Remove the escape characters from a JSON string and return it.
The escaped characters are denoted by the '' character:
'\"' quotation mark
'\\' reverse solidus
'\/' solidus
'\b' backspace
'\f' formfeed
'\n' newline (LF)
'\r' carriage return (CR)
'\t' horizontal tab
'\uXXXX' 4 hexadecimal digits
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| character(kind=CK,len=*), | intent(in) | :: | str_in | string as stored in a json_value |
||
| character(kind=CK,len=:), | intent(out), | allocatable | :: | str_out | decoded string |
|
| character(kind=CK,len=:), | intent(out), | allocatable | :: | error_message | will be allocated if there was an error |
subroutine unescape_string(str_in, str_out, error_message)
implicit none
character(kind=CK,len=*),intent(in) :: str_in !! string as stored in a [[json_value]]
character(kind=CK,len=:),allocatable,intent(out) :: str_out !! decoded string
character(kind=CK,len=:),allocatable,intent(out) :: error_message !! will be allocated if there was an error
integer :: i !! counter
integer :: n !! length of str_in
integer :: m !! length of str_out
character(kind=CK,len=1) :: c !! for scanning each character in string
#if defined __GFORTRAN__
character(kind=CK,len=:),allocatable :: tmp !! for GFortran bug workaround
#endif
if (scan(str_in,backslash)>0) then
!there is at least one escape character, so process this string:
n = len(str_in)
str_out = repeat(space,n) !size the output string (will be trimmed later)
m = 0 !counter in str_out
i = 0 !counter in str_in
do
i = i + 1
if (i>n) exit ! finished
c = str_in(i:i) ! get next character in the string
if (c == backslash) then
if (i<n) then
i = i + 1
c = str_in(i:i) !character after the escape
if (any(c == [quotation_mark,backslash,slash, &
to_unicode(['b','f','n','r','t'])])) then
select case(c)
case (quotation_mark,backslash,slash)
!use d as is
case (CK_'b')
c = bspace
case (CK_'f')
c = formfeed
case (CK_'n')
c = newline
case (CK_'r')
c = carriage_return
case (CK_'t')
c = horizontal_tab
end select
m = m + 1
str_out(m:m) = c
else if (c == 'u') then !expecting 4 hexadecimal digits after
!the escape character [\uXXXX]
!for now, we are just returning them as is
![not checking to see if it is a valid hex value]
!
! Example:
! 123456
! \uXXXX
if (i+4<=n) then
m = m + 1
str_out(m:m+5) = str_in(i-1:i+4)
i = i + 4
m = m + 5
else
error_message = 'Error in unescape_string:'//&
' Invalid hexadecimal sequence'//&
' in string: '//str_in(i-1:)
if (allocated(str_out)) deallocate(str_out)
return
end if
else
!unknown escape character
error_message = 'Error in unescape_string:'//&
' unknown escape sequence in string "'//&
trim(str_in)//'" ['//backslash//c//']'
if (allocated(str_out)) deallocate(str_out)
return
end if
else
!an escape character is the last character in
! the string [this may not be valid syntax,
! but just keep it]
m = m + 1
str_out(m:m) = c
end if
else
m = m + 1
str_out(m:m) = c
end if
end do
!trim trailing space:
#if defined __GFORTRAN__
! workaround for Gfortran 6.1.0 bug
tmp = str_out(1:m)
str_out = tmp
#else
str_out = str_out(1:m)
#endif
else
!there are no escape characters, so return as is:
str_out = str_in
end if
end subroutine unescape_string