/// <summary>
/// Project
/// </summary>
/// <param name="records"></param>
/// <param name="context"></param>
/// <returns></returns>
private IEnumerable <VariantValue> Project(IEnumerable <VariantValue> records,
SqlSelectParser.ParseContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
// TODO: Implement projection
return(records);
}
/// <summary>
/// Where
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="records"></param>
/// <param name="context"></param>
/// <returns></returns>
private IEnumerable <T> Select <T>(IEnumerable <T> records,
SqlSelectParser.ParseContext context)
{
var pe = Expression.Parameter(typeof(T));
// Top
if (context.selectList().topExpr() != null)
{
var maxCount = double.Parse(context.selectList().topExpr().maxCount().GetText(),
CultureInfo.InvariantCulture);
records = records.Take((int)maxCount);
}
// Where
if (context.expr() != null)
{
var where = (Expression <Func <T, bool> >)Expression.Lambda(
ParseWhereExpression(pe, context.expr()), pe);
var compiled = where.Compile();
records = records.Where(compiled);
}
return(records);
}
