Bug reports are the simplest way you can get involved. Bug reports take little time to file and are very helpful to developers. When you discover a problem, please report it. Make sure you provide information about your environment (OS, JDK and MPS version), steps to reproduce the issue, as well as a textual description of the problem. You can file a bug in JetBrains MPS YouTrack bug database. Before submitting an issue, you may also want to search for already submitted ones describing the same problem - and if you find one, feel free to vote for it.
Bug reports are helpful, but as you probably know, most of the problems can be reproduced/checked by automated JUnit tests. It's much more easy and convenient for our developers to reproduce the problem by running a test case instead of manually going through a list of steps to reproduce the bug. If you invest a little bit more time and create a JUnit test reproducing your problem, we will usually be able to fix/process your bug faster.
If you would like to improve the MPS code, you can submit a patch by attaching it to corresponding request in the JetBrains MPS YouTrack bug database. You can either file a new issue with the patch attached, or attach a patch to an issue submitted by another user. A developer will review your patch and, if it meets the quality criteria and fits with the rest of the code, you'll be notified about the acceptance of the patch. As it was already mentioned, patches having a unit-test attaches should be processed faster.
Although the main Git repository is located at JetBrains (see the Accessing MPS Git Repository section below), we keep a public mirror at GitHub. The mirror is primarily meant to be an easy-to-use repository for external contributors. Here's a cookbook on how to contribute your idea to MPS through GitHub
This section describes how you create a fork of the MPS github repository and open the MPS project in IntelliJ IDEA.
In order to build MPS from source you need to download the IDEA IntelliJ community edition and open the MPS project in idea. To do so, call "Open Project" and choose the folder in which the git repository is located. After that, trigger a rebuild. Once the rebuild is finished, open a shell and navigate into the build directory. The script to execute is called run.build.sh (assuming you have ant installed).
This section describes how you make changes to the source code.
This section explains how you can forward your local changes to JetBrains.
As you change your code and commit, you make changes to your own fork of the MPS github repository. Using pull requests, you can make the MPS developers aware of your changes, and they may or may not integrate your change into the original repository. However, in the meantime, the original MPS repository changes (as a consequence of the MPS team working on the code), and your fork is not kept in sync. To keep your local clone and your remote fork in sync with the changes in the original repository, please do the following:
In summary, you pull from the original, resolve conflicts and the push to your fork.
The main MPS repository is located at git://git.jetbrains.com/mps/mps.git and can be used as a base for submitting your patches to MPS. The process using GitHub should, however, be considered to be the preferred way.
To check out from IntelliJ IDEA, select “Version Control | Checkout from Version Control | Git” from the main menu. In the “Git Repository URL” field, enter:
To check out from the command line, use the following command:
git clone git://git.jetbrains.org/mps/mps.git
In addition you can browse MPS sources using git web access.
Admittedly the over project structure is very difficult to see from the hierarchy of modules and packages in IDEA and MPS and you'll be having hard time understanding how the pieces fit together. We've collected a few guidelines to help you in many cases. For the rest, please get in touch with us directly or through the forum.
MPS is being developed in both IntelliJ IDEA and MPS itself. So the code base consists of Java sources as well as MPS models. Whenever you open a Java file in IDEA, you can check whether the file contains a comment /*Generated by MPS */, which indicates, that the source was generated and the real source is to be found in MPS, most likely under a similar name. The shortcut Control/Cmd + N for opening files, classes and root nodes by name will certainly come in handy and luckily it is the same shortcut in both IDEA and MPS.
The Project View in MPS may give you rough guidelines on how the project is structured:
The MPS project stores generated artefacts in Git alongside the sources and models. Before committing please ensure that all the changed models have been regenerated - the (generation required) note must disappear. May you fail to do so, the TeamCity CI server will reject the commit by a failed build, since it checks all artefacts for being correctly generated. The best way to regenerate is to invoke Rebuild from the model's or module's context menu.