public SelectEnumerator(SelectClause <TResult> selectClause)
{
var rowLambda = selectClause.SelectExpression as LambdaExpression;
var compiledRowLambda = rowLambda.Compile();
var paramInfo = new List <ParameterResultInfo>();
var generatedSelect = selectClause.Model;
_selectList = generatedSelect.SelectList;
foreach (var x in rowLambda.Parameters)
{
//look for the type in the select list
var sel = _selectList.FirstOrDefault(s => s.SourceType == x.Type);
if (sel == null)
{
paramInfo.Add(null);
continue;
}
paramInfo.Add(new ParameterResultInfo()
{
Type = x.Type,
ArgumentMapping = ConstructorArgumentsMap(x.Type),
MemberMapping = PropertyMapping(x.Type),
Constructor = x.Type.GetConstructors()[0],
ConstArgumentsBuffer = new object[x.Type.GetConstructors()[0].GetParameters().Length]
});
}
var connection = VirtualDataSource.GetConnection();
_result = new List <TResult>();
connection.Run(selectClause, (reader) =>
{
/*
* for each row:
* for each parameter
* 1. instantiate parameter
* 2. set property values
* 3. execute lambda expression
* 4. cast to result
*/
var arguments = new object[paramInfo.Count];
for (var i = 0; i < paramInfo.Count; i++)
{
var p = paramInfo[i];
if (p != null)
{
arguments[i] = p.CreateInstance(reader);
}
}
_result.Add((TResult)compiledRowLambda.DynamicInvoke(arguments));
});
listEnumerator = _result.GetEnumerator();
}
public static VirtualDataSource GetConnection(string key = null)
{
if (_dataSourceInstance == null)
{
_dataSourceInstance = new VirtualDataSource(key);
}
return(_dataSourceInstance);
}