/src/NHibernate/Loader/Loader.cs

using System;

using System.Collections;

using System.Collections.Generic;

using System.Data;

using System.Diagnostics;

using System.Linq;

using System.Runtime.CompilerServices;

using Iesi.Collections;

using Iesi.Collections.Generic;



using NHibernate.AdoNet;

using NHibernate.Cache;

using NHibernate.Collection;

using NHibernate.Driver;

using NHibernate.Engine;

using NHibernate.Event;

using NHibernate.Exceptions;

using NHibernate.Hql.Classic;

using NHibernate.Hql.Util;

using NHibernate.Impl;

using NHibernate.Param;

using NHibernate.Persister.Collection;

using NHibernate.Persister.Entity;

using NHibernate.Proxy;

using NHibernate.SqlCommand;

using NHibernate.Transform;

using NHibernate.Type;

using NHibernate.Util;



namespace NHibernate.Loader

{

	/// <summary>

	/// Abstract superclass of object loading (and querying) strategies.

	/// </summary>

	/// <remarks>

	/// <p>

	/// This class implements useful common functionality that concrete loaders would delegate to.

	/// It is not intended that this functionality would be directly accessed by client code (Hence,

	/// all methods of this class are declared <c>protected</c> or <c>private</c>.) This class relies heavily upon the

	/// <see cref="ILoadable" /> interface, which is the contract between this class and 

	/// <see cref="IEntityPersister" />s that may be loaded by it.

	/// </p>

	/// <p>

	/// The present implementation is able to load any number of columns of entities and at most 

	/// one collection role per query.

	/// </p>

	/// </remarks>

	/// <seealso cref="NHibernate.Persister.Entity.ILoadable"/>

	public abstract class Loader

	{

		private static readonly IInternalLogger Log = LoggerProvider.LoggerFor(typeof(Loader));



		private readonly ISessionFactoryImplementor _factory;

		private readonly SessionFactoryHelper _helper;

		private ColumnNameCache _columnNameCache;



		protected Loader(ISessionFactoryImplementor factory)

		{

			_factory = factory;

			_helper = new SessionFactoryHelper(factory);

		}



		protected SessionFactoryHelper Helper

		{

			get { return _helper; }

		}



		/// <summary> 

		/// An array indicating whether the entities have eager property fetching

		/// enabled. 

		/// </summary>

		/// <value> Eager property fetching indicators. </value>

		protected virtual bool[] EntityEagerPropertyFetches

		{

			get { return null; }

		}



		/// <summary>

		/// An array of indexes of the entity that owns a one-to-one association

		/// to the entity at the given index (-1 if there is no "owner")

		/// </summary>

		/// <remarks>

		/// The indexes contained here are relative to the result of <see cref="EntityPersisters"/>.

		/// </remarks>

		protected virtual int[] Owners

		{

			get { return null; }

		}



		/// <summary> 

		/// An array of the owner types corresponding to the <see cref="Owners"/>

		/// returns.  Indices indicating no owner would be null here. 

		/// </summary>

		protected virtual EntityType[] OwnerAssociationTypes

		{

			get { return null; }

		}



		/// <summary>

		/// Get the index of the entity that owns the collection, or -1

		/// if there is no owner in the query results (i.e. in the case of a 

		/// collection initializer) or no collection.

		/// </summary>

		protected virtual int[] CollectionOwners

		{

			get { return null; }

		}



		/// <summary>

		/// Return false is this loader is a batch entity loader

		/// </summary>

		protected virtual bool IsSingleRowLoader

		{

			get { return false; }

		}



		public virtual bool IsSubselectLoadingEnabled

		{

			get { return false; }

		}



		/// <summary>

		/// Get the result set descriptor

		/// </summary>

		protected abstract IEntityAliases[] EntityAliases { get; }



		protected abstract ICollectionAliases[] CollectionAliases { get; }



		public ISessionFactoryImplementor Factory

		{

			get { return _factory; }

		}



		/// <summary>

		/// The SqlString to be called; implemented by all subclasses

		/// </summary>

		/// <remarks>

		/// <para>

		/// The <c>setter</c> was added so that class inheriting from Loader could write a 

		/// value using the Property instead of directly to the field.

		/// </para>

		/// <para>

		/// The scope is <c>protected internal</c> because the <see cref="Hql.Classic.WhereParser"/> needs to

		/// be able to <c>get</c> the SqlString of the <see cref="Hql.Classic.QueryTranslator"/> when

		/// it is parsing a subquery.

		/// </para>

		/// </remarks>

		public abstract SqlString SqlString { get; }



		/// <summary>

		/// An array of persisters of entity classes contained in each row of results;

		/// implemented by all subclasses

		/// </summary>

		/// <remarks>

		/// The <c>setter</c> was added so that classes inheriting from Loader could write a 

		/// value using the Property instead of directly to the field.

		/// </remarks>

		public abstract ILoadable[] EntityPersisters { get; }



		/// <summary>

		/// An (optional) persister for a collection to be initialized; only collection loaders

		/// return a non-null value

		/// </summary>

		protected virtual ICollectionPersister[] CollectionPersisters

		{

			get { return null; }

		}



		/// <summary>

		/// What lock mode does this load entities with?

		/// </summary>

		/// <param name="lockModes">A Collection of lock modes specified dynamically via the Query Interface</param>

		/// <returns></returns>

		public abstract LockMode[] GetLockModes(IDictionary<string, LockMode> lockModes);



		/// <summary>

		/// Append <c>FOR UPDATE OF</c> clause, if necessary. This

		/// empty superclass implementation merely returns its first

		/// argument.

		/// </summary>

		protected virtual SqlString ApplyLocks(SqlString sql, IDictionary<string, LockMode> lockModes, Dialect.Dialect dialect)

		{

			return sql;

		}



		/// <summary>

		/// Does this query return objects that might be already cached by 

		/// the session, whose lock mode may need upgrading.

		/// </summary>

		/// <returns></returns>

		protected virtual bool UpgradeLocks()

		{

			return false;

		}



		/// <summary>

		/// Get the SQL table aliases of entities whose

		/// associations are subselect-loadable, returning

		/// null if this loader does not support subselect

		/// loading

		/// </summary>

		protected virtual string[] Aliases

		{

			get { return null; }

		}



		/// <summary>

		/// Modify the SQL, adding lock hints and comments, if necessary

		/// </summary>

		protected virtual SqlString PreprocessSQL(SqlString sql, QueryParameters parameters, Dialect.Dialect dialect)

		{

			sql = ApplyLocks(sql, parameters.LockModes, dialect);



			return Factory.Settings.IsCommentsEnabled ? PrependComment(sql, parameters) : sql;

		}



		private static SqlString PrependComment(SqlString sql, QueryParameters parameters)

		{

			string comment = parameters.Comment;

			if (string.IsNullOrEmpty(comment))

			{

				return sql;

			}

			else

			{

				return sql.Insert(0, "/* " + comment + " */");

			}

		}



		/// <summary>

		/// Execute an SQL query and attempt to instantiate instances of the class mapped by the given

		/// persister from each row of the <c>DataReader</c>. If an object is supplied, will attempt to

		/// initialize that object. If a collection is supplied, attempt to initialize that collection.

