NH-902 - Switch from using string.Intern to only looking up the interned string if there is one already, otherwise using the original instance.

SVN: trunk@2639

Author: Sergey Koshcheyev

src/NHibernate/Loader/DefaultEntityAliases.cs

@@ -150,9 +150,8 @@ private static void Intern( string[] strings )
 		{
 			for( int i = 0; i < strings.Length; i++ )
 			{
-				strings[ i ] = string.Intern( strings[ i ] );
+				strings[i] = StringHelper.InternedIfPossible(strings[i]);
 			}
 		}
-
 	}
 }

src/NHibernate/Mapping/Collection.cs

@@ -358,7 +358,7 @@ public bool IsValid( IMapping mapping )
 		public string ReferencedPropertyName
 		{
 			get { return referencedPropertyName; }
-			set { referencedPropertyName = value == null ? null : string.Intern( value ); }
+			set { referencedPropertyName = StringHelper.InternedIfPossible(value); }
 		}
 
 		public virtual void Validate( IMapping mapping )
@@ -456,7 +456,7 @@ public IDictionary ManyToManyFilterMap
 		public string LoaderName
 		{
 			get { return loaderName; }
-			set { loaderName = value == null ? null : string.Intern(value); }
+			set { loaderName = StringHelper.InternedIfPossible(value); }
 		}
 
 		public bool IsSubselectLoadable

src/NHibernate/Mapping/ToOne.cs

@@ -1,5 +1,6 @@
 using System;
 using NHibernate.Loader;
+using NHibernate.Util;
 
 namespace NHibernate.Mapping
 {
@@ -37,7 +38,7 @@ public string ReferencedPropertyName
 		public string ReferencedEntityName
 		{
 			get { return referencedEntityName; }
-			set { referencedEntityName = value == null ? null : string.Intern(value); }
+			set { referencedEntityName = StringHelper.InternedIfPossible(value); }
 		}
 
 		public bool IsLazy

src/NHibernate/Util/StringHelper.cs

@@ -624,5 +624,27 @@ public static bool StartsWithCaseInsensitive(string source, string prefix)
 		{
 			return CultureInfo.InvariantCulture.CompareInfo.IsPrefix(source, prefix, CompareOptions.IgnoreCase);
 		}
+
+		/// <summary>
+		/// Returns the interned string equal to <paramref name="str"/> if there is one, or <paramref name="str"/>
+		/// otherwise.
+		/// </summary>
+		/// <param name="str">A <see cref="string" /></param>
+		/// <returns>A <see cref="string" /></returns>
+		public static string InternedIfPossible(string str)
+		{
+			if (str == null)
+			{
+				return null;
+			}
+			
+			string interned = string.IsInterned(str);
+			if (interned != null)
+			{
+				return interned;
+			}
+
+			return str;
+		}
 	}
 }