Add serialization example

[minhqdao]

Please add an example on how to build a JSON from scratch and serialize it.

[awvwgk]

For serialization the json_serialize, json_dump, and json_dumps procedures can be used. The simplest way is to print or write the return value of json_serialize:

  block
    use jonquil, only : json_serialize
    character(:), allocatable :: str

    str = json_serialize(object)
    print '(a)', str
  end block

To create the JSON object, have a look in the set_value function provided by TOML Fortran.

  block
    use jonquil, only : json_object, set_value
    type(json_object) :: object
    type(json_object), pointer :: child
    call set_value(object, "val", 1.0)
    call set_value(object, "sub", child)
    call set_value(child, "val", 2.0)
    ! ...
  end block

[minhqdao]

Thanks. I found the new_object procedure to create a JSON:

program main
  use jonquil

  implicit none

  type(json_object) :: json

  call new_object(json)

  call set_value(json, 'hello', 'world')

  print *, json_serialize(json)

end program

However, the output using gfortran is:

 ,"hello": "world"}

Is it maybe a bug? 🤔

[minhqdao]

Same result using json_dumps.

[awvwgk]

The comma is produced in

jonquil/src/jonquil/ser.f90

Line 347 in 02e3c4c

visitor%output = visitor%output // ","

Looks like I transcribed this incorrectly from

https://github.com/toml-f/toml-f/blob/2f04799adf9ecfff3f7a2a58e89496fd6556b21d/test/compliance/json_ser.f90#L211

which would produce an opening brace. So definitely a bug.

[awvwgk]

Fixed the serialization error. Let me know if you find any other discrepancies.

[minhqdao]

Looks good, thanks for the very quick fix.