olivierdemeijer / git-hooks-code-autoformat

git-hooks-code-autoformat

A collection of git pre-commit hooks to help with code auto-formatting.

Licensed under Apache License, Version 2.0.

Please, share your own formatters back. PRs are welcome!

How to use

You could just copy contents of this repo to $PROJECT/.git/hooks/. However, a slightly better way might be:

1. $ cd $PROJECT
2. $ git remote add git-hooks-code-autoformat https://github.com/michalrus/git-hooks-code-autoformat.git
3. $ git subtree add --prefix=git-hooks/ git-hooks-code-autoformat master

Now, you have $PROJECT/git-hooks/ directory with contents of this repo. This subtree is updateable with $ git subtree pull --prefix=git-hooks/ git-hooks-code-autoformat master. Any person can just clone your project and they'll have $PROJECT/git-hooks in place at the very moment.

What's left is to symlink $PROJECT/.git/hooks to $PROJECT/git-hooks:

1. $ cd .git && mv hooks hooks.old && ln -s ../git-hooks hooks

IMPORTANT: this linking step has to be done manually by every developer.

The usual workflow then is:

1. Modify some files.
2. $ git add them.
3. $ git commit them.

Now, for each staged ("git-added") file, an autoformatter will be called, and then the file will be re-added, and only then the git commit will continue. This might create a problem, see Known problems below.

If an error occurs (e.g. trying to format a not so well-formed XML), an error message is printed and the commit is aborted.

Existing formatters

• Java ← will format *.java files using a small wrapper—eclipse-code-formatter—around Eclipse’s CodeFormatter with Google’s Java Style definition,
• XML ← will format *.xml, *.bmml and *.owl (Balsamiq Mockups, Protégé) files and any file that is recognized as XML by libmagic,
• XMind ← will format *.xmind/**.xml files (an *.xmind file is really a ZIP archive and should be extracted—and autoformatted—before being added to VCS; you can then open a mindmap using $ XMind some/directory.xmind and it will then be added to the recently opened maps list),
• Flat OpenDocument Spreadsheet ← will format *.fods files, a format used by LibreOffice Calc for storing spreadsheets.

Adding your own formatters

1. Take a look at the existing formatters above.
2. Create autoformat/NAME.patterns file containing a regular expressions—1 per line—matching all file names to be treated with your NAME formatter.
3. AND/OR create autoformat/NAME.magic file containing a regular expressions—1 per line—matching outputs of libmagic’s /usr/bin/file "$FILE" for all files to be treated with your NAME formatter.
4. Create autoformat/NAME executable script. It might be called several times, but always with one argument, an absolute path to a file to format. When formatting, you've got to modify this file in place.
5. If you want to abort the commit, print an error message and exit from the formatter with a non-zero exit code.

Known problems

1. The pre-commit hook autoformats every staged ("git-added") file (if an applicable formatter exists) and then re-adds the file to the stage. Now, if you modify some file, $ git add it, then modify it again and then $ git commit—and there exists a formatter for this type of a file—second modification will also be commited.