Procedure

     LXIDNT ( Lex identifier )

     ENTRY LXIDNT ( IDSPEC, STRING, FIRST, LAST, NCHAR )

Abstract

     Scan an identifier, starting from a specified character
     position.

Required_Reading

     None.

Keywords

     CHARACTER
     PARSING
     SCANNING
     STRING
     UTILITY

Declarations

    IMPLICIT NONE

    INTEGER               LBCELL
    PARAMETER           ( LBCELL = -5 )

    INTEGER               IDSPEC ( LBCELL : * )
    CHARACTER*(*)         STRING
    INTEGER               FIRST
    INTEGER               LAST
    INTEGER               NCHAR

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     IDSPEC     I   Identifier character specification.
     STRING     I   String to be scanned.
     FIRST      I   Character position at which to start scanning.
     LAST       O   Character position of end of token.
     NCHAR      O   Number of characters in token.
     LBCELL     P   The SPICE cell lower bound.

Detailed_Input

     IDSPEC   is an integer cell containing a specification of
              the head and tail identifier character sets to be
              used in scanning the input argument STRING. IDSPEC
              should be obtained by calling LXDFID or LXCSID.
              The structure of IDSPEC is not part of the
              specification of this routine suite and should not
              be relied upon by calling code.

     STRING   is a character string that may contain an
              `identifier' starting at the character position
              indicated by the input argument FIRST (see
              below). Identifier tokens are sequences of
              characters that represent names. Syntactically, an
              identifier is a sequence of characters that begins
              with a character belonging to a set of valid `head'
              characters and is followed by zero or more
              characters belonging to a set of valid `tail'
              characters.

     FIRST    is the character position at which the routine
              is to start scanning an identifier. Note
              that the character STRING(FIRST:FIRST) must be a
              valid head character if an identifier is to
              be found; this routine does *not* attempt to locate
              the first identifier following the position
              FIRST.

Detailed_Output

     LAST     is the last character position such that the
              substring STRING(FIRST:LAST) is an identifier, if
              such a substring exists. Otherwise, the
              returned value of LAST is FIRST-1.

     NCHAR    is the length of the identifier found by this
              routine, if such a token exists. If an identifier
              is not found, the returned value of NCHAR is
              zero.

Parameters

     LBCELL   is the SPICE cell lower bound.

Exceptions

     Error free.

     1)  If the input argument FIRST is less than 1 or greater than
         LEN(STRING)-1, the returned value of LAST is FIRST-1, and the
         returned value of NCHAR is zero.

Files

     None.

Particulars

     The default syntax rules for valid identifiers are specified in
     the $Particulars section of the umbrella routine LXNAME. These
     rules may be overridden by calling LXCSID.

Examples

     See the $Examples section of the umbrella routine LXNAME.

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     N.J. Bachman       (JPL)
     J. Diaz del Rio    (ODC Space)
     B.V. Semenov       (JPL)

Version

    SPICELIB Version 1.1.0, 26-OCT-2021 (JDR)

        Added IMPLICIT NONE statement.

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.0.1, 10-FEB-2014 (BVS)

        Added LBCELL to the $Declarations, $Brief_I/O, and $Parameters
        sections.

    SPICELIB Version 1.0.0, 25-OCT-1995 (NJB)