#! %GUILE_BINDIR%/guile -s
# Emacs, it's -*- scheme -*-
!#
;;;; GNU Mailutils -- a suite of utilities for electronic mail
;;;; Copyright (C) 1999-2001, 2006-2007, 2009-2012, 2014 Free Software
;;;; Foundation, Inc.
;;;;
;;;; GNU Mailutils is free software; you can redistribute it and/or modify
;;;; it under the terms of the GNU General Public License as published by
;;;; the Free Software Foundation; either version 3, or (at your option)
;;;; any later version.
;;;; 
;;;; GNU Mailutils is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;;; GNU General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU General Public License along
;;;; with GNU Mailutils.  If not, see <http://www.gnu.org/licenses/>.
;;;;

;;;; This is a Sieve to Scheme translator.
;;;;
;;;; To convert a sieve script into equivalent Scheme program, run:
;;;;
;;;;  guile -s sieve2scm.scm --file <sieve-script-name> --output <output-file-name>
;;;;
;;;; To compile and execute a sieve script upon a mailbox, run:
;;;;
;;;;  guile -s sieve2scm.scm --file <sieve-script-name> [mailbox-name]
;;;;
(if (not (member "%GUILE_SITE%" %load-path))
    (set! %load-path (cons "%GUILE_SITE%" %load-path)))
(use-modules (ice-9 getopt-long)
	     (ice-9 rdelim)
	     (mailutils sieve-core))

(set! sieve-parser #t)

(define sieve-debug 0)
(define sieve-libdir "%LIBDIR%")
(define sieve-load-files '())
(define sieve-script-args '())
(define request-verbose #f)

(define error-count 0)
(define current-token #f)
(define putback-list '())
(define input-port #f)
(define input-file "")
(define input-line-number 0)
(define input-line "")
(define input-index 0)
(define input-length 0)
(define nesting-level 0)
(define recovery-line-number -1)
(define recovery-index -1)

(define (DEBUG level . rest)
  (if (>= sieve-debug level)
      (begin
	(display "DEBUG(")
	(display level)
	(display "):")
	(for-each (lambda (x)
		    (display x))
		  rest)
	(newline))))

;;;; Lexical scanner
(define (delimiter? c)
  (or (member c (list #\[ #\] #\{ #\} #\, #\; #\( #\)))
      (char-whitespace? c)))

(define (lex-error . rest)
  (set! error-count (1+ error-count))
  (with-output-to-port
      (current-error-port)
    (lambda ()
      (display input-file)
      (display ":")
      (display input-line-number)
      (display ": ")
      (for-each (lambda (x)
		  (display x))
		rest)
      (newline)))
  #t)

(define (syntax-error . rest)
  (set! error-count (1+ error-count))
  (with-output-to-port
      (current-error-port)
    (lambda ()
      (display input-file)
      (display ":")
      (display input-line-number)
      (display ": ")
      (for-each (lambda (x)
		  (display x))
		rest)
      (newline)))
  (throw 'syntax-error))

;;; If current input position points to end of line or to a start of
;;; # comment, return #f. Otherwise return cons whose car contains
;;; token type and cdr contains token itself (string). 
(define (next-token)
  (let ((start (do ((i input-index (1+ i)))
		   ((or (>= i input-length)
			(not (char-whitespace? (string-ref input-line i))))
		    i))))
;    (DEBUG 100 "START " start ": " (substring input-line start)) 
    (if (< start input-length)
	(let ((char (string-ref input-line start)))
	  (DEBUG 100 "CHAR " char)
	  (case char
	    ((#\#)
	     (set! input-index input-length)
	     #f)
	    ((#\[ #\] #\{ #\} #\( #\) #\, #\;)
	     (set! input-index (1+ start))
	     (cons 'delimiter char))
	    ((#\")
	     (let ((end (do ((end (1+ start) (1+ end)))
			    ((or (>= end input-length)
				 (char=? (string-ref input-line end) #\"))
			     end))))
	       (if (>= end input-length)
		   (lex-error "Unterminated string constant"))
		  (set! input-index (1+ end))
		  (cons 'string (substring input-line (1+ start) end))))
	    (else
	     (DEBUG 100 "MATCH else")
	     (cond
	      ((and (char=? (string-ref input-line start) #\/)
		    (< (1+ start) input-length)
		    (char=? (string-ref input-line (1+ start)) #\*))
	       (set! input-index (+ start 2))
	       (cons 'bracket-comment "/*"))
	      ((char-numeric? char)
	       (let* ((end (do ((end start (1+ end)))
			       ((or
				 (>= end (1- input-length))
				 (not (char-numeric?
				       (string-ref input-line end))))

