This page contains instructions for using Hermes to regenerate the WDL parser after making changes to the WDL grammar file, which is located at wdl/transforms/$version/src/main/resources/grammar.hgr. Note that there is a separate grammar file and parser for each WDL version.

Install Hermes

Requires Python 3 (tested with Python 3.5). Pyenv is the recommended way to install this older Python version. Newer Python versions may not work correctly.

Hermes can be installed via pip (https://pypi.python.org/pypi/hermes-parser/2.0rc6)

However, It is recommended that Hermes is installed from source into a virtual environment because PyPI isn’t updated very often.

First, clone Hermes and create then activate a new Python virtual environment (in directory ./hermes-venv)

$ git clone git@github.com:scottfrazer/hermes.git
$ cd hermes
$ pyenv virtualenv 3.5.10 hermes-venv
$ pyenv activate hermes-venv

In the Hermes repo, make sure you have the latest ‘develop’ branch checked out. Then, install Hermes into the virtual environment (need to separately run pip installs because the Python 3.5 default index URL doesn't work anymore):

$ pip install --index-url https://pypi.org/simple/ moody-templates xtermcolor nose pygments hermes_pygments
$ python setup.py install
$ hermes --help

With the virtual environment activated, navigate to cromwell/wdl/transforms/$version and run the below command, replacing $version with the correct package name (e.g. biscayne or cascades).:

hermes generate src/main/resources/grammar.hgr \
          --language=java \
          --directory=src/main/java \
          --name=wdl \
          --java-package=wdl.$version.parser \
          --java-use-apache-commons --java-imports=org.apache.commons.lang3.StringEscapeUtils \
          --header