findent 4.1.1

findent Fortran formatter test python wrapper

For installation instructions and usage, see README.1st and INSTALL

This document is a not very well structured story about findent. You can skip this and use findent after reading the output of findent -h.

Findent: what?

Findent is an indenter for Fortran programs, fixed and free format. Findent can also translate fixed format to free format and vice versa. Since version 3.0.0, findent can generate dependencies based on USE, MODULE, SUBMODULE, INCLUDE, #include, ??include and emit a sh script that, using findent, creates a dependency file to be used in a Makefile. Since version 4.1.0, findent can relabel Fortran sources. Findent indents more than 100K lines per second, so usage as a standard indenter in an editor works very well, see 'findent and vim', 'findent and gedit' and 'findent and emacs' below.

Findent will take care of:

  continuation lines
  multi-statement lines
  labelled and unlabelled do-loops
  IF
  IF ... THEN ... ENDIF
  where
  FORALL
  WHERE constructs
  FORALL constructs
  etc. see findentclass.cpp for details

Findent will remove trailing spaces and tabs, and convert tabs at the start of a line into spaces. By default, statement labels are placed at the start of a line. Apart from this and indenting, findent will not alter the input, trying to preserve alignment. For example, the alignment in:

  X = 3.0*A + 4*B +  &
  &   2  *C +   Y

will remain intact.

Optionally, findent will refactor lines that end a subroutine etc.:

  SUBROUTINE SUB
  ...
  END FUNCTION MYFUN

will become:

  SUBROUTINE SUB
  ...
  END SUBROUTINE SUB

Findent is space-insensitive, for example a line like:

  REALFUN  CTIONFUN(X)

is recognized as the start of a function definition.

Usage:

   findent -h

Findent: why?

There are a number of public domain Fortran indenting tools, for example:

• vim is shipped with an simple Fortran indenter
• emacs has a Fortran indenter
• floppy, only for fixed format: http://www.netlib.org/floppy/
• convert.f90: converts from fixed to free format, and indents: ftp://ftp.numerical.rl.ac.uk/pub/MandR/convert.f90
• f2f90: based on convert.f90: http://www.fortran.com/f2f90.tar.gz
• f90ppr: an impressive piece of software that beautifies Fortran code and contains a macro processor. http://fortranwiki.org/fortran/show/f90ppr
• fprettify: an indenter and beautifier, written in Python. IMHO not mature at the time of this writing (august 2018). https://github.com/pseewald/fprettify

For me, the problem with these tools is, that

- they are too simple (for example, do not recognize labelled 
  do-loops) 
- or do too much (destroying neatly aligned pieces of code)
- or are for me too complicated to adapt and extend.

Furthermore, I want that indenting does not make irreversible changes to the source: I want always be able to get back to the version after the first indenting. (Exceptions: converting from fixed to free format or vice-versa; adding 'subroutine foo' after 'end'; relabeling).

Therefore I decided, having some spare time after my retirement, to try to build a Fortran indenter, based on flex and bison for readability. As programming language I chose C++, because of the availability of string, deque, set and map.

After more or less finishing the indenting part, I realized that findent should be able to play a role in determining the dependencies based on (sub)modules and various kinds of includes. So I added some lines to accomplish this. Together with an simple script dependencies are easily created. See 'man findent' under '--deps' for details.

There are some tools that can generate dependencies for Fortran projects:

• makedepf90: see https://github.com/outpaddling/makedepf90, also in debian and ubuntu. It seems that there is no support for submodules, but apart from that it seems to work well.
• f90_mod_deps.py: see http://lagrange.mechse.illinois.edu/f90_mod_deps/f90_mod_deps.py does not seem to work properly.
• fortdepend: see https://github.com/ZedThree/fort_depend.py Does not work with submodules and is picky about END statements.

I did not investigate if these tools can cope with split MODULE and USE lines and fixed-format space-independent source code.