				(cond
				 ((char-numeric? (string-ref input-line end))
				  (1+ end))
				 (else
				  end)))))
		      (num (string->number (substring input-line start end))) 
		      (q (if (< end input-length)
			     (string-ref input-line end)
			 #f))
		      (k 1))
		 (case q
		   ((#f) #f) ;; nothing
		   ((#\K)
		    (set! end (1+ end))
		    (set! k 1024))
		   ((#\M)
		    (set! end (1+ end))
		    (set! k 1048576))
		   ((#\G)
		    (set! end (1+ end))
		    (set! k 1073741824))
		   (else
		    (if (not (delimiter? q))
		      (lex-error "Unknown qualifier (" q ")"))))
		 (set! input-index end)
		 (cons 'number (* num k))))
	      (else
	       (let ((end (do ((end start (1+ end)))
			      ((or (>= end input-length)
				   (delimiter? (string-ref input-line end)))
			       end))))
		 (DEBUG 100 "END " end)
		 (set! input-index end)
		 (cond
		  ((char=? char #\:)
		   (cons 'tag (substring input-line (1+ start) end)))
		  (else
		   (cons 'identifier (substring input-line start end))))))))))
	#f)))

(define (end-of-line?)
  (do ((i input-index (1+ i)))
      ((or (>= i input-length)
	   (not (char-whitespace? (string-ref input-line i))))
       (>= i input-length))))

(define (read-input-line port)
  (set! input-line (read-line port))
  (if (not (eof-object? input-line))
      (begin
	(set! input-line-number (1+ input-line-number))
	(set! input-length (string-length input-line))
	(set! input-index 0)))
  input-line)

(define (next-token-from-port port)
  (let ((tok (or (next-token)
		 (begin
		   (DEBUG 100 "2nd")
		   (set! input-line (read-line port))
		   (if (not (eof-object? input-line))
		       (begin
                         (set! input-line-number (1+ input-line-number))
			 (set! input-length (string-length input-line))
			 (set! input-index 0)
			 (next-token))
		       input-line)))))
    (cond
     ((or (not tok) (eof-object? tok))
      tok)
     ((and (eq? (car tok) 'identifier)
	   (string=? (cdr tok) "text:")
	   (end-of-line?))
      (let ((text "")
	    (string-start input-line-number))
	(do ((line (read-line port) (read-line port)))
	    ((or (and
		  (eof-object? line)
		  (lex-error
		   "Unexpected end of file in multiline string started on line "
		   string-start)
		  (throw 'end-of-file))
		 (let ((len (string-length line)))
		   (and (> len 0)
			(char=? (string-ref line 0) #\.)
			(do ((i 1 (1+ i)))
			    ((or (>= i len)
				 (not
				  (char-whitespace?
				   (string-ref line i))))
			     (>= i len))))))
	     #f)
          (set! input-line-number (1+ input-line-number))
	  (if (and (not (string-null? line))
                   (char=? (string-ref line 0) #\.)
		   (char=? (string-ref line 1) #\.))
	      (set! line (substring line 1)))
	  (set! text (string-append text "\n" line)))
	(set! input-length 0)
	(set! input-index 0)
	(cons 'string text)))
     ((eq? (car tok) 'bracket-comment)
      (let ((comment-start input-line-number))
	(set! input-length (- input-length input-index))
	   (if (> input-length 0)
	       (begin
		 (set! input-line
		       (substring input-line input-index input-length))
		 (set! input-index 0))
	       (read-input-line port))
	   (do ()
	       ((> input-index 0) #f)
	     (cond
	      ((eof-object? input-line)
	       (lex-error
		"Unexpected end of file in comment started on line "
		comment-start)
	       (throw 'end-of-file))
	      (else
	       (let ((t (string-index input-line #\*)))
		 (if (and t
			  (< (1+ t) input-length)
			  (char=? (string-ref input-line (1+ t)) #\/))
		     (set! input-index (+ t 2))
		     (read-input-line port))))))))
     (else
	tok))))

