public static void ReWrite(QueryModel queryModel, ISessionFactory sessionFactory)
{
var nsqmv = new NestedSelectDetector(sessionFactory);
nsqmv.Visit(queryModel.SelectClause.Selector);
if (!nsqmv.HasSubqueries)
{
return;
}
var elementExpression = new List <ExpressionHolder>();
var group = Expression.Parameter(typeof(IGrouping <Tuple, Tuple>), "g");
var replacements = new Dictionary <Expression, Expression>();
foreach (var expression in nsqmv.Expressions)
{
var processed = ProcessExpression(queryModel, sessionFactory, expression, elementExpression, group);
if (processed != null)
{
replacements.Add(expression, processed);
}
}
var key = Expression.Property(group, IGroupingKeyProperty);
var expressions = new List <ExpressionHolder>();
var identifier = GetIdentifier(sessionFactory, new QuerySourceReferenceExpression(queryModel.MainFromClause));
var rewriter = new SelectClauseRewriter(key, expressions, identifier, replacements);
var resultSelector = rewriter.Visit(queryModel.SelectClause.Selector);
elementExpression.AddRange(expressions);
var keySelector = CreateSelector(elementExpression, 0);
var elementSelector = CreateSelector(elementExpression, 1);
var input = Expression.Parameter(typeof(IEnumerable <object>), "input");
var lambda = Expression.Lambda(
Expression.Call(GroupByMethod,
Expression.Call(CastMethod, input),
keySelector,
elementSelector),
input);
queryModel.ResultOperators.Add(new ClientSideSelect2(lambda));
queryModel.ResultOperators.Add(new ClientSideSelect(Expression.Lambda(resultSelector, @group)));
var initializers = elementExpression.Select(e => ConvertToObject(e.Expression));
queryModel.SelectClause.Selector = Expression.NewArrayInit(typeof(object), initializers);
}
private static LambdaExpression MakeSelector(ICollection <ExpressionHolder> elementExpression, Expression @select, Expression identifier)
{
var parameter = Expression.Parameter(typeof(Tuple), "value");
var rewriter = new SelectClauseRewriter(parameter, elementExpression, identifier, 1, new Dictionary <Expression, Expression>());
var selectorBody = rewriter.Visit(@select);
return(Expression.Lambda(selectorBody, parameter));
}