Merge pull request #686 from sourceryinstitute/fix-#638-check-compiler-version

Fix #683 check compiler version

Author: Damian Rouson

prerequisites/acceptable_compiler.f90

@@ -33,21 +33,114 @@
 ! POSSIBILITY OF SUCH DAMAGE.
 
 program main
+  !! input: acceptable compiler version the form major.minor.patch
+  !! output:
+  !!   .true. if compiler version >= acceptable version
+  !!   .false. otherwise
   use iso_fortran_env, only : compiler_version
   implicit none
-  integer, parameter :: first_argument=1
+
+  integer, parameter :: first_argument=1, max_version_length=len('999.999.999')
   integer stat
-  character(len=9) version_number
-  call get_command_argument(first_argument,version_number,status=stat)
-  select case(stat)
-    case(-1)
-       error stop "acceptable_compiler.f90: insufficient string length in attempt to read command argument"
-    case(0)
-      ! successful command argument read
-    case(1:)
-       error stop "acceptable_compiler.f90: no version-number supplied"
-    case default
-       error stop "invalid status"
-  end select
-  print *,(compiler_version() >= "GCC version "//adjustl(trim(version_number))//" ")
+  character(len=max_version_length) acceptable_version
+
+  call get_command_argument(first_argument,acceptable_version,status=stat)
+  call validate_command_line( stat )
+
+  associate( compiler_version=> compiler_version() )
+    associate(major_version=>major(compiler_version), acceptable_major=>major(acceptable_version))
+      if ( major_version > acceptable_major ) then
+        print *,.true.
+      else if ( major_version == acceptable_major ) then
+        associate(minor_version=>minor(compiler_version), acceptable_minor=>minor(acceptable_version))
+          if ( minor_version > acceptable_minor ) then
+            print *,.true.
+          else if ( minor_version == acceptable_minor ) then
+            associate(patch_version=>patch(compiler_version), acceptable_patch=>patch(acceptable_version))
+              if ( patch_version >= acceptable_patch ) then
+                print *,.true.
+              else
+                print *,.false.
+              end if
+            end associate
+          else
+            print *,.false.
+          end if
+        end associate
+      else
+        print *,.false.
+      end if
+    end associate
+  end associate
+
+contains
+
+  subroutine validate_command_line( command_line_status )
+    integer, intent(in) :: command_line_status
+    select case(command_line_status)
+      case(-1)
+         error stop "acceptable_compiler.f90: insufficient string length in attempt to read command argument"
+      case(0)
+        ! successful command argument read
+      case(1:)
+         error stop "acceptable_compiler.f90: no version-number supplied"
+      case default
+         error stop "invalid status"
+    end select
+   end subroutine
+
+  pure function major(version_string) result(major_value)
+    character(len=*), intent(in) :: version_string
+    integer major_value
+    character(len=:), allocatable :: leading_digits
+
+    associate( first_dot => scan(version_string, '.') )
+      associate( first_digit => scan( version_string(1:first_dot-1), '0123456789' ) )
+        leading_digits = version_string( first_digit : first_dot-1  )
+        read(leading_digits,*) major_value
+      end associate
+    end associate
+
+  end function
+
+  pure function minor(version_string) result(minor_value)
+    character(len=*), intent(in) :: version_string
+    integer minor_value
+    character(len=:), allocatable :: middle_digits
+
+    associate( first_dot => scan(version_string, '.') )
+      associate( second_dot => first_dot + scan(version_string(first_dot+1:), '.') )
+        middle_digits = version_string( first_dot+1 : second_dot-1 )
+        read(middle_digits,*) minor_value
+      end associate
+    end associate
+
+  end function
+
+  pure function patch(version_string) result(patch_value)
+    character(len=*), intent(in) :: version_string
+    integer patch_value
+    character(len=:), allocatable :: trailing_digits
+
+    associate( first_dot => scan(version_string, '.') )
+      associate( second_dot => first_dot + scan(version_string(first_dot+1:), '.') )
+        associate( first_non_digit=> second_dot + first_printable_non_digit(version_string(second_dot+1:)) )
+          trailing_digits = version_string( second_dot+1 : first_non_digit-1 )
+          read(trailing_digits,*) patch_value
+        end associate
+      end associate
+    end associate
+
+  end function
+
+  pure function first_printable_non_digit( string ) result(location)
+    character(len=*), intent(in) :: string
+    integer i, location
+    integer, parameter :: ASCII_non_digit(*)=[(i,i=32,47),(i,i=58,126)]
+    character(len=1), parameter :: non_digit(*)=[( char(ASCII_non_digit(i)) , i=1, size(ASCII_non_digit) )]
+    character(len=size(non_digit)) non_digit_string
+    write(non_digit_string,'(85a)') non_digit
+    location = scan(string,non_digit_string)
+  end function
+
 end program