(define (delimiter token c)
  (and (pair? token)
       (eq? (car token) 'delimiter)
       (char=? (cdr token) c)))

(define (identifier token c)
  (and (eq? (car token) 'identifier)
       (string=? (cdr token) c)))

(define (putback-token)
  (set! putback-list (append (list current-token)
			     putback-list)))

(define (read-token)
  (cond
   ((not (null? putback-list))
    (set! current-token (car putback-list))
    (set! putback-list (cdr putback-list)))
   (else
    (set! current-token (do ((token (next-token-from-port input-port)
				    (next-token-from-port input-port)))
			    (token token)))))
  current-token)

(define (require-semicolon . read)
  (if (null? read)
      (read-token))
  (if (or (eof-object? current-token)
	  (not (delimiter current-token #\;)))
      (syntax-error "Missing ;")
      current-token))

(define (require-tag . read)
  (if (null? read)
      (read-token))
  (cond
   ((eof-object? current-token)
    (syntax-error "Expected tag but found " current-token))
   ((not (eq? (car current-token) 'tag))
    (syntax-error "Expected tag but found " (car current-token))))
  current-token)

(define (require-string . read)
  (if (null? read)
      (read-token))
  (cond
   ((eof-object? current-token)
    (syntax-error "Expected string but found " current-token))
   ((not (eq? (car current-token) 'string))
    (syntax-error "Expected string but found " (car current-token))))
  current-token)

(define (require-number . read)
  (if (null? read)
      (read-token))
  (cond
   ((eof-object? current-token)
    (syntax-error "Expected number but found " current-token))
   ((not (eq? (car current-token) 'number))
    (syntax-error "Expected number but found " (car current-token))))
  current-token)

(define (require-string-list . read)
  (if (null? read)
      (read-token))
  (cond
   ((eof-object? current-token)
    (syntax-error "Expected string-list but found " current-token))
   ((eq? (car current-token) 'string)
    (list 'string-list (cdr current-token)))
   ((not (eq? (car current-token) 'delimiter))
    (syntax-error "Expected string-list but found " (car current-token)))
   ((char=? (cdr current-token) #\[)
    (do ((slist '())
	 (token (read-token) (read-token)))
	((if (not (eq? (car token) 'string))
	     (begin
	       (syntax-error "Expected string but found " (car token))
	       #t)
	     (begin
	       (set! slist (append slist (list (cdr token))))
	       (read-token)
	       (cond
		((eof-object? current-token)
		 (syntax-error "Unexpected end of file in string list")
		 #t) ;; break;
		((eq? (car current-token) 'delimiter)
		 (cond
		  ((char=? (cdr current-token) #\,) #f) ;; continue
		  ((char=? (cdr current-token) #\]) #t) ;; break
		  (else
		   (lex-error "Expected ',' or ']' but found "
			      (cdr current-token))
		   #t)))
		(else
		 (lex-error "Expected delimiter but found "
			    (car current-token))
		 #t))))
	 (cons 'string-list slist))))
   (else
    (syntax-error "Expected '[' but found " (car current-token)))))
  
(define (require-identifier . read)
  (if (null? read)
      (read-token))
  (cond
   ((eof-object? current-token)
    (syntax-error "1. Expected identifier but found " current-token))
   ((not (eq? (car current-token) 'identifier))
    (syntax-error "2. Expected identifier but found " (car current-token))))
  current-token)

;;;;

;;; Syntax tables.
;;; A syntax table is a list of 
;;; Each entry is: (list NAME FUNCTION OPT-ARG-LIST REQ-ARG-LIST)
;;; NAME is a string representing the input language keyword,
;;; FUNCTION is a corresponding function:
;;;       (define (foo [arg [arg...]] . opt-args)
;;; OPT-ARG-LIST is a list of optional arguments (tags),
;;; REQ-ARG-LIST is a list of required (positional) arguments

(define (sieve-syntax-table-lookup table name)
  (let ((entry (assoc name table)))
    (if entry
	(cdr entry)
	#f)))

