public static IEnumerable <T> Where <T>(this IndexedCollection <T> source, Expression <Func <T, bool> > query)
{
Contract.Requires(source != null);
Contract.Requires(query != null);
Contract.Ensures(Contract.Result <IEnumerable <T> >() != null);
var concatenatedParts = new List <IEnumerable <T> >();
query = query.Reduce() as Expression <Func <T, bool> >;
var parameter = query.Parameters.First();
Expression outRawExpression = null;
Expression currentPart;
for (currentPart = query.Body; currentPart.NodeType == ExpressionType.And || currentPart.NodeType == ExpressionType.AndAlso; currentPart = (currentPart as BinaryExpression).Right)
{
var activePart = (currentPart as BinaryExpression).Left;
CheckForEqualExpression(source, concatenatedParts, activePart, ref outRawExpression, parameter);
}
if (currentPart.NodeType == ExpressionType.Equal)
{
CheckForEqualExpression(source, concatenatedParts, currentPart, ref outRawExpression, parameter);
}
if (!concatenatedParts.Any())
{
return(source.AsEnumerable().Where(query.Compile()));
}
var aggregatedObjects = concatenatedParts.Aggregate((a, s) => a == null ? s : a.Where(s.Contains));
if (!aggregatedObjects.Any() || outRawExpression == null)
{
return(aggregatedObjects);
}
var outExpression = Expression.Lambda <Func <T, bool> >(outRawExpression, parameter);
return(aggregatedObjects.Where(outExpression.Compile()));
}
