StringTokenize Subroutine

public subroutine StringTokenize(string, delims, args, nArgs)

It is often useful to represent a text as a list of tokens. The process of breaking a text up into its constituent tokens is known as tokenization. The subroutine parses the string in input into arguments args(1), ..., args(nargs) based on the delimiters contained in the string delims. Preceding a delimiter in string by a backslash \ makes this particular instance not a delimiter. The integer output variable nArgs contains the number of arguments found.

Arguments

Type IntentOptional Attributes Name
character(len=*), intent(in) :: string
character(len=*), intent(in) :: delims
character(len=*), POINTER :: args(:)

local copy of string to tokenize
integer(kind=short), intent(out) :: nArgs

Variables

Type Visibility Attributes Name Initial
integer(kind=short), public :: i
integer(kind=short), public :: na
character(len=LEN_TRIM), public :: strSav

Source Code

SUBROUTINE StringTokenize &
!
 (string, delims, args, nArgs)
 
! Declarations: 
  
IMPLICIT NONE 
     
! Subroutine arguments 
! Scalar arguments with intent(in): 
CHARACTER(LEN = *), INTENT(IN) :: string
CHARACTER(LEN = *), INTENT(IN) :: delims           
         
! Scalar arguments with intent(out): 
INTEGER (KIND = short), INTENT(OUT)  :: nArgs 
         
! Array  arguments with intent(out): 
CHARACTER (len=*), POINTER :: args(:)
                  
! Local scalars:
!! local copy of string to tokenize
CHARACTER (LEN = LEN_TRIM(string)) :: strSav
INTEGER (KIND = short)  :: na
INTEGER (KIND = short)  :: i
!------------end of declaration------------------------------------------------

strSav = StringCompact (string)
IF ( LEN_TRIM (strSav) == 0 ) RETURN      !string is empty

! Count number of tokens in string
nArgs = 0
DO i = 1, LEN_TRIM(strSav)
  IF ( INDEX ( delims,strSav(i:i) ) > 0 ) THEN !the character is a delimiter
    nArgs = nArgs + 1
  END IF
END DO

nArgs = nArgs + 1 !number of tokens are number of found delimiters + 1

!allocate space for tokens
ALLOCATE ( args(nArgs) )

!initialize tokens
DO i = 1,nArgs
  args(i) = ' '
END DO  

na = 0
DO
   IF (LEN_TRIM(strSav) == 0) EXIT
   na = na + 1
   CALL StringSplit(delims,strSav,args(na))
END DO   

END SUBROUTINE StringTokenize