protected override Expression VisitMethodCall(MethodCallExpression node)
{
if (node.Method.Name == nameof(Enumerable.Where))
{
var predicate = node.Arguments[1] is UnaryExpression quote ? (LambdaExpression)quote.Operand : (LambdaExpression)node.Arguments[1];
var joinVisitor = new JoinVisitor(_edmModel, node.Arguments[0], predicate.Parameters[0]);
Expression expression = joinVisitor.Visit(node.Arguments[1]);
if (node.Arguments[1] != expression)
{
Expression[] arguments = node.Arguments.ToArray();
arguments[1] = expression;
return(node.Update(node.Object !, arguments));
}
}
else if (node.Method.Name == nameof(Enumerable.SelectMany) && node.Arguments.Count == 2)
{
var predicate = node.Arguments[1] is UnaryExpression quote ? (LambdaExpression)quote.Operand : (LambdaExpression)node.Arguments[1];
var joinVisitor = new JoinVisitor(_edmModel, node.Arguments[0], predicate.Parameters[0]);
Expression body = joinVisitor.Visit(predicate.Body);
if (predicate.Body != body)
{
Expression[] arguments = node.Arguments.ToArray();
arguments[1] = Expression.Lambda(body, predicate.Parameters);
return(node.Update(node.Object !, arguments));
}
}
return(base.VisitMethodCall(node));
}
public static IEnumerable <Type> GetJoinTypes(System.Linq.Expressions.Expression expression)
{
var joinVisitor = new JoinVisitor();
joinVisitor.Visit(expression);
return(joinVisitor.Types);
}