Findent: how?

So, here it is, a Fortran indenter to my taste, based on flex, bison and g++.

The program performs the following major tasks:

- determine the input format: free or fixed
- glue together continuation lines removing comments
- pre-process the assembled input line, to make it better processable 
    by flex: remove white space, substitute strings, hollerith's, 
statement label and operators like .EQ. by special tokens
- perform a two-stage parsing:
  - try if the line is an assignment
  - if it is not an assignment, parse the line using as tokens the
    Fortran keywords (SUBROUTINE, DO, ...)
- based on the outcome of the parse, determine the indentation
- output the lines that were read in to compose the full line,
  trying to preserve the lay-out after the original leading white
  space, optionally converting from fixed-form to free-form.
  Also optionally, lines that end a subroutine, program etc.,
  are completed (or even modified) as in:
    END subroutine mysub
  Preprocessor statements are accounted for to prevent that code like:

    #ifdef one
    SUBROUTINE ONE
    #else
    SUBROUTINE TWO
    #endif

   would result in a double SUBROUTINE indentation.
   Moreover, track is kept of do-labels, in order to correctly indent
   constructs like:

       DO 10 I=1,20
     DO 10 J=1,10
	X(I) = Y(I)+J
    10 CONTINUE

Findent: structure

In version 2.8.4, a major reorganizing has been done, trying to make the source more readable and more object-oriented.

These are the classes (all starting with a capital):

• Debugostream

  This class contains code for debugging.

• Docs

  This class contains code (often generated) to output help- texts (includeing this text) etcetera.

• Findentclass

  Findentclass contains basic functions and variables that are used throughout the program, such as:

  int determine_fix_or_free() if the input format is not given (parameter -ifixed or -ifree), this function tries to find a proof that the program is free-format. If so, FREE is returned, else FIXED.

  Fortranline mygetline() Reads a line from STDIN. Optionally, the function builds a buffer to store the line just read, this option is used by determine_fixed_or_free().

  Fortranline Getline() Uses the buffer from mygetline() or mygetline() to return a Fortranline. Optionally, maintains a buffer (wizardbuffer) to enable a look-ahead for the wizard functions.

• Fortranline

  This class contains a line of fortran code, and has many frequently used functions operating on that line.

• Fortran

  This is an abstract class with functions and variables needed to construct a 'full_statement': a string that is composed of pure fortran code (stripped from comments, preprocessor directives, ..) and a deque of lines that constructed the full_statement, including comments and preprocessor statements.

  The pure virtual functions are filled in by class Fixed or class Free, depending on the format of the input.

  The indentation required is computed from full_statement and the current indentation.

  Special provisions are made for storing labelled do statements, preprocessor statements and more.

• Free

  This class is a child of Fortran, and contains functions to indent and output the deque containing the continuation lines of a free format fortran source. Also, when conversion from free to fixed format is required, there is code to store the continuation lines in a fixed (not properly indented) deque, and present this to Fixed to output this in a properly indented format.

• Fixed

  Basically the same as Free, but vice-versa. There is a special issue: to determine if there are continuation lines, a wizard has been created that can look ahead, see getnext() in Findentclass.

• Flags

  This class implements a container for the flags (-ifree, -i4 ...) and contains code to interpret the flags.

• Globals

  This class implements a container for a few global variables. Maybe, one would be tempted to make these static, but I tried not to use static variables in order to able to run more than one Findent in one program, one reading from STDIN, the other from a file for example.

• Line_prep

  This class contains code to pre-analyze a full_statement to make the work easier for the lexer and parser.

• Pre_analyzer

  This class contains code to see if a line is a preprocessor statement or a findentfix: line.

• Simpleostream

  This class implements a simple filter to std::cout.

The program starts in findent.cpp, and goes on in fortranrun.cpp.

The whole thing is somewhat more hairy than I would like to see. I did not succeed to make the whole thing strictly hierarchical, and solved this by giving classes access to the internals of other classes using pointers. But, like in biology, in creating a program, there is no law to keep it simple.

