json_get_by_path Subroutine

Source File

Variables

start_array_alt end_array_alt i length child_i c array tmp

Source Code

All Procedures

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private subroutine json_get_by_path(me, path, p, found)

Arguments

Type	Intent	Optional	Attributes		Name
type(json_value),	intent(in),		pointer	::	me
character(kind=CK,len=*),	intent(in)			::	path
type(json_value),	intent(out),		pointer	::	p
logical(kind=LK),	intent(out),	optional		::	found	true if it was found

Description

Returns the json_value pointer given the path string.

Example

     type(json_value),pointer :: dat,p
     logical :: found
     !...
     call json_get(dat,'data(2).version',p,found)

Notes

The following special characters are used to denote paths:

  $         - root
  @         - this
  .         - child object member
  [] or ()  - child array element

Thus, if any of these characters are present in the name key, this routine cannot be used to get the value. In that case, the json_get_child routines would need to be used.

Variables

Type	Visibility	Attributes		Name		Initial
character(kind=CK,len=1),	public,	parameter	::	start_array_alt	=	'('
character(kind=CK,len=1),	public,	parameter	::	end_array_alt	=	')'
integer(kind=IK),	public		::	i
integer(kind=IK),	public		::	length
integer(kind=IK),	public		::	child_i
character(kind=CK,len=1),	public		::	c
logical(kind=LK),	public		::	array
type(json_value),	public,	pointer	::	tmp

Source Code

    subroutine json_get_by_path(me, path, p, found)

    implicit none

    type(json_value),pointer,intent(in)  :: me
    character(kind=CK,len=*),intent(in)  :: path
    type(json_value),pointer,intent(out) :: p
    logical(LK),intent(out),optional     :: found  !! true if it was found

    character(kind=CK,len=1),parameter :: start_array_alt = '('
    character(kind=CK,len=1),parameter :: end_array_alt   = ')'

    integer(IK)              :: i,length,child_i
    character(kind=CK,len=1) :: c
    logical(LK)              :: array
    type(json_value),pointer :: tmp

    if (.not. exception_thrown) then

        nullify(p)

        ! default to assuming relative to this
        p => me

        child_i = 1

        array = .false.

        length = len_trim(path)

        do i=1, length

            c = path(i:i)

            select case (c)
            case (CK_'$')

                ! root
                do while (associated (p%parent))
                    p => p%parent
                end do
                child_i = i + 1

            case (CK_'@')

                ! this
                p => me
                child_i = i + 1

            case (CK_'.')

                ! get child member from p
                if (child_i < i) then
                    nullify(tmp)
                    call json_get_child(p, path(child_i:i-1), tmp)
                    p => tmp
                    nullify(tmp)
                else
                    child_i = i + 1
                    cycle
                end if

                if (.not. associated(p)) then
                    call throw_exception('Error in json_get_by_path:'//&
                                         ' Error getting child member.')
                    exit
                end if

                child_i = i+1

            case (start_array,start_array_alt)

                !....Modified to allow for 'var[3]' style syntax
                !Note: jmozmoz/fson has a slightly different version of this...

                ! start looking for the array element index
                array = .true.

                ! get child member from p
                if (child_i < i) then
                    nullify(tmp)
                    call json_get_child(p, path(child_i:i-1), tmp)
                    p => tmp
                    nullify(tmp)
                else
                    child_i = i + 1
                    cycle
                end if
                if (.not. associated(p)) then
                    call throw_exception('Error in json_get_by_path:'//&
                                         ' Error getting array element')
                    exit
                end if
                child_i = i + 1

            case (end_array,end_array_alt)

                if (.not.array) then
                    call throw_exception('Error in json_get_by_path: Unexpected ]')
                    exit
                end if
                array = .false.
                child_i = string_to_integer(path(child_i:i-1))

                nullify(tmp)
                call json_get_child(p, child_i, tmp)
                p => tmp
                nullify(tmp)

                child_i= i + 1

            end select

        end do

        if (exception_thrown) then

            if (present(found)) then
                found = .false.
                call json_clear_exceptions()
            end if

        else

            ! grab the last child if present in the path
            if (child_i <= length) then
                nullify(tmp)
                call json_get_child(p, path(child_i:i-1), tmp)
                p => tmp
                nullify(tmp)
            end if
            if (associated(p)) then
                if (present(found)) found = .true.    !everything seems to be ok
            else
                call throw_exception('Error in json_get_by_path:'//&
                                     ' variable not found: '//trim(path))
                if (present(found)) then
                    found = .false.
                    call json_clear_exceptions()
                end if
            end if

        end if

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

    end subroutine json_get_by_path