public static MethodCallExpression SubstituteWithWhere(this MethodCallExpression node, bool negate = false)
{
Check.NotNull(node, nameof(node));
Expression predicate = node.Arguments[1];
if (negate)
{
LambdaExpression lambdaExpression = node.GetLambda();
UnaryExpression body = Expression.Not(lambdaExpression.Body);
predicate = body.WrapInLambda(lambdaExpression.Parameters);
}
return(Expression.Call(typeof(Queryable), nameof(Queryable.Where), node.Method.GetGenericArguments(), node.Arguments[0], predicate));
}
protected override Expression VisitMethodCall(MethodCallExpression node)
{
Check.NotNull(node, nameof(node));
if (!node.Method.IsGenericMethod)
{
return(node);
}
if (!node.Method.IsSupportedNativelyOrByComposition())
{
throw new NotSupportedException($"Method {node.Method.Name} cannot be converter to a valid query.");
}
MethodInfo genericDefinition = node.Method.GetGenericMethodDefinition();
#region Bool member to constants
if (!_isVisitingWhereMethodOrChild && genericDefinition == QueryableMethods.Where)
{
_isVisitingWhereMethodOrChild = true;
Expression whereNode = VisitMethodCall(node);
_isVisitingWhereMethodOrChild = false;
return(whereNode);
}
#endregion
#region Multi-Where Optimization
if (genericDefinition == QueryableMethods.Where)
{
if (_nextWhereCalls.Count == 0)
{
_nextWhereCalls.Enqueue(node);
Expression tail = Visit(node.Arguments[0]);
LambdaExpression currentLambda = node.GetLambda();
Expression conditionExpression = Visit(currentLambda.Body);
_nextWhereCalls.Dequeue();
while (_nextWhereCalls.Count > 0)
{
Expression nextWhereBody = Visit(_nextWhereCalls.Dequeue().GetLambdaBody());
conditionExpression = Expression.And(nextWhereBody, conditionExpression);
}
Expression conditionLambda = conditionExpression.WrapInLambda(currentLambda.Parameters);
return(Expression.Call(typeof(Queryable), nameof(Queryable.Where),
node.Method.GetGenericArguments(), tail, conditionLambda));
}
_nextWhereCalls.Enqueue(node);
return(Visit(node.Arguments[0]));
}
#endregion
#region Min/Max
// Min(d => d.Property) == OrderBy(d => d.Property).Take(1).Select(d => d.Property).Min()
if (genericDefinition == QueryableMethods.MinWithSelector)
{
return(node
.SubstituteWithQueryableCall(nameof(Queryable.OrderBy))
.WrapInTake(1)
.WrapInSelect(node)
.WrapInMinMax(QueryableMethods.MinWithoutSelector));
}
// Max(d => d.Property) == OrderByDescending(d => d.Property).Take(1).Select(d => d.Property).Max()
if (genericDefinition == QueryableMethods.MaxWithSelector)
{
return(node
.SubstituteWithQueryableCall(nameof(Queryable.OrderByDescending))
.WrapInTake(1)
.WrapInSelect(node)
.WrapInMinMax(QueryableMethods.MaxWithoutSelector));
}
#endregion
#region Sum/Average
// Sum(d => d.Property) == Select(d => d.Property).Sum()
if (QueryableMethods.IsSumWithSelector(genericDefinition))
{
return(node
.SubstituteWithSelect(node)
.WrapInAverageSum(node));
}
// Average(d => d.Property) == Select(d => d.Property).Average()
if (QueryableMethods.IsAverageWithSelector(genericDefinition))
{
return(node
.SubstituteWithSelect(node)
.WrapInAverageSum(node));
}
#endregion
#region Any/All
// Any() => Take(1).Any()
if (genericDefinition == QueryableMethods.AnyWithoutPredicate)
{
return(node
.WrapInTake(1)
.WrapInMethodWithoutSelector(QueryableMethods.AnyWithoutPredicate));
}
// Any(d => condition) == Where(d => condition).Take(1).Any()
