/// <summary>
/// Does this predicate preserve nulls on the specified columns of the table?
/// If any of the columns participates in a comparison predicate, or in a
/// not-null predicate, then, nulls are not preserved
/// </summary>
/// <param name="simplePredNode">the "simple" predicate node</param>
/// <param name="tableColumns">list of table columns</param>
/// <returns>true, if nulls are preserved</returns>
private static bool PreservesNulls(Node simplePredNode, VarVec tableColumns)
{
VarRefOp varRefOp;
switch (simplePredNode.Op.OpType)
{
case OpType.EQ:
case OpType.NE:
case OpType.GT:
case OpType.GE:
case OpType.LT:
case OpType.LE:
varRefOp = simplePredNode.Child0.Op as VarRefOp;
if (varRefOp != null && tableColumns.IsSet(varRefOp.Var))
{
return(false);
}
varRefOp = simplePredNode.Child1.Op as VarRefOp;
if (varRefOp != null && tableColumns.IsSet(varRefOp.Var))
{
return(false);
}
return(true);
case OpType.Not:
if (simplePredNode.Child0.Op.OpType != OpType.IsNull)
{
return(true);
}
varRefOp = simplePredNode.Child0.Child0.Op as VarRefOp;
return(varRefOp == null || !tableColumns.IsSet(varRefOp.Var));
case OpType.Like:
// If the predicate is "column LIKE constant ...", then the
// predicate does not preserve nulls
ConstantBaseOp constantOp = simplePredNode.Child1.Op as ConstantBaseOp;
if (constantOp == null || (constantOp.OpType == OpType.Null))
{
return(true);
}
varRefOp = simplePredNode.Child0.Op as VarRefOp;
if (varRefOp != null && tableColumns.IsSet(varRefOp.Var))
{
return(false);
}
return(true);
default:
return(true);
}
}
protected override void VisitConstantOp(ConstantBaseOp op, Node n)
{
using (new AutoString(this, op)) {
if (null == op.Value)
{
WriteString("null");
}
else
{
WriteString("(");
WriteString(op.Type.EdmType.FullName);
WriteString(")");
WriteString(String.Format(CultureInfo.InvariantCulture, "{0}", op.Value));
}
VisitChildren(n);
}
}
private static bool PreservesNulls(System.Data.Entity.Core.Query.InternalTrees.Node simplePredNode, VarVec tableColumns)
{
switch (simplePredNode.Op.OpType)
{
case OpType.GT:
case OpType.GE:
case OpType.LE:
case OpType.LT:
case OpType.EQ:
case OpType.NE:
VarRefOp op1 = simplePredNode.Child0.Op as VarRefOp;
if (op1 != null && tableColumns.IsSet(op1.Var))
{
return(false);
}
VarRefOp op2 = simplePredNode.Child1.Op as VarRefOp;
return(op2 == null || !tableColumns.IsSet(op2.Var));
case OpType.Like:
ConstantBaseOp op3 = simplePredNode.Child1.Op as ConstantBaseOp;
if (op3 == null || op3.OpType == OpType.Null)
{
return(true);
}
VarRefOp op4 = simplePredNode.Child0.Op as VarRefOp;
return(op4 == null || !tableColumns.IsSet(op4.Var));
case OpType.Not:
if (simplePredNode.Child0.Op.OpType != OpType.IsNull)
{
return(true);
}
VarRefOp op5 = simplePredNode.Child0.Child0.Op as VarRefOp;
if (op5 != null)
{
return(!tableColumns.IsSet(op5.Var));
}
return(true);
default:
return(true);
}
}
/// <summary>
/// Copies a ConstantOp
/// </summary>
/// <param name="op">The Op to Copy</param>
/// <param name="n">The Node that references the Op</param>
/// <returns>A copy of the original Node that references a copy of the original Op</returns>
public override Node Visit(ConstantOp op, Node n)
{
ConstantBaseOp newOp = m_destCmd.CreateConstantOp(op.Type, op.Value);
return(m_destCmd.CreateNode(newOp));
}
