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https://github.com/mikr/whatstyle

whatstyle finds a code format style that fits given source files
https://github.com/mikr/whatstyle

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whatstyle finds a code format style that fits given source files

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README 

        
whatstyle

=============



whatstyle finds a code format style that fits given source files.



Code formatters like clang-format or uncrustify usually need a specific style

definition how to reformat the code.

This program looks at your source code and generates a style definition

that the reformatted source fits its original formatting as closely

as possible.



It should help programmers to begin using a formatting tool right away

without the need to invest hours of reading the formatting tool

documentation.



The currently supported formatters are `clang-format`_, YAPF_, Tidy_, indent_,

`Artistic Style`_, Uncrustify_, scalariform_, scalafmt_, rfmt_ and rustfmt_.



.. _`clang-format`: http://clang.llvm.org/docs/ClangFormat.html

.. _YAPF: https://github.com/google/yapf

.. _Tidy: http://www.html-tidy.org

.. _indent: http://www.freebsd.org/cgi/man.cgi?query=indent

.. _Artistic Style: http://astyle.sourceforge.net

.. _Uncrustify: https://github.com/uncrustify/uncrustify

.. _scalariform: https://github.com/scala-ide/scalariform

.. _scalafmt: https://github.com/olafurpg/scalafmt

.. _rfmt: https://github.com/google/rfmt

.. _rustfmt: https://github.com/rust-lang-nursery/rustfmt



.. contents::



How to run

------------------



First you choose one or more of your source files whose style you find

representative of the style you want to keep.

The source files should cover a wide range of language constructs and

to keep runtime down not exceed a few thousand lines if possible.



You specify the formatter and source files as follows:



.. code-block:: bash



    $ whatstyle.py -f clang-format tests/examples/gumbo-parser/utf8.c



whatstyle will then try different options while reporting intermediate results.

After a while you get back a result like this:



.. code-block:: bash



    ### This style was chosen for your .clang-format - it perfectly matches your sources.

    BasedOnStyle: Google

    AlignAfterOpenBracket: DontAlign

    SpaceAfterCStyleCast: true



Adding the option ``--mode resilient`` will usually add more options to your style so

that a heavily out of shape version of your sources can be better retransformed into your

style.



Style difference effects vs options documentation

-------------------------------------------------



Reading the documention of the invidual options of a formatter takes time and does not

necessarily make clear how an option influences the formatting.

You can try something like this instead:



.. code-block:: bash



    $ whatstyle.py --variants tests/examples/xv6/printf.c



First the best matching style is chosen and then every option is replaced or augmented by

every possible value. All combinations that actually made a difference are grouped and

displayed side by side.

The variant on the left is the original from the best style, on the right is another

option setting that usually makes things worse.

Below the option values, differing code fragments are shown, you can use ``--numhunks``

to show more diff hunks per variation.

Use ``--ansi`` to display the variants table in an ANSI terminal, ``--html`` to open it

in a browser or ``--ansihtml`` for a darker look in a browser.



.. image:: https://raw.github.com/wiki/mikr/whatstyle/images/variants.png

    :target: https://raw.github.com/wiki/mikr/whatstyle/images/variants.png

    :alt: Format Style Variants



Usage scenarios

---------------



For information about some useful scenarios run:



.. code-block:: bash



    $ whatstyle.py --usage-examples



or read the text at the beginning of whatstyle.py.



Requirements

------------------



whatstyle needs at least Python 2.7 and it works as well with

Python 3.2, 3.3, 3.4 and 3.5. Jython and pypy are supported.



Also whatstyle needs at least one code formatter in the current ``PATH``.



The presence of either ``diff`` or ``git`` is optional but useful because the diff quality of

both of them may be better than Python's difflib and this results in a different and usually

better matching style.



This program should work on OS X, Windows, Linux, FreeBSD and OpenBSD.



How it works

------------------



The program basically works by reformatting the source with many

combinations of options and running a diff between the original

and the reformatted source code.



First the major standard styles (e.g. WebKit, GNU, LLVM) are evaluated

and the closest one chosen as a baseline.



Successively every choice of every style option is added to test

if the additional option further reduces the differences.

When no more option settings can improve the result the most appropriate

style has been found.



Among a number of candidate styles with the same diff quality

the one with the least number of explicit options is chosen

to keep the style definition brief.



Author

------



whatstyle was written by `Michael Krause `_.



License

-------



whatstyle is available under the `MIT license `_. See the LICENSE file for more info.



The project specific Open Source licenses of the source codes in tests/examples are present in their respective directories.



See also

--------



`Unformat: Python3 utility to generate a .clang-format file from example code-base `_.