(define-macro (sieve-syntax-table-add table name function req-arg-list opt-arg-list)
  `(cond
    ((not (list? ,opt-arg-list))
     (lex-error "sieve-syntax-table-add: opt-arg-list must be a list"))
    ((not (list? ,req-arg-list))
     (lex-error "sieve-syntax-table-add: req-arg-list must be a list"))
    ((not (or (eq? ,function #f)
	      (eq? ,function #t)
	      (procedure? ,function)))
     (lex-error "sieve-syntax-table-add: bad type for function " ,function))
    (else
     (set! ,table
	   (append ,table
		   (list
		    (list ,name ,function ,opt-arg-list ,req-arg-list)))))))
   
;;;;

(defmacro do-for-all (fun rest)
  `(for-each
    (lambda (x)
      (apply ,fun x))
    ,rest))


;;;; Available syntax tables.

;;;; Comparators

;;; Syntax table for comparators. The opt-arg-list and req-arg-list have
;;; no meaning for comparators, so they are ignored. The handler function
;;; names must start with "comparator-"
(define sieve-comparator-table '())

(define (sieve-find-comparator name)
  (sieve-syntax-table-lookup sieve-comparator-table name))

(define (sieve-register-comparator name function)
  (sieve-syntax-table-add sieve-comparator-table name function '() '()))

;;; Register standard comparators
(do-for-all sieve-register-comparator sieve-standard-comparators)

;;;; Sieve Tests

;;; Syntax table for tests. Function names must start with "test-"
(define sieve-test-table '())

(define (sieve-find-test name)
  (sieve-syntax-table-lookup sieve-test-table name))

(define (sieve-register-test name function req-arg-list opt-arg-list)
  (sieve-syntax-table-add sieve-test-table name function
			  req-arg-list opt-arg-list))

;;; Register standard tests
(do-for-all sieve-register-test sieve-standard-tests) 

;;;; Sieve Actions

;;; Syntax table for actions. Function names start with "action-"
(define sieve-action-table '())

(define (sieve-find-action name)
  (sieve-syntax-table-lookup sieve-action-table name))

(define (sieve-register-action name function req-arg-list opt-arg-list)
  (sieve-syntax-table-add sieve-action-table name function
			  req-arg-list opt-arg-list))

;;; Register standard actions
(do-for-all sieve-register-action sieve-standard-actions)

;;;;

;;;; Command parsers

;;; sieve-preprocess-arguments: Preprocess and group the arguments. Returns
;;; a cons whose car is a list of all optional arguments, and the cdr is
;;; a list of the rest of the arguments.
;;;
;;; arguments = *argument [test / test-list]
;;; argument = string-list / number / tag

(define (sieve-preprocess-arguments tag-gram)
  (do ((opt-list '())   ;; List of optional arguments (tags)
       (arg-list '())   ;; List of positional arguments
       (last-tag #f)    ;; Description of the last tag from tag-gram
       (state 'opt)     ;; 'opt when scanning optional arguments,
                        ;; 'arg when scanning positional arguments
       (token (read-token) (read-token))) ;; Obtain next token
      ((cond
	((eof-object? token)
	 (syntax-error "Expected argument but found " token))
	((eq? (car token) 'tag)
	 (if (not (eq? state 'opt))
	     (syntax-error "Misplaced tag: :" (cdr token)))
	 (set! last-tag (assoc (cdr token) tag-gram))
	 (if (not last-tag)
	     (syntax-error
	      "Tag :" (cdr token) " is not allowed in this context"))
	 (set! opt-list (append opt-list (list token)))
	 #f)
	((or (eq? (car token) 'number)
	     (eq? (car token) 'string))
	 (cond
	  ((and (eq? state 'opt) (pair? last-tag))
	   (cond
	    ((cdr last-tag)
	     (if (not (eq? (cdr last-tag) (car token)))
		 (syntax-error
		  "Tag :" (car last-tag) " takes " (cdr last-tag) " argument"))
	     (cond
	      ((string=? (car last-tag) "comparator")
	       (let ((comp (sieve-find-comparator (cdr token))))
		 (if (not comp)
		     (syntax-error "Undefined comparator: " (cdr token)))
		 (set-cdr! token (car comp)))))
	     (set! opt-list (append opt-list (list token)))
	     (set! last-tag #f))
	    (else
	     (set! state 'arg)
	     (set! arg-list (append arg-list (list token))))))
	  (else
	   (set! arg-list (append arg-list (list token)))))
	 #f)
	((delimiter token #\[) 
	 (putback-token)
	 (cond
	  ((and (eq? state 'opt) (pair? last-tag))
	   (cond
	    ((cdr last-tag)
	     (if (not (eq? (cdr last-tag) 'string-list))
		 (syntax-error
		  "Tag :" (car last-tag) " takes string list argument"))
	     (set! opt-list (append opt-list (list (require-string-list))))
	     (set! last-tag #f))
	    (else
	     (set! state 'arg)
	     (set! arg-list (append arg-list (list (require-string-list)))))))
	  (else
	   (set! arg-list (append arg-list (list (require-string-list))))))
 	 #f)
	(else
	 #t)) 
       (cons opt-list arg-list))))

