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CacheableResultTransformer.cs
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CacheableResultTransformer.cs
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using System;
using System.Collections;
using NHibernate.SqlCommand;
using NHibernate.Type;
using NHibernate.Util;
namespace NHibernate.Transform
{
/// <summary>
/// A ResultTransformer that is used to transform tuples to a value(s) that can be cached.
/// </summary>
/// @author Gail Badner
[Serializable]
public class CacheableResultTransformer : IResultTransformer
{
// Applies to Java original:
// would be nice to be able to have this class extend
// PassThroughResultTransformer, but the default constructor
// is private (as it should be for a singleton)
//private const PassThroughResultTransformer ACTUAL_TRANSFORMER =
// PassThroughResultTransformer.INSTANCE;
private readonly PassThroughResultTransformer _actualTransformer = PassThroughResultTransformer.Instance;
public bool AutoDiscoverTypes { get; }
/// <summary>
/// The auto-discovered aliases.
/// </summary>
public string[] AutoDiscoveredAliases { get; private set; }
private readonly SqlString _autoDiscoveredQuery;
private readonly bool _skipTransformer;
private int _tupleLength;
private int _tupleSubsetLength;
/// <summary>
/// Array with the i-th element indicating whether the i-th
/// expression returned by a query is included in the tuple.
/// </summary>
/// IMPLEMENTATION NOTE:
/// "joined" and "fetched" associations may use the same SQL,
/// but result in different tuple and cached values. This is
/// because "fetched" associations are excluded from the tuple.
/// includeInTuple provides a way to distinguish these 2 cases.
private bool[] _includeInTuple;
/// <summary>
/// Indexes for tuple that are included in the transformation.
/// Set to null if all elements in the tuple are included.
/// </summary>
private int[] _includeInTransformIndex;
/// <summary>
/// Returns a CacheableResultTransformer that is used to transform
/// tuples to a value(s) that can be cached.
/// </summary>
/// <param name="transformer">result transformer that will ultimately be used (after caching results)</param>
/// <param name="aliases">the aliases that correspond to the tuple;
/// if it is non-null, its length must equal the number
/// of true elements in includeInTuple[]</param>
/// <param name="includeInTuple">array with the i-th element indicating
/// whether the i-th expression returned by a query is
/// included in the tuple; the number of true values equals
/// the length of the tuple that will be transformed;
/// must be non-null</param>
/// <returns>a CacheableResultTransformer that is used to transform
/// tuples to a value(s) that can be cached.</returns>
// Since v5.1
[Obsolete("Please use overload with skipTransformer parameter.")]
public static CacheableResultTransformer Create(IResultTransformer transformer,
string[] aliases,
bool[] includeInTuple)
{
return Create(transformer, aliases, includeInTuple, false, null);
}
// Since 5.2
[Obsolete("Please use overload with skipTransformer parameter.")]
public static CacheableResultTransformer Create(
IResultTransformer transformer, string[] aliases, bool[] includeInTuple, bool autoDiscoverTypes,
SqlString autoDiscoveredQuery)
{
return autoDiscoverTypes
? Create(autoDiscoveredQuery)
: Create(includeInTuple, GetIncludeInTransform(transformer, aliases, includeInTuple), false);
}
/// <summary>
/// Returns a CacheableResultTransformer that is used to transform
/// tuples to a value(s) that can be cached.
/// </summary>
/// <param name="transformer">result transformer that will ultimately be used (after caching results)</param>
/// <param name="aliases">the aliases that correspond to the tuple;
/// if it is non-null, its length must equal the number
/// of true elements in includeInTuple[]</param>
/// <param name="includeInTuple">array with the i-th element indicating
/// whether the i-th expression returned by a query is
/// included in the tuple; the number of true values equals
/// the length of the tuple that will be transformed;
/// must be non-null</param>
/// <param name="autoDiscoverTypes">Indicates if types auto-discovery is enabled.</param>
/// <param name="autoDiscoveredQuery">If <paramref name="autoDiscoverTypes"/>, the query for which they
/// will be autodiscovered.</param>
/// <param name="skipTransformer">If true cache results untransformed.</param>
/// <returns>a CacheableResultTransformer that is used to transform
/// tuples to a value(s) that can be cached.</returns>
public static CacheableResultTransformer Create(
IResultTransformer transformer,
string[] aliases,
bool[] includeInTuple,
bool autoDiscoverTypes,
SqlString autoDiscoveredQuery,
bool skipTransformer)
{
return autoDiscoverTypes
? Create(autoDiscoveredQuery)
: Create(
includeInTuple,
skipTransformer
? null
: GetIncludeInTransform(transformer, aliases, includeInTuple),
skipTransformer);
}
/// <summary>
/// Returns a CacheableResultTransformer that is used to transform
/// tuples to a value(s) that can be cached.
