protected override Expression VisitSqlUnary(SqlUnaryExpression sqlUnaryExpression)
{
var parentSearchCondition = _isSearchCondition;
bool resultCondition;
switch (sqlUnaryExpression.OperatorType)
{
case ExpressionType.Not:
_isSearchCondition = true;
resultCondition = true;
break;
case ExpressionType.Convert:
case ExpressionType.Negate:
_isSearchCondition = false;
resultCondition = false;
break;
default:
_isSearchCondition = false;
resultCondition = true;
break;
}
var operand = (SqlExpression)Visit(sqlUnaryExpression.Operand);
_isSearchCondition = parentSearchCondition;
return(ApplyConversion(sqlUnaryExpression.Update(operand), condition: resultCondition));
}
protected override Expression VisitSqlUnary(SqlUnaryExpression sqlUnaryExpression)
{
var parentSearchCondition = _isSearchCondition;
bool resultCondition;
switch (sqlUnaryExpression.OperatorType)
{
case ExpressionType.Not:
_isSearchCondition = true;
resultCondition = true;
break;
case ExpressionType.Convert:
case ExpressionType.Negate:
_isSearchCondition = false;
resultCondition = false;
break;
case ExpressionType.Equal:
case ExpressionType.NotEqual:
_isSearchCondition = false;
resultCondition = true;
break;
default:
throw new InvalidOperationException("Unknown operator type encountered in SqlUnaryExpression.");
}
var operand = (SqlExpression)Visit(sqlUnaryExpression.Operand);
_isSearchCondition = parentSearchCondition;
return(ApplyConversion(sqlUnaryExpression.Update(operand), condition: resultCondition));
}
private SqlUnaryExpression VisitSqlUnaryExpression(SqlUnaryExpression sqlUnaryExpression)
{
var newOperand = (SqlExpression)Visit(sqlUnaryExpression.Operand);
// IsNull/IsNotNull
if (sqlUnaryExpression.OperatorType == ExpressionType.Equal ||
sqlUnaryExpression.OperatorType == ExpressionType.NotEqual)
{
_isNullable = false;
}
return(sqlUnaryExpression.Update(newOperand));
}
private Expression VisitSqlUnaryExpression(SqlUnaryExpression sqlUnaryExpression)
{
if (sqlUnaryExpression.OperatorType == ExpressionType.Not)
{
return(VisitNot(sqlUnaryExpression));
}
// NULL IS NULL -> true
// non_nullablee_constant IS NULL -> false
if (sqlUnaryExpression.OperatorType == ExpressionType.Equal &&
sqlUnaryExpression.Operand is SqlConstantExpression innerConstantNull1)
{
return(_sqlExpressionFactory.Constant(innerConstantNull1.Value == null, sqlUnaryExpression.TypeMapping));
}
// NULL IS NOT NULL -> false
// non_nullablee_constant IS NOT NULL -> true
if (sqlUnaryExpression.OperatorType == ExpressionType.NotEqual &&
sqlUnaryExpression.Operand is SqlConstantExpression innerConstantNull2)
{
return(_sqlExpressionFactory.Constant(innerConstantNull2.Value != null, sqlUnaryExpression.TypeMapping));
}
if (sqlUnaryExpression.Operand is SqlUnaryExpression innerUnary)
{
// (!a) IS NULL <==> a IS NULL
if (sqlUnaryExpression.OperatorType == ExpressionType.Equal &&
innerUnary.OperatorType == ExpressionType.Not)
{
return(Visit(_sqlExpressionFactory.IsNull(innerUnary.Operand)));
}
// (!a) IS NOT NULL <==> a IS NOT NULL
if (sqlUnaryExpression.OperatorType == ExpressionType.NotEqual &&
innerUnary.OperatorType == ExpressionType.Not)
{
return(Visit(_sqlExpressionFactory.IsNotNull(innerUnary.Operand)));
}
}
var newOperand = (SqlExpression)Visit(sqlUnaryExpression.Operand);
return(sqlUnaryExpression.Update(newOperand));
}
protected override Expression VisitSqlUnary(SqlUnaryExpression sqlCastExpression)
{
_isNullable = false;
var canOptimize = _canOptimize;
_canOptimize = false;
var newOperand = (SqlExpression)Visit(sqlCastExpression.Operand);
// result of IsNull/IsNotNull can never be null
if (sqlCastExpression.OperatorType == ExpressionType.Equal ||
