fprettify

fprettify is an auto-formatter for modern Fortran code that imposes strict whitespace formatting, written in Python.

NOTE: I'm looking for help to maintain this repository, see #127.

Features

Auto-indentation.
Line continuations are aligned with the previous opening delimiter (, [ or (/ or with an assignment operator = or =>. If none of the above is present, a default hanging indent is applied.
Consistent amount of whitespace around operators and delimiters.
Removal of extraneous whitespace and consecutive blank lines.
Change letter case (upper case / lower case conventions) of intrinsics
Tested for editor integration.
By default, fprettify causes whitespace changes only and thus preserves revision history.
fprettify can handle cpp and fypp preprocessor directives.

Limitations

Works only for modern Fortran (Fortran 90 upwards).
Feature missing? Please create an issue.

Requirements

Python 3 (Python 2.7 no longer supported)
ConfigArgParse: optional, enables use of config file

Examples

Compare examples/*before.f90 (original Fortran files) with examples/*after.f90 (reformatted Fortran files) to see what fprettify does. A quick demonstration:

program demo
integer :: endif,if,elseif
integer,DIMENSION(2) :: function
endif=3;if=2
if(endif==2)then
endif=5
elseif=if+4*(endif+&
2**10)
elseif(endif==3)then
function(if)=endif/elseif
print*,endif
endif
end program

⇩⇩⇩⇩⇩⇩⇩⇩⇩⇩ fprettify ⇩⇩⇩⇩⇩⇩⇩⇩⇩⇩

program demo
   integer :: endif, if, elseif
   integer, DIMENSION(2) :: function
   endif = 3; if = 2
   if (endif == 2) then
      endif = 5
      elseif = if + 4*(endif + &
                       2**10)
   elseif (endif == 3) then
      function(if) = endif/elseif
      print *, endif
   endif
end program

Installation

The latest release can be installed using pip:

pip install --upgrade fprettify

Installation from source requires Python Setuptools:

pip install .

For local installation, use --user option.

If you use the Conda package manager, fprettify is available from the conda-forge channel:

conda install -c conda-forge fprettify

Command line tool

Autoformat file1, file2, ... inplace by

fprettify file1, file2, ...

The default indent is 3. If you prefer something else, use --indent n argument.

In order to apply fprettify recursively to an entire Fortran project instead of a single file, use the -r option.

For more options, read

fprettify -h

Editor integration

For editor integration, use

fprettify --silent

For instance, with Vim, use fprettify with gq by putting the following commands in your .vimrc:

autocmd Filetype fortran setlocal formatprg=fprettify\ --silent

Deactivation and manual formatting (experimental feature)

fprettify can be deactivated for selected lines: a single line followed by an inline comment starting with !& is not auto-formatted and consecutive lines that are enclosed between two comment lines !&< and !&> are not auto-formatted. This is useful for cases where manual alignment is preferred over auto-formatting. Furthermore, deactivation is necessary when non-standard Fortran syntax (such as advanced usage of preprocessor directives) prevents proper formatting. As an example, consider the following snippet of fprettify formatted code:

A = [-1, 10, 0, &
     0, 1000, 0, &
     0, -1, 1]

In order to manually align the columns, fprettify needs to be deactivated by

A = [-1,   10, 0, & !&
      0, 1000, 0, & !&
      0,   -1, 1]   !&

or, equivalently by

!&<
A = [-1,   10, 0, &
      0, 1000, 0, &
      0,   -1, 1]
!&>

Contributing / Testing

The testing mechanism allows you to easily test fprettify with any Fortran project of your choice. Simply clone or copy your entire project into fortran_tests/before and run python setup.py test. The directory fortran_tests/after contains the test output (reformatted Fortran files). If testing fails, please submit an issue!

pseewald / fprettify