public void SetCondition(Expression e)
{
ExpressionType type = e.Type;
Expression e1 = e.Arg;
Expression e2 = e.Arg2;
if (type == ExpressionType.And)
{
SetCondition(e1);
SetCondition(e2);
return;
}
int candidate;
switch (type)
{
case ExpressionType.NotEqual:
case ExpressionType.Like: // todo: maybe use index
case ExpressionType.In:
candidate = 0;
break;
case ExpressionType.Equal:
candidate = 1;
break;
case ExpressionType.Bigger:
case ExpressionType.BiggerEqual:
candidate = 2;
break;
case ExpressionType.Smaller:
case ExpressionType.SmallerEqual:
candidate = 3;
break;
default:
// not a condition so forget it
return;
}
if (e1.Filter == this)
{
// ok include this
}
else if (e2.Filter == this && candidate != 0)
{
// swap and try again to allow index usage
e.SwapCondition();
SetCondition(e);
return;
}
else
{
// unrelated: don't include
return;
}
Trace.Assert(e1.Filter == this, "setCondition");
if (!e2.IsResolved)
{
return;
}
if (candidate == 0)
{
AddAndCondition(e);
return;
}
int i = e1.ColumnNumber;
Index index = tTable.GetIndexForColumn(i);
if (index == null || (iIndex != index && iIndex != null))
{
// no index or already another index is used
AddAndCondition(e);
return;
}
iIndex = index;
if (candidate == 1)
{
// candidate for both start & end
if (eStart != null || eEnd != null)
{
AddAndCondition(e);
return;
}
eStart = new Expression(e);
eEnd = eStart;
}
else if (candidate == 2)
{
// candidate for start
if (eStart != null)
{
AddAndCondition(e);
return;
}
eStart = new Expression(e);
}
else if (candidate == 3)
{
// candidate for end
if (eEnd != null)
{
AddAndCondition(e);
return;
}
eEnd = new Expression(e);
}
e.SetTrue();
}