public static Expression CreateSelection(
this QueryableProjectionScope scope,
Expression source,
Type sourceType)
{
MethodCallExpression selection = Expression.Call(
typeof(Enumerable),
nameof(Enumerable.Select),
new[]
{
scope.RuntimeType,
scope.RuntimeType
},
source,
scope.CreateMemberInitLambda());
if (sourceType.IsArray)
{
return(ToArray(scope, selection));
}
if (TryGetSetType(sourceType, out Type? setType))
{
return(ToSet(selection, setType));
}
return(ToList(scope, selection));
}
public static Expression CreateMemberInit(this QueryableProjectionScope scope)
{
if (scope.HasAbstractTypes())
{
Expression lastValue = Expression.Default(scope.RuntimeType);
foreach (KeyValuePair <Type, Queue <MemberAssignment> > val in
scope.GetAbstractTypes())
{
NewExpression ctor = Expression.New(val.Key);
Expression memberInit = Expression.MemberInit(ctor, val.Value);
lastValue = Expression.Condition(
Expression.TypeIs(scope.Instance.Peek(), val.Key),
Expression.Convert(memberInit, scope.RuntimeType),
lastValue);
}
return(lastValue);
}
else
{
NewExpression ctor = Expression.New(scope.RuntimeType);
return(Expression.MemberInit(ctor, scope.Level.Peek()));
}
}
private static Expression ToList(QueryableProjectionScope scope, Expression source)
{
return(Expression.Call(
typeof(Enumerable),
nameof(Enumerable.ToList),
new[]
{
scope.RuntimeType
},
source));
}
public static QueryableProjectionScope AddScope(
this QueryableProjectionContext context,
Type runtimeType)
{
var parameterName = "p" + context.Scopes.Count;
var closure =
new QueryableProjectionScope(runtimeType, parameterName);
context.Scopes.Push(closure);
return(closure);
}
public static Expression CreateMemberInitLambda(this QueryableProjectionScope scope)
{
return(Expression.Lambda(scope.CreateMemberInit(), scope.Parameter));
}
public static Expression <Func <T, T> > Project <T>(this QueryableProjectionScope scope)
{
return((Expression <Func <T, T> >)scope.CreateMemberInitLambda());
}