		/// </summary>

		private IList DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, bool returnProxies)

		{

			IPersistenceContext persistenceContext = session.PersistenceContext;

			bool defaultReadOnlyOrig = persistenceContext.DefaultReadOnly;



			if (queryParameters.IsReadOnlyInitialized)

				persistenceContext.DefaultReadOnly = queryParameters.ReadOnly;

			else

				queryParameters.ReadOnly = persistenceContext.DefaultReadOnly;



			persistenceContext.BeforeLoad();

			IList result;

			try

			{

				try

				{

					result = DoQuery(session, queryParameters, returnProxies);

				}

				finally

				{

					persistenceContext.AfterLoad();

				}

				persistenceContext.InitializeNonLazyCollections();

			}

			finally

			{

				persistenceContext.DefaultReadOnly = defaultReadOnlyOrig;

			}



			return result;

		}



		/// <summary>

		/// Loads a single row from the result set.  This is the processing used from the

		/// ScrollableResults where no collection fetches were encountered.

		/// </summary>

		/// <param name="resultSet">The result set from which to do the load.</param>

		/// <param name="session">The session from which the request originated.</param>

		/// <param name="queryParameters">The query parameters specified by the user.</param>

		/// <param name="returnProxies">Should proxies be generated</param>

		/// <returns>The loaded "row".</returns>

		/// <exception cref="HibernateException" />

		protected object LoadSingleRow(IDataReader resultSet, ISessionImplementor session, QueryParameters queryParameters,

									   bool returnProxies)

		{

			int entitySpan = EntityPersisters.Length;

			IList hydratedObjects = entitySpan == 0 ? null : new List<object>(entitySpan);



			object result;

			try

			{

				result =

					GetRowFromResultSet(resultSet, session, queryParameters, GetLockModes(queryParameters.LockModes), null,

										hydratedObjects, new EntityKey[entitySpan], returnProxies);

			}

			catch (HibernateException)

			{

				throw; // Don't call Convert on HibernateExceptions

			}

			catch (Exception sqle)

			{

				throw ADOExceptionHelper.Convert(Factory.SQLExceptionConverter, sqle, "could not read next row of results",

												 SqlString, queryParameters.PositionalParameterValues,

												 queryParameters.NamedParameters);

			}



			InitializeEntitiesAndCollections(hydratedObjects, resultSet, session, queryParameters.IsReadOnly(session));

			session.PersistenceContext.InitializeNonLazyCollections();

			return result;

		}



		// Not ported: sequentialLoad, loadSequentialRowsForward, loadSequentialRowsReverse



		internal static EntityKey GetOptionalObjectKey(QueryParameters queryParameters, ISessionImplementor session)

		{

			object optionalObject = queryParameters.OptionalObject;

			object optionalId = queryParameters.OptionalId;

			string optionalEntityName = queryParameters.OptionalEntityName;



			if (optionalObject != null && !string.IsNullOrEmpty(optionalEntityName))

			{

				return new EntityKey(optionalId, session.GetEntityPersister(optionalEntityName, optionalObject), session.EntityMode);

			}

			else

			{

				return null;

			}

		}



		internal object GetRowFromResultSet(IDataReader resultSet, ISessionImplementor session,

											QueryParameters queryParameters, LockMode[] lockModeArray,

											EntityKey optionalObjectKey, IList hydratedObjects, EntityKey[] keys,

											bool returnProxies)

		{

			ILoadable[] persisters = EntityPersisters;

			int entitySpan = persisters.Length;



			for (int i = 0; i < entitySpan; i++)

			{

				keys[i] =

					GetKeyFromResultSet(i, persisters[i], i == entitySpan - 1 ? queryParameters.OptionalId : null, resultSet, session);

				//TODO: the i==entitySpan-1 bit depends upon subclass implementation (very bad)

			}



			RegisterNonExists(keys, session);



			// this call is side-effecty

			object[] row =

				GetRow(resultSet, persisters, keys, queryParameters.OptionalObject, optionalObjectKey, lockModeArray,

					   hydratedObjects, session);



			ReadCollectionElements(row, resultSet, session);



			if (returnProxies)

			{

				// now get an existing proxy for each row element (if there is one)

				for (int i = 0; i < entitySpan; i++)

				{

					object entity = row[i];

					object proxy = session.PersistenceContext.ProxyFor(persisters[i], keys[i], entity);



					if (entity != proxy)

					{

						// Force the proxy to resolve itself

						((INHibernateProxy)proxy).HibernateLazyInitializer.SetImplementation(entity);

						row[i] = proxy;

					}

				}

			}



			return GetResultColumnOrRow(row, queryParameters.ResultTransformer, resultSet, session);

		}



		/// <summary>

		/// Read any collection elements contained in a single row of the result set

		/// </summary>

		private void ReadCollectionElements(object[] row, IDataReader resultSet, ISessionImplementor session)

		{

			//TODO: make this handle multiple collection roles!



			ICollectionPersister[] collectionPersisters = CollectionPersisters;



			if (collectionPersisters != null)

			{

				ICollectionAliases[] descriptors = CollectionAliases;

				int[] collectionOwners = CollectionOwners;



				for (int i = 0; i < collectionPersisters.Length; i++)

				{

					bool hasCollectionOwners = collectionOwners != null && collectionOwners[i] > -1;

					//true if this is a query and we are loading multiple instances of the same collection role

					//otherwise this is a CollectionInitializer and we are loading up a single collection or batch



					object owner = hasCollectionOwners ? row[collectionOwners[i]] : null;

					//if null, owner will be retrieved from session



					ICollectionPersister collectionPersister = collectionPersisters[i];

					object key;



					if (owner == null)

					{

						key = null;

					}

					else

					{

						key = collectionPersister.CollectionType.GetKeyOfOwner(owner, session);

						//TODO: old version did not require hashmap lookup:

						//keys[collectionOwner].getIdentifier()

					}



					ReadCollectionElement(owner, key, collectionPersister, descriptors[i], resultSet, session);

				}

			}

		}



		private IList DoQuery(ISessionImplementor session, QueryParameters queryParameters, bool returnProxies)

		{

			RowSelection selection = queryParameters.RowSelection;

			int maxRows = HasMaxRows(selection) ? selection.MaxRows : int.MaxValue;



			int entitySpan = EntityPersisters.Length;



			List<object> hydratedObjects = entitySpan == 0 ? null : new List<object>(entitySpan * 10);



			IDbCommand st = PrepareQueryCommand(queryParameters, false, session);



			IDataReader rs = GetResultSet(st, queryParameters.HasAutoDiscoverScalarTypes, queryParameters.Callable, selection,

										  session);



			// would be great to move all this below here into another method that could also be used

			// from the new scrolling stuff.

			//

			// Would need to change the way the max-row stuff is handled (i.e. behind an interface) so

			// that I could do the control breaking at the means to know when to stop

			LockMode[] lockModeArray = GetLockModes(queryParameters.LockModes);

			EntityKey optionalObjectKey = GetOptionalObjectKey(queryParameters, session);



			bool createSubselects = IsSubselectLoadingEnabled;

			List<EntityKey[]> subselectResultKeys = createSubselects ? new List<EntityKey[]>() : null;

			IList results = new List<object>();



			try

			{

				HandleEmptyCollections(queryParameters.CollectionKeys, rs, session);

				EntityKey[] keys = new EntityKey[entitySpan]; // we can reuse it each time



				if (Log.IsDebugEnabled)

				{

					Log.Debug("processing result set");

				}



				int count;

				for (count = 0; count < maxRows && rs.Read(); count++)

				{

					if (Log.IsDebugEnabled)

					{

						Log.Debug("result set row: " + count);

					}



					object result = GetRowFromResultSet(rs, session, queryParameters, lockModeArray, optionalObjectKey, hydratedObjects,

														keys, returnProxies);

					results.Add(result);



					if (createSubselects)

					{

						subselectResultKeys.Add(keys);

						keys = new EntityKey[entitySpan]; //can't reuse in this case

					}

				}



				if (Log.IsDebugEnabled)