;;; sieve-parse-arguments: Parse the arguments to a test or an action.
;;; ENTRY is the syntax table entry to guide the parsing
;;;
(define (sieve-parse-arguments ident entry)
  (DEBUG 100 "sieve-parse-arguments" entry)
  (let ((arg-list (sieve-preprocess-arguments (car (cdr entry)))))
    ;; Process positional arguments
    (do ((expect (car (cdr (cdr entry))) (cdr expect))
	 (argl (cdr arg-list) (cdr argl))
	 (n 1 (1+ n)))
	((cond
	  ((null? expect)
	   (if (not (null? argl))
	       (syntax-error
		"Too many positional arguments for " ident
		" (bailed out at " (car argl) ")"))
	   #t)
	  ((null? argl)
	   (if (not (null? expect))
	       (syntax-error
		"Too few positional arguments for " ident))
	   #t)
	  (else #f)) #f)
      (let ((expect-type (car expect))
	    (arg (car argl)))
	(cond
	 ((and (eq? expect-type 'string-list)
	       (eq? (car arg) 'string))
	  ;; Coerce string to string-list
	  (sieve-exp-append (list 'list (cdr arg))))
	 ((eq? expect-type (car arg))
	  (if (eq? expect-type 'string-list)
	      (sieve-exp-append (append (list 'list) (cdr arg)))
	      (sieve-exp-append (cdr arg))))
	 (else
	  (syntax-error
	   "Type mismatch in argument " n " to " (cdr ident)
	   "; expected " expect-type ", but got " (car arg))))))
    ;; Process optional arguments (tags).
    ;; They have already been tested
    (for-each
     (lambda (tag)
       (sieve-exp-append (cond
			  ((eq? (car tag) 'tag)
			   (symbol->keyword
			    (string->symbol (cdr tag))))
			  ((eq? (car tag) 'string-list)
			   (append (list 'list) (cdr tag)))
			  (else
			   (cdr tag)))))
     (car arg-list))))

;;;;

;;;; Parser functions for tests

;;; test-list = "(" test *("," test) ")"
(define (sieve-parse-test-list)
  (do ((token (sieve-parse-test) (sieve-parse-test)))
      ((cond
	((delimiter token #\))
	 #t) ;; break;
	((delimiter token #\,)
	 #f) ;; continue
	((eof-object? token)
	 (syntax-error "Unexpected end of file in test-list")
	 #t) ;; break
	(else
	 (syntax-error "Expected ',' or ')' but found " (cdr token))
	 #t)) ;; break
       (read-token))))
	
;;; test = identifier arguments
(define (sieve-parse-test)
  (let ((ident (require-identifier)))
    (cond
     ((string=? (cdr ident) "not")
      (sieve-exp-begin)
      (sieve-exp-append 'not)
      (sieve-parse-test)
      (sieve-exp-finish))
     (else
      (read-token)
      (cond
       ((eof-object? current-token)
	(syntax-error "Unexpected end of file in conditional"))
       ((delimiter current-token #\()
	(sieve-exp-begin)
	(cond
	 ((string=? (cdr ident) "allof")
	  (sieve-exp-append 'and))
	 ((string=? (cdr ident) "anyof")
	  (sieve-exp-append 'or))
	 (else
	  (syntax-error "Unexpected '('")))
	(sieve-parse-test-list)
	(sieve-exp-finish))
       (else
	(let ((test (sieve-find-test (cdr ident))))
	  (if (not test)
	      (syntax-error "Unknown test name: " (cdr ident)))
	  (cond
	   ((procedure? (car test))
	    (putback-token)
	    (sieve-exp-begin)
	    (sieve-exp-append (car test))
	    (sieve-parse-arguments (cdr ident) test)
	    (sieve-exp-finish))
	   (else
	    (sieve-exp-append (car test))))))))))
  current-token)

