protected override Expression VisitUnary(UnaryExpression node)
{
#if (DEBUGPRINT)
System.Diagnostics.Debug.Print("VisitUnary: {0}", node);
#endif
var expression = base.VisitUnary(node) as UnaryExpression;
DbExpression operandExpression = GetDbExpressionForExpression(expression.Operand);
switch (expression.NodeType)
{
case ExpressionType.Not:
MapExpressionToDbExpression(expression, operandExpression.Not());
break;
case ExpressionType.Convert:
MapExpressionToDbExpression(expression, operandExpression.CastTo(TypeUsageForPrimitiveType(expression.Operand.Type)));
break;
default:
throw new NotImplementedException(string.Format("Unhandled NodeType of {0} in LambdaToDbExpressionVisitor.VisitUnary", expression.NodeType));
}
return(expression);
}
/// <summary>
/// Maps a comparison of an expression to a "null" constant.
/// </summary>
/// <returns></returns>
private DbExpression MapNullComparison(Expression expression, ExpressionType comparisonType)
{
DbExpression dbExpression = GetDbExpressionForExpression(expression).IsNull();
switch (comparisonType)
{
case ExpressionType.Equal:
return(dbExpression);
case ExpressionType.NotEqual:
// Creates expression: !([expression] is null)
return(dbExpression.Not());
}
throw new NotImplementedException(string.Format("Unhandled comparisonType of {0} in LambdaToDbExpressionVisitor.MapNullComparison", comparisonType));
}
private DbExpression TransformIntersectOrExcept(
DbExpression left,
DbExpression right,
DbExpressionKind expressionKind,
IList <DbPropertyExpression> sortExpressionsOverLeft,
string sortExpressionsBindingVariableName)
{
bool flag1 = expressionKind == DbExpressionKind.Except || expressionKind == DbExpressionKind.Skip;
bool flag2 = expressionKind == DbExpressionKind.Except || expressionKind == DbExpressionKind.Intersect;
DbExpressionBinding input = left.Bind();
DbExpressionBinding expressionBinding = right.Bind();
IList <DbPropertyExpression> propertyExpressionList1 = (IList <DbPropertyExpression>) new List <DbPropertyExpression>();
IList <DbPropertyExpression> propertyExpressionList2 = (IList <DbPropertyExpression>) new List <DbPropertyExpression>();
this.FlattenProperties((DbExpression)input.Variable, propertyExpressionList1);
this.FlattenProperties((DbExpression)expressionBinding.Variable, propertyExpressionList2);
if (expressionKind == DbExpressionKind.Skip && Sql8ExpressionRewriter.RemoveNonSortProperties(propertyExpressionList1, propertyExpressionList2, sortExpressionsOverLeft, input.VariableName, sortExpressionsBindingVariableName))
{
expressionBinding = Sql8ExpressionRewriter.CapWithProject(expressionBinding, propertyExpressionList2);
}
DbExpression dbExpression1 = (DbExpression)null;
for (int index = 0; index < propertyExpressionList1.Count; ++index)
{
DbExpression right1 = (DbExpression)propertyExpressionList1[index].Equal((DbExpression)propertyExpressionList2[index]).Or((DbExpression)propertyExpressionList1[index].IsNull().And((DbExpression)propertyExpressionList2[index].IsNull()));
dbExpression1 = index != 0 ? (DbExpression)dbExpression1.And(right1) : right1;
}
DbExpression dbExpression2 = (DbExpression)expressionBinding.Any(dbExpression1);
DbExpression predicate = !flag1 ? dbExpression2 : (DbExpression)dbExpression2.Not();
DbExpression dbExpression3 = (DbExpression)input.Filter(predicate);
if (flag2)
{
dbExpression3 = (DbExpression)dbExpression3.Distinct();
}
return(dbExpression3);
}
// <summary>
// This method is used for translating <see cref="DbIntersectExpression" /> and <see cref="DbExceptExpression" />,
// and for translating the "Except" part of <see cref="DbSkipExpression" />.
// into the follwoing expression:
// A INTERSECT B, A EXCEPT B
// (DISTINCT)
// |
// FILTER
// |
// | - Input: A
// | - Predicate:(NOT)
// |
// ANY
// |
// | - Input: B
// | - Predicate: (B.b1 = A.a1 or (B.b1 is null and A.a1 is null))
// AND (B.b2 = A.a2 or (B.b2 is null and A.a2 is null))
// AND ...
// AND (B.bn = A.an or (B.bn is null and A.an is null)))
// Here, A corresponds to right and B to left.
// (NOT) is present when transforming Except
// for the purpose of translating <see cref="DbExceptExpression" /> or <see cref="DbSkipExpression" />.
// (DISTINCT) is present when transforming for the purpose of translating
// <see cref="DbExceptExpression" /> or <see cref="DbIntersectExpression" />.