Btw, when adding the relabel option, I had to revise class-related things a bit, so maybe the information above is not entirely correct.

Findent: relabel

Since version 4.1.0, findent optionally relabels, see the man page.

Relevant flags (see the man page):

--relabel --relabel-restart --query-relabel

I strongly advise to check your Fortran program after relabeling, please let me know if there are problems.

Relabeling is done on a subroutine/function/program basis: the input is read until a start of a subroutine etc. is found, and stored in a buffer until the corresponding end is found, creating a list of defined and used labels.

If something goes wrong (for example: usage of an undefined label), relabeling is abandoned for the current subroutine etc, and for the rest of the input.

If everything seems ok, a second pass is started to perform the actual relabeling.

The complete input, relabeled or not, is presented to the indenter/converter, so all flags are honoured.

The following constructs are candidates for relabeling:

   - 100,110,120,130: label
   - X:         integer or real or logical expression
   - I:         identifier
   - [,]:       optional comma
   - ...:       not parsed by findent, can be almost anything except '=...'
   - [IF]:      optional IF(...)

   100 ...         ! statement or format label
   IF(...) 110,120,130
   IF(...) 110,120       ! CDC extension
   DO 100[,] I=X,...
   DO 100[,] WHILE(...)
   DO 100
   [IF] GOTO 100
   [IF] GOTO(100,110,120)...
   [IF] GOTO I[,](100,110,120)
   [IF] ASSIGN 100 TO I
   [IF] READ 100...
   [IF] PRINT 100...
   [IF] READ(...,100,...)
   [IF] READ(...,ERR=100,...,END=110,EOR=120,...,FMT=130)...
   [IF] WRITE(...,100) ...
   [IF] WRITE(...,ERR=100,...,FMT=110,...,EOR=120)...
   [IF] OPEN(...,ERR=100,...)
   [IF] CLOSE(...,ERR=100,...)
   [IF] ENDFILE(...,ERR=100,...)
   [IF] REWIND(...,ERR=100,...)
   [IF] FLUSH(...,ERR=100,...)
   [IF] BACKSPACE(...,ERR=100,...)
   [IF] INQUIRE(...,ERR=100,...)
   [IF] WAIT(...,ERR=100,...,END=110,...,EOR=120,...)
   [IF] CALL I(...,*100,...,*110,...)

Findent: usage

Findent reads from standard input and writes to standard output:

  findent < prog.f90 > prog1.f90

See also 'wfindent' below.

The command

  findent -h

gives an overview of the possible flags and there effect. Most interesting are:

  -i<n>  
    example: -i5
    which determines the amount of indent to be used by every
    item that calls for indenting
  -Ia
    The starting indent is determined from the first line (more
    or less), useful when using findent within vim, for example
    to intent a selected region:

       '<,'>:!findent -Ia

  -ofree
    converts from fixed format to free format.

  -L<n>
    example: -L72
    limit input line length to 72 characters.

NOTE 1: Findent knows about tabbed input: for fixed-format input, the following transformations are made:

       10<tab>I=   -> 10<sp><sp><sp><sp>I=
       <tab>1K*J   -> <sp><sp><sp><sp><sp>1K*J
       <tab>X=Y    -> <sp><sp><sp><sp><sp><sp>X=Y

       So, a tab followed by 1-9 is transformed to a continuation line,
       otherwise to a normal line, starting in column 7.

NOTE 2: Findent silently ignores errors in the flags

NOTE 3: Handling of continuation lines Example:

          a = &
             (/ 3, 10, 12, 4, &
                5,  9,  1, 0, &
               13,  2, 25, 6 /)

       After running findent, with standard parameters, you get this:

          a = &
             (/ 3, 10, 12, 4, &
             5,  9,  1, 0, &
             13,  2, 25, 6 /)

      That is probably not what you really want.

