public static IQueryable <T> Wrap <T, M>(this IQueryable <M> queryable, WrapperContext context = null)
where M : T
{
if (queryable == null)
{
throw new ArgumentNullException(nameof(queryable));
}
if (context == null)
{
context = new WrapperContext();
}
WrappedQueryableProvider <T, M> provider = new WrappedQueryableProvider <T, M>(queryable.Provider, context);
return(provider.CreateQuery <T>(queryable.Expression));
}
public static IQueryable <M> Unwrap <T, M>(this IQueryable <T> queryable, WrapperContext context = null)
where M : T
{
if (queryable == null)
{
throw new ArgumentNullException(nameof(queryable));
}
WrappedQueryable <T, M> wrapped = queryable as WrappedQueryable <T, M>;
if (wrapped == null)
{
throw new NotSupportedException("不支持的类型。");
}
WrappedQueryableProvider <T, M> provider = wrapped.Provider;
var visitor = new WrapperVisitor(context ?? provider.Context);
var expression = visitor.Visit(wrapped.Expression);
return(provider.InnerQueryProvider.CreateQuery <M>(expression));
}
public WrappedOrderedQueryable(WrappedQueryableProvider <T, M> provider, Expression expression)
: base(provider, expression)
{
}
public WrappedQueryable(WrappedQueryableProvider <T, M> provider, Expression expression)
{
Expression = expression ?? throw new ArgumentNullException(nameof(expression));
Provider = provider ?? throw new ArgumentNullException(nameof(provider));
}