				{

					Log.Debug(string.Format("done processing result set ({0} rows)", count));

				}

			}

			catch (Exception e)

			{

				e.Data["actual-sql-query"] = st.CommandText;

				throw;

			}

			finally

			{

				session.Batcher.CloseCommand(st, rs);

			}



			InitializeEntitiesAndCollections(hydratedObjects, rs, session, queryParameters.IsReadOnly(session));



			if (createSubselects)

			{

				CreateSubselects(subselectResultKeys, queryParameters, session);

			}



			return results;

		}



		protected bool HasSubselectLoadableCollections()

		{

			foreach (ILoadable loadable in EntityPersisters)

			{

				if (loadable.HasSubselectLoadableCollections)

				{

					return true;

				}

			}



			return false;

		}



		private static ISet<EntityKey>[] Transpose(IList<EntityKey[]> keys)

		{

			ISet<EntityKey>[] result = new ISet<EntityKey>[keys[0].Length];

			for (int j = 0; j < result.Length; j++)

			{

				result[j] = new HashedSet<EntityKey>();

				for (int i = 0; i < keys.Count; i++)

				{

					EntityKey key = keys[i][j];

					if (key != null)

					{

						result[j].Add(key);

					}

				}

			}

			return result;

		}



		internal void CreateSubselects(IList<EntityKey[]> keys, QueryParameters queryParameters, ISessionImplementor session)

		{

			if (keys.Count > 1)

			{

				//if we only returned one entity, query by key is more efficient

				var subSelects = CreateSubselects(keys, queryParameters).ToArray();



				foreach (EntityKey[] rowKeys in keys)

				{

					for (int i = 0; i < rowKeys.Length; i++)

					{

						if (rowKeys[i] != null && subSelects[i] != null)

						{

							session.PersistenceContext.BatchFetchQueue.AddSubselect(rowKeys[i], subSelects[i]);

						}

					}

				}

			}

		}



		private IEnumerable<SubselectFetch> CreateSubselects(IList<EntityKey[]> keys, QueryParameters queryParameters)

		{

			// see NH-2123 NH-2125

			ISet<EntityKey>[] keySets = Transpose(keys);

			ILoadable[] loadables = EntityPersisters;

			string[] aliases = Aliases;



			for (int i = 0; i < loadables.Length; i++)

			{

				if (loadables[i].HasSubselectLoadableCollections)

				{

					yield return new SubselectFetch(aliases[i], loadables[i], queryParameters, keySets[i]);

				}

				else

				{

					yield return null;

				}

			}

		}



		internal void InitializeEntitiesAndCollections(IList hydratedObjects, object resultSetId, ISessionImplementor session, bool readOnly)

		{

			ICollectionPersister[] collectionPersisters = CollectionPersisters;

			if (collectionPersisters != null)

			{

				for (int i = 0; i < collectionPersisters.Length; i++)

				{

					if (collectionPersisters[i].IsArray)

					{

						//for arrays, we should end the collection load before resolving

						//the entities, since the actual array instances are not instantiated

						//during loading

						//TODO: or we could do this polymorphically, and have two

						//      different operations implemented differently for arrays

						EndCollectionLoad(resultSetId, session, collectionPersisters[i]);

					}

				}

			}

			//important: reuse the same event instances for performance!

			PreLoadEvent pre;

			PostLoadEvent post;

			if (session.IsEventSource)

			{

				var eventSourceSession = (IEventSource)session;

				pre = new PreLoadEvent(eventSourceSession);

				post = new PostLoadEvent(eventSourceSession);

			}

			else

			{

				pre = null;

				post = null;

			}



			if (hydratedObjects != null)

			{

				int hydratedObjectsSize = hydratedObjects.Count;



				if (Log.IsDebugEnabled)

				{

					Log.Debug(string.Format("total objects hydrated: {0}", hydratedObjectsSize));

				}



				for (int i = 0; i < hydratedObjectsSize; i++)

				{

					TwoPhaseLoad.InitializeEntity(hydratedObjects[i], readOnly, session, pre, post);

				}

			}



			if (collectionPersisters != null)

			{

				for (int i = 0; i < collectionPersisters.Length; i++)

				{

					if (!collectionPersisters[i].IsArray)

					{

						//for sets, we should end the collection load after resolving

						//the entities, since we might call hashCode() on the elements

						//TODO: or we could do this polymorphically, and have two

						//      different operations implemented differently for arrays

						EndCollectionLoad(resultSetId, session, collectionPersisters[i]);

					}

				}

			}

		}



		private static void EndCollectionLoad(object resultSetId, ISessionImplementor session, ICollectionPersister collectionPersister)

		{

			//this is a query and we are loading multiple instances of the same collection role

			session.PersistenceContext.LoadContexts.GetCollectionLoadContext((IDataReader)resultSetId).EndLoadingCollections(

				collectionPersister);

		}



		public virtual IList GetResultList(IList results, IResultTransformer resultTransformer)

		{

			return results;

		}



		/// <summary>

		/// Get the actual object that is returned in the user-visible result list.

		/// </summary>

		/// <remarks>

		/// This empty implementation merely returns its first argument. This is

		/// overridden by some subclasses.

		/// </remarks>

		protected virtual object GetResultColumnOrRow(object[] row, IResultTransformer resultTransformer, IDataReader rs, ISessionImplementor session)

		{

			return row;

		}



		/// <summary>

		/// For missing objects associated by one-to-one with another object in the

		/// result set, register the fact that the the object is missing with the

		/// session.

		/// </summary>

		private void RegisterNonExists(EntityKey[] keys, ISessionImplementor session)

		{

			int[] owners = Owners;

			if (owners != null)

			{

				EntityType[] ownerAssociationTypes = OwnerAssociationTypes;

				for (int i = 0; i < keys.Length; i++)

				{

					int owner = owners[i];

					if (owner > -1)

					{

						EntityKey ownerKey = keys[owner];

						if (keys[i] == null && ownerKey != null)

						{

							bool isOneToOneAssociation = ownerAssociationTypes != null && ownerAssociationTypes[i] != null

														 && ownerAssociationTypes[i].IsOneToOne;

							if (isOneToOneAssociation)

							{

								session.PersistenceContext.AddNullProperty(ownerKey, ownerAssociationTypes[i].PropertyName);

							}

						}

					}

				}

			}

		}



		/// <summary>

		/// Read one collection element from the current row of the ADO.NET result set

		/// </summary>

		private static void ReadCollectionElement(object optionalOwner, object optionalKey, ICollectionPersister persister,

												  ICollectionAliases descriptor, IDataReader rs, ISessionImplementor session)

		{

			IPersistenceContext persistenceContext = session.PersistenceContext;



			object collectionRowKey = persister.ReadKey(rs, descriptor.SuffixedKeyAliases, session);



			if (collectionRowKey != null)

			{

				// we found a collection element in the result set



				if (Log.IsDebugEnabled)

				{

					Log.Debug("found row of collection: " + MessageHelper.InfoString(persister, collectionRowKey));

				}



				object owner = optionalOwner;

				if (owner == null)

				{

					owner = persistenceContext.GetCollectionOwner(collectionRowKey, persister);

					if (owner == null)

					{

						//TODO: This is assertion is disabled because there is a bug that means the

						//      original owner of a transient, uninitialized collection is not known 

						//      if the collection is re-referenced by a different object associated 

						//      with the current Session

						//throw new AssertionFailure("bug loading unowned collection");

					}

				}

				IPersistentCollection rowCollection =

					persistenceContext.LoadContexts.GetCollectionLoadContext(rs).GetLoadingCollection(persister, collectionRowKey);



				if (rowCollection != null)

				{

					rowCollection.ReadFrom(rs, persister, descriptor, owner);

				}

			}

			else if (optionalKey != null)

			{

				// we did not find a collection element in the result set, so we

				// ensure that a collection is created with the owner's identifier,

				// since what we have is an empty collection



				if (Log.IsDebugEnabled)

				{

					Log.Debug("result set contains (possibly empty) collection: " + MessageHelper.InfoString(persister, optionalKey));

				}

				persistenceContext.LoadContexts.GetCollectionLoadContext(rs).GetLoadingCollection(persister, optionalKey);

				// handle empty collection

			}



			// else no collection element, but also no owner

		}



		/// <summary>

		/// If this is a collection initializer, we need to tell the session that a collection

		/// is being initilized, to account for the possibility of the collection having

		/// no elements (hence no rows in the result set).

