte)'I', (byte)'n', (byte)'f', (byte)'i', (byte)'n', (byte)'i', (byte)'t', (byte)'y' };
+        public static ReadOnlySpan<byte> NegativeInfinityValue => new byte[] { (byte)'-', (byte)'I', (byte)'n', (byte)'f', (byte)'i', (byte)'n', (byte)'i', (byte)'t', (byte)'y' };
+
         // Used to search for the end of a number
         public static ReadOnlySpan<byte> Delimiters => new byte[] { ListSeparator, CloseBrace, CloseBracket, Space, LineFeed, CarriageReturn, Tab, Slash };
 

src/libraries/System.Text.Json/src/System/Text/Json/Reader/JsonReaderHelper.cs

@@ -321,5 +321,82 @@ public static bool TryGetEscapedGuid(ReadOnlySpan<byte> source, out Guid value)
             value = default;
             return false;
         }
+
+        public static char GetFloatingPointStandardParseFormat(ReadOnlySpan<byte> span)
+        {
+            // Assume that 'e/E' is closer to the end.
+            int startIndex = span.Length - 1;
+            for (int i = startIndex; i >= 0; i--)
+            {
+                byte token = span[i];
+                if (token == 'E' || token == 'e')
+                {
+                    return JsonConstants.ScientificNotationFormat;
+                }
+            }
+            return default;
+        }
+
+        public static bool TryGetFloatingPointConstant(ReadOnlySpan<byte> span, out float value)
+        {
+            if (span.Length == 3)
+            {
+                if (span.SequenceEqual(JsonConstants.NaNValue))
+                {
+                    value = float.NaN;
+                    return true;
+                }
+            }
+            else if (span.Length == 8)
+            {
+                if (span.SequenceEqual(JsonConstants.PositiveInfinityValue))
+                {
+                    value = float.PositiveInfinity;
+                    return true;
+                }
+            }
+            else if (span.Length == 9)
+            {
+                if (span.SequenceEqual(JsonConstants.NegativeInfinityValue))
+                {
+                    value = float.NegativeInfinity;
+                    return true;
+                }
+            }
+
+            value = 0;
+            return false;
+        }
+
+        public static bool TryGetFloatingPointConstant(ReadOnlySpan<byte> span, out double value)
+        {
+            if (span.Length == 3)
+            {
+                if (span.SequenceEqual(JsonConstants.NaNValue))
+                {
+                    value = double.NaN;
+                    return true;
+                }
+            }
+            else if (span.Length == 8)
+            {
+                if (span.SequenceEqual(JsonConstants.PositiveInfinityValue))
+                {
+                    value = double.PositiveInfinity;
+                    return true;
+                }
+            }
+            else if (span.Length == 9)
+            {
+                if (span.SequenceEqual(JsonConstants.NegativeInfinityValue))
+                {
+                    value = double.NegativeInfinity;
+                    return true;
+                }
+            }
+
+            value = 0;
+            return false;
+        }
     }
 }

src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.TryGet.cs

@@ -416,11 +416,38 @@ public float GetSingle()
         internal float GetSingleWithQuotes()
         {
             ReadOnlySpan<byte> span = GetUnescapedSpan();
-            if (!TryGetSingleCore(out float value, span))
+
+            if (JsonReaderHelper.TryGetFloatingPointConstant(span, out float value))
             {
-                throw ThrowHelper.GetFormatException(NumericType.Single);
+                return value;
             }
-            return value;
+
+            char numberFormat = JsonReaderHelper.GetFloatingPointStandardParseFormat(span);
+            if (Utf8Parser.TryParse(span, out value, out int bytesConsumed, numberFormat)
+                && span.Length == bytesConsumed)
+            {
+                // NETCOREAPP implementation of the TryParse method above permits case-insenstive variants of the
+                // float constants "NaN", "Infinity", "-Infinity". This differs from the NETFRAMEWORK implementation.
+                // The following logic reconciles the two implementations to enforce consistent behavior.
+                if (!float.IsNaN(value) && !float.IsPositiveInfinity(value) && !float.IsNegativeInfinity(value))
+                {
+                    return value;
+                }
+            }
+
+            throw ThrowHelper.GetFormatException(NumericType.Single);
+        }
+
+        internal float GetSingleFloatingPointConstant()
+        {
+            ReadOnlySpan<byte> span = GetUnescapedSpan();
+
+            if (JsonReaderHelper.TryGetFloatingPointConstant(span, out float value))
+            {
+                return value;
+            }
+
+            throw ThrowHelper.GetFormatException(NumericType.Single);
         }
 