sqlCastExpression.OperatorType == ExpressionType.NotEqual)
{
_isNullable = false;
}
_canOptimize = canOptimize;
return(sqlCastExpression.Update(newOperand));
}
private Expression VisitSqlUnaryExpression(SqlUnaryExpression sqlUnaryExpression)
{
// !(true) -> false
// !(false) -> true
if (sqlUnaryExpression.OperatorType == ExpressionType.Not &&
sqlUnaryExpression.Operand is SqlConstantExpression innerConstantBool &&
innerConstantBool.Value is bool value)
{
return(value
? _sqlExpressionFactory.Constant(false, sqlUnaryExpression.TypeMapping)
: _sqlExpressionFactory.Constant(true, sqlUnaryExpression.TypeMapping));
}
// NULL IS NULL -> true
// non_nullablee_constant IS NULL -> false
if (sqlUnaryExpression.OperatorType == ExpressionType.Equal &&
sqlUnaryExpression.Operand is SqlConstantExpression innerConstantNull1)
{
return(_sqlExpressionFactory.Constant(innerConstantNull1.Value == null, sqlUnaryExpression.TypeMapping));
}
// NULL IS NOT NULL -> false
// non_nullablee_constant IS NOT NULL -> true
if (sqlUnaryExpression.OperatorType == ExpressionType.NotEqual &&
sqlUnaryExpression.Operand is SqlConstantExpression innerConstantNull2)
{
return(_sqlExpressionFactory.Constant(innerConstantNull2.Value != null, sqlUnaryExpression.TypeMapping));
}
if (sqlUnaryExpression.Operand is SqlUnaryExpression innerUnary)
{
if (sqlUnaryExpression.OperatorType == ExpressionType.Not)
{
// !(!a) -> a
if (innerUnary.OperatorType == ExpressionType.Not)
{
return(Visit(innerUnary.Operand));
}
if (innerUnary.OperatorType == ExpressionType.Equal)
{
//!(a IS NULL) -> a IS NOT NULL
return(Visit(_sqlExpressionFactory.IsNotNull(innerUnary.Operand)));
}
//!(a IS NOT NULL) -> a IS NULL
if (innerUnary.OperatorType == ExpressionType.NotEqual)
{
return(Visit(_sqlExpressionFactory.IsNull(innerUnary.Operand)));
}
}
// (!a) IS NULL <==> a IS NULL
if (sqlUnaryExpression.OperatorType == ExpressionType.Equal &&
innerUnary.OperatorType == ExpressionType.Not)
{
return(Visit(_sqlExpressionFactory.IsNull(innerUnary.Operand)));
}
// (!a) IS NOT NULL <==> a IS NOT NULL
if (sqlUnaryExpression.OperatorType == ExpressionType.NotEqual &&
innerUnary.OperatorType == ExpressionType.Not)
{
return(Visit(_sqlExpressionFactory.IsNotNull(innerUnary.Operand)));
}
}
if (sqlUnaryExpression.Operand is SqlBinaryExpression innerBinary)
{
// De Morgan's
if (innerBinary.OperatorType == ExpressionType.AndAlso ||
innerBinary.OperatorType == ExpressionType.OrElse)
{
var newLeft = (SqlExpression)Visit(_sqlExpressionFactory.Not(innerBinary.Left));
var newRight = (SqlExpression)Visit(_sqlExpressionFactory.Not(innerBinary.Right));
return(innerBinary.OperatorType == ExpressionType.AndAlso
? _sqlExpressionFactory.OrElse(newLeft, newRight)
: _sqlExpressionFactory.AndAlso(newLeft, newRight));
}
// note that those optimizations are only valid in 2-value logic
// they are safe to do here because null semantics removes possibility of nulls in the tree
// however if we decide to do "partial" null semantics (that doesn't distinguish between NULL and FALSE, e.g. for predicates)
// we need to be extra careful here
if (TryNegate(innerBinary.OperatorType, out var negated))
{
return(Visit(
_sqlExpressionFactory.MakeBinary(
negated,
innerBinary.Left,
innerBinary.Right,
innerBinary.TypeMapping)));
}
}
var newOperand = (SqlExpression)Visit(sqlUnaryExpression.Operand);
return(sqlUnaryExpression.Update(newOperand));
}
protected override Expression VisitSqlUnary(SqlUnaryExpression sqlCastExpression)
{
var op = Visit(sqlCastExpression.Operand) as SqlExpression;
return(sqlCastExpression.Update(op));
}
protected override Expression VisitSqlUnary(SqlUnaryExpression x)
{
return(x?.Update(x.Operand.VisitNode(this)));
}
