private void TranslateThenBy(MethodCallExpression methodCallExpression)
{
if (methodCallExpression.Arguments.Count != 2)
{
throw new ArgumentOutOfRangeException("methodCallExpression");
}
if (_orderBy == null)
{
throw new NotSupportedException("ThenBy or ThenByDescending can only be used after OrderBy or OrderByDescending.");
}
var key = (LambdaExpression)StripQuote(methodCallExpression.Arguments[1]);
var direction = (methodCallExpression.Method.Name == "ThenByDescending") ? OrderByDirection.Descending : OrderByDirection.Ascending;
var clause = new OrderByClause(key, direction);
_orderBy.Add(clause);
}
private void TranslateOrderBy(MethodCallExpression methodCallExpression)
{
if (methodCallExpression.Arguments.Count != 2)
{
throw new ArgumentOutOfRangeException("methodCallExpression");
}
if (_orderBy != null)
{
throw new NotSupportedException("Only one OrderBy or OrderByDescending clause is allowed (use ThenBy or ThenByDescending for multiple order by clauses).");
}
var key = (LambdaExpression)StripQuote(methodCallExpression.Arguments[1]);
var direction = (methodCallExpression.Method.Name == "OrderByDescending") ? OrderByDirection.Descending : OrderByDirection.Ascending;
var clause = new OrderByClause(key, direction);
_orderBy = new List<OrderByClause>();
_orderBy.Add(clause);
}
private void TranslateMaxMin(MethodCallExpression methodCallExpression)
{
var methodName = methodCallExpression.Method.Name;
if (_orderBy != null)
{
var message = string.Format("{0} cannot be used with OrderBy.", methodName);
throw new NotSupportedException(message);
}
if (_skip != null || _take != null)
{
var message = string.Format("{0} cannot be used with Skip or Take.", methodName);
throw new NotSupportedException(message);
}
switch (methodCallExpression.Arguments.Count)
{
case 1:
break;
case 2:
if (_projection != null)
{
var message = string.Format("{0} must be used with either Select or a selector argument, but not both.", methodName);
throw new NotSupportedException(message);
}
_projection = (LambdaExpression)StripQuote(methodCallExpression.Arguments[1]);
break;
default:
throw new ArgumentOutOfRangeException("methodCallExpression");
}
if (_projection == null)
{
var message = string.Format("{0} must be used with either Select or a selector argument.", methodName);
throw new NotSupportedException(message);
}
// implement Max/Min by sorting on the relevant field(s) and taking the first result
_orderBy = new List<OrderByClause>();
if (_projection.Body.NodeType == ExpressionType.New)
{
// take the individual constructor arguments and make new lambdas out of them for the OrderByClauses
var newExpression = (NewExpression)_projection.Body;
foreach (var keyExpression in newExpression.Arguments)
{
var delegateTypeGenericDefinition = typeof(Func<,>);
var delegateType = delegateTypeGenericDefinition.MakeGenericType(_projection.Parameters[0].Type, keyExpression.Type);
var keyLambda = Expression.Lambda(delegateType, keyExpression, _projection.Parameters);
var clause = new OrderByClause(keyLambda, (methodName == "Min") ? OrderByDirection.Ascending : OrderByDirection.Descending);
_orderBy.Add(clause);
}
}
else
{
var clause = new OrderByClause(_projection, (methodName == "Min") ? OrderByDirection.Ascending : OrderByDirection.Descending);
_orderBy.Add(clause);
}
_take = Expression.Constant(1);
SetElementSelector(methodCallExpression, source => source.Cast<object>().First());
}
private void TranslateLast(MethodCallExpression methodCallExpression)
{
LambdaExpression predicate = null;
switch (methodCallExpression.Arguments.Count)
{
case 1:
break;
case 2:
predicate = (LambdaExpression)StripQuote(methodCallExpression.Arguments[1]);
break;
default:
throw new ArgumentOutOfRangeException("methodCallExpression");
}
CombinePredicateWithWhereClause(methodCallExpression, predicate);
// when using OrderBy without Take Last can be much faster by reversing the sort order and using First instead of Last
if (_orderBy != null && _take == null)
{
for (int i = 0; i < _orderBy.Count; i++)
{
var clause = _orderBy[i];
var oppositeDirection = (clause.Direction == OrderByDirection.Descending) ? OrderByDirection.Ascending : OrderByDirection.Descending;