      The recommended solution is: add '&' at the start of the 
      continuation lines:

       a = &
          &   (/ 3, 10, 12, 4, &
          &      5,  9,  1, 0, &
          &     13,  2, 25, 6 /) 

      Findent will indent this as:

       a = &
       &   (/ 3, 10, 12, 4, &
       &      5,  9,  1, 0, &
       &     13,  2, 25, 6 /)

     Not recommended solution: You can use the '-k-' flag, like:
       findent -k- < prog.f90 > prog1.f90
      
     Findent will in this case not touch continuation lines without 
     a starting '&', but leave them as they are.

NOTE 4:

    Findent does not check the length of an output line, so it could
    be that the length will be larger than 72 or 132 for fixed and 
    free format respectively. In fact, indenting old fixed format
    sources will very likely result in lines longer than 72 columns.
    If you are lucky, the compiler will generate an error message,
    but too long lines can result in changing the semantics of a 
program without notice.
    Advice: use a compiler flag that allows long lines:

      gfortran, free format:    -ffree-line-length-none  # unlimited
      gfortran, fixed formtat:  -ffixed-line-length-none # unlimited
      ifort, free format:       # no flag needed, default is unlimited
      ifort, fixed format:      -132  # max line length is 132
      pgf90, free format:       # max line length is 264, 
                            # error if longer
      pgf90, fixed format:      -Mextend  # max line length is 132, 
                                #           no error if longer

NOTE 4.1: Here a script to check for line length:

snip ---------- checklength ---------------------------------------

#!/bin/sh

checks file line lengths

Usage:

checklength [file ...]

outputs "filename:line number:line length:line" for lines longer than length

tabs are converted to spaces using expand

if no file is given, read from stdin

usage() { echo "Usage:" echo "$0 [file ...]" } if [ -z "$1" ] ; then usage exit 1 fi l="$1" doit() { expand | awk -v l="$1" -v f="$2" '{ if (length($0) > l) printf "%s:%d:%d:%s\n",f,FNR,length($0),$0 }' }

if [ -z "$2" ] ; then doit "$l" "-" exit 0 fi

shift while [ "$1" ] ; do cat "$1" | doit "$l" "$1" shift done

<<<< snip ---------- checklength --------------------------------------

Example of usage: checklength 72 *.f

NOTE 5: handling of comment lines

    Findent indents comment lines, but does not touch comment lines
    with the '!' in column one.

NOTE 5.1: handling of comment lines converting fixed to free format

    As said above, findent does not touch comments starting
    in column 1. Since all vintage comments start in column 1,
    this has the effect that these comments will not be indented
    when converting from fixed to free format (using -ofree).
    If you want the comments indented, convert to free format,
    add a space before every line and use findent again.

    Example if the stream editor 'sed' is available:

      findent -ofree < prog.f | sed 's/^/ /' | findent > prog.f90

    If 'sed' is not available (on Windows for example), you
    can create the program 'addspace' or, on Windows, 'addspace.exe'
    by compiling this program:

snip -------- addspace.f ------------------------------------------ program addspace implicit none character(1000) :: line integer :: io do read(,'(a)',iostat=io) line if (io .ne. 0) exit write(,'(1x,a)') trim(line) enddo end program addspace <<<< snip -------- addspace.f ------------------------------------------

    Or, if you have a vintage Fortran-4 compiler, by compiling
    this program:

snip -------- ADDSPACE.F ------------------------------------------ DIMENSION L(1000) DATA LB/1H / 10 DO 15 I=1,1000 15 L(I)=LB READ(5,100,END=30) L DO 20 I=1000,1,-1 IF (L(I)-LB) 25,20,25 20 CONTINUE WRITE(6,110) GOTO 10 25 WRITE(6,110) (L(J),J=1,I) GOTO 10 30 CONTINUE 100 FORMAT(1000A1) 110 FORMAT(1H ,1000A1) END <<<< snip -------- ADDSPACE.F ------------------------------------------

    Use the generated program 'addspace' in stead of 'sed':

    findent -ofree < prog.f | addspace | findent > prog.f90

Findent: failure, findentfix:

One thing is certain: findent contains errors. I appreciate it if you bring errors to my attention. If possible I will fix them.

