fortran-pcre2

A work-in-progress collection of Fortran 2018 ISO_C_BINDING interfaces to Perl-compatible Regular Expressions 2 (PCRE2). The library is also available on MacPorts.

Build Instructions

You will need libpcre2 with development headers. On FreeBSD, run:

# pkg install devel/pcre2

On Debian Linux, install:

# apt-get install libpcre2-8-0 libpcre2-dev

Clone the repository and execute the provided Makefile to create the static library libfortran-pcre2.a containing the interfaces:

$ git clone https://github.com/interkosmos/fortran-pcre2
$ cd fortran-pcre2/
$ make

Install the library and the modules files system-wide to /opt:

$ make install PREFIX=/opt

Instead of make, you may want to build the library using the Fortran Package Manager:

$ fpm build --profile release

Link your Fortran programs against libfortran-pcre2.a and -lpcre2-8.

Example

The following program just compiles and executes a basic regular expression.

! example.f90
program main
    use, intrinsic :: iso_c_binding
    use :: pcre2
    implicit none (type, external)

    integer, parameter :: OVECSIZE = 30 ! Must be multiple of 3.

    character(len=128)            :: buffer
    character(len=:), allocatable :: pattern, subject
    integer                       :: err_code, rc
    integer(kind=pcre2_size)      :: err_offset
    type(c_ptr)                   :: match_data, re

    pattern = '^([A-Z][a-z]+)$'
    subject = 'Fortran'

    ! Compile regular expression.
    re = pcre2_compile(pattern     = pattern, &
                       length      = len(pattern, kind=pcre2_size), &
                       options     = 0, &
                       errorcode   = err_code, &
                       erroroffset = err_offset, &
                       ccontext    = c_null_ptr)

    if (.not. c_associated(re)) then
        buffer = ' '
        rc = pcre2_get_error_message(err_code, buffer, len(buffer, kind=pcre2_size))
        print '("Error ", i0, ": ", a)', err_code, trim(buffer)
        stop
    end if

    ! Execute regular expression.
    match_data = pcre2_match_data_create(OVECSIZE, c_null_ptr)

    rc = pcre2_match(code        = re, &
                     subject     = subject, &
                     length      = len(subject, kind=pcre2_size), &
                     startoffset = int(0, kind=pcre2_size), &
                     options     = 0, &
                     match_data  = match_data, &
                     mcontext    = c_null_ptr)

    if (rc == 0) then
        print '("OVECSIZE too small")'
    else if (rc < 0) then
        select case (rc)
            case (PCRE2_ERROR_NOMATCH)
                print '("No match")'
            case default
                print '("Matching error ", i0)', rc
        end select
    else if (rc > 0) then
        print '("Match!")'
    end if

    call pcre2_match_data_free(match_data)
    call pcre2_code_free(re)
end program main

If the library has been installed to /opt, then compile, link, and run the program with:

$ gfortran -I/opt/include/libfortran-pcre2 -o example example.f90 /opt/lib/libfortran-pcre2.a -lpcre2-8
$ ./example

Fortran Package Manager

You can add fortran-pcre2 as an FPM dependency:

[dependencies]
fortran-pcre2 = { git = "https://github.com/interkosmos/fortran-pcre2.git" }

Compatibility

It is not necessary to null-terminate character strings given to the procedures of fortran-pcre2. In contrast to the C API of PCRE2, you must not free substrings with pcre2_substring_free(), as this will be done by the wrapper functions.

Coverage

C API	Fortran interface
`pcre2_code_free_8`	`pcre2_code_free`
`pcre2_compile_8`	`pcre2_compile`
`pcre2_compile_context_free_8`	`pcre2_compile_context_free`
`pcre2_get_error_message_8`	`pcre2_get_error_message`
`pcre2_get_ovector_count_8`	`pcre2_get_ovector_count`
`pcre2_get_ovector_pointer_8`	`pcre2_get_ovector_pointer`
`pcre2_match_8`	`pcre2_match`
`pcre2_match_data_create_8`	`pcre2_match_data_create`
`pcre2_match_data_free_8`	`pcre2_match_data_free`
`pcre2_substring_copy_byname_8`	`pcre2_substring_copy_byname`
`pcre2_substring_copy_bynumber_8`	`pcre2_substring_copy_bynumber`
`pcre2_substring_free_8`	`pcre2_substring_free`
`pcre2_substring_get_byname_8`	`pcre2_substring_get_byname`
`pcre2_substring_get_bynumber_8`	`pcre2_substring_get_bynumber`
`pcre2_substring_number_from_name_8`	`pcre2_substring_number_from_name`

Licence

ISC