The Definitive ANTLR 4 Reference, 2nd Edition

Executing ANTLR and Testing Recognizers

Here’s a simple grammar that recognizes phrases like hello parrt and hello world:

install/Hello.g4

​grammar​ Hello​;​            ​// Define a grammar called Hello​
r  ​:​ ​'hello'​ ID ​;​         ​// match keyword hello followed by an identifier​
ID ​:​ ​[​a​-​z​]+​ ​;​             ​// match lower-case identifiers​
WS ​:​ ​[​ ​\​t​\​r​\​n​]+​ ​->​ skip ​;​ ​// skip spaces, tabs, newlines, \r (Windows)​

To keep things tidy, let’s put grammar file Hello.g4 in its own directory, such as /tmp/test. Then we can run ANTLR on it and compile the results.

​$ ​​cd​​ ​​/tmp/test​
​$ ​​# copy-n-paste Hello.g4 ...