Extract stable and useful features from cp2k fprettify

Examples and improved tester
add README.md

README.md

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+# fprettify
+
+fprettify is an auto-formatter for modern Fortran code that imposes strict whitespace formatting.
+
+
+## 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.
+* All operators are surrounded by exactly one whitespace character, except for arithmetic operators.
+* Removal of extraneous whitespace and consecutive blank lines.
+* Works only for modern Fortran (Fortran 90 upwards).
+
+
+## Requirements
+
+Python 2.7 or Python 3.x
+
+
+## Examples
+
+Have a look at examples/fortran_after.f90 to see reformatted Fortran code.
+
+
+## Installation
+
+```
+./setup install
+```
+
+For local installation, use `--user` option.
+
+
+## Usage
+
+```
+fprettify file1, file2, ...
+```
+The default indent is 3. If you prefer something else, use `--indent=<n>` argument.
+
+For editor integration, use
+```
+fprettify --no-report-errors
+```
+
+For more information, read
+```
+fprettify --help
+```
+
+
+## Trivia
+
+fprettify is part of the coding conventions of [CP2K](https://www.cp2k.org/) and thus tested with a large code base. Compared with CP2K's internal version (cp2k branch), this version is reduced in functionality. It contains only stable and general features that don't rely on specific coding conventions.