On the other hand, it is possible to fool findent, for example by using #ifdef, #else, #endif in a way that confuses findent.

Both cases can be solved using ! findentfix: , read on:

The next program will not be indented correctly:

snip -------- fixdemo.f90 ----------------------------------------- ! compile with: gfortran -cpp fixdemo.f90 ! or ! gfortran -cpp -DLOOPJ fixdemo.f90 program fixdemo implicit none integer i,j j=4 do i=1,3 #ifdef LOOPJ do j=1,2 #endif print ,ij enddo #ifdef LOOPJ enddo print *,'with j-loop' #else print *,'without j-loop' #endif continue end program fixdemo <<<< snip -------- fixdemo.f90 -----------------------------------------

That is because findent takes the indentation from: #ifdef LOOPJ do j=1,2 #endif and #else print *,'without j-loop' #endif

So, findent is missing an enddo for the j-loop.

In this case, the solution would be to insert #else just before the first #endif. If, however, in a real-world example this is not possible, or when findent really makes an error, you can use findentfix. In the example above, insert directly after the last #endif: ! findentfix: enddo and findent will indent correctly. In general, the text after ! findentfix: will be used by findent as a normal source line, so the following could also be useful: ! FINDENTfix: subroutine dummy ! findentFIX: do;do;do ! FINDENTFIX: end;end ! findentfix: where () But the following would do nothing: ! findentfix: continue

Findent: creating a dependency file for use in an Makefile.

  findent --deps < prog.f90

prints the dependencies found in prog.f90, based on USE, MODULE, SUBMODULE, INCLUDE, #include and ??include.

This is used by the sh script makefdeps to create a dependency file for use in an Makefile. Creation of the makefdeps script:

  findent --makefdeps > makefdeps
  chmod +x makefdeps

The command:

  ./makefdeps *.f90

will output a dependency file, to be used in an Makefile. The dependencies are based on .o files, for example:

  main.o: sub1.o sub2.o
  sub1.o: sub1.inc

Example Makefile and fortran sources to create 'program' from main.f90 sub1.f90 sub2.f90 sub.inc:

snip ---------- Makefile --------------------------------------- SRCS = main.f90 sub1.f90 sub2.f90 OBJS = $(SRCS:.f90=.o) %.o: %.f90 gfortran -c -o $@ $< program: $(OBJS) gfortran -o $@ $(OBJS) include deps dep deps: findent --makefdeps < /dev/null > makefdeps.sh @if [ "head -n 1 makefdeps.sh" != "#!/bin/sh" ] ; then
findent -v 1>&2;
echo "Use findent version >= 3.0.0" 1>&2 ; exit 1 ; fi chmod +x makefdeps.sh ./makefdeps.sh $(SRCS) > deps clean: rm -f *.o *.mod *.smod program deps <<<< snip ---------- Makefile ---------------------------------------

snip ---------- main.f90 --------------------------------------- program main use mymod1 use mymod call sub1 call sub end <<<< snip ---------- main.f90 ---------------------------------------

snip ---------- sub1.f90 --------------------------------------- module mymod1 contains subroutine sub1 print *,'this is sub1' end end module mymod interface module subroutine sub end subroutine end interface end module <<<< snip ---------- sub1.f90 ---------------------------------------

snip ---------- sub2.f90 --------------------------------------- submodule (mymod) mymod2 contains module procedure sub include 'sub.inc' end procedure end submodule <<<< snip ---------- sub2.f90 ---------------------------------------

snip ---------- sub.inc --------------------------------------- print *,'this is sub' <<<< snip ---------- sub.inc ---------------------------------------

The fortran sources will be compiled in correct order, you can even use parallel make (make -j). BTW: this example uses the SUBMODULE statement: you need to have gfortran >= 6 to compile.

