Make boolean packing optional through PackAttribute

BinarySerializer.Test/PackedBoolean/ConstantSizePackedBooleanClass.cs

@@ -10,11 +10,11 @@ public class ConstantSizePackedBooleanClass
         [Ignore] public const int LengthConstraint = 2;
 
         [FieldCount(CountConstraint)]
-        [FieldOrder(0)]
+        [FieldOrder(0), Pack]
         public bool[] ConstantCountArray { get; set; }
 
-        [FieldLength(2)]
-        [FieldOrder(1)]
+        [FieldLength(LengthConstraint)]
+        [FieldOrder(1), Pack]
         public bool[] ConstantLengthArray { get; set; }
     }
 }

BinarySerializer.Test/PackedBoolean/EndianAwarePackedBooleanClass.cs

@@ -5,11 +5,11 @@ namespace BinarySerialization.Test.PackedBoolean
     public class EndianAwarePackedBooleanClass
     {
         [FieldEndianness(BinarySerialization.Endianness.Little)]
-        [FieldOrder(0)]
+        [FieldOrder(0), Pack]
         public bool[] LittleEndianArray { get; set; }
 
         [FieldEndianness(BinarySerialization.Endianness.Big)]
-        [FieldOrder(1)]
+        [FieldOrder(1), Pack]
         public bool[] BigEndianArray { get; set; }        
     }
 }

BinarySerializer.Test/PackedBoolean/ValidPackedBooleanClass.cs

@@ -10,7 +10,7 @@ public class ValidPackedBooleanClass
         [FieldOrder(1)] public long BooleanArrayLength { get; set; }
 
         [FieldCount(nameof(BooleanArrayCount)), FieldLength(nameof(BooleanArrayLength))]
-        [FieldOrder(2)]
+        [FieldOrder(2), Pack]
         public bool[] BooleanArray { get; set; }
     }
 }

BinarySerializer/Graph/TypeGraph/ContainerTypeNode.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections;
+using System.Collections.Generic;
 using System.IO;
+using System.Linq;
 using System.Reflection;
 
 namespace BinarySerialization.Graph.TypeGraph
@@ -45,7 +47,7 @@ protected TypeNode GenerateChild(Type parentType, MemberInfo memberInfo)
             {
                 ThrowOnBadType(memberType);
 
-                var nodeType = GetNodeType(memberType);
+                var nodeType = GetNodeType(memberType, memberInfo.GetCustomAttributes());
 
                 return (TypeNode)Activator.CreateInstance(nodeType, this, parentType, memberInfo);
             }
@@ -64,7 +66,8 @@ private static void ThrowOnBadType(Type type)
         }
 // ReSharper restore UnusedParameter.Local
 
-        private static Type GetNodeType(Type type)
+        private static Type GetNodeType(Type type) => GetNodeType(type, Enumerable.Empty<Attribute>());
+        private static Type GetNodeType(Type type, IEnumerable<Attribute> attributes)
         {
             var nullableType = Nullable.GetUnderlyingType(type);
 
@@ -76,8 +79,14 @@ private static Type GetNodeType(Type type)
             if (IsValueType(effectiveType))
                 return typeof (ValueTypeNode);
 
-            if (type == typeof(bool[]))
-                return typeof(PackedBooleanArrayTypeNode);
+            if (attributes.OfType<PackAttribute>().Any())
+            {
+                if (type == typeof(bool[]))
+                    return typeof(PackedBooleanArrayTypeNode);
+
+                throw new InvalidOperationException($"Cannot use the Pack attribute on member of type {type.Name}.");
+            }
+
             if (type.IsArray)
                 return typeof(ArrayTypeNode);
             if (typeof(IList).IsAssignableFrom(type))

BinarySerializer/PackAttribute.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace BinarySerialization
+{
+    /// <summary> Tells the <see cref="BinarySerializer"/> to pack the decorated member. </summary>
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false)]
+    public sealed class PackAttribute : Attribute
+    {
+        /// <summary> Initializes a new instance of the <see cref="PackAttribute"/> class. </summary>
+        public PackAttribute() { }
+    }
+}