This is a basic cli implementation used for testing and development of the peg-src library. If your are planning to use peg please use http://github.com/peg-org/peg-cli which is the official and fully featured cli interface of the project.
PEG uses Composer for dependencies. To start, download or clone into peg-custom. Open a terminal in the root of the repository and run these commands to install composer:
curl -sS https://getcomposer.org/installer | php
php composer.phar install
If all goes well, PEG should now be set up and ready to use! Just run php main.php to get started.