Findent: installation:

(For a more comprehensive text, see README.1st and INSTALL)

Linux: $ ./configure --prefix=/usr/local $ make On systems with sudo (Debian, Ubuntu, Mint, ...): $ sudo make install On systems without sudo (Redhat, Scientific Linux, ...): $ su -c 'make install'

Windows: copy findent.exe C:\WINDOWS

wfindent

wfindent, a sh shell script, indents Fortran source in-place, performing a sanity check. It accepts all flags that findent accepts.

Usage:

 wfindent [ findent flags ] files

example

 wfindent -I4 *.f90

Installation:

  If you installed findent with the ./configure, make, make install 
  method, wfindent is installed as well.
  Otherwise:
  On systems with sudo (Debian, Ubuntu, Mint, ...):
  $ sudo install scripts/wfindent /usr/local/bin
  On systems without sudo (Redhat, Scientific Linux, ...):
  $ su -c 'make install'

wfindent.bat

wfindent.bat is for usage in the cmd shell of Windows and has the same functionality as wfindent, described just above.

Installation:

copy wfindent.bat C:\WINDOWS

jfindent or jfindent.jar

jfindent is a graphical front end for findent, and is available as a separate package on findent.sourceforge.net

Findent and vim

Findent is since version 2.7 very vim-aware. When using the vim scripts (look at findent --vim-help), findent is used as equalprg ( :help equalprg ) and indentexpr ( :help indentexpr )

Findent can emit configuration files, look at the output of:

  findent --vim_help

Findent and gedit

To enable findent in gedit, look at the output of:

  findent --gedit_help

Findent and emacs

To enable findent in emacs, look at the output of:

  findent --emacs_help

Issues

Since findent parses line-by-line, there are situations that are ambiguous:

 F(X) = X**2        An assignment or a statement function?

 ELSE WHERE          Is this an ELSEWHERE as in
                    WHERE(X .EQ. 0)
                       Y=10
                    ELSE WHERE
                       Y=1
                    END WHERE

                     or is it part of an IF construct with name WHERE:
                    WHERE: IF (X .EQ. 0) THEN
                              Y=10
                           ELSE WHERE
                              Y=1
                           ENDIF WHERE

                     Findent chooses the first possibility.

And there must be more ... Luckily, it seems that these ambiguities do not affect indentation.

I tried to make findent Fortran-2008 compatible. This raised another ambiguity, because findent is space-insensitive:

MODULE PROCEDURE MYPROC Is this an module PROCEDUREMYPROC or an moduleprocedure MYPROC? Findent assumes the last.

Thanks to

It would not be possible for me to create findent if I could not stand of the shoulders of other free software projects. In alphabetical order (and probably forgetting some):

autoconf: https://www.gnu.org/software/autoconf/autoconf.html bash: https://www.gnu.org/software/bash/ bison: https://www.gnu.org/software/bison/ debian: https://www.debian.org/ flex: https://github.com/westes/flex g++: https://gcc.gnu.org/ gcc: https://gcc.gnu.org/ gfortran: https://gcc.gnu.org/wiki/GFortran gnu software: https://www.gnu.org/ kcachegrind: https://kcachegrind.github.io/html/Home.html linux: https://en.wikipedia.org/wiki/Linux make: https://www.gnu.org/software/make/ ubuntu: https://www.ubuntu.com/ valgrind: http://valgrind.org/ vim: https://www.vim.org/

The website http://www.cplusplus.com/ helped me to find a way through C++.

I like to thank the people who gave suggestions to improve the functionality of findent.

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

I am happy to receive comments, error reports and suggestions for improvements.

September 2021, Willem Vermin, [e-mail]