Megatest

(define configf:key-no-val (regexp "^(\\S+)(\\s*)$"))
(define configf:comment-rx (regexp "^\\s*#.*"))
(define configf:cont-ln-rx (regexp "^(\\s+)(\\S+.*)$"))

;; read a line and process any #{ ... } constructs

(define configf:var-expand-regex (regexp "^(.*)#\\{(scheme|system|shell|getenv|get|runconfigs-get|rget)\\s+([^\\}\\{]*)\\}(.*)"))
(define (configf:process-line l ht allow-system)
  (let loop ((res l))
    (if (string? res)
	(let ((matchdat (string-search configf:var-expand-regex res)))
	  (if matchdat
	      (let* ((prestr  (list-ref matchdat 1))
		     (cmdtype (list-ref matchdat 2)) ;; eval, system, shell, getenv
		     (cmd     (list-ref matchdat 3))

					(sect  (car parts))
					(var   (cadr parts)))
				   (conc "(lambda (ht)(config-lookup ht \"" sect "\" \"" var "\"))")))
				((runconfigs-get) (conc "(lambda (ht)(runconfigs-get ht \"" cmd "\"))"))
				((rget)           (conc "(lambda (ht)(runconfigs-get ht \"" cmd "\"))"))
				(else "(lambda (ht)(print \"ERROR\") \"ERROR\")"))))
		;; (print "fullcmd=" fullcmd)
		(if (or allow-system
			(not (member cmdtype '("system" "shell"))))
		    (with-input-from-string fullcmd
		      (lambda ()
			(set! result ((eval (read)) ht))))
		    (set! result (conc "#{(" cmdtype ") "  cmd "}")))		(loop (conc prestr result poststr)))
	      res))
	res)))

;; Run a shell command and return the output as a string
(define (shell cmd)
  (let* ((output (cmd-run->list cmd))
	 (res    (car output))

(define (runconfigs-get config var)
  (let ((targ (or (args:get-arg "-reqtarg")(args:get-arg "-target")(getenv "MT_TARGET"))))
    (if targ
	(or (configf:lookup config targ var)
	    (configf:lookup config "default" var))
	(configf:lookup config "default" var))))

;; this was inline but I'm pretty sure that is a hold over from when it was *very* simple ...
;;
(define (configf:read-line p ht allow-processing)
  (let loop ((inl (read-line p)))
    (let ((cont-line (and (string? inl)
			  (not (string-null? inl))
			  (equal? "\\" (string-take-right inl 1)))))
      (if cont-line ;; last character is \ 
	  (let ((nextl (read-line p)))
	    (if (not (eof-object? nextl))
		(loop (string-append (if cont-line 
					 (string-take inl (- (string-length inl) 1))
					 inl)
				     nextl))))
	  (case allow-processing ;; if (and allow-processing 
	    ;;	   (not (eq? allow-processing 'return-string)))
	    ((#t #f)
	     (configf:process-line inl ht allow-processing))
	    ((return-string)
	     inl)
	    (else
	     (configf:process-line inl ht allow-processing)))))))

;; read a config file, returns hash table of alists

;; read a config file, returns hash table of alists
;; adds to ht if given (must be #f otherwise)
;; envion-patt is a regex spec that identifies sections that will be eval'd
;; in the environment on the fly
;; sections: #f => get all, else list of sections to gather
(define (read-config path ht allow-system #!key (environ-patt #f)(curr-section #f)(sections #f))
  (debug:print-info 5 "read-config " path " allow-system " allow-system " environ-patt " environ-patt " curr-section: " curr-section " sections: " sections " pwd: " (current-directory))
  (debug:print 9 "START: " path)
  (if (not (file-exists? path))
      (begin 
	(debug:print-info 1 "read-config - file not found " path " current path: " (current-directory))
	;; WARNING: This is a risky change but really, we should not return an empty hash table if no file read?
	#f) ;; (if (not ht)(make-hash-table) ht))
      (let ((inp        (open-input-file path))
	    (res        (if (not ht)(make-hash-table) ht)))
	(let loop ((inl               (configf:read-line inp res allow-system)) ;; (read-line inp))
		   (curr-section-name (if curr-section curr-section "default"))
		   (var-flag #f);; turn on for key-var-pr and cont-ln-rx, turn off elsewhere
		   (lead     #f))
	  (debug:print-info 8 "curr-section-name: " curr-section-name " var-flag: " var-flag "\n   inl: \"" inl "\"")
	  (if (eof-object? inl) 
	      (begin
		(close-input-port inp)
		(hash-table-delete! res "") ;; we are using "" as a dumping ground and must remove it before returning the ht
		(debug:print 9 "END: " path)
		res)
	      (regex-case 
	       inl 
	       (configf:comment-rx _                  (loop (configf:read-line inp res allow-system) curr-section-name #f #f))
	       (configf:blank-l-rx _                  (loop (configf:read-line inp res allow-system) curr-section-name #f #f))
	       (configf:include-rx ( x include-file ) (let* ((curr-conf-dir (pathname-directory path))
							     (full-conf     (if (absolute-pathname? include-file)
										include-file
										(nice-path 
										 (conc (if curr-conf-dir
											   curr-conf-dir
											   ".")
										       "/" include-file)))))
							(if (file-exists? full-conf)
							    (begin
							      ;; (push-directory conf-dir)
							      (debug:print 9 "Including: " full-conf)
							      (read-config full-conf res allow-system environ-patt: environ-patt curr-section: curr-section-name sections: sections)
							      ;; (pop-directory)
							      (loop (configf:read-line inp res allow-system) curr-section-name #f #f))
							    (begin
							      (debug:print '(2 9) "INFO: include file " include-file " not found (called from " path ")")
							      (debug:print 2 "        " full-conf)
							      (loop (configf:read-line inp res allow-system) curr-section-name #f #f)))))
	       (configf:section-rx ( x section-name ) (loop (configf:read-line inp res allow-system)
							    ;; if we have the sections list then force all settings into "" and delete it later?
							    (if (or (not sections) 
								    (member section-name sections))
								section-name "") ;; stick everything into ""

