json_get_by_path_rfc6901 Subroutine

private subroutine json_get_by_path_rfc6901(json, me, path, p, found)

Returns the json_value pointer given the path string, using the “JSON Pointer” path specification defined by RFC 6901.

Note that trailing whitespace significance and case sensitivity are user-specified. To fully conform to the RFC 6901 standard, should probably set (via initialize):

  • case_sensitive_keys = .true. [this is the default setting]
  • trailing_spaces_significant = .true. [this is not the default setting]
  • allow_duplicate_keys = .false. [this is not the default setting]

Example

    type(json_core) :: json
    type(json_value),pointer :: dat,p
    logical :: found
    !...
    call json%initialize(path_mode=2)
    call json%get(dat,'/data/2/version',p,found)

See also

Reference

Arguments

Type IntentOptional AttributesName
class(json_core), intent(inout) :: json
type(json_value), intent(in), pointer:: me

a JSON linked list

character(kind=CK,len=*), intent(in) :: path

path to the variable (an RFC 6901 “JSON Pointer”)

type(json_value), intent(out), pointer:: p

pointer to the variable specify by path

logical(kind=LK), intent(out), optional :: found

true if it was found


Calls

proc~~json_get_by_path_rfc6901~~CallsGraph proc~json_get_by_path_rfc6901 json_get_by_path_rfc6901 proc~string_to_integer string_to_integer proc~json_get_by_path_rfc6901->proc~string_to_integer proc~decode_rfc6901 decode_rfc6901 proc~json_get_by_path_rfc6901->proc~decode_rfc6901 proc~replace_string replace_string proc~decode_rfc6901->proc~replace_string

Contents


Source Code

    subroutine json_get_by_path_rfc6901(json, me, path, p, found)

    implicit none

    class(json_core),intent(inout)       :: json
    type(json_value),pointer,intent(in)  :: me     !! a JSON linked list
    character(kind=CK,len=*),intent(in)  :: path   !! path to the variable
                                                   !! (an RFC 6901 "JSON Pointer")
    type(json_value),pointer,intent(out) :: p      !! pointer to the variable
                                                   !! specify by `path`
    logical(LK),intent(out),optional     :: found  !! true if it was found

    character(kind=CK,len=:),allocatable :: token  !! a token in the path (between the `/` characters)
    integer(IK)              :: i                  !! counter
    integer(IK)              :: islash_curr        !! location of current '/' character in the path
    integer(IK)              :: islash_next        !! location of next '/' character in the path
    integer(IK)              :: ilen               !! length of `path` string
    type(json_value),pointer :: tmp                !! temporary variable for traversing the structure
    integer(IK)              :: ival               !! integer array index value (0-based)
    logical(LK)              :: status_ok          !! error flag
    logical(LK)              :: child_found        !! for getting child values

    nullify(p)

    if (.not. json%exception_thrown) then

        p => me ! initialize

        if (path/=CK_'') then

            if (path(1:1)==slash) then  ! the first character must be a slash

                islash_curr = 1   ! initialize current slash index

                !keep trailing space or not:
                if (json%trailing_spaces_significant) then
                    ilen = len(path)
                else
                    ilen = len_trim(path)
                end if

                do

                    ! get the next token by finding the slashes
                    !
                    !  1   2 3
                    !  /abc/d/efg

                    if (islash_curr==ilen) then
                        !the last token is an empty string
                        token = CK_''
                        islash_next = 0  ! will signal to stop
                    else

                        !      .
                        ! '/123/567/'

                        ! index in remaining string:
                        islash_next = index(path(islash_curr+1:ilen),slash)
                        if (islash_next<=0) then
                            !last token:
                            token = path(islash_curr+1:ilen)
                        else
                            ! convert to actual index in path:
                            islash_next = islash_curr + index(path(islash_curr+1:ilen),slash)
                            if (islash_next>islash_curr+1) then
                                token = path(islash_curr+1:islash_next-1)
                            else
                                !empty token:
                                token = CK_''
                            end if
                        end if

                    end if

                    ! remove trailing spaces in the token here if necessary:
                    if (.not. json%trailing_spaces_significant) &
                        token = trim(token)

                    ! decode the token:
                    token = decode_rfc6901(token)

                    ! now, parse the token:

                    ! first see if there is a child with this name
                    call json%get_child(p,token,tmp,child_found)
                    if (child_found) then
                        ! it was found
                        p => tmp
                    else
                        ! No key with this name.
                        ! Is it an integer? If so,
                        ! it might be an array index.
                        status_ok = (len(token)>0)
                        if (status_ok) then
                            do i=1,len(token)
                                ! It must only contain (0..9) characters
                                ! (it must be unsigned)
                                if (scan(token(i:i),CK_'0123456789')<1) then
                                    status_ok = .false.
                                    exit
                                end if
                            end do
                            if (status_ok) then
                                if (len(token)>1 .and. token(1:1)==CK_'0') then
                                    ! leading zeros not allowed for some reason
                                    status_ok = .false.
                                end if
                            end if
                            if (status_ok) then
                                ! if we make it this far, it should be
                                ! convertible to an integer, so do it.
                                call string_to_integer(token,ival,status_ok)
                            end if
                        end if
                        if (status_ok) then
                            ! ival is an array index (0-based)
                            call json%get_child(p,ival+1_IK,tmp,child_found)
                            if (child_found) then
                                p => tmp
                            else
                                ! not found
                                status_ok = .false.
                            end if
                        end if
                        if (.not. status_ok) then
                            call json%throw_exception('Error in json_get_by_path_rfc6901: '//&
                                                        'invalid path specification: '//trim(path))
                            exit
                        end if
                    end if

                    if (islash_next<=0) exit ! finished

                    ! set up for next token:
                    islash_curr = islash_next

                end do

            else
                call json%throw_exception('Error in json_get_by_path_rfc6901: '//&
                                            'invalid path specification: '//trim(path))
            end if
        end if

        if (json%exception_thrown) then
            nullify(p)
            if (present(found)) then
                found = .false.
                call json%clear_exceptions()
            end if
        else
            if (present(found)) found = .true.
        end if

    else
        if (present(found)) found = .false.
    end if

    end subroutine json_get_by_path_rfc6901