ArgsParsingResult ParseInternal(IList<string> args)
{
/*
* (start) --[EoA]--> (no default? error|stop)
* (start) --[command]--> (save command|continue with command)
* (start) --[option(kv) in default command]--> (save default command|waiting value with command)
* (start) --[option-groups(f) in default command]--> (save default command|yield flag|continue with command)
* (start) --[other]--> (save default command|yield free value|continue with command-free value)
*
* (continue with command) --[option(kv) in command]--> (waiting value with command)
* (continue with command) --[option-groups(f) in command]--> (yield flag|continue with command)
* (continue with command) --[EoA]--> (stop)
* (continue with command) --[other]--> (yield free value|continue with command-free value)
*
* (waiting value with command) --[EoA]--> (error|stop)
* (waiting value with command) --[other]--> (yield key value|continue with command)
*
* (continue with command-free value) --[EoA]--> (stop)
* (continue with command-free value) --[other] --> (yield free value|continue with command-free value)
*/
var builder = new PreParserResultBuilder();
IPreParsingState state = new StartState(definition, builder);
foreach (string arg in args)
{
state = state.MoveToNext(arg);
if (state == null) { return builder.Build(); }
}
state.MoveToNext(null);
return builder.Build();
}