Class NGramTokenizer

Tokenizes the input into n-grams of the given size(s).

On the contrary to NGramTokenFilter, this class sets offsets so that characters between startOffset and endOffset in the original stream are the same as the term chars.

For example, "abcde" would be tokenized as (minGram=2, maxGram=3):

This tokenizer changed a lot in Lucene 4.4 in order to:

• tokenize in a streaming fashion to support streams which are larger than 1024 chars (limit of the previous version),
• count grams based on unicode code points instead of java chars (and never split in the middle of surrogate pairs),
• give the ability to pre-tokenize the stream (IsTokenChar(Int32)) before computing n-grams.

Additionally, this class doesn't trim trailing whitespaces and emits tokens in a different order, tokens are now emitted by increasing start offsets while they used to be emitted by increasing lengths (which prevented from supporting large input streams).

Although highly discouraged, it is still possible to use the old behavior through Lucene43NGramTokenizer.