Lucene.Net 1.9.1 Class Library

CharStream.Backup Method 

Backs up the input stream by amount steps. Lexer calls this method if it had already read some characters, but could not use them to match a (longer) token. So, they will be used again as the prefix of the next token and it is the implemetation's responsibility to do this right.

void Backup(
   int amount
);

See Also

CharStream Interface | Lucene.Net.Analysis.Standard Namespace