libgit2/PROJECTS.md

Projects For LibGit2
====================

So, you want to start helping out with `libgit2`? That's fantastic! We
welcome contributions and we promise we'll try to be nice.

This is a list of libgit2 related projects that new contributors can take
on.  It includes a number of good starter projects and well as some larger
ideas that no one is actively working on.

## Before You Start

Please start by reading the README.md, CONTRIBUTING.md, and CONVENTIONS.md
files before diving into one of these projects.  Those will explain our
work flow and coding conventions to help ensure that your work will be
easily integrated into libgit2.

Next, work through the build instructions and make sure you can clone the
repository, compile it, and run the tests successfully.  That will make
sure that your development environment is set up correctly and you are
ready to start on libgit2 development.

## Starter Projects

These are good small projects to get started with libgit2.

* Look at the `examples/` programs, find an existing one that mirrors a
  core Git command and add a missing command-line option.  There are many
  gaps right now and this helps demonstrate how to use the library.  Here
  are some specific ideas:
    * Fix the `examples/diff.c` implementation of the `-B`
      (a.k.a. `--break-rewrites`) command line option to actually look for
      the optional `[<n>][/<m>]` configuration values. There is an
      existing comment that reads `/* TODO: parse thresholds */`. The
      trick to this one will be doing it in a manner that is clean and
      simple, but still handles the various cases correctly (e.g. `-B/70%`
      is apparently a legal setting).
    * Implement the `--log-size` option for `examples/log.c`. I think all
      the data is available, you would just need to add the code into the
      `print_commit()` routine (along with a way of passing the option
      into that function).
    * For `examples/log.c`, implement any one of `--author=<...>`,
      `--committer=<...>`, or `--grep=<...>` but just use simple string
      match with `strstr()` instead of full regular expression
      matching. (I.e. I'm suggesting implementing this as if
      `--fixed-strings` was always turned on, because it will be a simpler
      project.)
    * As an extension to the matching idea for `examples/log.c`, add the
      `-i` option to use `strcasestr()` for matches.
    * For `examples/log.c`, implement the `--first-parent` option now that
      libgit2 supports it in the revwalk API.
* Pick a Git command that is not already emulated in `examples/` and write
  a new example that mirrors the behavior.  Examples don't have to be
  perfect emulations, but should demonstrate how to use the libgit2 APIs
  to get results that are similar to Git commands.  This lets you (and us)
  easily exercise a particular facet of the API and measure compatability
  and feature parity with core git.
* Submit a PR to clarify documentation! While we do try to document all of
  the APIs, your fresh eyes on the documentation will find areas that are
  confusing much more easily.
* Add support for the symref protocol extension, so we don't guess
  what the remote's default branch is
  [#2006](https://github.com/libgit2/libgit2/issues/2006)

If none of these appeal to you, take a look at our issues list to see if
there are any unresolved issues you'd like to jump in on.

## Larger Projects

These are ideas for larger projects mostly taken from our backlog of
[Issues](https://github.com/libgit2/libgit2/issues).  Please don't dive
into one of these as a first project for libgit2 - we'd rather get to
know you first by successfully shipping your work on one of the smaller
projects above.

* Port part of the Git test suite to run against the command line emulation
  in examples/
* Fix symlink support for files in the .git directory (i.e. don't overwrite
  the symlinks when writing the file contents back out)
* Implement a 'git describe' like API
* Add hooks API to enumerate and manage hooks (not run them at this point)
* Isolate logic of ignore evaluation into a standalone API
* Upgrade internal libxdiff code to latest from core Git
* Add a hashtable lookup for files in the index instead of binary search
  every time
* Make the index write the cache out to disk (with tests to gain
  confidence that the caching invalidation works correctly)
* Have the tree builder use a hash table when building instead of a
  list.
* Move the tagopt mechanism to the newer git 1.9 interpretation of
  --tags [#2120](https://github.com/libgit2/libgit2/issues/2120)