public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
Visit(expression.Expression);
Label loadTrue = _ilEmitContext.ILGenerator.DefineLabel();
Label finishLabel = _ilEmitContext.ILGenerator.DefineLabel();
if (expression.Negated)
{
_ilEmitContext.ILGenerator.Emit(OpCodes.Brtrue, loadTrue);
}
else
{
_ilEmitContext.ILGenerator.Emit(OpCodes.Brfalse, loadTrue);
}
_ilEmitContext.ILGenerator.Emit(OpCodes.Ldc_I4_0);
_ilEmitContext.ILGenerator.Emit(OpCodes.Br, finishLabel);
_ilEmitContext.ILGenerator.MarkLabel(loadTrue);
_ilEmitContext.ILGenerator.Emit(OpCodes.Ldc_I4_1);
_ilEmitContext.ILGenerator.MarkLabel(finishLabel);
_ilEmitContext.ILGenerator.Emit(OpCodes.Box, typeof(bool));
return(expression);
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
Visit(expression.Expression);
if (_lastExpressionsYieldsNullOrFalse && !expression.Negated)
_lastExpressionsYieldsNullOrFalse = false;
return expression;
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
Visit(expression.Expression);
if (_lastExpressionsYieldsNullOrFalse && !expression.Negated)
{
_lastExpressionsYieldsNullOrFalse = false;
}
return(expression);
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
_xmlWriter.WriteStartElement("isNullExpression");
_xmlWriter.WriteAttributeString("negated", XmlConvert.ToString(expression.Negated));
WriteTypeAttribute(expression.ExpressionType);
WriteAstNode("expression", expression.Expression);
_xmlWriter.WriteEndElement();
return(expression);
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
Visit(expression.Expression);
_writer.Write(" IS ");
if (expression.Negated)
{
_writer.Write("NOT ");
}
_writer.Write("NULL");
return(expression);
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
base.VisitIsNullExpression(expression);
ConstantExpression constantExpression = expression.Expression as ConstantExpression;
if (constantExpression != null)
{
if (expression.Negated)
{
return(LiteralExpression.FromBoolean(constantExpression.GetValue() != null));
}
else
{
return(LiteralExpression.FromBoolean(constantExpression.GetValue() == null));
}
}
return(expression);
}
private static bool VisitIsNullExpression(IsNullExpression node1, IsNullExpression node2)
{
return node2 != null &&
node1.Negated == node2.Negated &&
Visit(node1.Expression, node2.Expression);
}
private static bool VisitIsNullExpression(IsNullExpression node1, IsNullExpression node2)
{
return(node2 != null &&
node1.Negated == node2.Negated &&
Visit(node1.Expression, node2.Expression));
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
Visit(expression.Expression);
_writer.Write(" IS ");
if (expression.Negated)
_writer.Write("NOT ");
_writer.Write("NULL");
return expression;
}
public void PushIsNull()
{
ExpressionNode operand = _expressionStack.Pop();
IsNullExpression isNullExpression = new IsNullExpression(false, operand);
_expressionStack.Push(isNullExpression);
}
public virtual ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
expression.Expression = VisitExpression(expression.Expression);
return(expression);
}
public virtual ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
expression.Expression = VisitExpression(expression.Expression);
return expression;
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
Visit(expression.Expression);
Label loadTrue = _ilEmitContext.ILGenerator.DefineLabel();
Label finishLabel = _ilEmitContext.ILGenerator.DefineLabel();
if (expression.Negated)
_ilEmitContext.ILGenerator.Emit(OpCodes.Brtrue, loadTrue);
else
_ilEmitContext.ILGenerator.Emit(OpCodes.Brfalse, loadTrue);
_ilEmitContext.ILGenerator.Emit(OpCodes.Ldc_I4_0);
_ilEmitContext.ILGenerator.Emit(OpCodes.Br, finishLabel);
_ilEmitContext.ILGenerator.MarkLabel(loadTrue);
_ilEmitContext.ILGenerator.Emit(OpCodes.Ldc_I4_1);
_ilEmitContext.ILGenerator.MarkLabel(finishLabel);
_ilEmitContext.ILGenerator.Emit(OpCodes.Box, typeof(bool));
return expression;
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
base.VisitIsNullExpression(expression);
ConstantExpression constantExpression = expression.Expression as ConstantExpression;
if (constantExpression != null)
{
if (expression.Negated)
return LiteralExpression.FromBoolean(constantExpression.GetValue() != null);
else
return LiteralExpression.FromBoolean(constantExpression.GetValue() == null);
}
return expression;
}
public override ExpressionNode VisitUnaryExpression(UnaryExpression expression)
{
// First visit arguments
base.VisitUnaryExpression(expression);
if (expression.Op == UnaryOperator.LogicalNot)
{
// Replace "NOT NOT expr" by "expr"
UnaryExpression unOp = expression.Operand as UnaryExpression;
if (unOp != null)
{
if (unOp.Op == UnaryOperator.LogicalNot)
{
return(VisitExpression(unOp.Operand));
}
}
// Replace "NOT expr IS NULL" and "NOT expr IS NOT NULL" by
// "expr IS NOT NULL" and "expr IS NULL" resp.
IsNullExpression isNull = expression.Operand as IsNullExpression;
if (isNull != null)
{
isNull.Negated = !isNull.Negated;
return(VisitExpression(isNull));
}
// Apply negation on EXISTS
ExistsSubselect existsSubselect = expression.Operand as ExistsSubselect;
if (existsSubselect != null)
{
existsSubselect.Negated = !existsSubselect.Negated;
return(existsSubselect);
}
// Apply negation on ALL/ANY subquery
AllAnySubselect allAnySubselect = expression.Operand as AllAnySubselect;
if (allAnySubselect != null)
{
allAnySubselect.Op = AstUtil.NegateBinaryOp(allAnySubselect.Op);
allAnySubselect.Type = (allAnySubselect.Type == AllAnySubselect.AllAnyType.All) ? AllAnySubselect.AllAnyType.Any : AllAnySubselect.AllAnyType.All;
return(allAnySubselect);
}
// Apply De Morgan's law
BinaryExpression binOp = expression.Operand as BinaryExpression;
if (binOp != null)
{
BinaryOperator negatedOp = AstUtil.NegateBinaryOp(binOp.Op);
if (negatedOp != null)
{
ExpressionNode newLeft;
ExpressionNode newRight;
if (binOp.Op == BinaryOperator.LogicalAnd || binOp.Op == BinaryOperator.LogicalOr)
{
newLeft = new UnaryExpression(expression.Op, binOp.Left);
newRight = new UnaryExpression(expression.Op, binOp.Right);
}
else
{
newLeft = binOp.Left;
newRight = binOp.Right;
}
binOp.Op = negatedOp;
binOp.Left = newLeft;
binOp.Right = newRight;
return(VisitExpression(binOp));
}
}
}
return(expression);
}
public override ExpressionNode VisitIsNullExpression(IsNullExpression expression)
{
_xmlWriter.WriteStartElement("isNullExpression");
_xmlWriter.WriteAttributeString("negated", XmlConvert.ToString(expression.Negated));
WriteTypeAttribute(expression.ExpressionType);
WriteAstNode("expression", expression.Expression);
_xmlWriter.WriteEndElement();
return expression;
}