private static Expression TryRemoveNullCheck(ConditionalExpression node)
{
var binaryTest = node.Test as BinaryExpression;
if (binaryTest == null ||
!(binaryTest.NodeType == ExpressionType.Equal ||
binaryTest.NodeType == ExpressionType.NotEqual))
{
return(null);
}
var leftConstant = binaryTest.Left as ConstantExpression;
var isLeftNullConstant = leftConstant != null && leftConstant.Value == null;
var rightConstant = binaryTest.Right as ConstantExpression;
var isRightNullConstant = rightConstant != null && rightConstant.Value == null;
if (isLeftNullConstant == isRightNullConstant)
{
return(null);
}
if (binaryTest.NodeType == ExpressionType.Equal)
{
var ifTrueConstant = node.IfTrue as ConstantExpression;
if (ifTrueConstant == null || ifTrueConstant.Value != null)
{
return(null);
}
}
else
{
var ifFalseConstant = node.IfFalse as ConstantExpression;
if (ifFalseConstant == null || ifFalseConstant.Value != null)
{
return(null);
}
}
var testExpression = isLeftNullConstant ? binaryTest.Right : binaryTest.Left;
var resultExpression = binaryTest.NodeType == ExpressionType.Equal ? node.IfFalse : node.IfTrue;
var nullCheckRemovalTestingVisitor = new NullCheckRemovalTestingVisitor();
if (nullCheckRemovalTestingVisitor.CanRemoveNullCheck(testExpression, resultExpression))
{
return(resultExpression);
}
return(null);
}
private Expression TryRemoveNullCheck(ConditionalExpression node)
{
var binaryTest = node.Test as BinaryExpression;
if (binaryTest == null ||
!(binaryTest.NodeType == ExpressionType.Equal ||
binaryTest.NodeType == ExpressionType.NotEqual))
{
return(null);
}
var isLeftNullConstant = binaryTest.Left.IsNullConstantExpression();
var isRightNullConstant = binaryTest.Right.IsNullConstantExpression();
if (isLeftNullConstant == isRightNullConstant)
{
return(null);
}
if (binaryTest.NodeType == ExpressionType.Equal)
{
var ifTrueConstant = node.IfTrue as ConstantExpression;
if (ifTrueConstant == null ||
ifTrueConstant.Value != null)
{
return(null);
}
}
else
{
var ifFalseConstant = node.IfFalse as ConstantExpression;
if (ifFalseConstant == null ||
ifFalseConstant.Value != null)
{
return(null);
}
}
var testExpression = isLeftNullConstant ? binaryTest.Right : binaryTest.Left;
var resultExpression = binaryTest.NodeType == ExpressionType.Equal ? node.IfFalse : node.IfTrue;
var nullCheckRemovalTestingVisitor = new NullCheckRemovalTestingVisitor(_queryModelVisitor.QueryCompilationContext);
return(nullCheckRemovalTestingVisitor.CanRemoveNullCheck(testExpression, resultExpression)
? resultExpression
: null);
}
/// <summary>
/// Creates a new instance of <see cref="SqlTranslatingExpressionVisitor" />.
/// </summary>
/// <param name="dependencies"> Parameter object containing dependencies for this service. </param>
/// <param name="queryModelVisitor"> The query model visitor. </param>
/// <param name="targetSelectExpression"> The target select expression. </param>
/// <param name="topLevelPredicate"> The top level predicate. </param>
/// <param name="inProjection"> true if the expression to be translated is a LINQ projection. </param>
public SqlTranslatingExpressionVisitor(
[NotNull] SqlTranslatingExpressionVisitorDependencies dependencies,
[NotNull] RelationalQueryModelVisitor queryModelVisitor,
[CanBeNull] SelectExpression targetSelectExpression = null,
[CanBeNull] Expression topLevelPredicate = null,
bool inProjection = false)
{
Check.NotNull(dependencies, nameof(dependencies));
Check.NotNull(queryModelVisitor, nameof(queryModelVisitor));
_typeMappingSource = dependencies.TypeMappingSource;
_queryModelVisitor = queryModelVisitor;
_targetSelectExpression = targetSelectExpression;
_topLevelPredicate = topLevelPredicate;
_inProjection = inProjection;
_nullCheckRemovalTestingVisitor = new NullCheckRemovalTestingVisitor(_queryModelVisitor);
_isTopLevelProjection = inProjection;
}
/// <summary>
/// Creates a new instance of <see cref="SqlTranslatingExpressionVisitor" />.
/// </summary>
/// <param name="dependencies"> Parameter object containing dependencies for this service. </param>
/// <param name="queryModelVisitor"> The query model visitor. </param>
/// <param name="targetSelectExpression"> The target select expression. </param>
/// <param name="topLevelPredicate"> The top level predicate. </param>
/// <param name="inProjection"> true if the expression to be translated is a LINQ projection. </param>
public SqlTranslatingExpressionVisitor(
[NotNull] SqlTranslatingExpressionVisitorDependencies dependencies,
[NotNull] RelationalQueryModelVisitor queryModelVisitor,
[CanBeNull] SelectExpression targetSelectExpression = null,
[CanBeNull] Expression topLevelPredicate = null,
bool inProjection = false)
{
Check.NotNull(dependencies, nameof(dependencies));
Check.NotNull(queryModelVisitor, nameof(queryModelVisitor));
_compositeExpressionFragmentTranslator = dependencies.CompositeExpressionFragmentTranslator;
_methodCallTranslator = dependencies.MethodCallTranslator;
_memberTranslator = dependencies.MemberTranslator;
_relationalTypeMapper = dependencies.RelationalTypeMapper;
_queryModelVisitor = queryModelVisitor;
_targetSelectExpression = targetSelectExpression;
_topLevelPredicate = topLevelPredicate;
_inProjection = inProjection;
_nullCheckRemovalTestingVisitor = new NullCheckRemovalTestingVisitor(_queryModelVisitor);
_isTopLevelProjection = inProjection;
}
