Python powered Fortran preprocessor
Project description
Fypp is a Python powered Fortran preprocessor. It extends Fortran with condititional compiling and template metaprogramming capabilities. Instead of introducing its own expression syntax, it uses Python expressions in its preprocessor directives, offering the consistency and flexibility of Python when formulating metaprogramming tasks. It puts strong emphasis on robustness and on neat integration into Fortran developing toolchains.
The project is hosted on bitbucket.
Detailed DOCUMENTATION is available on readthedocs.org.
Fypp is released under the BSD 2-clause license.
Main features
Definition and evaluation of preprocessor variables:
#:if DEBUG > 0 print *, "Some debug information" #:endif #:setvar LOGLEVEL 2
Macro defintions and macro calls (apart of minor syntax differences similar to scoped intelligent Fortran macros, which probably will be once part of the Fortran standard):
#:def assertTrue(cond) if (.not. ${cond}$) then print *, "Assert failed in file ${_FILE_}$, line ${_LINE_}$" error stop end if #:enddef $:assertTrue('size(myArray) > 0')
Conditional output:
program test #:if defined('WITH_MPI') use mpi #:elif defined('WITH_OPENMP') use openmp #:else use serial #:endif
Iterated output:
interface myfunc #:for dtype in [ 'real', 'dreal', 'complex', 'dcomplex' ] module procedure myfunc_${dtype}$ #:endfor end interface myfunc
Inline directives:
logical, parameter :: hasMpi = #{if defined('MPI')}#.true.#{else}#.false.#{endif}#
Insertion of arbitrary Python eval-expressions:
character(*), parameter :: comp_date = "${time.strftime('%Y-%m-%d')}$"
Inclusion of files during preprocessing:
#:include "macrodefs.fypp"
Using Fortran-style continutation lines in preprocessor directives:
#:if var1 > var2 & & or var2 > var4 print *, "Doing something here" #:endif
Passing multiline arguments to macros:
#:def debug_code(code) #:if DEBUG > 0 $:code #:endif #:enddef #:call debug_code if (size(array) > 100) then print *, "DEBUG: spuriously large array" end if #:endcall
Preprocessor comments:
#! This will not show up in the output #! Also the newline characters at the end of the lines will be suppressed
Suppressing the preprocessor output in selected regions:
#! Definitions are read, but no output (e.g. newlines) will be produced #:mute #:include "macrodefs.fypp" #:endmute
Installing
Fypp needs a working Python interpreter either with version 2.7 or with version 3.2 or above.
The command line tool is a single stand-alone script. You can run it directly from the source folder
FYPP_SOURCE_FOLDER/bin/fypp
or after copying it from the bin folder to any location listed in your PATH environment variable, by just issuing
fypp
Alternatively, you can use Pythons installer (pip) to install Fypp on your system:
pip install fypp
This installs the command line tool fypp as well as the Python module fypp. Latter you can import if you want to access the functionality of Fypp directly from within your Python scripts.
Running
The Fypp command line tool reads a file, preprocesses it and writes it to another file, so you would typically invoke it like:
fypp source.fypp source.f90
which would process source.fypp and write the result to source.f90. If input and output files are not specified, information is read from stdin and written to stdout.
The behavior of Fypp can be influenced with various command line options. A summary of all command line options can be obtained by:
fypp -h
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