Replace overload with delegates to read token values.

src/Microsoft.IdentityModel.JsonWebTokens/Json/JsonClaimSet.cs

@@ -28,7 +28,7 @@ internal class JsonClaimSet
 
         internal JsonClaimSet()
         {
-            _jsonClaims = new Dictionary<string, object>();
+            _jsonClaims = [];
         }
 
         internal JsonClaimSet(Dictionary<string, object> jsonClaims)

src/Microsoft.IdentityModel.JsonWebTokens/JsonWebToken.cs

@@ -86,6 +86,29 @@ public JsonWebToken(string jwtEncodedString)
             _encodedToken = jwtEncodedString;
         }
 
+        /// <summary>
+        /// Initializes a new instance of <see cref="JsonWebToken"/> from a ReadOnlyMemory{char} in JWS or JWE Compact serialized format.
+        /// </summary>
+        /// <param name="encodedTokenMemory">A ReadOnlyMemory{char} containing the JSON Web Token serialized in JWS or JWE Compact format.</param>
+        /// <param name="readTokenHeaderValueDelegate">A custom delegate to be called when each header claim is being read. If null, default implementation is called.</param>
+        /// <param name="readTokenPayloadValueDelegate">A custom delegate to be called when each payload claim is being read. If null, default implementation is called.</param>
+        public JsonWebToken(
+            ReadOnlyMemory<char> encodedTokenMemory,
+            ReadTokenHeaderValueDelegate readTokenHeaderValueDelegate,
+            ReadTokenPayloadValueDelegate readTokenPayloadValueDelegate)
+        {
+            if (encodedTokenMemory.IsEmpty)
+                throw LogHelper.LogExceptionMessage(new ArgumentNullException(nameof(encodedTokenMemory)));
+
+            ReadTokenHeaderValueDelegate = readTokenHeaderValueDelegate ?? ReadTokenHeaderValue;
+            ReadTokenPayloadValueDelegate = readTokenPayloadValueDelegate ?? ReadTokenPayloadValue;
+
+            ReadToken(encodedTokenMemory);
+
+            _encodedTokenMemory = encodedTokenMemory;
+
+        }
+
         /// <summary>
         /// Initializes a new instance of <see cref="JsonWebToken"/> from a ReadOnlyMemory{char} in JWS or JWE Compact serialized format.
         /// </summary>
@@ -141,6 +164,43 @@ public JsonWebToken(string header, string payload)
             _encodedToken = encodedToken;
         }
 
+        /// <summary>
+        /// Called for each claim when token header is being read.
+        /// </summary>
+        /// <remarks>
+        /// An example implementation:
+        /// <code>
+        /// object ReadPayloadValueDelegate(ref Utf8JsonReader reader, string claimName) =>
+        /// {
+        ///     if (reader.ValueTextEquals("CustomProp"))
+        ///     {
+        ///         return JsonSerializerPrimitives.ReadString(ref reader, JwtRegisteredClaimNames.CustomProp, ClassName, true);    
+        ///     }
+        ///     return JsonWebToken.ReadTokenHeaderValue(ref reader, claimName);
+        /// }
+        /// </code>
+        /// </remarks>
+        internal ReadTokenHeaderValueDelegate ReadTokenHeaderValueDelegate { get; set; } = ReadTokenHeaderValue;
+
+
+        /// <summary>
+        /// Called for each claim when token payload is being read.
+        /// </summary>
+        /// <remarks>
+        /// An example implementation:
+        /// <code>
+        /// object ReadPayloadValueDelegate(ref Utf8JsonReader reader, string claimName) =>
+        /// {
+        ///     if (reader.ValueTextEquals("CustomProp"))
+        ///     {
+        ///         return JsonSerializerPrimitives.ReadString(ref reader, JwtRegisteredClaimNames.CustomProp, ClassName, true);    
+        ///     }
+        ///     return JsonWebToken.ReadTokenPayloadValue(ref reader, claimName);
+        /// }
+        /// </code>
+        /// </remarks>
+        internal ReadTokenPayloadValueDelegate ReadTokenPayloadValueDelegate { get; set; } = ReadTokenPayloadValue;
+
         internal string ActualIssuer { get; set; }
 
         internal ClaimsIdentity ActorClaimsIdentity { get; set; }

src/Microsoft.IdentityModel.Tokens/Delegates.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Text.Json;
 using System.Threading.Tasks;
 
 namespace Microsoft.IdentityModel.Tokens
@@ -206,4 +207,22 @@ namespace Microsoft.IdentityModel.Tokens
     /// <returns>The validated <see cref="SecurityToken"/>.</returns>
     internal delegate ValidationResult<SecurityKey> SignatureValidationDelegate(SecurityToken token, ValidationParameters validationParameters, BaseConfiguration? configuration, CallContext? callContext);
 #nullable restore
+
+    /// <summary>
+    /// Definition for ReadTokenHeaderValueDelegate.
+    /// Called for each claim when token header is being read.
+    /// </summary>
+    /// <param name="reader">Reader for the underlying token bytes.</param>
+    /// <param name="claimName">The name of the claim being read.</param>
+    /// <returns></returns>
+    public delegate object ReadTokenHeaderValueDelegate(ref Utf8JsonReader reader, string claimName);
+
+    /// <summary>
+    /// Definition for ReadTokenPayloadValueDelegate.
+    /// Called for each claim when token payload is being read.
+    /// </summary>
+    /// <param name="reader">Reader for the underlying token bytes.</param>
+    /// <param name="claimName">The name of the claim being read.</param>
+    /// <returns></returns>
+    public delegate object ReadTokenPayloadValueDelegate(ref Utf8JsonReader reader, string claimName);
 }

src/Microsoft.IdentityModel.Tokens/TokenValidationParameters.cs

@@ -449,6 +449,16 @@ public string NameClaimType
         /// </summary>
         public IDictionary<string, object> PropertyBag { get; set; }
 
+        /// <summary>
+        /// Gets or sets a delegate that will be called when reading token payload claims.
+        /// </summary>
+        public ReadTokenHeaderValueDelegate ReadTokenHeaderValue { get; set; }
+
+        /// <summary>
+        /// Gets or sets a delegate that will be called when reading token payload claims.
+        /// </summary>
+        public ReadTokenPayloadValueDelegate ReadTokenPayloadValue { get; set; }
+
         /// <summary>
         /// Gets or sets a boolean to control if configuration required to be refreshed before token validation.
         /// </summary>