/// </summary>
/// <param name="includeInTuple">array with the i-th element indicating
/// whether the i-th expression returned by a query is
/// included in the tuple; the number of true values equals
/// the length of the tuple that will be transformed;
/// must be non-null</param>
/// <param name="includeInTransform">Indexes that are included in the transformation.
/// <c>null</c> if all elements in the tuple are included.</param>
/// <param name="skipTransformer"></param>
/// <returns>a CacheableResultTransformer that is used to transform
/// tuples to a value(s) that can be cached.</returns>
private static CacheableResultTransformer Create(bool[] includeInTuple, bool[] includeInTransform, bool skipTransformer)
{
return new CacheableResultTransformer(includeInTuple, includeInTransform, skipTransformer);
}
private static CacheableResultTransformer Create(SqlString autoDiscoveredQuery)
{
return new CacheableResultTransformer(autoDiscoveredQuery);
}
private static bool[] GetIncludeInTransform(IResultTransformer transformer, string[] aliases, bool[] includeInTuple)
{
if (!(transformer is ITupleSubsetResultTransformer resultTransformer))
return null;
var tupleLength = ArrayHelper.CountTrue(includeInTuple);
if (aliases != null && aliases.Length != tupleLength)
{
throw new ArgumentException(
$"If {nameof(aliases)} is not null, then the length of {nameof(aliases)}[] must equal the number " +
$"of true elements in {nameof(includeInTuple)}; " +
$"{nameof(aliases)}.Length={aliases.Length}; tuple 'true' length={tupleLength}",
nameof(aliases));
}
return resultTransformer.IncludeInTransform(aliases, tupleLength);
}
private CacheableResultTransformer(bool[] includeInTuple, bool[] includeInTransform, bool skipTransformer)
{
_skipTransformer = skipTransformer;
InitializeTransformer(includeInTuple, includeInTransform);
}
private CacheableResultTransformer(SqlString autoDiscoveredQuery)
{
AutoDiscoverTypes = true;
_autoDiscoveredQuery = autoDiscoveredQuery;
}
private void InitializeTransformer(bool[] includeInTuple, bool[] includeInTransform)
{
_includeInTuple = includeInTuple ?? throw new ArgumentNullException(nameof(includeInTuple));
_tupleLength = ArrayHelper.CountTrue(includeInTuple);
_tupleSubsetLength = includeInTransform == null
? _tupleLength
: ArrayHelper.CountTrue(includeInTransform);
if (_tupleSubsetLength == _tupleLength)
{
_includeInTransformIndex = null;
}
else
{
_includeInTransformIndex = new int[_tupleSubsetLength];
for (int i = 0, j = 0; i < includeInTransform.Length; i++)
{
if (includeInTransform[i])
{
_includeInTransformIndex[j] = i;
j++;
}
}
}
}
internal void SupplyAutoDiscoveredParameters(IResultTransformer transformer, string[] aliases)
{
if (!AutoDiscoverTypes)
throw new InvalidOperationException(
"Cannot supply auto-discovered parameters when it is not enabled on the transformer.");
AutoDiscoveredAliases = aliases;
var includeInTuple = ArrayHelper.Fill(true, aliases?.Length ?? 0);
InitializeTransformer(includeInTuple, GetIncludeInTransform(transformer, aliases, includeInTuple));
}
public object TransformTuple(object[] tuple, string[] aliases)
{
if (_includeInTuple == null)
throw new InvalidOperationException("This transformer is not initialized");
return _actualTransformer.TransformTuple(Index(tuple), null);
}
/// <summary>
/// Re-transforms, if necessary, a List of values previously
/// transformed by this (or an equivalent) CacheableResultTransformer.
/// Each element of the list is re-transformed in place (i.e, List
/// elements are replaced with re-transformed values) and the original
/// List is returned. If re-transformation is unnecessary, the original List is returned
/// unchanged.
/// </summary>
/// <param name="transformedResults">Results that were previously transformed.</param>
/// <param name="aliases">The aliases that correspond to the untransformed tuple.</param>
/// <param name="transformer">The transformer for the re-transformation.</param>
/// <param name="includeInTuple"></param>
/// <returns><paramref name="transformedResults"/>, with each element re-transformed (if necessary).</returns>
public IList RetransformResults(IList transformedResults,
string[] aliases,
IResultTransformer transformer,
bool[] includeInTuple)
{
if (transformedResults.Count == 0)
return transformedResults;
if (transformer == null)
throw new ArgumentNullException(nameof(transformer));
if (_includeInTuple == null)
throw new InvalidOperationException("This transformer is not initialized");
if (!HasSameParameters(Create(transformer, aliases, includeInTuple, false, null, _skipTransformer)))
{
throw new InvalidOperationException(
"this CacheableResultTransformer is inconsistent with specified arguments; cannot re-transform"
);
}
bool requiresRetransform = true;
string[] aliasesToUse = aliases == null ? null : Index(aliases);
if (_skipTransformer)
{
}
else if (transformer.Equals(_actualTransformer))
{
requiresRetransform = false;
}
else if (transformer is ITupleSubsetResultTransformer)
{
requiresRetransform =
!((ITupleSubsetResultTransformer) transformer).IsTransformedValueATupleElement(aliasesToUse, _tupleLength);
}
if (requiresRetransform)
{
for (int i = 0; i < transformedResults.Count; i++)
{
object[] tuple = _actualTransformer.UntransformToTuple(
transformedResults[i],
_tupleSubsetLength == 1
);
transformedResults[i] = transformer.TransformTuple(tuple, aliasesToUse);
}
}
return transformedResults;
}
/// <summary>
/// Untransforms, if necessary, a List of values previously
/// transformed by this (or an equivalent) CacheableResultTransformer.
