Fortran regex

Regular expression for Fortran

Description

Fortran module to wrap regex.h.

Demo

program test
   use regex_module
   type(regex) :: re

   re%compile("abc(.*)(ghi)")
   re%match("abcdefghi")
   write(*,*) re%group(0) ! abcdefghi
   write(*,*) re%group(1) ! def
   write(*,*) re%group(2) ! ghi
end program test

program rem_operator_test
   use regex_module
   type(regex) :: re

   re = "abcdefghi" .rem. "abc(.*)(ghi)"
   write(*,*) re%group(0) ! abcdefghi
   write(*,*) re%group(1) ! def
   write(*,*) re%group(2) ! ghi
end program rem_operator_test

Compile and run

gfortran demo.f90 regex.f90
./a.out

Requirement

• Check that regex library is available.
• GCC gfortran

Install and Usage

Copy regex.f90 to the directory where you want to use regex_module.

• Fundamental functions

  • ret = re%compile(pattern) compile pattern characters and the return a status integer ret.
  • ret = re%match(string) do regular expression match on string and the return a status integer ret.
  • str = re%group(i) obtains i-th matched substring from string
  • str = re%get_error_message(ret) get error message of regex corresponds to status ret

• Other definitions

  • Assignment operator = is the copy constructor of type(regex)
  • operator re = A .rem. B is equivalent to:

  ret = temp%re_compile(B)
  ret = temp%re_match(A)
  re = temp
  

  • call re%print_status() prints compile and matching status to stdout

Files

• README.md
  • This file.
• regex.f90
  • Module source file.
• test.f90
  • A program to test functions.
• demo.f90
  • One of examples in the Demo section.
• check_structure_size.c
  • Supplemental C program to check regex_t structure size.

Note

• Assinment operator = do the regular expression matching of lhs again in order to make the regex_t pointer unique.
  • This means the sentense re = "str" .rem. "pat" will do compile and match twice.
• If the size of regex_t changes, especially bigger than 32 byte, please change REGEX_T_SIZE value.
  • regex_t_size_checker.c is a simple program to print the size of regex_t.

TODO

• Find a way to solve regex structure size dependency.
• Modify copy constructor to avoid doing the same matching twice
• Check compability for other fortran compiler

Licence

MIT

Author

Seiji Ueno

ブログ（日本語）