         /// <summary>
@@ -449,11 +476,38 @@ public double GetDouble()
         internal double GetDoubleWithQuotes()
         {
             ReadOnlySpan<byte> span = GetUnescapedSpan();
-            if (!TryGetDoubleCore(out double value, span))
+
+            if (JsonReaderHelper.TryGetFloatingPointConstant(span, out double value))
             {
-                throw ThrowHelper.GetFormatException(NumericType.Double);
+                return value;
             }
-            return value;
+
+            char numberFormat = JsonReaderHelper.GetFloatingPointStandardParseFormat(span);
+            if (Utf8Parser.TryParse(span, out value, out int bytesConsumed, numberFormat)
+                && span.Length == bytesConsumed)
+            {
+                // NETCOREAPP implmentation of the TryParse method above permits case-insenstive variants of the
+                // float constants "NaN", "Infinity", "-Infinity". This differs from the NETFRAMEWORK implementation.
+                // The following logic reconciles the two implementations to enforce consistent behavior.
+                if (!double.IsNaN(value) && !double.IsPositiveInfinity(value) && !double.IsNegativeInfinity(value))
+                {
+                    return value;
+                }
+            }
+
+            throw ThrowHelper.GetFormatException(NumericType.Double);
+        }
+
+        internal double GetDoubleFloatingPointConstant()
+        {
+            ReadOnlySpan<byte> span = GetUnescapedSpan();
+
+            if (JsonReaderHelper.TryGetFloatingPointConstant(span, out double value))
+            {
+                return value;
+            }
+
+            throw ThrowHelper.GetFormatException(NumericType.Double);
         }
 
         /// <summary>
@@ -482,11 +536,15 @@ public decimal GetDecimal()
         internal decimal GetDecimalWithQuotes()
         {
             ReadOnlySpan<byte> span = GetUnescapedSpan();
-            if (!TryGetDecimalCore(out decimal value, span))
+
+            char numberFormat = JsonReaderHelper.GetFloatingPointStandardParseFormat(span);
+            if (Utf8Parser.TryParse(span, out decimal value, out int bytesConsumed, numberFormat)
+                && span.Length == bytesConsumed)
             {
-                throw ThrowHelper.GetFormatException(NumericType.Decimal);
+                return value;
             }
-            return value;
+
+            throw ThrowHelper.GetFormatException(NumericType.Decimal);
         }
 
         /// <summary>
@@ -919,13 +977,8 @@ public bool TryGetSingle(out float value)
                 throw ThrowHelper.GetInvalidOperationException_ExpectedNumber(TokenType);
             }
 
-            ReadOnlySpan<byte> span = HasValueSequence ? ValueSequence.ToArray() : ValueSpan;
-            return TryGetSingleCore(out value, span);
-        }
+            ReadOnlySpan<byte> span = HasValueSequence ? ValueSequence.ToArray() : ValueSpan;;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal bool TryGetSingleCore(out float value, ReadOnlySpan<byte> span)
-        {
             if (Utf8Parser.TryParse(span, out float tmp, out int bytesConsumed, _numberFormat)
                 && span.Length == bytesConsumed)
             {
@@ -955,12 +1008,7 @@ public bool TryGetDouble(out double value)
             }
 
             ReadOnlySpan<byte> span = HasValueSequence ? ValueSequence.ToArray() : ValueSpan;
-            return TryGetDoubleCore(out value, span);
-        }
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal bool TryGetDoubleCore(out double value, ReadOnlySpan<byte> span)
-        {
             if (Utf8Parser.TryParse(span, out double tmp, out int bytesConsumed, _numberFormat)
                 && span.Length == bytesConsumed)
             {
@@ -990,12 +1038,7 @@ public bool TryGetDecimal(out decimal value)
             }
 
             ReadOnlySpan<byte> span = HasValueSequence ? ValueSequence.ToArray() : ValueSpan;
-            return TryGetDecimalCore(out value, span);
-        }
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal bool TryGetDecimalCore(out decimal value, ReadOnlySpan<byte> span)
-        {
             if (Utf8Parser.TryParse(span, out decimal tmp, out int bytesConsumed, _numberFormat)
                 && span.Length == bytesConsumed)
             {

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Attributes/JsonNumberHandlingAttribute.cs

@@ -0,0 +1,30 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System.Text.Json.Serialization
+{
+    /// <summary>
+    /// When placed on a type, property, or field, indicates what <see cref="JsonNumberHandling"/>
+    /// settings should be used when serializing or deserialing numbers.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Property | AttributeTargets.Field, AllowMultiple = false)]
+    public sealed class JsonNumberHandlingAttribute : JsonAttribute
+    {
+        /// <summary>
+        /// Indicates what settings should be used when serializing or deserialing numbers.
+        /// </summary>
+        public JsonNumberHandling Handling { get; }
+
+        /// <summary>
+        /// Initializes a new instance of <see cref="JsonNumberHandlingAttribute"/>.
+        /// </summary>
+        public JsonNumberHandlingAttribute(JsonNumberHandling handling)
+        {
+            if (!JsonSerializer.IsValidNumberHandlingValue(handling))
+            {
+                throw new ArgumentOutOfRangeException(nameof(handling));
+            }
+            Handling = handling;
+        }
+    }
+}

src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Converters/Collection/ArrayConverter.cs

@@ -38,7 +38,7 @@ protected override bool OnWriteResume(Utf8JsonWriter writer, TCollection value,
             int index = state.Current.EnumeratorIndex;
 
             JsonConverter<TElement> elementConverter = GetElementConverter(ref state);
-            if (elementConverter.CanUseDirectReadOrWrite)
+            if (elementConverter.CanUseDirectReadOrWrite && state.Current.NumberHandling == null)
             {
                 // Fast path that avoids validation and extra indirection.
                 for (; index < array.Length; index++)