Exceptions.

Author: Berrysoft

src/Berrysoft.Data/ExceptionHelper.cs

@@ -7,21 +7,25 @@ internal static class ExceptionHelper
     {
         public static Exception ArgumentNull(string paramName)
             => new ArgumentNullException(paramName);
-        public static Exception RootHasParent()
-            => new ArgumentException("The root can't have a parent.");
         public static Exception PairExisted()
-            => new ArgumentException("The key pair is existed.");
+            => new PairExistedException();
         public static Exception KeyNotFound()
             => new KeyNotFoundException();
-        public static Exception KeyExisted(string keyMessage)
-            => new ArgumentException($"{keyMessage} is existed.");
-        public static Exception KeysExisted()
-            => new ArgumentException("Both keys are existed.");
         public static Exception ArgumentOutOfRange(string paramName)
             => new ArgumentOutOfRangeException(paramName);
-        public static Exception NotSupported()
-            => new NotSupportedException();
         public static Exception ArrayTooSmall()
             => new ArgumentException("The array is too small.");
     }
+    /// <summary>
+    /// Represents errors that a key pair is existed.
+    /// </summary>
+    public class PairExistedException : ArgumentException
+    {
+        /// <summary>
+        /// Initializes a new instance of <see cref="PairExistedException"/> class.
+        /// </summary>
+        public PairExistedException()
+            : base("The key pair is existed.")
+        { }
+    }
 }

src/Berrysoft.Unsafe/ByReference.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using static System.Runtime.CompilerServices.Unsafe;
 
@@ -8,6 +9,8 @@ namespace Berrysoft.Unsafe
     /// Represents a .NET CLR reference.
     /// </summary>
     /// <typeparam name="T">Type of the reference pointed to.</typeparam>
+    [DebuggerDisplay("{Value}")]
+    [DebuggerTypeProxy(typeof(PointerDebugView<>))]
     public readonly unsafe struct ByReference<T>
     {
         private readonly void* _ptr;

src/Berrysoft.Unsafe/PointerDebugView.cs

@@ -26,6 +26,14 @@ public unsafe PointerDebugView(Pointer<T> ptr)
             }
         }
         /// <summary>
+        /// Initializes a new instance of <see cref="PointerDebugView{T}"/> class. This method is called by the debugger.
+        /// </summary>
+        /// <param name="ptr">The reference.</param>
+        public PointerDebugView(ByReference<T> ptr)
+        {
+            target = ptr.Value;
+        }
+        /// <summary>
         /// Target of the pointer.
         /// </summary>
         [DebuggerBrowsable(DebuggerBrowsableState.Collapsed)]

tests/Berrysoft.Data.Test/MapTest.vb

@@ -56,7 +56,7 @@ Public Class MapTest
         Dim key1values() As String = keylook.GetValuesFromKey1(123).ToArray()
         Assert.AreEqual(key1values(0), "123")
         Assert.AreEqual(key1values(1), "abc")
-        Assert.ThrowsException(Of ArgumentException)(Sub() keylook.Add(123, "123"))
+        Assert.ThrowsException(Of PairExistedException)(Sub() keylook.Add(123, "123"))
     End Sub
 
     <TestMethod()>