Start adding enum helpers

SabreTools.Core/Tools/AttributeHelper.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Linq;
+
+namespace SabreTools.Core.Tools
+{
+    public static class AttributeHelper<T>
+    {
+        /// <summary>
+        /// Get the MappingAttribute from a supported value
+        /// </summary>
+        /// <param name="value">Value to use</param>
+        /// <returns>MappingAttribute attached to the value</returns>
+        public static MappingAttribute GetAttribute(T value)
+        {
+            // Null value in, null value out
+            if (value == null)
+                return null;
+
+            // Current enumeration type
+            var enumType = typeof(T);
+            if (Nullable.GetUnderlyingType(enumType) != null)
+                enumType = Nullable.GetUnderlyingType(enumType);
+
+            // If the value returns a null on ToString, just return null
+            string valueStr = value.ToString();
+            if (string.IsNullOrWhiteSpace(valueStr))
+                return null;
+            
+            // Get the member info array
+            var memberInfos = enumType?.GetMember(valueStr);
+            if (memberInfos == null)
+                return null;
+
+            // Get the enum value info from the array, if possible
+            var enumValueMemberInfo = memberInfos.FirstOrDefault(m => m.DeclaringType == enumType);
+            if (enumValueMemberInfo == null)
+                return null;
+            
+            // Try to get the relevant attribute
+            var attributes = enumValueMemberInfo.GetCustomAttributes(typeof(MappingAttribute), true);
+            if (attributes == null)
+                return null;
+            
+            // Return the first attribute, if possible
+            return (MappingAttribute)attributes.FirstOrDefault();
+        }
+    }
+}