/// Each element of the list is untransformed in place (i.e, List
/// elements are replaced with untransformed values) and the original
/// List is returned.
/// <para>
/// If not necessary, the original List is returned unchanged.
/// </para>
/// </summary>
/// <remarks>
/// NOTE: If transformed values are a subset of the original
/// tuple, then, on return, elements corresponding to
/// excluded tuple elements will be null.
/// </remarks>
/// <param name="results">Results that were previously transformed.</param>
/// <returns><paramref name="results"/>, with each element untransformed (if necessary).</returns>
public IList UntransformToTuples(IList results)
{
if (results.Count == 0)
return results;
if (_includeInTuple == null)
throw new InvalidOperationException("This transformer is not initialized");
if (_includeInTransformIndex == null)
{
results = _actualTransformer.UntransformToTuples(
results,
_tupleSubsetLength == 1
);
}
else
{
for (int i = 0; i < results.Count; i++)
{
object[] tuple = _actualTransformer.UntransformToTuple(
results[i], _tupleSubsetLength == 1);
results[i] = Unindex(tuple);
}
}
return results;
}
/// <summary>
/// Returns the result types for the transformed value.
/// </summary>
public IType[] GetCachedResultTypes(IType[] tupleResultTypes)
{
if (_includeInTuple == null)
throw new InvalidOperationException("This transformer is not initialized");
return _tupleLength != _tupleSubsetLength
? Index(tupleResultTypes)
: tupleResultTypes;
}
public IList TransformList(IList list)
{
return list;
}
/// <summary>
/// "Compact" the given array by picking only the elements identified by
/// the _includeInTransformIndex array. The picked elements are returned
/// in a new array.
/// </summary>
private T[] Index<T>(T[] objects)
{
T[] objectsIndexed = objects;
if (objects != null &&
_includeInTransformIndex != null &&
objects.Length != _tupleSubsetLength)
{
objectsIndexed = new T[_tupleSubsetLength];
for (int i = 0; i < _tupleSubsetLength; i++)
{
objectsIndexed[i] = objects[_includeInTransformIndex[i]];
}
}
return objectsIndexed;
}
/// <summary>
/// Expand the given array by putting each of its elements at the
/// position identified by the _includeInTransformIndex array. The
/// elements are placed in a new array - the original array will
/// not be modified.
/// </summary>
private T[] Unindex<T>(T[] objects)
{
T[] objectsUnindexed = objects;
if (objects != null &&
_includeInTransformIndex != null &&
objects.Length != _tupleLength)
{
objectsUnindexed = new T[_tupleLength];
for (int i = 0; i < _tupleSubsetLength; i++)
{
objectsUnindexed[_includeInTransformIndex[i]] = objects[i];
}
}
return objectsUnindexed;
}
public override bool Equals(object o)
{
if (this == o)
return true;
if (o == null || GetType() != o.GetType())
return false;
var that = (CacheableResultTransformer) o;
// Auto-discovery does not allow distinguishing by transformer: just compare their queries
if (AutoDiscoverTypes && that.AutoDiscoverTypes)
return Equals(_autoDiscoveredQuery, that._autoDiscoveredQuery);
return HasSameParameters(that);
}
private bool HasSameParameters(CacheableResultTransformer other)
{
return _tupleLength == other._tupleLength
&& _tupleSubsetLength == other._tupleSubsetLength
&& ArrayHelper.ArrayEquals(_includeInTuple, other._includeInTuple)
&& ArrayHelper.ArrayEquals(_includeInTransformIndex, other._includeInTransformIndex);
}
public override int GetHashCode()
{
if (AutoDiscoverTypes)
return _autoDiscoveredQuery.GetHashCode();
var result = _tupleLength;
result = 31*result + _tupleSubsetLength;
result = 31*result + (_includeInTuple != null ? ArrayHelper.ArrayGetHashCode(_includeInTuple) : 0);
result = 31*result + (_includeInTransformIndex != null ? ArrayHelper.ArrayGetHashCode(_includeInTransformIndex) : 0);
return result;
}
}
}