Antlr 4 + Python setup on ubuntu

antlr4

#!/bin/sh

java -cp "/opt/antlr/antlr4/dist/antlr-4.4-complete.jar:$CLASSPATH" org.antlr.v4.Tool $*

execute.py

from antlr4 import *
import sys
from HelloLexer import HelloLexer
from HelloParser import HelloParser

def main(argv):
    input = FileStream(argv[1])
    lexer = HelloLexer(input)
    stream = CommonTokenStream(lexer)
    parser = HelloParser(stream)
    tree = parser.r()

if __name__ == '__main__':
    main(sys.argv)

gistfile1.txt

Python target support for ANTLR landed in version 4.4.
In this short writeup, I would like to document the installation process.

git clone git@github.com:parrt/antlr4-python2.git

mkdir -p /opt/antlr 
cd /opt/antlr
git clone git@github.com:parrt/antlr4.git
git clone git@github.com:parrt/antlr4-python3.git
git clone git@github.com:parrt/antlr4-python2.git

cd antlr4
./bild.py mkjar

cd /opt/antlr/antlr4-python3
sudo python3 setup.py install

antlr4 -Dlanguage=Python3 Hello.g4

python3 execute.py hello-me

hello-me

hello World

Hello.g4

// Define a grammar called Hello
grammar 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