if (genericDefinition == QueryableMethods.AnyWithPredicate)
{
return(node
.SubstituteWithWhere()
.WrapInTake(1)
.WrapInMethodWithoutSelector(QueryableMethods.AnyWithoutPredicate));
}
// All(d => condition) == Where(d => !condition).Take(1).Any()
if (genericDefinition == QueryableMethods.All)
{
return(node
.SubstituteWithWhere(true)
.WrapInTake(1)
.WrapInMethodWithoutSelector(QueryableMethods.AnyWithoutPredicate));
}
#endregion
#region Single/SingleOrDefault
// Single() == Take(2).Single()
if (genericDefinition == QueryableMethods.SingleWithoutPredicate)
{
return(node
.SubstituteWithTake(2)
.WrapInMethodWithoutSelector(QueryableMethods.SingleWithoutPredicate));
}
// SingleOrDefault() == Take(2).SingleOrDefault()
if (genericDefinition == QueryableMethods.SingleOrDefaultWithoutPredicate)
{
return(node
.SubstituteWithTake(2)
.WrapInMethodWithoutSelector(QueryableMethods.SingleOrDefaultWithoutPredicate));
}
// Single(d => condition) == Where(d => condition).Take(2).Single()
if (genericDefinition == QueryableMethods.SingleWithPredicate)
{
return(node
.SubstituteWithWhere()
.SubstituteWithTake(2)
.WrapInMethodWithoutSelector(QueryableMethods.SingleWithoutPredicate));
}
// SingleOrDefault(d => condition) == Where(d => condition).Take(2).SingleOrDefault()
if (genericDefinition == QueryableMethods.SingleOrDefaultWithPredicate)
{
return(node
.SubstituteWithWhere()
.SubstituteWithTake(2)
.WrapInMethodWithoutSelector(QueryableMethods.SingleOrDefaultWithoutPredicate));
}
#endregion
#region First/FirstOrDefault
// First() == Take(1).First()
if (genericDefinition == QueryableMethods.FirstWithoutPredicate)
{
return(node
.SubstituteWithTake(1)
.WrapInMethodWithoutSelector(QueryableMethods.FirstWithoutPredicate));
}
// FirstOrDefault() == Take(1).FirstOrDefault()
if (genericDefinition == QueryableMethods.FirstOrDefaultWithoutPredicate)
{
return(node
.SubstituteWithTake(1)
.WrapInMethodWithoutSelector(QueryableMethods.FirstOrDefaultWithoutPredicate));
}
// First(d => condition) == Where(d => condition).Take(1).First()
if (genericDefinition == QueryableMethods.FirstWithPredicate)
{
return(node
.SubstituteWithWhere()
.SubstituteWithTake(1)
.WrapInMethodWithoutSelector(QueryableMethods.FirstWithoutPredicate));
}
// FirstOrDefault(d => condition) == Where(d => condition).Take(1).FirstOrDefault()
if (genericDefinition == QueryableMethods.FirstOrDefaultWithPredicate)
{
return(node
.SubstituteWithWhere()
.SubstituteWithTake(1)
.WrapInMethodWithoutSelector(QueryableMethods.FirstOrDefaultWithoutPredicate));
}
#endregion
#region Last/LastOrDefault
// Last() == Last()
// LastOrDefault() == LastOrDefault()
if (genericDefinition == QueryableMethods.LastWithoutPredicate ||
genericDefinition == QueryableMethods.LastOrDefaultWithoutPredicate)
{
return(node);
}
// Last(d => condition) == Where(d => condition).Last()
if (genericDefinition == QueryableMethods.LastWithPredicate)
{
return(node
.SubstituteWithWhere()
.WrapInMethodWithoutSelector(QueryableMethods.LastWithoutPredicate));
}
// LastOrDefault(d => condition) == Where(d => condition).LastOrDefault()
if (genericDefinition == QueryableMethods.LastOrDefaultWithPredicate)
{
return(node
.SubstituteWithWhere()
.WrapInMethodWithoutSelector(QueryableMethods.LastOrDefaultWithoutPredicate));
}
#endregion
return(base.VisitMethodCall(node));
}