		/// </summary>

		internal void HandleEmptyCollections(object[] keys, object resultSetId, ISessionImplementor session)

		{

			if (keys != null)

			{

				// this is a collection initializer, so we must create a collection

				// for each of the passed-in keys, to account for the possibility

				// that the collection is empty and has no rows in the result set



				ICollectionPersister[] collectionPersisters = CollectionPersisters;

				for (int j = 0; j < collectionPersisters.Length; j++)

				{

					for (int i = 0; i < keys.Length; i++)

					{

						// handle empty collections

						if (Log.IsDebugEnabled)

						{

							Log.Debug("result set contains (possibly empty) collection: "

									  + MessageHelper.InfoString(collectionPersisters[j], keys[i]));

						}

						session.PersistenceContext.LoadContexts.GetCollectionLoadContext((IDataReader)resultSetId).GetLoadingCollection(

							collectionPersisters[j], keys[i]);

					}

				}

			}

			// else this is not a collection initializer (and empty collections will

			// be detected by looking for the owner's identifier in the result set)

		}



		/// <summary>

		/// Read a row of <c>EntityKey</c>s from the <c>IDataReader</c> into the given array.

		/// </summary>

		/// <remarks>

		/// Warning: this method is side-effecty. If an <c>id</c> is given, don't bother going

		/// to the <c>IDataReader</c>

		/// </remarks>

		private EntityKey GetKeyFromResultSet(int i, IEntityPersister persister, object id, IDataReader rs, ISessionImplementor session)

		{

			object resultId;



			// if we know there is exactly 1 row, we can skip.

			// it would be great if we could _always_ skip this;

			// it is a problem for <key-many-to-one>



			if (IsSingleRowLoader && id != null)

			{

				resultId = id;

			}

			else

			{

				IType idType = persister.IdentifierType;

				resultId = idType.NullSafeGet(rs, EntityAliases[i].SuffixedKeyAliases, session, null);



				bool idIsResultId = id != null && resultId != null && idType.IsEqual(id, resultId, session.EntityMode, _factory);



				if (idIsResultId)

				{

					resultId = id; //use the id passed in

				}

			}



			return resultId == null ? null : new EntityKey(resultId, persister, session.EntityMode);

		}



		/// <summary>

		/// Check the version of the object in the <c>IDataReader</c> against

		/// the object version in the session cache, throwing an exception

		/// if the version numbers are different.

		/// </summary>

		/// <exception cref="StaleObjectStateException"></exception>

		private void CheckVersion(int i, IEntityPersister persister, object id, object entity, IDataReader rs, ISessionImplementor session)

		{

			object version = session.PersistenceContext.GetEntry(entity).Version;



			// null version means the object is in the process of being loaded somewhere else in the ResultSet

			if (version != null)

			{

				IVersionType versionType = persister.VersionType;

				object currentVersion = versionType.NullSafeGet(rs, EntityAliases[i].SuffixedVersionAliases, session, null);

				if (!versionType.IsEqual(version, currentVersion))

				{

					if (session.Factory.Statistics.IsStatisticsEnabled)

					{

						session.Factory.StatisticsImplementor.OptimisticFailure(persister.EntityName);

					}



					throw new StaleObjectStateException(persister.EntityName, id);

				}

			}

		}



		/// <summary>

		/// Resolve any ids for currently loaded objects, duplications within the <c>IDataReader</c>,

		/// etc. Instanciate empty objects to be initialized from the <c>IDataReader</c>. Return an

		/// array of objects (a row of results) and an array of booleans (by side-effect) that determine

		/// wheter the corresponding object should be initialized

		/// </summary>

		private object[] GetRow(IDataReader rs, ILoadable[] persisters, EntityKey[] keys, object optionalObject,

								EntityKey optionalObjectKey, LockMode[] lockModes, IList hydratedObjects,

								ISessionImplementor session)

		{

			int cols = persisters.Length;

			IEntityAliases[] descriptors = EntityAliases;



			if (Log.IsDebugEnabled)

			{

				Log.Debug("result row: " + StringHelper.ToString(keys));

			}



			object[] rowResults = new object[cols];



			for (int i = 0; i < cols; i++)

			{

				object obj = null;

				EntityKey key = keys[i];



				if (keys[i] == null)

				{

					// do nothing

					/* TODO NH-1001 : if (persisters[i]...EntityType) is an OneToMany or a ManyToOne and

					 * the keys.length > 1 and the relation IsIgnoreNotFound probably we are in presence of

					 * an load with "outer join" the relation can be considerer loaded even if the key is null (mean not found)

					*/

				}

				else

				{

					//If the object is already loaded, return the loaded one

					obj = session.GetEntityUsingInterceptor(key);

					if (obj != null)

					{

						//its already loaded so dont need to hydrate it

						InstanceAlreadyLoaded(rs, i, persisters[i], key, obj, lockModes[i], session);

					}

					else

					{

						obj =

							InstanceNotYetLoaded(rs, i, persisters[i], key, lockModes[i], descriptors[i].RowIdAlias, optionalObjectKey,

												 optionalObject, hydratedObjects, session);

					}

				}



				rowResults[i] = obj;

			}

			return rowResults;

		}



		/// <summary>

		/// The entity instance is already in the session cache

		/// </summary>

		private void InstanceAlreadyLoaded(IDataReader rs, int i, IEntityPersister persister, EntityKey key, object obj,

										   LockMode lockMode, ISessionImplementor session)

		{

			if (!persister.IsInstance(obj, session.EntityMode))

			{

				string errorMsg = string.Format("loading object was of wrong class [{0}]", obj.GetType().FullName);

				throw new WrongClassException(errorMsg, key.Identifier, persister.EntityName);

			}



			if (LockMode.None != lockMode && UpgradeLocks())

			{

				EntityEntry entry = session.PersistenceContext.GetEntry(obj);

				bool isVersionCheckNeeded = persister.IsVersioned && entry.LockMode.LessThan(lockMode);



				// we don't need to worry about existing version being uninitialized

				// because this block isn't called by a re-entrant load (re-entrant

				// load _always_ have lock mode NONE

				if (isVersionCheckNeeded)

				{

					// we only check the version when _upgrading_ lock modes

					CheckVersion(i, persister, key.Identifier, obj, rs, session);

					// we need to upgrade the lock mode to the mode requested

					entry.LockMode = lockMode;

				}

			}

		}



		/// <summary>

		/// The entity instance is not in the session cache

		/// </summary>

		private object InstanceNotYetLoaded(IDataReader dr, int i, ILoadable persister, EntityKey key, LockMode lockMode,

											string rowIdAlias, EntityKey optionalObjectKey, object optionalObject,

											IList hydratedObjects, ISessionImplementor session)

