Notes on CodeMirror

The core text editor in Brackets is CodeMirror. The Brackets team has submitted or contributed to a number of features and bug fixes in CodeMirror, and has also given input into the design of features like line widgets and document/view separation.

Currently, Brackets uses a fork of CodeMirror as a submodule. Originally, this was because of a number of experimental features that Brackets implemented (including a prototype implementation of inline widgets) that we hadn't yet contributed upstream. Now that the upstream CodeMirror repo has versions of these features, we've ported Brackets to use the upstream version.

As of Sprint 20, where we merged with the latest CodeMirror v3, the adobe/CodeMirror2 fork's master has been reset to upstream master. Going forward, we will keep our master completely in sync with upstream; we will never add our own commits directly to master, and we'll plan to pull from upstream as often as we can, keeping the Brackets submodule pointing at master. However, in cases where there are last-minute upstream changes that we don't want to pull into a given sprint, and we need other fixes, we might make short-lived sprint branches.

Current status

There are currently three branches of note in the adobe/CodeMirror2 fork:

• master - this has now been reset to upstream master, and will always reflect the state of upstream.
• v2-master - this is the last commit we made in our old (diverged) master. We won't be using this branch going forward, but older versions of Brackets refer to it in their submodule SHAs, so we need to keep it around for archival purposes.
• brackets-sprint20 - this is a temporary branch that pulls in a couple of fixes we needed from upstream but avoids a couple that seemed potentially destabilizing; the main Brackets source currently points to this branch. In the next sprint we plan to get rid of this branch and point directly at master.

Going forward, we'll generally submit pull requests directly to the main CodeMirror repo rather than making fixes in branches in our fork, then pull them down once they've been merged upstream. Similarly, if you have fixes you need in CodeMirror, please submit them upstream (you can file an issue with us to let us know that it's important for us to merge it soon, or refer to your upstream fix from a dependent pull request). We generally won't accept pull requests directly into our CodeMirror fork.

If you have an existing fork or clone of adobe/CodeMirror2 from before Sprint 20, you shouldn't try to pull into your master from our master--instead, you'll want to do a direct reset of your master branch to our master (e.g. if you have your upstream remote set to adobe/CodeMirror2, then do git checkout master and git reset upstream/master).

Note that we have not yet renamed the submodule or the repo to reflect the current naming of the upstream repo--it's still "CodeMirror2". This renaming is a bit tricky and isn't urgent, so we've put it off until later. See this Google Group thread for more info.