myfriendsaround/main/Libs/PushRecipe_WP7_SL/Source/WindowsPhone.Recipes.Push.Messasges/Guard.cs

using System;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;

using WindowsPhone.Recipes.Push.Messasges.Properties;

namespace WindowsPhone.Recipes.Push.Messasges
{
    /// <summary>
    /// A static helper class that includes various parameter checking routines.
    /// </summary>
    public static partial class Guard
    {
        /// <summary>
        /// Throws <see cref="ArgumentNullException"/> if the given argument is null.
        /// </summary>
        /// <exception cref="ArgumentNullException"> if tested value if null.</exception>
        /// <param name="argumentValue">Argument value to test.</param>
        /// <param name="argumentName">Name of the argument being tested.</param>
        public static void ArgumentNotNull(object argumentValue,
                                           string argumentName)
        {
            if (argumentValue == null)
            {
                throw new ArgumentNullException(argumentName);
            }
        }

        /// <summary>
        /// Throws an exception if the tested string argument is null or the empty string.
        /// </summary>
        /// <exception cref="ArgumentNullException">Thrown if string value is null.</exception>
        /// <exception cref="ArgumentException">Thrown if the string is empty</exception>
        /// <param name="argumentValue">Argument value to check.</param>
        /// <param name="argumentName">Name of argument being checked.</param>
        public static void ArgumentNotNullOrEmpty(string argumentValue,
                                                  string argumentName)
        {
            if (argumentValue == null)
            {
                throw new ArgumentNullException(argumentName);
            }

            if (argumentValue.Length == 0)
            {
                throw new ArgumentException(Resources.ArgumentMustNotBeEmpty, argumentName);
            }
        }

        /// <summary>
        /// Verifies that an argument type is assignable from the provided type (meaning
        /// interfaces are implemented, or classes exist in the base class hierarchy).
        /// </summary>
        /// <param name="assignmentTargetType">The argument type that will be assigned to.</param>
        /// <param name="assignmentValueType">The type of the value being assigned.</param>
        /// <param name="argumentName">Argument name.</param>
        public static void TypeIsAssignable(Type assignmentTargetType, Type assignmentValueType, string argumentName)
        {
            if (assignmentTargetType == null)
            {
                throw new ArgumentNullException("assignmentTargetType");
            }

            if (assignmentValueType == null)
            {
                throw new ArgumentNullException("assignmentValueType");
            }

            if (!assignmentTargetType.IsAssignableFrom(assignmentValueType))
            {
                throw new ArgumentException(string.Format(
                    CultureInfo.CurrentCulture,
                    Resources.TypesAreNotAssignable,
                    assignmentTargetType,
                    assignmentValueType),
                    argumentName);
            }
        }

        /// <summary>
        /// Verifies that an argument instance is assignable from the provided type (meaning
        /// interfaces are implemented, or classes exist in the base class hierarchy, or instance can be 
        /// assigned through a runtime wrapper, as is the case for COM Objects).
        /// </summary>
        /// <param name="assignmentTargetType">The argument type that will be assigned to.</param>
        /// <param name="assignmentInstance">The instance that will be assigned.</param>
        /// <param name="argumentName">Argument name.</param>
        [SuppressMessage(
            "Microsoft.Design",
            "CA1031:DoNotCatchGeneralExceptionTypes",
            Justification = "GetType() invoked for diagnostics purposes")]
        public static void InstanceIsAssignable(Type assignmentTargetType, object assignmentInstance, string argumentName)
        {
            if (assignmentTargetType == null)
            {
                throw new ArgumentNullException("assignmentTargetType");
            }

            if (assignmentInstance == null)
            {
                throw new ArgumentNullException("assignmentInstance");
            }

            if (!assignmentTargetType.IsInstanceOfType(assignmentInstance))
            {
                throw new ArgumentException(
                    string.Format(
                        CultureInfo.CurrentCulture,
                        Resources.TypesAreNotAssignable,
                        assignmentTargetType,
                        GetTypeName(assignmentInstance)),
                    argumentName);
            }
        }        

        [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes",
            Justification = "Need to use exception as flow control here, no other choice")]
        private static string GetTypeName(object assignmentInstance)
        {
            string assignmentInstanceType;
            try
            {
                assignmentInstanceType = assignmentInstance.GetType().FullName;
            }
            catch (Exception)
            {
                assignmentInstanceType = Resources.UnknownType;
            }
            return assignmentInstanceType;
        }        
    }
}