		{

			object obj;



			string instanceClass = GetInstanceClass(dr, i, persister, key.Identifier, session);



			if (optionalObjectKey != null && key.Equals(optionalObjectKey))

			{

				// its the given optional object

				obj = optionalObject;

			}

			else

			{

				obj = session.Instantiate(instanceClass, key.Identifier);

			}



			// need to hydrate it



			// grab its state from the DataReader and keep it in the Session

			// (but don't yet initialize the object itself)

			// note that we acquired LockMode.READ even if it was not requested

			LockMode acquiredLockMode = lockMode == LockMode.None ? LockMode.Read : lockMode;

			LoadFromResultSet(dr, i, obj, instanceClass, key, rowIdAlias, acquiredLockMode, persister, session);



			// materialize associations (and initialize the object) later

			hydratedObjects.Add(obj);



			return obj;

		}



		private bool IsEagerPropertyFetchEnabled(int i)

		{

			bool[] array = EntityEagerPropertyFetches;

			return array != null && array[i];

		}



		/// <summary>

		/// Hydrate the state of an object from the SQL <c>IDataReader</c>, into

		/// an array of "hydrated" values (do not resolve associations yet),

		/// and pass the hydrated state to the session.

		/// </summary>

		private void LoadFromResultSet(IDataReader rs, int i, object obj, string instanceClass, EntityKey key,

									   string rowIdAlias, LockMode lockMode, ILoadable rootPersister,

									   ISessionImplementor session)

		{

			object id = key.Identifier;



			// Get the persister for the _subclass_

			ILoadable persister = (ILoadable)Factory.GetEntityPersister(instanceClass);



			if (Log.IsDebugEnabled)

			{

				Log.Debug("Initializing object from DataReader: " + MessageHelper.InfoString(persister, id));

			}



			bool eagerPropertyFetch = IsEagerPropertyFetchEnabled(i);



			// add temp entry so that the next step is circular-reference

			// safe - only needed because some types don't take proper

			// advantage of two-phase-load (esp. components)

			TwoPhaseLoad.AddUninitializedEntity(key, obj, persister, lockMode, !eagerPropertyFetch, session);



			// This is not very nice (and quite slow):

			string[][] cols = persister == rootPersister

								? EntityAliases[i].SuffixedPropertyAliases

								: EntityAliases[i].GetSuffixedPropertyAliases(persister);



			object[] values = persister.Hydrate(rs, id, obj, rootPersister, cols, eagerPropertyFetch, session);



			object rowId = persister.HasRowId ? rs[rowIdAlias] : null;



			IAssociationType[] ownerAssociationTypes = OwnerAssociationTypes;

			if (ownerAssociationTypes != null && ownerAssociationTypes[i] != null)

			{

				string ukName = ownerAssociationTypes[i].RHSUniqueKeyPropertyName;

				if (ukName != null)

				{

					int index = ((IUniqueKeyLoadable)persister).GetPropertyIndex(ukName);

					IType type = persister.PropertyTypes[index];



					// polymorphism not really handled completely correctly,

					// perhaps...well, actually its ok, assuming that the

					// entity name used in the lookup is the same as the

					// the one used here, which it will be



					EntityUniqueKey euk =

						new EntityUniqueKey(rootPersister.EntityName, ukName, type.SemiResolve(values[index], session, obj), type,

											session.EntityMode, session.Factory);

					session.PersistenceContext.AddEntity(euk, obj);

				}

			}



			TwoPhaseLoad.PostHydrate(persister, id, values, rowId, obj, lockMode, !eagerPropertyFetch, session);

		}



		/// <summary>

		/// Determine the concrete class of an instance for the <c>IDataReader</c>

		/// </summary>

		private string GetInstanceClass(IDataReader rs, int i, ILoadable persister, object id, ISessionImplementor session)

		{

			if (persister.HasSubclasses)

			{

				// code to handle subclasses of topClass

				object discriminatorValue =

					persister.DiscriminatorType.NullSafeGet(rs, EntityAliases[i].SuffixedDiscriminatorAlias, session, null);



				string result = persister.GetSubclassForDiscriminatorValue(discriminatorValue);



				if (result == null)

				{

					// woops we got an instance of another class hierarchy branch.

					throw new WrongClassException(string.Format("Discriminator was: '{0}'", discriminatorValue), id,

												  persister.EntityName);

				}



				return result;

			}

			return persister.EntityName;

		}



		/// <summary>

		/// Advance the cursor to the first required row of the <c>IDataReader</c>

		/// </summary>

		internal static void Advance(IDataReader rs, RowSelection selection)

		{

			int firstRow = GetFirstRow(selection);



			if (firstRow != 0)

			{

				// DataReaders are forward-only, readonly, so we have to step through

				for (int i = 0; i < firstRow; i++)

				{

					rs.Read();

				}

			}

		}



		internal static bool HasMaxRows(RowSelection selection)

		{

			// it used to be selection.MaxRows != null -> since an Int32 will always

			// have a value I'll compare it to the static field NoValue used to initialize 

			// max rows to nothing

			return selection != null && selection.MaxRows != RowSelection.NoValue;

		}



		private static bool HasOffset(RowSelection selection)

		{

			return selection != null && selection.FirstRow != RowSelection.NoValue;

		}



		internal static int GetFirstRow(RowSelection selection)

		{

			if (selection == null || !selection.DefinesLimits)

			{

				return 0;

			}

			return selection.FirstRow > 0 ? selection.FirstRow : 0;

		}



		/// <summary>

		/// Should we pre-process the SQL string, adding a dialect-specific

		/// LIMIT clause.

		/// </summary>

		/// <param name="selection"></param>

		/// <param name="dialect"></param>

		/// <returns></returns>

		internal bool UseLimit(RowSelection selection, Dialect.Dialect dialect)

		{

			return dialect.SupportsLimit && (HasMaxRows(selection) || HasOffset(selection));

		}



		/// <summary>

		/// Performs dialect-specific manipulations on the offset value before returning it.

		/// This method is applicable for use in limit statements only.

		/// </summary>

		internal static int? GetOffsetUsingDialect(RowSelection selection, Dialect.Dialect dialect)

		{

			int firstRow = GetFirstRow(selection);

			if (firstRow == 0)

				return null;

			return dialect.GetOffsetValue(firstRow);

		}



		/// <summary>

		/// Performs dialect-specific manipulations on the limit value before returning it.

		/// This method is applicable for use in limit statements only.

		/// </summary>

		internal static int? GetLimitUsingDialect(RowSelection selection, Dialect.Dialect dialect)

		{

			if (selection == null || selection.MaxRows == RowSelection.NoValue)

				return null;

			return dialect.GetLimitValue(GetFirstRow(selection), selection.MaxRows);

		}



		/// <summary>

		/// Obtain an <c>IDbCommand</c> with all parameters pre-bound. Bind positional parameters,

		/// named parameters, and limit parameters.

		/// </summary>

		/// <remarks>

		/// Creates an IDbCommand object and populates it with the values necessary to execute it against the 

		/// database to Load an Entity.

