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 or download the file into /tmp/test
$ antlr4 Hello.g4  # Generate parser and lexer using antlr4 alias from before
$  ...