/// <summary>
/// Visit :: x => x.Customer.Name.`ToUpper()`
/// </summary>
protected override Expression VisitMethodCall(MethodCallExpression node)
{
// get method declaring type - if is from any kind of list, read as Enumerable
var isList = Reflection.IsList(node.Method.DeclaringType);
var declaringType = isList ? typeof(Enumerable) : node.Method.DeclaringType;
// if special method for index access, eval index value (do not use parameters)
if (this.IsMethodIndexEval(node, out var obj, out var idx))
{
this.Visit(obj);
var index = this.Evaluate(idx, typeof(string), typeof(int));
if (index is string)
{
_builder.Append(".");
_builder.Append($"['{index}']");
}
else
{
_builder.Append($"[{index}]");
}
return(node);
}
// if not found in resolver, try run method
if (!_resolver.TryGetValue(declaringType, out var type))
{
// if method are called by parameter expression and it's not exists, throw error
var isParam = ParameterExpressionVisitor.Test(node);
if (isParam)
{
throw new NotSupportedException($"Method {node.Method.Name} not available to convert to BsonExpression ({node.ToString()}).");
}
// otherwise, try compile and execute
var value = this.Evaluate(node);
base.Visit(Expression.Constant(value));
return(node);
}
// otherwise I have resolver for this method
var pattern = type.ResolveMethod(node.Method);
if (pattern == null)
{
throw new NotSupportedException($"Method {Reflection.MethodName(node.Method)} in {node.Method.DeclaringType.Name} are not supported when convert to BsonExpression ({node.ToString()}).");
}
// run pattern using object as # and args as @n
this.ResolvePattern(pattern, node.Object, node.Arguments);
return(node);
}
public string ResolveMethod(MethodInfo method)
{
// all methods in Enumerable are Extensions (static methods), so first parameter is IEnumerable
var name = Reflection.MethodName(method, 1);
switch (name)
{
// get all items
case "AsEnumerable()": return("@0[*]");
// get fixed index item
case "get_Item(int)": return("#[@0]");
case "ElementAt(int)": return("@0[@1]");
case "Single()":
case "First()":
case "SingleOrDefault()":
case "FirstOrDefault()": return("@0[0]");
case "Last()":
case "LastOrDefault()": return("@0[-1]");
// get single item but with predicate function
case "Single(Func<T,TResult>)":
case "First(Func<T,TResult>)":
case "SingleOrDefault(Func<T,TResult>)":
case "FirstOrDefault(Func<T,TResult>)": return("FIRST(@0[@1])");
case "Last(Func<T,TResult>)":
case "LastOrDefault(Func<T,TResult>)": return("LAST(@0[@1])");
// filter
case "Where(Func<T,TResult>)": return("@0[@1]");
// map
case "Select(Func<T,TResult>)": return("(@0 => @1)");
// aggregate
case "Count()": return("COUNT(@0)");
case "Sum()": return("SUM(@0)");
case "Average()": return("AVG(@0)");
case "Max()": return("MAX(@0)");
case "Min()": return("MIN(@0)");
// aggregate with map function
case "Count(Func<T,TResult>)": return("COUNT(@0 => @1)");
case "Sum(Func<T,TResult>)": return("SUM(@0 => @1)");
case "Average(Func<T,TResult>)": return("AVG(@0 => @1)");
case "Max(Func<T,TResult>)": return("MAX(@0 => @1)");
case "Min(Func<T,TResult>)": return("MIN(@0 => @1)");
// convert to array
case "ToList()":
case "ToArray()": return("ARRAY(@0)");
// any/all special cases
case "Any(Func<T,TResult>)": return("@0 ANY %");
case "ALL(Func<T,TResult>)": return("@0 ANY %");
}
;
return(null);
}