		/// </remarks>

		/// <param name="queryParameters">The <see cref="QueryParameters"/> to use for the IDbCommand.</param>

		/// <param name="scroll">TODO: find out where this is used...</param>

		/// <param name="session">The SessionImpl this Command is being prepared in.</param>

		/// <returns>A CommandWrapper wrapping an IDbCommand that is ready to be executed.</returns>

		protected internal virtual IDbCommand PrepareQueryCommand(QueryParameters queryParameters, bool scroll, ISessionImplementor session)

		{

			ISqlCommand sqlCommand = CreateSqlCommand(queryParameters, session);

			SqlString sqlString = sqlCommand.Query;



			sqlCommand.ResetParametersIndexesForTheCommand(0);

			IDbCommand command = session.Batcher.PrepareQueryCommand(CommandType.Text, sqlString, sqlCommand.ParameterTypes);



			try

			{

				RowSelection selection = queryParameters.RowSelection;

				if (selection != null && selection.Timeout != RowSelection.NoValue)

				{

					command.CommandTimeout = selection.Timeout;

				}



				sqlCommand.Bind(command, session);



				IDriver driver = _factory.ConnectionProvider.Driver;

				driver.RemoveUnusedCommandParameters(command, sqlString);

				driver.ExpandQueryParameters(command, sqlString);

			}

			catch (HibernateException)

			{

				session.Batcher.CloseCommand(command, null);

				throw;

			}

			catch (Exception sqle)

			{

				session.Batcher.CloseCommand(command, null);

				ADOExceptionReporter.LogExceptions(sqle);

				throw;

			}

			return command;

		}



		/// <summary> 

		/// Some dialect-specific LIMIT clauses require the maximium last row number

		/// (aka, first_row_number + total_row_count), while others require the maximum

		/// returned row count (the total maximum number of rows to return). 

		/// </summary>

		/// <param name="selection">The selection criteria </param>

		/// <param name="dialect">The dialect </param>

		/// <returns> The appropriate value to bind into the limit clause. </returns>

		internal static int GetMaxOrLimit(Dialect.Dialect dialect, RowSelection selection)

		{

			int firstRow = GetFirstRow(selection);

			int rowCount = selection.MaxRows;



			if (rowCount == RowSelection.NoValue)

				return int.MaxValue;



			return dialect.GetLimitValue(firstRow, rowCount);

		}



		/// <summary>

		/// Fetch a <c>IDbCommand</c>, call <c>SetMaxRows</c> and then execute it,

		/// advance to the first result and return an SQL <c>IDataReader</c>

		/// </summary>

		/// <param name="st">The <see cref="IDbCommand" /> to execute.</param>

		/// <param name="selection">The <see cref="RowSelection"/> to apply to the <see cref="IDbCommand"/> and <see cref="IDataReader"/>.</param>

		/// <param name="autoDiscoverTypes">true if result types need to be auto-discovered by the loader; false otherwise.</param>

		/// <param name="session">The <see cref="ISession" /> to load in.</param>

		/// <param name="callable"></param>

		/// <returns>An IDataReader advanced to the first record in RowSelection.</returns>

		protected IDataReader GetResultSet(IDbCommand st, bool autoDiscoverTypes, bool callable, RowSelection selection, ISessionImplementor session)

		{

			IDataReader rs = null;

			try

			{

				Log.Info(st.CommandText);

				// TODO NH: Callable

				rs = session.Batcher.ExecuteReader(st);



				//NH: this is checked outside the WrapResultSet because we

				// want to avoid the syncronization overhead in the vast majority

				// of cases where IsWrapResultSetsEnabled is set to false

				if (session.Factory.Settings.IsWrapResultSetsEnabled)

					rs = WrapResultSet(rs);



				Dialect.Dialect dialect = session.Factory.Dialect;

				if (!dialect.SupportsLimitOffset || !UseLimit(selection, dialect))

				{

					Advance(rs, selection);

				}



				if (autoDiscoverTypes)

				{

					AutoDiscoverTypes(rs);

				}

				return rs;

			}

			catch (Exception sqle)

			{

				ADOExceptionReporter.LogExceptions(sqle);

				session.Batcher.CloseCommand(st, rs);

				throw;

			}

		}



		protected virtual void AutoDiscoverTypes(IDataReader rs)

		{

			throw new AssertionFailure("Auto discover types not supported in this loader");

		}



		[MethodImpl(MethodImplOptions.Synchronized)]

		private IDataReader WrapResultSet(IDataReader rs)

		{

			// synchronized to avoid multi-thread access issues; defined as method synch to avoid

			// potential deadlock issues due to nature of code.

			try

			{

				Log.Debug("Wrapping result set [" + rs + "]");

				return new ResultSetWrapper(rs, RetreiveColumnNameToIndexCache(rs));

			}

			catch (Exception e)

			{

				Log.Info("Error wrapping result set", e);

				return rs;

			}

		}



		private ColumnNameCache RetreiveColumnNameToIndexCache(IDataReader rs)

		{

			if (_columnNameCache == null)

			{

				Log.Debug("Building columnName->columnIndex cache");

				_columnNameCache = new ColumnNameCache(rs.GetSchemaTable().Rows.Count);

			}



			return _columnNameCache;

		}



		/// <summary>

		/// Called by subclasses that load entities

		/// </summary>

		protected IList LoadEntity(ISessionImplementor session, object id, IType identifierType, object optionalObject,

								   string optionalEntityName, object optionalIdentifier, IEntityPersister persister)

		{

			if (Log.IsDebugEnabled)

			{

				Log.Debug("loading entity: " + MessageHelper.InfoString(persister, id, identifierType, Factory));

			}



			IList result;



			try

			{

				QueryParameters qp =

					new QueryParameters(new IType[] { identifierType }, new object[] { id }, optionalObject, optionalEntityName,

										optionalIdentifier);

				result = DoQueryAndInitializeNonLazyCollections(session, qp, false);

			}

			catch (HibernateException)

			{

				throw;

			}

			catch (Exception sqle)

			{

				ILoadable[] persisters = EntityPersisters;

				throw ADOExceptionHelper.Convert(Factory.SQLExceptionConverter, sqle,

												 "could not load an entity: "

												 +

												 MessageHelper.InfoString(persisters[persisters.Length - 1], id, identifierType,

																		  Factory), SqlString);

			}



			Log.Debug("done entity load");



			return result;

		}



		protected IList LoadEntity(ISessionImplementor session, object key, object index, IType keyType, IType indexType,

								   IEntityPersister persister)

		{

			Log.Debug("loading collection element by index");



			IList result;

			try

			{

				result =

					DoQueryAndInitializeNonLazyCollections(session,

														   new QueryParameters(new IType[] { keyType, indexType },

																			   new object[] { key, index }), false);

			}

			catch (Exception sqle)

			{

				throw ADOExceptionHelper.Convert(_factory.SQLExceptionConverter, sqle, "could not collection element by index",

												 SqlString);

			}



			Log.Debug("done entity load");



			return result;

		}



		/// <summary>

		/// Called by subclasses that batch load entities

		/// </summary>

		protected internal IList LoadEntityBatch(ISessionImplementor session, object[] ids, IType idType,

												 object optionalObject, string optionalEntityName, object optionalId,

												 IEntityPersister persister)

		{

			if (Log.IsDebugEnabled)

			{

				Log.Debug("batch loading entity: " + MessageHelper.InfoString(persister, ids, Factory));

			}



			IType[] types = new IType[ids.Length];

			ArrayHelper.Fill(types, idType);

			IList result;

			try

			{

				result =

					DoQueryAndInitializeNonLazyCollections(session,

														   new QueryParameters(types, ids, optionalObject, optionalEntityName,

																			   optionalId), false);

			}

			catch (HibernateException)

			{

				throw;

			}

			catch (Exception sqle)

			{

				throw ADOExceptionHelper.Convert(Factory.SQLExceptionConverter, sqle,

												 "could not load an entity batch: "

												 + MessageHelper.InfoString(persister, ids, Factory), SqlString);

				// NH: Hibernate3 passes EntityPersisters[0] instead of persister, I think it's wrong.

