public static IEnumerable <T> WhereUsingIndex <T>(IndexSet <T> indexSet, Expression <Func <T, bool> > predicate)
{
if (!(predicate.Body is BinaryExpression))
{
throw new NotSupportedException();
}
var binaryBody = (BinaryExpression)predicate.Body;
switch (binaryBody.NodeType)
{
case ExpressionType.Or:
case ExpressionType.OrElse:
{
var leftResults = WhereUsingIndex(indexSet, Expression.Lambda <Func <T, bool> >(binaryBody.Left, predicate.Parameters));
var rightResults = WhereUsingIndex(indexSet, Expression.Lambda <Func <T, bool> >(binaryBody.Right, predicate.Parameters));
return(leftResults.Union(rightResults));
}
case ExpressionType.And:
case ExpressionType.AndAlso:
{
var leftResults = WhereUsingIndex(indexSet, Expression.Lambda <Func <T, bool> >(binaryBody.Left, predicate.Parameters));
var rightResults = WhereUsingIndex(indexSet, Expression.Lambda <Func <T, bool> >(binaryBody.Right, predicate.Parameters));
return(leftResults.Intersect(rightResults));
}
case ExpressionType.Equal:
return(indexSet.WhereUsingIndex(predicate));
default:
return(Enumerable.Where(indexSet, predicate.Compile()));
}
}
public static IEnumerable <T> Where <T>(this IndexSet <T> indexSet, Expression <Func <T, bool> > predicate)
{
return(WhereUsingIndex(indexSet, predicate));
}