// For <see cref="DbSkipExpression" />, the input to ANY is caped with project which projects out only
// the columns represented in the sortExpressionsOverLeft list and only these are used in the predicate.
// This is because we want to support skip over input with non-equal comarable columns and we have no way to recognize these.
// </summary>
// <param name="sortExpressionsOverLeft"> note that this list gets destroyed by this method </param>
private DbExpression TransformIntersectOrExcept(
DbExpression left, DbExpression right, DbExpressionKind expressionKind, IList <DbPropertyExpression> sortExpressionsOverLeft,
string sortExpressionsBindingVariableName)
{
var negate = (expressionKind == DbExpressionKind.Except) || (expressionKind == DbExpressionKind.Skip);
var distinct = (expressionKind == DbExpressionKind.Except) || (expressionKind == DbExpressionKind.Intersect);
var leftInputBinding = left.Bind();
var rightInputBinding = right.Bind();
IList <DbPropertyExpression> leftFlattenedProperties = new List <DbPropertyExpression>();
IList <DbPropertyExpression> rightFlattenedProperties = new List <DbPropertyExpression>();
FlattenProperties(leftInputBinding.Variable, leftFlattenedProperties);
FlattenProperties(rightInputBinding.Variable, rightFlattenedProperties);
//For Skip, we need to ignore any columns that are not in the original sort list. We can recognize these by comparing the left flattened properties and
// the properties in the list sortExpressionsOverLeft
// If any such columns exist, we need to add an additional project, to keep the rest of the columns from being projected, as if any among these
// are non equal comparable, SQL Server 2000 throws.
if (expressionKind == DbExpressionKind.Skip)
{
if (RemoveNonSortProperties(
leftFlattenedProperties, rightFlattenedProperties, sortExpressionsOverLeft, leftInputBinding.VariableName,
sortExpressionsBindingVariableName))
{
rightInputBinding = CapWithProject(rightInputBinding, rightFlattenedProperties);
}
}
Debug.Assert(
leftFlattenedProperties.Count == rightFlattenedProperties.Count,
"The left and the right input to INTERSECT or EXCEPT have a different number of properties");
Debug.Assert(leftFlattenedProperties.Count != 0, "The inputs to INTERSECT or EXCEPT have no properties");
//Build the predicate for the quantifier:
// (B.b1 = A.a1 or (B.b1 is null and A.a1 is null))
// AND (B.b2 = A.a2 or (B.b2 is null and A.a2 is null))
// AND ...
// AND (B.bn = A.an or (B.bn is null and A.an is null)))
DbExpression existsPredicate = null;
for (var i = 0; i < leftFlattenedProperties.Count; i++)
{
//A.ai == B.bi
DbExpression equalsExpression = leftFlattenedProperties[i].Equal(rightFlattenedProperties[i]);
//A.ai is null AND B.bi is null
DbExpression leftIsNullExpression = leftFlattenedProperties[i].IsNull();
DbExpression rightIsNullExpression = rightFlattenedProperties[i].IsNull();
DbExpression bothNullExpression = leftIsNullExpression.And(rightIsNullExpression);
DbExpression orExpression = equalsExpression.Or(bothNullExpression);
if (i == 0)
{
existsPredicate = orExpression;
}
else
{
existsPredicate = existsPredicate.And(orExpression);
}
}
//Build the quantifier
DbExpression quantifierExpression = rightInputBinding.Any(existsPredicate);
DbExpression filterPredicate;
//Negate if needed
if (negate)
{
filterPredicate = quantifierExpression.Not();
}
else
{
filterPredicate = quantifierExpression;
}
//Build the filter
DbExpression result = leftInputBinding.Filter(filterPredicate);
//Apply distinct in needed
if (distinct)
{
result = result.Distinct();
}
return(result);
}
public static DbCaseWhenExpression ConstructReturnCSharpBooleanCaseWhenExpression(DbExpression exp)
{
// case when 1>0 then 1 when not (1>0) then 0 else Null end
DbCaseWhenExpression.WhenThenExpressionPair whenThenPair = new DbCaseWhenExpression.WhenThenExpressionPair(exp, DbConstantExpression.True);
DbCaseWhenExpression.WhenThenExpressionPair whenThenPair1 = new DbCaseWhenExpression.WhenThenExpressionPair(DbExpression.Not(exp), DbConstantExpression.False);
List <DbCaseWhenExpression.WhenThenExpressionPair> whenThenExps = new List <DbCaseWhenExpression.WhenThenExpressionPair>(2);
whenThenExps.Add(whenThenPair);
whenThenExps.Add(whenThenPair1);
DbCaseWhenExpression caseWhenExpression = DbExpression.CaseWhen(whenThenExps, DbConstantExpression.Null, PublicConstants.TypeOfBoolean);
return(caseWhenExpression);
}