			}



			Log.Debug("done entity batch load");

			return result;

		}



		/// <summary>

		/// Called by subclasses that load collections

		/// </summary>

		public void LoadCollection(ISessionImplementor session, object id, IType type)

		{

			if (Log.IsDebugEnabled)

			{

				Log.Debug("loading collection: " + MessageHelper.InfoString(CollectionPersisters[0], id));

			}



			object[] ids = new object[] { id };

			try

			{

				DoQueryAndInitializeNonLazyCollections(session, new QueryParameters(new IType[] { type }, ids, ids), true);

			}

			catch (HibernateException)

			{

				// Do not call Convert on HibernateExceptions

				throw;

			}

			catch (Exception sqle)

			{

				throw ADOExceptionHelper.Convert(Factory.SQLExceptionConverter, sqle,

												 "could not initialize a collection: "

												 + MessageHelper.InfoString(CollectionPersisters[0], id), SqlString);

			}



			Log.Debug("done loading collection");

		}



		/// <summary>

		/// Called by wrappers that batch initialize collections

		/// </summary>

		public void LoadCollectionBatch(ISessionImplementor session, object[] ids, IType type)

		{

			if (Log.IsDebugEnabled)

			{

				Log.Debug("batch loading collection: " + MessageHelper.InfoString(CollectionPersisters[0], ids));

			}



			IType[] idTypes = new IType[ids.Length];

			ArrayHelper.Fill(idTypes, type);

			try

			{

				DoQueryAndInitializeNonLazyCollections(session, new QueryParameters(idTypes, ids, ids), true);

			}

			catch (HibernateException)

			{

				// Do not call Convert on HibernateExceptions

				throw;

			}

			catch (Exception sqle)

			{

				throw ADOExceptionHelper.Convert(Factory.SQLExceptionConverter, sqle,

												 "could not initialize a collection batch: "

												 + MessageHelper.InfoString(CollectionPersisters[0], ids), SqlString);

			}



			Log.Debug("done batch load");

		}



		/// <summary>

		/// Called by subclasses that batch initialize collections

		/// </summary>

		protected void LoadCollectionSubselect(ISessionImplementor session, object[] ids, object[] parameterValues,

											   IType[] parameterTypes, IDictionary<string, TypedValue> namedParameters,

											   IType type)

		{

			try

			{

				DoQueryAndInitializeNonLazyCollections(session,

													   new QueryParameters(parameterTypes, parameterValues, namedParameters, ids),

													   true);

			}

			catch (HibernateException)

			{

				// Do not call Convert on HibernateExceptions

				throw;

			}

			catch (Exception sqle)

			{

				throw ADOExceptionHelper.Convert(Factory.SQLExceptionConverter, sqle,

												 "could not load collection by subselect: "

												 + MessageHelper.InfoString(CollectionPersisters[0], ids), SqlString,

												 parameterValues, namedParameters);

			}

		}



		/// <summary>

		/// Return the query results, using the query cache, called

		/// by subclasses that implement cacheable queries

		/// </summary>

		/// <param name="session"></param>

		/// <param name="queryParameters"></param>

		/// <param name="querySpaces"></param>

		/// <param name="resultTypes"></param>

		/// <returns></returns>

		protected IList List(ISessionImplementor session, QueryParameters queryParameters, ISet<string> querySpaces, IType[] resultTypes)

		{

			bool cacheable = _factory.Settings.IsQueryCacheEnabled && queryParameters.Cacheable;



			if (cacheable)

			{

				return ListUsingQueryCache(session, queryParameters, querySpaces, resultTypes);

			}

			return ListIgnoreQueryCache(session, queryParameters);

		}



		private IList ListIgnoreQueryCache(ISessionImplementor session, QueryParameters queryParameters)

		{

			return GetResultList(DoList(session, queryParameters), queryParameters.ResultTransformer);

		}



		private IList ListUsingQueryCache(ISessionImplementor session, QueryParameters queryParameters, ISet<string> querySpaces, IType[] resultTypes)

		{

			IQueryCache queryCache = _factory.GetQueryCache(queryParameters.CacheRegion);



			ISet filterKeys = FilterKey.CreateFilterKeys(session.EnabledFilters, session.EntityMode);

			QueryKey key = new QueryKey(Factory, SqlString, queryParameters, filterKeys);



			IList result = GetResultFromQueryCache(session, queryParameters, querySpaces, resultTypes, queryCache, key);



			if (result == null)

			{

				result = DoList(session, queryParameters);

				PutResultInQueryCache(session, queryParameters, resultTypes, queryCache, key, result);

			}



			return GetResultList(result, queryParameters.ResultTransformer);

		}



		private IList GetResultFromQueryCache(ISessionImplementor session, QueryParameters queryParameters,

											  ISet<string> querySpaces, IType[] resultTypes, IQueryCache queryCache,

											  QueryKey key)

		{

			IList result = null;



			if ((!queryParameters.ForceCacheRefresh) && (session.CacheMode & CacheMode.Get) == CacheMode.Get)

			{

				IPersistenceContext persistenceContext = session.PersistenceContext;



				bool defaultReadOnlyOrig = persistenceContext.DefaultReadOnly;



				if (queryParameters.IsReadOnlyInitialized)

					persistenceContext.DefaultReadOnly = queryParameters.ReadOnly;

				else

					queryParameters.ReadOnly = persistenceContext.DefaultReadOnly;



				try

				{

					result = queryCache.Get(key, resultTypes, queryParameters.NaturalKeyLookup, querySpaces, session);

					if (_factory.Statistics.IsStatisticsEnabled)

					{

						if (result == null)

						{

							_factory.StatisticsImplementor.QueryCacheMiss(QueryIdentifier, queryCache.RegionName);

						}

						else

						{

							_factory.StatisticsImplementor.QueryCacheHit(QueryIdentifier, queryCache.RegionName);

						}

					}

				}

				finally

				{

					persistenceContext.DefaultReadOnly = defaultReadOnlyOrig;

				}

			}

			return result;

		}



		private void PutResultInQueryCache(ISessionImplementor session, QueryParameters queryParameters, IType[] resultTypes,

										   IQueryCache queryCache, QueryKey key, IList result)

		{

			if ((session.CacheMode & CacheMode.Put) == CacheMode.Put)

			{

				bool put = queryCache.Put(key, resultTypes, result, queryParameters.NaturalKeyLookup, session);

				if (put && _factory.Statistics.IsStatisticsEnabled)

				{

					_factory.StatisticsImplementor.QueryCachePut(QueryIdentifier, queryCache.RegionName);

				}

			}

		}



		/// <summary>

		/// Actually execute a query, ignoring the query cache

		/// </summary>

		/// <param name="session"></param>

		/// <param name="queryParameters"></param>

		/// <returns></returns>

		protected IList DoList(ISessionImplementor session, QueryParameters queryParameters)

		{

			bool statsEnabled = Factory.Statistics.IsStatisticsEnabled;

			var stopWatch = new Stopwatch();

			if (statsEnabled)

			{

				stopWatch.Start();

			}



			IList result;

			try

			{

				result = DoQueryAndInitializeNonLazyCollections(session, queryParameters, true);

			}

			catch (HibernateException)

			{

				// Do not call Convert on HibernateExceptions

				throw;

			}

			catch (Exception sqle)

			{

				throw ADOExceptionHelper.Convert(Factory.SQLExceptionConverter, sqle, "could not execute query", SqlString,

												 queryParameters.PositionalParameterValues, queryParameters.NamedParameters);

			}

			if (statsEnabled)

			{

				stopWatch.Stop();

				Factory.StatisticsImplementor.QueryExecuted(QueryIdentifier, result.Count, stopWatch.Elapsed);

			}

			return result;

		}



		/// <summary>

		/// Calculate and cache select-clause suffixes. Must be

		/// called by subclasses after instantiation.

