1 files changed, 94 insertions, 0 deletions
diff --git a/src/DotNetOpenAuth.Core/RequiresEx.cs b/src/DotNetOpenAuth.Core/RequiresEx.cs
new file mode 100644
index 0000000..1a077c4
--- /dev/null
+++ b/src/DotNetOpenAuth.Core/RequiresEx.cs
@@ -0,0 +1,94 @@
+//-----------------------------------------------------------------------
+// <copyright file="RequiresEx.cs" company="Outercurve Foundation">
+//     Copyright (c) Outercurve Foundation. All rights reserved.
+// </copyright>
+//-----------------------------------------------------------------------
+
+namespace DotNetOpenAuth {
+	using System;
+	using System.Collections.Generic;
+	using System.Diagnostics;
+	using System.Diagnostics.Contracts;
+	using System.Globalization;
+	using System.Linq;
+	using System.Text;
+	using DotNetOpenAuth.Messaging;
+	using Validation;
+
+	/// <summary>
+	/// Argument validation checks that throw some kind of ArgumentException when they fail (unless otherwise noted).
+	/// </summary>
+	internal static class RequiresEx {
+		/// <summary>
+		/// Validates some expression describing the acceptable condition for an argument evaluates to true.
+		/// </summary>
+		/// <param name="condition">The expression that must evaluate to true to avoid an <see cref="InvalidOperationException"/>.</param>
+		[Pure, DebuggerStepThrough]
+		internal static void ValidState(bool condition) {
+			if (!condition) {
+				throw new InvalidOperationException();
+			}
+		}
+
+		/// <summary>
+		/// Validates some expression describing the acceptable condition for an argument evaluates to true.
+		/// </summary>
+		/// <param name="condition">The expression that must evaluate to true to avoid an <see cref="InvalidOperationException"/>.</param>
+		/// <param name="message">The message to include with the exception.</param>
+		[Pure, DebuggerStepThrough]
+		internal static void ValidState(bool condition, string message) {
+			if (!condition) {
+				throw new InvalidOperationException(message);
+			}
+		}
+
+		/// <summary>
+		/// Validates some expression describing the acceptable condition for an argument evaluates to true.
+		/// </summary>
+		/// <param name="condition">The expression that must evaluate to true to avoid an <see cref="InvalidOperationException"/>.</param>
+		/// <param name="unformattedMessage">The unformatted message.</param>
+		/// <param name="args">Formatting arguments.</param>
+		[Pure, DebuggerStepThrough]
+		internal static void ValidState(bool condition, string unformattedMessage, params object[] args) {
+			if (!condition) {
+				throw new InvalidOperationException(string.Format(CultureInfo.CurrentCulture, unformattedMessage, args));
+			}
+		}
+
+		/// <summary>
+		/// Validates that some argument describes a type that is or derives from a required type.
+		/// </summary>
+		/// <typeparam name="T">The type that the argument must be or derive from.</typeparam>
+		/// <param name="type">The type given in the argument.</param>
+		/// <param name="parameterName">Name of the parameter.</param>
+		[Pure, DebuggerStepThrough]
+		internal static void NotNullSubtype<T>(Type type, string parameterName) {
+			Requires.NotNull(type, parameterName);
+			Requires.That(typeof(T).IsAssignableFrom(type), parameterName, MessagingStrings.UnexpectedType, typeof(T).FullName, type.FullName);
+		}
+
+		/// <summary>
+		/// Validates some expression describing the acceptable condition for an argument evaluates to true.
+		/// </summary>
+		/// <param name="condition">The expression that must evaluate to true to avoid an <see cref="FormatException"/>.</param>
+		/// <param name="message">The message.</param>
+		[Pure, DebuggerStepThrough]
+		internal static void Format(bool condition, string message) {
+			if (!condition) {
+				throw new FormatException(message);
+			}
+		}
+
+		/// <summary>
+		/// Throws an <see cref="NotSupportedException"/> if a condition does not evaluate to <c>true</c>.
+		/// </summary>
+		/// <param name="condition">The expression that must evaluate to true to avoid an <see cref="NotSupportedException"/>.</param>
+		/// <param name="message">The message.</param>
+		[Pure, DebuggerStepThrough]
+		internal static void Support(bool condition, string message) {
+			if (!condition) {
+				throw new NotSupportedException(message);
+			}
+		}
+	}
+}