Some string.Intern's for minimizing duplicate strings count

src/NHibernate/Criterion/EntityProjection.cs

@@ -1,11 +1,12 @@
-using System;
+using System;
 using System.Collections.Generic;
 using NHibernate.Engine;
-using NHibernate.Loader;
 using NHibernate.Loader.Criteria;
 using NHibernate.Persister.Entity;
 using NHibernate.SqlCommand;
 using NHibernate.Type;
+using NHibernate.Util;
+
 using IQueryable = NHibernate.Persister.Entity.IQueryable;
 
 namespace NHibernate.Criterion
@@ -204,7 +205,7 @@ private void SetFields(ICriteriaQuery criteriaQuery)
 				subcriteria,
 				Persister.IdentifierPropertyName ?? string.Empty);
 
-			ColumnAliasSuffix = BasicLoader.GenerateSuffix(criteriaQuery.GetIndexForAlias());
+			ColumnAliasSuffix = StringHelper.GenerateSuffix(criteriaQuery.GetIndexForAlias());
 
 			_identifierColumnAliases = Persister.GetIdentifierAliases(ColumnAliasSuffix);
 

src/NHibernate/Hql/Ast/ANTLR/HqlSqlWalker.cs

@@ -485,7 +485,7 @@ internal string GetSuffix(FromElement fromElement)
 				return suffix;
 			}
 
-			suffix = _suffixes.Count == 0 ? string.Empty : _suffixes.Count.ToString() + '_';
+			suffix = _suffixes.Count == 0 ? string.Empty : StringHelper.GenerateSuffix(_suffixes.Count);
 			_suffixes.Add(fromElement, suffix);
 
 			return suffix;

src/NHibernate/Hql/Ast/ANTLR/Tree/FromElementType.cs

@@ -532,7 +532,7 @@ private static string GetSuffix(int size, int sequence)
 
 		private static string GenerateSuffix(int size, int k)
 		{
-			String suffix = size == 1 ? "" : k.ToString() + '_';
+			String suffix = size == 1 ? "" : StringHelper.GenerateSuffix(k);
 			return suffix;
 		}
 

src/NHibernate/Loader/BasicLoader.cs

@@ -99,15 +99,10 @@ public static string[] GenerateSuffixes(int seed, int length)
 
 			for (int i = 0; i < length; i++)
 			{
-				suffixes[i] = GenerateSuffix(i + seed);
+				suffixes[i] = StringHelper.GenerateSuffix(i + seed);
 			}
 
 			return suffixes;
 		}
-
-		public static string GenerateSuffix(int index)
-		{
-			return index.ToString() + StringHelper.Underscore;
-		}
 	}
 }

src/NHibernate/Mapping/Property.cs

@@ -66,7 +66,7 @@ public IEnumerable<ISelectable> ColumnIterator
 		public string Name
 		{
 			get { return name; }
-			set { name = value; }
+			set { name = value == null ? null : string.Intern(value); }
 		}
 
 		public bool IsComposite
@@ -122,7 +122,7 @@ public CascadeStyle CascadeStyle
 		public string Cascade
 		{
 			get { return cascade; }
-			set { cascade = value; }
+			set { cascade = value == null ? null : string.Intern(value); }
 		}
 
 		public bool IsUpdateable
@@ -168,7 +168,7 @@ public bool IsOptional
 		public string PropertyAccessorName
 		{
 			get { return propertyAccessorName; }
-			set { propertyAccessorName = value; }
+			set { propertyAccessorName = value == null ? null : string.Intern(value); }
 		}
 
 		public IGetter GetGetter(System.Type clazz)

src/NHibernate/Mapping/SimpleValue.cs

@@ -60,7 +60,7 @@ public IDictionary<string, string> IdentifierGeneratorProperties
 		public string IdentifierGeneratorStrategy
 		{
 			get { return identifierGeneratorStrategy; }
-			set { identifierGeneratorStrategy = value; }
+			set { identifierGeneratorStrategy = value == null ? null : string.Intern(value); }
 		}
 
