installAntlr.md

Installing ANTLR

This document describes how to install ANTLR (version 4.9.2) in a persistent way so that it does not need to be re-downloaded for each practical session.

Before starting, make sure you know the location of your permanent home directory.
If needed, refer to your UNIX/Shell course documentation.
You may also consult memoshell.pdf for a reminder of basic shell commands.

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A) Installation of ANTLR

1. Create a Local Bin Directory

Open a terminal and create a bin directory in your home directory:

mkdir ~/bin

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2. Download ANTLR

Download the file:

antlr-4.9.2-complete.jar

Place it inside:

~/bin

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B) Configure the Environment

The ANTLR commands are long. It is recommended to define aliases.

You have two options.

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Option 1 --- Temporary Configuration (per session)

Each time you open a terminal, run:

export CLASSPATH=.:~/bin/antlr-4.9.2-complete.jar:$CLASSPATH
alias antlr4='java -Xmx500M -cp "~/bin/antlr-4.9.2-complete.jar:$CLASSPATH" org.antlr.v4.Tool'
alias grun='java -Xmx500M -cp "~/bin/antlr-4.9.2-complete.jar:$CLASSPATH" org.antlr.v4.gui.TestRig'

This makes antlr4 and grun available for the current session only.

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Option 2 --- Permanent Configuration

To avoid repeating the commands at every session, modify your shell configuration file.

If you are using bash, edit:

~/.bashrc

Add the following lines:

export CLASSPATH=.:~/bin/antlr-4.9.2-complete.jar:$CLASSPATH
alias antlr4='java -Xmx500M -cp "~/bin/antlr-4.9.2-complete.jar:$CLASSPATH" org.antlr.v4.Tool'
alias grun='java -Xmx500M -cp "~/bin/antlr-4.9.2-complete.jar:$CLASSPATH" org.antlr.v4.gui.TestRig'

Save the file.

If a terminal was already open, reload the configuration:

source ~/.bashrc

After this, the commands antlr4 and grun will be available automatically.

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C) Basic Usage of ANTLR

To compile a grammar file named Fic.g4, run:

antlr4 Fic.g4
javac Fic*.java

This generates and compiles the lexer and parser corresponding to the grammar.