		/// </summary>

		protected virtual void PostInstantiate() { }



		/// <summary> 

		/// Identifies the query for statistics reporting, if null,

		/// no statistics will be reported

		/// </summary>

		public virtual string QueryIdentifier

		{

			get { return null; }

		}



		public override string ToString()

		{

			return GetType().FullName + '(' + SqlString + ')';

		}



		#region NHibernate specific



		public virtual ISqlCommand CreateSqlCommand(QueryParameters queryParameters, ISessionImplementor session)

		{

			// A distinct-copy of parameter specifications collected during query construction

			var parameterSpecs = new HashSet<IParameterSpecification>(GetParameterSpecifications());

			SqlString sqlString = SqlString.Copy();



			// dynamic-filter parameters: during the createion of the SqlString of allLoader implementation, filters can be added as SQL_TOKEN/string for this reason we have to re-parse the SQL.

			sqlString = ExpandDynamicFilterParameters(sqlString, parameterSpecs, session);

			AdjustQueryParametersForSubSelectFetching(sqlString, parameterSpecs, queryParameters);



			// Add limits

			sqlString = AddLimitsParametersIfNeeded(sqlString, parameterSpecs, queryParameters, session);



			// The PreprocessSQL method can modify the SqlString but should never add parameters (or we have to override it)

			sqlString = PreprocessSQL(sqlString, queryParameters, session.Factory.Dialect);



			// After the last modification to the SqlString we can collect all parameters types (there are cases where we can't infer the type during the creation of the query)

			ResetEffectiveExpectedType(parameterSpecs, queryParameters);



			return new SqlCommandImpl(sqlString, parameterSpecs, queryParameters, session.Factory);

		}



		protected virtual void ResetEffectiveExpectedType(IEnumerable<IParameterSpecification> parameterSpecs, QueryParameters queryParameters)

		{

			// Have to be overridden just by those loaders that can't infer the type during the parse process

		}



		protected abstract IEnumerable<IParameterSpecification> GetParameterSpecifications();



		protected void AdjustQueryParametersForSubSelectFetching(SqlString filteredSqlString, IEnumerable<IParameterSpecification> parameterSpecsWithFilters, QueryParameters queryParameters)

		{

			queryParameters.ProcessedSql = filteredSqlString;

			queryParameters.ProcessedSqlParameters = parameterSpecsWithFilters.ToList();

			if (queryParameters.RowSelection != null)

			{

				queryParameters.ProcessedRowSelection = new RowSelection { FirstRow = queryParameters.RowSelection.FirstRow, MaxRows = queryParameters.RowSelection.MaxRows };

			}

		}



		protected SqlString ExpandDynamicFilterParameters(SqlString sqlString, ICollection<IParameterSpecification> parameterSpecs, ISessionImplementor session)

		{

			var enabledFilters = session.EnabledFilters;

			if (enabledFilters.Count == 0 || sqlString.ToString().IndexOf(ParserHelper.HqlVariablePrefix) < 0)

			{

				return sqlString;

			}



			Dialect.Dialect dialect = session.Factory.Dialect;

			string symbols = ParserHelper.HqlSeparators + dialect.OpenQuote + dialect.CloseQuote;



			var originSql = sqlString.Compact();

			var result = new SqlStringBuilder();

			foreach (var sqlPart in originSql.Parts)

			{

				var parameter = sqlPart as Parameter;

				if (parameter != null)

				{

					result.Add(parameter);

					continue;

				}



				var sqlFragment = sqlPart.ToString();

				var tokens = new StringTokenizer(sqlFragment, symbols, true);



				foreach (string token in tokens)

				{

					if (token.StartsWith(ParserHelper.HqlVariablePrefix))

					{

						string filterParameterName = token.Substring(1);

						string[] parts = StringHelper.ParseFilterParameterName(filterParameterName);

						string filterName = parts[0];

						string parameterName = parts[1];

						var filter = (FilterImpl)enabledFilters[filterName];



						object value = filter.GetParameter(parameterName);

						IType type = filter.FilterDefinition.GetParameterType(parameterName);

						int parameterColumnSpan = type.GetColumnSpan(session.Factory);

						var collectionValue = value as ICollection;

						int? collectionSpan = null;



						// Add query chunk

						string typeBindFragment = string.Join(", ", Enumerable.Repeat("?", parameterColumnSpan).ToArray());

						string bindFragment;

						if (collectionValue != null && !type.ReturnedClass.IsArray)

						{

							collectionSpan = collectionValue.Count;

							bindFragment = string.Join(", ", Enumerable.Repeat(typeBindFragment, collectionValue.Count).ToArray());

						}

						else

						{

							bindFragment = typeBindFragment;

						}



						// dynamic-filter parameter tracking

						var filterParameterFragment = SqlString.Parse(bindFragment);

						var dynamicFilterParameterSpecification = new DynamicFilterParameterSpecification(filterName, parameterName, type, collectionSpan);

						var parameters = filterParameterFragment.GetParameters().ToArray();

						var sqlParameterPos = 0;

						var paramTrackers = dynamicFilterParameterSpecification.GetIdsForBackTrack(session.Factory);

						foreach (var paramTracker in paramTrackers)

						{

							parameters[sqlParameterPos++].BackTrack = paramTracker;

						}



						parameterSpecs.Add(dynamicFilterParameterSpecification);

						result.Add(filterParameterFragment);

					}

					else

					{

						result.Add(token);

					}

				}

			}

			return result.ToSqlString().Compact();

		}



		protected SqlString AddLimitsParametersIfNeeded(SqlString sqlString, ICollection<IParameterSpecification> parameterSpecs, QueryParameters queryParameters, ISessionImplementor session)

		{

			var sessionFactory = session.Factory;

			Dialect.Dialect dialect = sessionFactory.Dialect;



			RowSelection selection = queryParameters.RowSelection;

			bool useLimit = UseLimit(selection, dialect);

			if (useLimit)

			{

				bool hasFirstRow = GetFirstRow(selection) > 0;

				bool useOffset = hasFirstRow && dialect.SupportsLimitOffset;

				int max = GetMaxOrLimit(dialect, selection);

				int? skip = useOffset ? (int?)dialect.GetOffsetValue(GetFirstRow(selection)) : null;

				int? take = max != int.MaxValue ? (int?)max : null;



				Parameter skipSqlParameter = null;

				Parameter takeSqlParameter = null;

				if (skip.HasValue)

				{

					var skipParameter = new QuerySkipParameterSpecification();

					skipSqlParameter = Parameter.Placeholder;

					skipSqlParameter.BackTrack = EnumerableExtensions.First(skipParameter.GetIdsForBackTrack(sessionFactory));

					parameterSpecs.Add(skipParameter);

				}

				if (take.HasValue)

				{

					var takeParameter = new QueryTakeParameterSpecification();

					takeSqlParameter = Parameter.Placeholder;

					takeSqlParameter.BackTrack = EnumerableExtensions.First(takeParameter.GetIdsForBackTrack(sessionFactory));

					parameterSpecs.Add(takeParameter);

				}

				// The dialect can move the given parameters where he need, what it can't do is generates new parameters loosing the BackTrack.

				return dialect.GetLimitString(sqlString, skip, take, skipSqlParameter, takeSqlParameter);

			}

			return sqlString;

		}



		#endregion

	}

}