PRO flt_clean, StrIn, FmtIn, StrOut, FmtOut, nocheck=NoCheck,	$
	strcrumbs=StrCrumbs, numcrumbs=NumCrumbs

;+
; NAME:
;	flt_clean
; PURPOSE:
;	Check a specified format against a specified string.
; CALLING SEQUENCE:
;	flt_clean, StrIn, FmtIn, StrOut, FmtOut, /nocheck
; INPUTS:
;	StrIn		character string (usually a record read from file)
;	FmtIn		format to be matched against string
; OPTIONAL INPUTS:
;	/nocheck	see procedure
; OUTPUTS:
;	StrOut		reduced character string (see procedure)
;	FmtOut		reduced format; = '()' if the input format does not
;			match the input string
; OPTIONAL OUTPUTS:
;	StrCrumbs	string array containing the discarded portions of the
;			input string
;	NumCrumbs	# elements in StrCrumbs
; INCLUDE:
	@compile_opt.pro		; On error, return to caller
; CALLS:
;	InitVar
; PROCEDURE:
;	The input format is searched for the character descriptor 'A'. All 'A'
;	occurrences are removed from the format, and the corresponding
;	substrings are removed from the input string.
;	The reduced output format will contain only numeric format desciptors
;	(I,F,D,E).
;	If the input string does not adequately match the format,
;	string '()' is returned as output format. This occurs if:
; >	If the string is longer or shorter than the length implied by the
;	input format, i.e. the lengths must match exactly
; >	(Only if the keyword NoCheck is not set)
;	If the substring for an 'A' descriptor contains a numerical digit (0..9)
; MODIFICATION HISTORY:
;	MAY-1994, Paul Hick (ARC)
;	SEP-2003, Paul Hick (UCSD/CASS; pphick@ucsd.edu)
;		Bug fix. If format would end with a string (e.g. A3) then this would not
;		be cleaned up properly.
;-

StrOut = StrIn
FmtOut = FmtIn
FmtL   = strlen(FmtIn)

IF FmtL EQ 0 THEN RETURN					; Empty input string

InitVar, NoCheck, /key
DoCheck = 1-NoCheck

FmtOut = strmid( FmtOut, 1, FmtL-2 )+','	; Remove brackets, add comma
FmtL  -= 1

StrA = ['0','1','2','3','4','5','6','7','8','9']
FmtList = ['A','I','F','E','D','.',',']
FmtN = n_elements(FmtList)
PosN = intarr(FmtN, /nozero)

Ntot = 0
pos = 0

NumCrumbs = 0

WHILE pos LT FmtL DO BEGIN
											; Pick up positions of FmtList chars
	FOR i=0,FmtN-1 DO PosN[i] = strpos( FmtOut, FmtList[i], pos )

	p = where( PosN NE -1 )
	posmin = min( PosN[p], pmin )
	pmin = p[pmin]
	ch = FmtList[pmin]						; 1st FmtList char following 'pos'

	IF pmin GT 4 THEN message, 'should not have happened'

	CASE posmin OF							; Format counter
	pos :  N = 1
	ELSE: reads, strmid( FmtOut, pos, posmin-pos ), N
	ENDCASE

	pend = (PosN[where(FmtList EQ '.')])[0] ; Check for dot

	CASE pend EQ -1 OF
	0: pend = min( [pend, PosN[ where(FmtList EQ ',') ] ] )
	1: pend = PosN[ where(FmtList EQ ',') ]
	ENDCASE

	pend = pend[0]

	m = 0									; reads, S,M crashes if S is 1-char string and M doesn't exist
	CASE pend-posmin EQ 1 of				; Format length
	0: reads, strmid( FmtOut, posmin+1, pend-posmin-1 ), M
	1: message, 'Format specifier of undetermined length'
	ENDCASE

	CASE ch OF
	'A': BEGIN								; 'AN' DETECTED IN FORMAT
		IF DoCheck THEN BEGIN				; If DoCheck is set ..
			StrDmp = strmid(StrOut,Ntot,M*N); .. Check whether the 'An' part
											; .. of StrOut contains digits
			i = -1
			REPEAT BEGIN
				i += 1
				d = where( StrDmp EQ StrA[i] )
				IF d[0] NE -1 THEN BEGIN	; Digit found
					i = n_elements(StrA)
					FmtOut = ''				; Format does not fit StrOut
					pos = FmtL
				ENDIF
			ENDREP until i ge n_elements(StrA)-1
		ENDIF

		IF FmtOut NE '' THEN BEGIN			; Remove 'An' part from FmtOut
			FmtOut = strmid(FmtOut,0,pos)+strmid(FmtOut,pend+1)
			FmtL = strlen(FmtOut)

			IF Ntot+M*N GT strlen(StrOut) THEN BEGIN	; SEP-2003 bugfix: used to be 'ge'
				FmtOut = ''					; StrOut too short
				pos = FmtL					; Break while loop
			ENDIF ELSE BEGIN				; Remove 'An' substring from StrOut
				NumCrumbs += 1
				CASE NumCrumbs EQ 1 OF		; Collect the 'An' substrings
				0: StrCrumbs = [StrCrumbs,strmid(StrOut,Ntot,M*N)]
				1: StrCrumbs = strmid(StrOut,Ntot,M*N)
				ENDCASE
				StrOut = strmid(StrOut,0,Ntot)+strmid(StrOut,Ntot+M*N)
			ENDELSE
		ENDIF

	END

	ELSE: BEGIN								; I,F,E,D detected in format
		Ntot += M*N						; # chars in StrOut
		IF strlen(StrOut) LT Ntot THEN BEGIN; StrOut too short
			FmtOut = ''
			pos = FmtL						; Break while loop
		ENDIF ELSE	$						; Set pos after I,F,E,D format
			pos = (PosN[ where(FmtList EQ ',') ])[0]+1

	END

	ENDCASE

ENDWHILE
			; If not whole StrOut processed: format does not fit string
IF FmtOut NE '' THEN IF Ntot LT strlen(StrOut) THEN FmtOut = ''
			; Reconstruct valid format descriptor: remove comma, add brackets
FmtOut = '('+strmid( FmtOut,0,strlen(FmtOut)-1 )+')'

RETURN  &  END