public override object VisitSelectExpression(QueryFilteringParser.SelectExpressionContext context)
{
var properties = context.PROPERTYACCESS()
.Select(x => x.Symbol.Text)
.ToHashSet();
var typeProperties = _parameter.Type
.GetCashedProperties()
.Where(p => properties.Contains(p.Name))
.ToDictionary(p => p.Name, p => p.PropertyType);
var dynamicType = DynamicTypeBuilder.CreateDynamicType(typeProperties);
var propExpressions = properties.ToDictionary(x => x, x => new PropertyNode(x, _parameter).CreateExpression());
var body = Expression.MemberInit(
Expression.New(dynamicType.GetConstructors().Single()),
dynamicType.GetFields().Select(f => Expression.Bind(f, propExpressions[f.Name])));
var lambda = ReflectionCache.Lambda.MakeGenericMethod(
typeof(Func <,>).MakeGenericType(_parameter.Type, dynamicType));
var expression = lambda.Invoke(null, new object[] { body, new ParameterExpression[] { _parameter } });
var select = ReflectionCache.Select
.MakeGenericMethod(_parameter.Type, dynamicType);
return(select.Invoke(null, new [] { _sourceQueryable, expression }));
}
/// <summary>
/// Visit a parse tree produced by <see cref="QueryFilteringParser.selectExpression"/>.
/// <para>
/// The default implementation returns the result of calling <see cref="AbstractParseTreeVisitor{Result}.VisitChildren(IRuleNode)"/>
/// on <paramref name="context"/>.
/// </para>
/// </summary>
/// <param name="context">The parse tree.</param>
/// <return>The visitor result.</return>
public virtual Result VisitSelectExpression([NotNull] QueryFilteringParser.SelectExpressionContext context)
{
return(VisitChildren(context));
}
