;+
; NAME:
;	strbreak
; PURPOSE:
;	Split string in pieces at white space
; CALLING SEQUENCE:
	FUNCTION strbreak, label, tokens=tokens
; COMMON:
	@compile_opt.pro
; PROCEDURE:
;	Substrings enclosed by double quotes are left intact,
;	i.e. are treated as a single piece without whitespace.
;-

destroyvar, tokens

p = 0
p_open = strpos( strmid(label,p), '"' )

WHILE p_open NE -1 DO BEGIN
	IF p_open GT 0 THEN BEGIN
		q = strmid(label,p,p_open)
		IF strlen( strcompress(q,/rem) ) GT 0 THEN boost, tokens, strtok( q,' ',/extract )
	ENDIF
	p_close = strpos( strmid(label,p+p_open+1), '"' )
	IF p_close EQ -1 THEN BEGIN
		message, /info, 'bad label: missing closing quote: "'+label+'"'
		destroyvar, tokens
		RETURN, 0
	ENDIF
	IF p_close GT 0 THEN boost, tokens, strmid( label, p+p_open+1, p_close )
	p += p_open+1+p_close+1
        p_open = strpos( strmid(label,p), '"' )
ENDWHILE

IF p LT strlen(label) THEN boost, tokens, strtok( strmid(label,p),' ',/extract )

RETURN, n_elements(tokens)  & END