examples/fortran_after.f90

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+module prettify_selftest
+   implicit none
+   private
+   public :: dp, test_routine, &
+             test_function, test_type, str_function
+   integer, parameter :: dp = selected_real_kind(15, 307)
+   type test_type
+      real(kind=dp) :: r = 1.0d-3
+      integer :: i
+   end type test_type
+
+contains
+
+   subroutine test_routine( &
+      r, i, j, k, l)
+      integer, intent(in)                                :: r, i, j, k
+      integer, intent(out)                               :: l
+
+      l = test_function(r, i, j, k)
+   end &
+      subroutine
+
+   pure function test_function(r, i, j, &
+                               k) &
+      result(l)
+      integer, intent(in)                                :: r, i, j, k
+      integer                                            :: l
+
+      l = r + i + j + k
+   end function
+   function &
+      str_function(a) result(l)
+      character(len=*)                                   :: a
+      integer                                            :: l
+
+      if (len(a) < 5) then
+         l = 0
+      else
+         l = 1
+      endif
+   end function
+
+end module
+
+program example_prog
+ use example, only: dp, test_routine, test_function, test_type,str_function
+
+   implicit none
+   integer :: r, i, j, k, l, my_integer, m
+   integer, dimension(5) :: arr
+   integer, dimension(20) :: big_arr
+   integer :: endif
+   type(test_type) :: t
+   real(kind=dp) :: r1, r2, r3, r4, r5, r6
+   integer, pointer :: point
+
+   point => null()
+
+! 1) white space formatting !
+!***************************!
+! example 1.1
+   r = 1; i = -2; j = 3; k = 4; l = 5
+   r2 = 0.0_dp; r3 = 1.0_dp; r4 = 2.0_dp; r5 = 3.0_dp; r6 = 4.0_dp
+   r1 = -(r2**i*(r3 + r5*(-r4) - r6)) - 2.e+2
+   if (r .eq. 2 .and. r <= 5) i = 3
+   write (*, *) (merge(3, 1, i <= 2))
+   write (*, *) test_function(r, i, j, k)
+   t%r = 4.0_dp
+   t%i = str_function("t  % i   =  ")
+
+! example 1.2
+   my_integer = 2
+   i = 3
+   j = 5
+
+   big_arr = [1, 2, 3, 4, 5, &
+              6, 7, 8, 9, 10, &
+              11, 12, 13, 14, 15, &
+              16, 17, 18, 19, 20]
+
+! example 1.3: disabling auto-formatter:
+   my_integer = 2 !&
+   i          = 3 !&
+   j          = 5 !&
+
+!&<
+   my_integer = 2
+   i          = 3
+   j          = 5
+!&>
+
+   big_arr = [ 1,  2,  3,  4,  5, & !&
+               6,  7,  8,  9, 10, & !&
+              11, 12, 13, 14, 15, & !&
+              16, 17, 18, 19, 20] !&
+
+! example 1.4:
+
+   big_arr = [1, 2, 3, 4, 5,&
+           &  6, 7, 8, 9, 10, &
+           & 11, 12, 13, 14, 15,&
+            &16, 17, 18, 19, 20]
+
+! 2) auto indentation for loops !
+!*******************************!
+
+! example 2.1
+   l = 0
+   do r = 1, 10
+      select case (r)
+      case (1)
+         do_label: do i = 1, 100
+            if (i <= 2) then
+               m = 0
+               do while (m < 4)
+                  m = m + 1
+                  do k = 1, 3
+                     if (k == 1) l = l + 1
+                  end do
+               enddo
+            endif
+         enddo do_label
+      case (2)
+         l = i + j + k
+      end select
+   enddo
+
+! example 2.2
+   do m = 1, 2
+      do r = 1, 3
+         write (*, *) r
+         do k = 1, 4
+         do l = 1, 3
+         do i = 4, 5
+            do my_integer = 1, 1
+            do j = 1, 2
+               write (*, *) test_function(m, r, k, l) + i
+            enddo
+            enddo
+         enddo
+         enddo
+         enddo
+      enddo
+   enddo
+
+! 3) auto alignment for linebreaks   !
+!************************************!
+
+! example 3.1
+   l = test_function(1, 2, test_function(1, 2, 3, 4), 4) + 3*(2 + 1)
+
+   l = test_function(1, 2, test_function(1, 2, 3, 4), 4) + &
+       3*(2 + 1)
+
+   l = test_function(1, 2, &
+                     test_function(1, 2, 3, 4), 4) + &
+       3*(2 + 1)
+
+   l = test_function(1, 2, &
+                     test_function(1, 2, 3, &
+                                   4), 4) + &
+       3*(2 + 1)
+
+! example 3.2
+   arr = [1, (/3, 4, 5/), 6] + [1, 2, 3, 4, 5]
+
+   arr = [1, (/3, 4, 5/), &
+          6] + [1, 2, 3, 4, 5]
+
+   arr = [1, (/3, 4, 5/), &
+          6] + &
+         [1, 2, 3, 4, 5]
+
+   arr = [1, (/3, 4, &
+               5/), &
+          6] + &
+         [1, 2, 3, 4, 5]
+
+! example 3.3
+   l = test_function(1, 2, &
+                     3, 4)
+
+   l = test_function( &
+       1, 2, 3, 4)
+
+   arr = [1, 2, &
+          3, 4, 5]
+   arr = [ &
+         1, 2, 3, 4, 5]
+
+! 4) more complex formatting and tricky test cases !
+!**************************************************!
+
+! example 4.1
+   l = 0
+   do r = 1, 10
+      select case (r)
+      case (1)
+         do i = 1, 100; if (i <= 2) then ! comment
+               do j = 1, 5
+                  do k = 1, 3
+                     l = l + 1
+! unindented comment
+                     ! indented comment
+                  end do; enddo
+            elseif (.not. j == 4) then
+               my_integer = 4
+            else
+               write (*, *) " hello"
+            endif
+         enddo
+      case (2)
+         l = i + j + k
+      end select
+   enddo
+
+! example 4.2
+   if ( &
+      l == &
+      111) &
+      then
+      do k = 1, 2
+         if (k == 1) &
+            l = test_function(1, &
+                              test_function(r=4, i=5, &
+                                            j=6, k=test_function(1, 2*(3*(1 + 1)), str_function(")a!(b['(;=dfe"), &
+                                                                 9) + &
+                                            test_function(1, 2, 3, 4)), 9, 10) &
+                ! test_function(1,2,3,4)),9,10) &
+                ! +13*str_function('') + str_function('"')
+                + 13*str_function('') + str_function('"')
+      end & ! comment
+         ! comment
+         do
+   endif
+
+! example 4.3
+   arr = [1, (/3, 4, &
+               5/), &
+          6] + &
+         [1, 2, 3, 4, 5]; arr = [1, 2, &
+ 3, 4, 5]
+
+! example 4.4
+   endif = 3
+   if (endif == 2) then
+      endif = 5
+   else if (endif == 3) then
+      write (*, *) endif
+   endif
+
+! example 4.5
+   do i = 1, 2; if (.true.) then
+         write (*, *) "hello"
+      endif; enddo
+
+end program