prep
fpm-tools:prep
A Fortran source code pre-processor written in Fortran
Documentation 
- man-pages reformatted as HTML.
- the demos/ directory has example input files for a variety of cases
- The CHANGELOG
- The CI/CD results
- Developer ford(1) output
Description
prep(1) is a streamlined pre-processor primarily designed for use with
Fortran. It does not support procedural macros but does support variable
substitution and reusable free-format text blocks which allows for basic
templating and easy construction of multi-line CHARACTER variables;
and is quite capable of supporting traditional conditional compilation.
It is written in standard Fortran so those in the Fortran community will find it easy to modify and to use portably.
prep(1) is intentionally simple enough to be well described with
a one-page crib sheet, and should take no more than an hour to
master. Fortran-like (and some POSIX shell-like) syntax is used to
leverage familiarity with Fortran.
In particular, prep(1) allows for maintaining documentation in the body
of the source code in a variety of formats via the $BLOCK directive.
Example Showing Templating
The most distinct feature of prep(1) compared to basic preprocessors is the ability to define a block of text and apply special processing to it to simplify maintaining documentation but also to repeat the code with different string expansions, allowing for a form of templating a generic routine. A relatively advanced example:
$import USER
$! write the routine generically with ${NAME} variables
$parcel ex1
! created by ${USER} on ${DATE} at ${TIME}
subroutine testit_${KIND}(value)
real(kind=${KIND}) :: value
write(*,*)'big subroutine with type ${KIND} and value=',value
end subroutine testit_${KIND}
$endparcel
$!
module M_testit
use, intrinsic :: iso_fortran_env, only : real32, real64, real128
implicit none
private
public testit
interface testit
module procedure testit_real32
module procedure testit_real64
module procedure testit_real128
end interface testit
contains
$! now just $POST the routine multiple times changing the kind ...
$set kind real32
$post ex1
$set kind real64
$post ex1
$set kind real128
$post ex1
end module M_testit
The output looks like
module M_testit
use, intrinsic :: iso_fortran_env, only : real32, real64, real128
implicit none
private
public testit
interface testit
module procedure testit_real32
module procedure testit_real64
module procedure testit_real128
end interface testit
contains
! created by urbanjs on Jun 19 2021 at 11:55:43
subroutine testit_real32(value)
real(kind=real32) :: value
write(*,*)'big subroutine with type real32 and value=',value
end subroutine testit_real32
! created by urbanjs on Jun 19 2021 at 11:55:43
subroutine testit_real64(value)
real(kind=real64) :: value
write(*,*)'big subroutine with type real64 and value=',value
end subroutine testit_real64
! created by urbanjs on Jun 19 2021 at 11:55:43
subroutine testit_real128(value)
real(kind=real128) :: value
write(*,*)'big subroutine with type real128 and value=',value
end subroutine testit_real128
end module M_testit
Building
To build it requires git, fpm(Fortran Package Manager), a modern
Fortran compiler and WWW access or you will need to compile the single-file
bootstrap version.
It was tested with
- GNU Fortran (GCC) 8.3.1 on 20191121
- GNU Fortran 9.3.0 on 20210612
- GNU Fortran 10.3.0 on 20220305
- ifort (IFORT) 19.1.3.304 on 20200925
- ifort (IFORT) 2021.3.0 20210609 on 20220305
- nvfortran 21.5-0 on 20220329
V9.0.0
- GNU Fortran 10.3.0 on 20220804
- ifort (IFORT) 2021.3.0 20210609 on 20220804
- nvfortran 21.5-0 on 20220804
Accessing
# go to where you want to create the `prep` directory. For example:
mkdir github
cd github
# get a clone of the repository
git clone https://github.com/urbanjost/prep.git
# enter the repository directory
cd prep
Building and Installing
# build and install (in the default location) using fpm(1)
fpm install
or
# examples of building standalone version
gfortran standalone/prep.f90 -o prep
ifort standalone/prep.f90 -o prep
nvfortran -Mbackslash standalone/prep.f90 -o prep
# example of moving to a location in your path
mv prep $HOME/.local/bin/
Try It
# if you placed the program in a directory in your command path you are ready to go!
prep --help
Without intermediate files
Normally, you would run prep to make your standard source file, like a *.f90 file. Mileage may vary, but for some common Fortran compilers you can directly compile your files; at least in simple cases.
prep -i $FILE.FF |gfortran -x f95 - # free-format Fortran
prep -i $FILE.FF |gfortran -x f77 - # fixed-format Fortran
Preprocessing is not standardized, so creating .f90 and .f files is probably far more reliable.
Homepage
https://github.com/urbanjost/prep.git
Feedback is welcome. leave a comment!