public bool TryCreateKeyInfoHelper(Type keyType, out IKeyInfoHelper result)
{
if (!typeof(DataRow).IsAssignableFrom(keyType))
{
result = null;
return(false);
}
result = new DataRowKeyInfoHelper(keyType);
return(true);
}
private static Expression CreateDataRowSelector(
Expression body,
Expression[] memberSelectors)
{
Dictionary<string, Type> members = new Dictionary<string, Type>();
int index = 0;
foreach (var selector in memberSelectors)
{
members.Add(string.Format("Item{0:D2}", index), selector.Type);
index++;
}
Type rowType = DataRowFactory.Create(members);
var helper = new DataRowKeyInfoHelper(rowType);
body = helper.CreateKeyFactoryExpression(memberSelectors);
return body;
}
private Expression CreateCrossJoin(
Expression first,
LambdaExpression collectionSelector,
string firstName,
string secondName)
{
Type firstType = TypeHelper.GetElementType(first.Type);
Type secondType = TypeHelper.GetElementType(collectionSelector.Body.Type);
Dictionary<string, Type> resultTypeProps =
new Dictionary<string, Type>
{
{ firstName, firstType },
{ secondName, secondType }
};
// Create result selector
Type resultType = DataRowFactory.Create(resultTypeProps);
IKeyInfoHelper helper = new DataRowKeyInfoHelper(resultType);
ParameterExpression firstParam = Expression.Parameter(firstType);
ParameterExpression secondParam = Expression.Parameter(secondType);
LambdaExpression resultSelector =
Expression.Lambda(
helper.CreateKeyFactoryExpression(firstParam, secondParam),
firstParam,
secondParam);
return queryMethodExpressionBuilder.SelectMany(
first,
collectionSelector,
resultSelector);
}
