/// <summary>
/// Return a String or Batch Message from a MessageContext
/// </summary>
/// <param name="selector"></param>
/// <param name="context"></param>
/// <returns></returns>
public async static Task <Message> SelectMessageAsync(this DataSelector selector, MessageContext context)
{
List <object> results = new List <object>();
var enumerator = selector.Select(context).GetAsyncEnumerator();
while (await enumerator.MoveNextAsync())
{
results.Add(enumerator.Current.ToString());
}
if (results.Count > 1)
{
return new Batch
{
DerivedFrom = context.msg,
Messages = results.Select(x => new StringMessage
{
DerivedFrom = context.msg,
Value = x.ToString()
})
}
}
;
else
{
return new StringMessage
{
DerivedFrom = context.msg,
Value = results.First().ToString()
}
};
}
}
/// <summary>
/// Return the first string selected from a MessageContext
/// </summary>
/// <param name="selector"></param>
/// <param name="context"></param>
/// <returns></returns>
public static string SelectString(this DataSelector selector, MessageContext context)
{
var stringTask = selector.SelectStringAsync(context);
stringTask.Wait();
return(stringTask.Result);
}
/// <summary>
/// Attempt to return the first long selected from a MessageContext
/// </summary>
/// <param name="selector"></param>
/// <param name="context"></param>
/// <returns></returns>
public static (bool Parsed, long Value) TrySelectLong(this DataSelector selector, MessageContext context)
{
var selectTask = selector.TrySelectLongAsync(context);
selectTask.Wait();
return(selectTask.Result);
}
/// <summary>
/// Return the first string selected from a MessageContext
/// </summary>
/// <param name="selector"></param>
/// <param name="context"></param>
/// <returns></returns>
/// <remarks>For when we're only expecting, or only need one result.</remarks>
public async static Task <string> SelectStringAsync(this DataSelector selector, MessageContext context)
{
// At time-of-writing, Microsoft hadn't added all the LINQ extension methods for IAsyncEnumerable (there
// would be between 200-600 of them, and I couldn't find any clear discussion about what they were
// planning), so we need to do it ourselves.
var enumerator = selector.Select(context).GetAsyncEnumerator();
if (await enumerator.MoveNextAsync())
{
return(enumerator.Current.ToString());
}
return(null);
}
/// <summary>
/// Attemt to return the first int selected from a MessageContext
/// </summary>
/// <param name="selector"></param>
/// <param name="context"></param>
/// <returns></returns>
public async static Task <(bool Parsed, int Value)> TrySelectIntAsync(this DataSelector selector, MessageContext context)
{
string val = await selector.SelectStringAsync(context);
if (String.IsNullOrWhiteSpace(val))
{
return(false, 0);
}
if (int.TryParse(val, out int result))
{
return(true, result);
}
else
{
return(false, 0);
}
}
/// <summary>
/// Message selection as a ReadOnlyMemory of bytes
/// </summary>
/// <param name="selector"></param>
/// <param name="context"></param>
/// <param name="encoding"></param>
/// <returns></returns>
public async static Task <ReadOnlyMemory <byte> > SelectROMByteAsync(this DataSelector selector,
MessageContext context,
Encoding encoding = null)
{
if (encoding is null)
{
encoding = Encoding.UTF8;
}
// ToDo: I'm expecting there to be a more efficient way of doing this, probably by going to each of the
// DataSelector subclasses and looking for methods unique to just SmartFormat, JPath, XPath, etc.
// Until then, this is just a convenience method that does it the dumb way.
var enumerator = selector.Select(context).GetAsyncEnumerator();
if (await enumerator.MoveNextAsync())
{
return(new ReadOnlyMemory <byte>(encoding.GetBytes(enumerator.Current.ToString())));
}
return(null);
}