												 " output: " cmdres)
										    (exit 1)))
									      (if (null? res)
										  ""
										  (string-intersperse res " "))))))
							    (hash-table-set! res curr-section-name 
									     (config:assoc-safe-add alist
									   			    key 
												    (case allow-system
												      ((return-procs) val-proc)
												      ((return-string) cmd)
												      (else (val-proc)))))
							    (loop (configf:read-line inp res allow-system) curr-section-name #f #f))
							  (loop (configf:read-line inp res allow-system) curr-section-name #f #f)))
	       (configf:key-val-pr ( x key unk1 val unk2 ) (let* ((alist   (hash-table-ref/default res curr-section-name '()))
								  (envar   (and environ-patt (string-search (regexp environ-patt) curr-section-name)))
								  (realval (if envar
									       (config:eval-string-in-environment val)
									       val)))
							     (debug:print-info 6 "read-config env setting, envar: " envar " realval: " realval " val: " val " key: " key " curr-section-name: " curr-section-name)
							     (if envar (safe-setenv key realval))

							     (debug:print 10 "   setting: [" curr-section-name "] " key " = " val)

							     (hash-table-set! res curr-section-name 
									      (config:assoc-safe-add alist key realval))
							     (loop (configf:read-line inp res allow-system) curr-section-name key #f)))
	       (configf:key-no-val ( x key val)             (let* ((alist   (hash-table-ref/default res curr-section-name '())))
							      (debug:print 10 "   setting: [" curr-section-name "] " key " = #t")
							      (hash-table-set! res curr-section-name 
									       (config:assoc-safe-add alist key #t))
							      (loop (configf:read-line inp res allow-system) curr-section-name key #f)))
	       ;; if a continued line
	       (configf:cont-ln-rx ( x whsp val     ) (let ((alist (hash-table-ref/default res curr-section-name '())))
						(if var-flag             ;; if set to a string then we have a continued var
						    (let ((newval (conc 

	       (lambda (sheet-name)
		 (let* ((dat-path  (conc refdb-path "/" sheet-name ".dat"))
			(ref-dat   (configf:read-file dat-path #f #t))
			(ref-assoc (map (lambda (key)
					  (list key (hash-table-ref ref-dat key)))
					(hash-table-keys ref-dat))))
				   ;; (hash-table->alist ref-dat)))
		   ;; (set! data (append data (list (list sheet-name ref-assoc))))))
		   (set! data (cons (list sheet-name ref-assoc) data))))
	       sheets)
	      (list data "NO ERRORS"))))))

;; map over all pairs in a three level hierarchial alist and apply a function to the keys/val
;;
(define (configf:map-all-hier-alist data proc #!key (initproc1 #f)(initproc2 #f)(initproc3 #f))
  (for-each 

	    (for-each
	     (lambda (varname)
	       (let* ((valtmp (assoc varname sectiondat))
		      (val    (if valtmp (cadr valtmp) "")))
		 (proc sheetname sectionname varname val)))
	     (map car sectiondat))))
	(map car sheetdat))))
   (map car data))
  data)

;;======================================================================
;;  C O N F I G   T O / F R O M   A L I S T
;;======================================================================

(define (configf:config->alist cfgdat)
  (hash-table->alist cfgdat))

(define (configf:alist->config adat)
  (let ((ht (make-hash-table)))
    (for-each
     (lambda (section)
       (hash-table-set! ht (car section)(cdr section)))
     adat)
    ht))

(define (configf:read-alist fname)
  (configf:alist->config
   (with-input-from-file fname read)))

(define (configf:write-alist cdat fname)
  (with-output-to-file fname
    (lambda ()
      (pp (configf:config->alist cdat)))))