 		public virtual bool IsComposite
@@ -127,7 +127,7 @@ public string TypeName
 				if ((typeName == null && value != null) || (typeName != null && !typeName.Equals(value)))
 				{
 					// the property change
-					typeName = value;
+					typeName = value == null ? null : string.Intern(value);
 					type = null; // invalidate type
 				}
 			}
@@ -353,7 +353,8 @@ public virtual void SetTypeUsingReflection(string className, string propertyName
 				}
 				try
 				{
-					typeName = ReflectHelper.ReflectedPropertyClass(className, propertyName, accesorName).AssemblyQualifiedName;
+					var aqn = ReflectHelper.ReflectedPropertyClass(className, propertyName, accesorName).AssemblyQualifiedName;
+					typeName = aqn == null ? null : string.Intern(aqn);
 				}
 				catch (HibernateException he)
 				{
@@ -372,7 +373,8 @@ public virtual void SetTypeUsingReflection(System.Type propertyOwnerType, string
 				}
 				try
 				{
-					typeName = ReflectHelper.ReflectedPropertyClass(propertyOwnerType, propertyName, accessorName).AssemblyQualifiedName;
+					var aqn = ReflectHelper.ReflectedPropertyClass(propertyOwnerType, propertyName, accessorName).AssemblyQualifiedName;
+					typeName = aqn == null ? null : string.Intern(aqn);
 				}
 				catch (HibernateException he)
 				{

src/NHibernate/Persister/Entity/AbstractEntityPersister.cs

@@ -2376,14 +2376,14 @@ protected void InitSubclassPropertyAliasesMap(PersistentClass model)
 				{
 					if (entityMetamodel.HasNonIdentifierPropertyNamedId)
 					{
-						subclassPropertyAliases[EntityPersister.EntityID + "." + idPropertyNames[i]] = new string[] { idAliases[i] };
-						subclassPropertyColumnNames[EntityPersister.EntityID + "." + IdentifierPropertyName + "." + idPropertyNames[i]] = new string[] { idColumnNames[i] };
+						subclassPropertyAliases[string.Intern(EntityPersister.EntityID + "." + idPropertyNames[i])] = new string[] { idAliases[i] };
+						subclassPropertyColumnNames[string.Intern(EntityPersister.EntityID + "." + IdentifierPropertyName + "." + idPropertyNames[i])] = new string[] { idColumnNames[i] };
 					}
 					//				if (hasIdentifierProperty() && !ENTITY_ID.equals( getIdentifierPropertyName() ) ) {
 					if (HasIdentifierProperty)
 					{
-						subclassPropertyAliases[IdentifierPropertyName + "." + idPropertyNames[i]] = new string[] { idAliases[i] };
-						subclassPropertyColumnNames[IdentifierPropertyName + "." + idPropertyNames[i]] = new string[] { idColumnNames[i] };
+						subclassPropertyAliases[string.Intern(IdentifierPropertyName + "." + idPropertyNames[i])] = new string[] { idAliases[i] };
+						subclassPropertyColumnNames[string.Intern(IdentifierPropertyName + "." + idPropertyNames[i])] = new string[] { idColumnNames[i] };
 					}
 					else
 					{

src/NHibernate/Persister/Entity/AbstractPropertyMapping.cs

@@ -211,7 +211,7 @@ private static string ExtendPath(string path, string property)
 			if (string.IsNullOrEmpty(path))
 				return property;
 
-			return StringHelper.Qualify(path, property);
+			return string.Intern(StringHelper.Qualify(path, property));
 		}
 
 		public string[] GetColumnNames(string propertyName)

src/NHibernate/Tuple/Entity/EntityMetamodel.cs

@@ -449,7 +449,7 @@ private void MapIdentifierPropertyTypes(string path, IType propertyType)
 				for (var i = 0; i < componentType.PropertyNames.Length; i++)
 				{
 					MapIdentifierPropertyTypes(
-						!string.IsNullOrEmpty(path) ? $"{path}.{componentType.PropertyNames[i]}" : componentType.PropertyNames[i],
+						!string.IsNullOrEmpty(path) ? string.Intern($"{path}.{componentType.PropertyNames[i]}") : componentType.PropertyNames[i],
 						componentType.Subtypes[i]);
 				}
 			}

src/NHibernate/Type/PersistentEnumType.cs

@@ -294,7 +294,7 @@ public class EnumType<T> : PersistentEnumType
 		public EnumType() : base(typeof (T))
 		{
 			System.Type type = GetType();
-			typeName = type.FullName + ", " + type.Assembly.GetName().Name;
+			typeName = string.Intern(type.FullName + ", " + type.Assembly.GetName().Name);
 		}
 
 		public override string Name

src/NHibernate/Util/StringHelper.cs

@@ -871,5 +871,15 @@ public static bool IsAnyNewLine(this string str, int index, out int newLineLengt
 			newLineLength = 0;
 			return false;
 		}
+
+		public static string GenerateSuffix(int index)
+		{
+			return index switch
+			{
+				0 => "0_",
+				1 => "1_",
+				_ => string.Intern(index.ToString() + Underscore)
+			};
+		}
 	}
 }