(define (sieve-parse-block . read)
  (if (not (null? read))
      (read-token))
  (if (delimiter current-token #\{)
      (begin
	(set! nesting-level (1+ nesting-level))
	(do ((token (read-token) (read-token)))
	    ((cond
	      ((eof-object? token)
	       (syntax-error "Unexpected end of file in block")
	       #t)
	      ((delimiter token #\})
	       #t)
	      (else
	       (putback-token)
	       (sieve-parse-command)
	       #f))) #f)
	(set! nesting-level (1- nesting-level)))
      (require-semicolon 'dont-read)))

;;; if <test1: test> <block1: block>
(define (sieve-parse-if-internal)
  (DEBUG 10 "sieve-parse-if-internal" current-token)
  (sieve-exp-begin)
  
  (sieve-parse-test)
  
  (sieve-parse-block)
  (sieve-exp-finish)
  
  (read-token)
  (cond
   ((eof-object? current-token) )
   ((identifier current-token "elsif")
    (sieve-parse-if-internal))
   ((identifier current-token "else")
    (sieve-exp-begin 'else)
    (sieve-parse-block 'read)
    (sieve-exp-finish))
   (else
    (putback-token))))

(define (sieve-parse-if)
  (sieve-exp-begin 'cond)
  (sieve-parse-if-internal)
  (sieve-exp-finish))

(define (sieve-parse-else)
  (syntax-error "else without if"))

(define (sieve-parse-elsif)
  (syntax-error "elsif without if"))

;;; require <capabilities: string-list>
(define (sieve-parse-require)
  (for-each
   (lambda (capability)
     (if (not
	  (cond
	   ((and
	     (>= (string-length capability) 5)
	     (string=? (substring capability 0 5) "test-"))
	    (sieve-find-test (substring capability 5)))
	   ((and
	     (>= (string-length capability) 11)
	     (string=? (substring capability 0 11) "comparator-"))
	    (sieve-find-comparator (substring capability 11)))
	   (else
	    (sieve-find-action capability))))
	 (let ((name (string-append sieve-libdir
				    "/" capability ".scm")))
	   (set! sieve-load-files (append sieve-load-files (list name)))
	   (catch #t
		  (lambda ()
		    (load name))
		  (lambda args
		    (lex-error "Can't load required capability "
			       capability)
		    args)))))
   (cdr (require-string-list)))
  (require-semicolon))

;;; stop
(define (sieve-parse-stop)
  (sieve-exp-begin sieve-stop)
  (sieve-exp-finish)
  (require-semicolon))

;;;;

;;;; Parser functions for actions

(define (sieve-parse-action)
  (let* ((name (cdr current-token))
	 (descr (sieve-find-action name)))
    (cond
     (descr
      (cond
       ((car descr)
	(sieve-exp-begin 'reg-action)
	(sieve-exp-finish)
	(sieve-exp-begin (car descr))
	(sieve-parse-arguments name descr)
	(require-semicolon 'dont-read)
	(sieve-exp-finish))
       (else
	(require-semicolon))))
     (else
      (syntax-error "Unknown identifier: " name)))))

;;;;

;;;; The parser

(define (sieve-parse-command)
  (DEBUG 10 "sieve-parse-command" current-token)
  (catch 'syntax-error
   (lambda ()
     (read-token)
     (cond
      ((or (not current-token)
	   (eof-object? current-token))) ;; Skip comments and #<eof>
      ((eq? (car current-token) 'identifier)
       ;; Process a command
       (let ((elt (assoc (string->symbol (cdr current-token))
			 (list
			  (cons 'if sieve-parse-if)
			  (cons 'elsif sieve-parse-elsif)
			  (cons 'else sieve-parse-else)
		          (cons 'require sieve-parse-require)
		          (cons 'stop sieve-parse-stop)))))
	 (if (not elt)
	     (sieve-parse-action)
	     (apply (cdr elt) '()))))
      (else
       (syntax-error "3. Expected identifier but found "
		     (cdr current-token)))))
   (lambda args
     ;; Error recovery: skip until we find a ';' or '}'.
     (if (and (= input-line-number recovery-line-number)
	      (= input-index recovery-index))
	 (begin
	   (lex-error "ERROR RECOVERY: Skipping to end of file")
	   (throw 'end-of-file)))
     (set! recovery-line-number input-line-number)
     (set! recovery-index input-index)

