pro zparcheck,progname,parameter,parnum,types,dimens,message
;+
; NAME:
;    ZPARCHECK
; PURPOSE:
;    Routine to check user parameters to a procedure
;
; CALLING SEQUENCE:
;    zparcheck, progname, parameter, parnum, types, dimens, [ message ]
;
; INPUTS:
;    progname  - scalar string name of calling procedure
;    parameter - parameter passed to the routine
;    parnum    - integer parameter number
;    types     - integer scalar or vector of valid types
;         1 - byte        2 - integer   3 - int*4
;         4 - real*4      5 - real*8    6 - complex
;         7 - string      8 - structure 9 - double complex
;    dimens   - integer scalar or vector giving number
;              of allowed dimensions.
; OPTIONAL INPUT:
;    message - string message describing the parameter to be printed if an 
;        error is found
;
; OUTPUTS:
;    none
;
; EXAMPLE:
;    IDL> zparcheck, 'HREBIN', hdr, 2, 7, 1, 'FITS Image Header'
;
;    This example checks whether the parameter 'hdr' is of type string (=7)
;    and is a vector (1 dimension).   If either of these tests fail, a 
;    message will be printed
;        "Parameter 2 (FITS Image Header) is undefined"
;        "Valid dimensions are 1"
;        "Valid types are string"    
;
; SIDE EFFECTS:
;    If an error in the parameter is a message is printed
;    a RETALL issued
;
; HISTORY
;    version 1  D. Lindler  Dec. 86
;    documentation updated.  M. Greason, May 1990.
;    Recognize double complex datatype    W. Landsman   September 1995
;    Converted to IDL V5.0   W. Landsman   September 1997
;-
;    Converted to IDL V5.0   W. Landsman   September 1997
;----------------------------------------------------------

  if N_params() LT 4 then begin
    print, $
   'Syntax -  ZPARCHECK, progname, parameter, parnum, types, dimens, [message ]
    return
  endif

; get type and size of parameter

  s = size(parameter)
  ndim = s[0]
  type = s[ndim+1]

; check if parameter defined.

  if type EQ 0 then begin
    err = ' is undefined.'
    goto, ABORT 
  endif

; check for valid dimensions

  valid = where( ndim EQ dimens, Nvalid)
  if Nvalid LT 1 then begin
    err = 'has wrong number of dimensions'
    goto, ABORT   
  endif

; check for valid type

  valid = where(type EQ types, Ngood)
  if ngood lt 1 then begin
    err = 'is an invalid data type'
    goto, ABORT   
  endif

  return

; bad parameter

ABORT:
  mess = ' '
  if N_params() lt 6 then message = ''
  if message NE '' then mess = ' ('+message+') '
  print,string(7b) + 'Parameter '+strtrim(parnum,2) + mess,$
    ' of routine ', strupcase(progname) + ' ', err
  sdim = ' '
  for i = 0,N_elements(dimens)-1 do begin
    if dimens[i] eq 0 then sdim = sdim + 'scalar' $
              else sdim = sdim + string(dimens[i],'(i3)')
  end
  print,'Valid dimensions are:'+sdim

  stype = ' '
  for i = 0, N_elements( types )-1 do begin
    case types[i] of
        1: stype = stype + ' byte'
        2: stype = stype + ' integer'
        3: stype = stype + ' longword'
        4: stype = stype + ' real*4'
        5: stype = stype + ' real*8'
        6: stype = stype + ' complex'
        7: stype = stype + ' string'
                8: stype = stype + ' structure'
        9: stype = stype + ' dcomplex'
    endcase
  endfor
  print,'Valid types are:' + stype
  ;if !debug then stop
  retall  ; zparcheck
  end