_orderBy[i] = new OrderByClause(clause.Key, oppositeDirection);
}
_take = Expression.Constant(1);
switch (methodCallExpression.Method.Name)
{
case "Last":
SetElementSelector(methodCallExpression, source => source.Cast<object>().First());
break;
case "LastOrDefault":
SetElementSelector(methodCallExpression, source => source.Cast<object>().FirstOrDefault());
break;
}
}
else
{
switch (methodCallExpression.Method.Name)
{
case "Last":
SetElementSelector(methodCallExpression, source => source.Cast<object>().Last());
break;
case "LastOrDefault":
SetElementSelector(methodCallExpression, source => source.Cast<object>().LastOrDefault());
break;
}
}
}
private void TranslateMaxMin(MethodCallExpression methodCallExpression)
{
var methodName = methodCallExpression.Method.Name;
if (_orderBy != null)
{
var message = string.Format("{0} cannot be used with OrderBy.", methodName);
throw new NotSupportedException(message);
}
if (_skip != null || _take != null)
{
var message = string.Format("{0} cannot be used with Skip or Take.", methodName);
throw new NotSupportedException(message);
}
switch (methodCallExpression.Arguments.Count)
{
case 1:
break;
case 2:
if (_projection != null)
{
var message = string.Format("{0} must be used with either Select or a selector argument, but not both.", methodName);
throw new NotSupportedException(message);
}
_projection = (LambdaExpression)StripQuote(methodCallExpression.Arguments[1]);
break;
default:
throw new ArgumentOutOfRangeException("methodCallExpression");
}
if (_projection == null)
{
var message = string.Format("{0} must be used with either Select or a selector argument.", methodName);
throw new NotSupportedException(message);
}
// implement Max/Min by sorting on the relevant field(s) and taking the first result
_orderBy = new List <OrderByClause>();
if (_projection.Body.NodeType == ExpressionType.New)
{
// take the individual constructor arguments and make new lambdas out of them for the OrderByClauses
var newExpression = (NewExpression)_projection.Body;
foreach (var keyExpression in newExpression.Arguments)
{
var delegateTypeGenericDefinition = typeof(Func <,>);
var delegateType = delegateTypeGenericDefinition.MakeGenericType(_projection.Parameters[0].Type, keyExpression.Type);
var keyLambda = Expression.Lambda(delegateType, keyExpression, _projection.Parameters);
var clause = new OrderByClause(keyLambda, (methodName == "Min") ? OrderByDirection.Ascending : OrderByDirection.Descending);
_orderBy.Add(clause);
}
}
else
{
var clause = new OrderByClause(_projection, (methodName == "Min") ? OrderByDirection.Ascending : OrderByDirection.Descending);
_orderBy.Add(clause);
}
_take = 1;
SetElementSelector(methodCallExpression, source => source.Cast <object>().First());
}
private void TranslateLast(MethodCallExpression methodCallExpression)
{
if (methodCallExpression.Arguments.Count != 1)
{
throw new ArgumentOutOfRangeException("methodCallExpression");
}
if (_elementSelector != null)
{
var message = string.Format("{0} cannot be combined with any other element selector.", methodCallExpression.Method.Name);
throw new InvalidOperationException(message);
}
// when using OrderBy without Take Last can be much faster by reversing the sort order and using First instead of Last
if (_orderBy != null && _take == null)
{
for (int i = 0; i < _orderBy.Count; i++)
{
var clause = _orderBy[i];
var oppositeDirection = (clause.Direction == OrderByDirection.Descending) ? OrderByDirection.Ascending : OrderByDirection.Descending;
_orderBy[i] = new OrderByClause(clause.Key, oppositeDirection);
}
_take = Expression.Constant(1);
switch (methodCallExpression.Method.Name)
{
case "Last":
_elementSelector = (IEnumerable source) => source.Cast<object>().First();
break;
case "LastOrDefault":
_elementSelector = (IEnumerable source) => source.Cast<object>().FirstOrDefault();
break;
}
}
else
{
switch (methodCallExpression.Method.Name)
{
case "Last":
_elementSelector = (IEnumerable source) => source.Cast<object>().Last();
break;
case "LastOrDefault":
_elementSelector = (IEnumerable source) => source.Cast<object>().LastOrDefault();
break;
}
}
}