     (if (or (delimiter current-token #\})
	     (delimiter current-token #\;))
	 (read-token))
     (DEBUG 50 "ERROR RECOVERY at " current-token)
     (do ((token current-token (read-token)))
	 ((cond
	   ((eof-object? token)
	    (throw 'end-of-file))
	   ((delimiter token #\;)
	    #t)
	   ((delimiter token #\})
	    (cond
	     ((> nesting-level 0)
	      (putback-token)
	      #t)
	     (else
	      #f)))
	   ((delimiter token #\{)
	    (sieve-skip-block)
	    (putback-token)
	    #f)
	   (else
	    #f)) #f))
     (DEBUG 50 "ERROR RECOVERY FINISHED AT " current-token)))
  current-token)

(define (sieve-skip-block)
  (do ((token (read-token) (read-token)))
      ((cond
	((eof-object? token)
	 (throw 'end-of-file))
	((delimiter token #\{)
	 (sieve-skip-block)
	 #f)
	((delimiter token #\})
	 #t)
	(else
	 #f)) #f)))

(define (sieve-parse-from-port port)
  (set! input-port port)
  (do ((token (sieve-parse-command) (sieve-parse-command)))
      ((eof-object? token) #f)) )

(define (sieve-parse filename)
  (if (file-exists? filename)
      (catch 'end-of-file 
        (lambda ()
	  (set! error-count 0)
	  (set! current-token #f)
	  (set! input-file filename)
	  (set! input-line-number 0)
	  (set! putback-list '())
	  (call-with-input-file filename sieve-parse-from-port))
	(lambda args args))))

;;;;

;;;; Code generator

(define sieve-exp '())  ;; Expression currently being built
(define sieve-exp-stack '())
(define sieve-code-list '())  ;; Resulting scheme code

(define (sieve-exp-begin . exp)
  (set! sieve-exp-stack (append (list sieve-exp) sieve-exp-stack))
  (set! sieve-exp exp))

(define (sieve-exp-append exp)
  (set! sieve-exp (append sieve-exp (list exp))))

(define (sieve-exp-finish)
  (set! sieve-exp (append (car sieve-exp-stack) (list sieve-exp)))
  (set! sieve-exp-stack (cdr sieve-exp-stack)))

(define (sieve-code-begin)
  (set! sieve-exp-stack '())
  (set! sieve-exp '()))

(define (sieve-code-prologue code-list)
  (sieve-exp-begin (car code-list))
  (let loop ((code-list (cdr code-list)))
    (for-each
     (lambda (elt)
       (cond
	((and (list? elt) (not (null? elt)))
	 (sieve-exp-begin (car elt))
	 (loop (cdr elt))
	 (sieve-exp-finish))
	(else
	 (sieve-exp-append elt))))
     code-list)))
		 
(define (sieve-code-finish)
  (if (not (null? sieve-exp))
      (set! sieve-code-list (append sieve-code-list sieve-exp))))

;;; Print the program

(define (sieve-code-print-list exp)
  (display "(")
  (for-each
   (lambda (x)
     (cond
      ((procedure? x)
       (display (procedure-name x)))
      ((list? x)
       (sieve-code-print-list x))
      (else
       (write x)))
     (display " "))
   exp)
  (display ")"))

;;; Save the program

(define (sieve-save-program outfile)
  (with-output-to-file
      outfile
    (lambda ()
      (display "#! ")
      (display "/bin/sh\n\
# aside from this initial boilerplate, this is actually -*- scheme -*- code\n\
exec ${GUILE-guile} -l $0 -c '(mailutils-main)'\n")
      (display (string-append
		"# This Guile mailbox parser was made from " filename))
      (newline) 
      (display "# by sieve.scm, GNU %PACKAGE% %VERSION%\n!#")
      (newline)
      
      (display 
       "(if (not (member \"%GUILE_SITE%\" %load-path))\n
           (set! %load-path (cons \"%GUILE_SITE%\" %load-path)))\n")
      
