lexer

Ragel

• https://www.colm.net/open-source/ragel/
• http://www.blevesearch.com/news/Faster-Tokenization-with-Ragel-generated-FSM/

GoLex

• https://github.com/cznic/golex

ANTLR

• Golang is supported but https://github.com/antlr/antlr4/issues/1459