1 files changed, 67 insertions, 0 deletions
diff --git a/src/DotNetOpenAuth.Core/Messaging/Reflection/ValueMapping.cs b/src/DotNetOpenAuth.Core/Messaging/Reflection/ValueMapping.cs
new file mode 100644
index 0000000..9c0fa83
--- /dev/null
+++ b/src/DotNetOpenAuth.Core/Messaging/Reflection/ValueMapping.cs
@@ -0,0 +1,67 @@
+//-----------------------------------------------------------------------
+// <copyright file="ValueMapping.cs" company="Andrew Arnott">
+//     Copyright (c) Andrew Arnott. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth.Messaging.Reflection {
+	using System;
+	using System.Diagnostics.Contracts;
+
+	/// <summary>
+	/// A pair of conversion functions to map some type to a string and back again.
+	/// </summary>
+	[ContractVerification(true)]
+	internal struct ValueMapping {
+		/// <summary>
+		/// The mapping function that converts some custom type to a string.
+		/// </summary>
+		internal readonly Func<object, string> ValueToString;
+
+		/// <summary>
+		/// The mapping function that converts some custom type to the original string
+		/// (possibly non-normalized) that represents it.
+		/// </summary>
+		internal readonly Func<object, string> ValueToOriginalString;
+
+		/// <summary>
+		/// The mapping function that converts a string to some custom type.
+		/// </summary>
+		internal readonly Func<string, object> StringToValue;
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="ValueMapping"/> struct.
+		/// </summary>
+		/// <param name="toString">The mapping function that converts some custom value to a string.</param>
+		/// <param name="toOriginalString">The mapping function that converts some custom value to its original (non-normalized) string.  May be null if the same as the <paramref name="toString"/> function.</param>
+		/// <param name="toValue">The mapping function that converts a string to some custom value.</param>
+		internal ValueMapping(Func<object, string> toString, Func<object, string> toOriginalString, Func<string, object> toValue) {
+			Requires.NotNull(toString, "toString");
+			Requires.NotNull(toValue, "toValue");
+
+			this.ValueToString = toString;
+			this.ValueToOriginalString = toOriginalString ?? toString;
+			this.StringToValue = toValue;
+		}
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="ValueMapping"/> struct.
+		/// </summary>
+		/// <param name="encoder">The encoder.</param>
+		internal ValueMapping(IMessagePartEncoder encoder) {
+			Requires.NotNull(encoder, "encoder");
+			var nullEncoder = encoder as IMessagePartNullEncoder;
+			string nullString = nullEncoder != null ? nullEncoder.EncodedNullValue : null;
+
+			var originalStringEncoder = encoder as IMessagePartOriginalEncoder;
+			Func<object, string> originalStringEncode = encoder.Encode;
+			if (originalStringEncoder != null) {
+				originalStringEncode = originalStringEncoder.EncodeAsOriginalString;
+			}
+
+			this.ValueToString = obj => (obj != null) ? encoder.Encode(obj) : nullString;
+			this.StringToValue = str => (str != null) ? encoder.Decode(str) : null;
+			this.ValueToOriginalString = obj => (obj != null) ? originalStringEncode(obj) : nullString;
+		}
+	}
+}