      (display "(use-modules (mailutils sieve-core))\n")
      (display (string-append
		"(set! sieve-source \"" filename "\")"))
      (newline)
      
      (for-each
       (lambda (file)
	 (display (string-append
		   "(load \"" file "\")"))
	 (newline))
       sieve-load-files)
      (newline)
      (if request-verbose
	  (display "(set! sieve-verbose #t)\n"))
      (display "(define (sieve-filter-thunk) ")
      
      (sieve-code-print-list (car sieve-code-list))
      (display ")\n\n")

      (display "(define (mailutils-main . rest)\n")
      (display "  (sieve-main sieve-filter-thunk))\n\n")

      (display "(define (mailutils-check-message msg)\n\
  (set! sieve-current-message msg)\n\
  (sieve-run-current-message sieve-filter-thunk))\n")
      
      (display "\n\
;;;; Local Variables:\n\
;;;; buffer-read-only: t\n\
;;;; End:\n"))))

;;;;

;;;; Main

(define filename #f)
(define output #f)

(define (sieve-usage)
  (display "usage: sieve2scm [OPTIONS][mailbox]\n")
  (display "GNU sieve2scm -- compile a Sieve program into Scheme code\n\n")
  (display "   -f, --file FILENAME      Set input file name\n")
  (display "   -o, --output FILENAME    Set output file name\n")
  (display "   -L, --lib-dir DIRNAME    Set sieve library directory name\n")
  (display "   -d, --debug LEVEL        Set debugging level\n")
  (display "       --version            Show program version\n\n")
  (display "If -o option is not given, the compiled program is executed\n")
  (display "immediately. It operates on the user system mailbox unless\n")
  (display "mailbox is given in the command line.\n")
  (exit 0))

(define (sieve-version)
  (format #t "sieve2scm (~A) ~A~%" mu-package mu-version)
  (exit 0))

;;; Parse command line 

(define grammar
  `((file   (single-char #\f)
            (value #t))
    (output (single-char #\o)
	    (value #t))
    (debug  (single-char #\d)
	    (value #t))
    (lib-dir (single-char #\L)
	     (value #t))
    (version)
    (verbose (single-char #\v))
    (help   (single-char #\h))))

(define program-name (car (command-line)))

(for-each
 (lambda (x)
   (cond
    ((pair? x)
     (case (car x)
       ((debug)
	(set! sieve-debug (string->number (cdr x))))
       ((file)
	(set! filename (cdr x)))
       ((lib-dir)
	(set! sieve-libdir (cdr x)))
       ((output)
	(set! output (cdr x)))
       ((version)
	(sieve-version))
       ((verbose)
	(set! request-verbose #t))
       ((help)
	(sieve-usage))
       ('()
	(set! sieve-script-args (cdr x)))))))
 (getopt-long (command-line) grammar))

(cond
 ((not filename)
  (format (current-error-port) "~A: missing input filename~%" program-name)
  (sieve-usage))
 ((not (file-exists? filename))
  (format (current-error-port) "~A: Input file ~A does not exist~%" filename)
  (exit 0)))
	
(if (not sieve-libdir)
    (set! sieve-libdir
	    (let ((myname (car (command-line))))
	      (if (not (char=? (string-ref myname 0) #\/))
		  (set! myname (string-append (getcwd) "/" myname)))
	      (let ((slash (string-rindex myname #\/)))
		(substring myname 0 slash)))))

(sieve-code-prologue
 '(letrec
      ((implicit-keep #t)
       (reg-action (lambda () (set! implicit-keep #f))))))

(sieve-parse filename)
(sieve-exp-append 'implicit-keep)
(sieve-exp-finish)
(sieve-code-finish)

(cond
 ((> error-count 0)
  (display error-count)
  (display " errors.")
  (newline)
  (exit 1))
 (output
  (sieve-save-program output))
 (else
  (let ((temp-file (tmpnam))
	(saved-umask (umask #o077)))
    (sieve-save-program temp-file)
    (catch #t
	   (lambda ()
	     (set-cdr! (command-line) sieve-script-args)
	     (load temp-file))
	   (lambda (key . args)
	     (apply display-error the-last-stack (current-error-port) args)))
    (delete-file temp-file)	
    (umask saved-umask))))

;;;; End of sieve.scm