Implements "numaddr" extension test. The test counts Internet addresses

in structured headers that contain addresses.  It returns true if the
total number of addresses satisfies the requested relation, e.g.:

	if numaddr :over [ "To", "Cc" ] 50 { discard; }

+;;;; GNU mailutils - a suite of utilities for electronic mail
+;;;; Copyright (C) 1999, 2000, 2001 Free Software Foundation, Inc.
+;;;;
+;;;; This program 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 2, or (at your option)
+;;;; any later version.
+;;;; 
+;;;; This program 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 this program; if not, write to the Free Software
+;;;; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
+
+;;;; This module provides GNU extension test "numaddr".
+
+;;;; Syntax:   numaddr [":over" / ":under"] <header-names: string-list>
+;;;;           <limit: number>
+;;;; The "numaddr" test counts Internet addresses in structured headers
+;;;; that contain addresses.  It returns true if the total number of
+;;;; addresses satisfies the requested relation:
+;;;;
+;;;; If the argument is ":over" and the number of addresses is greater than
+;;;; the number provided, the test is true; otherwise, it is false.
+;;;;
+;;;; If the argument is ":under" and the number of addresses is less than
+;;;; the number provided, the test is true; otherwise, it is false.
+;;;;
+;;;; If the argument is empty, ":over" is assumed.
+
+;;;; Example:
+;;;;
+;;;; require [ "numaddr" ];
+;;;; if numaddr :over [ "To", "Cc" ] 50 { discard; }
+
+(define (test-numaddr header-list count . comp)
+  (let ((total-count 0)
+	(header-fields (mu-message-get-header-fields
+			sieve-current-message
+			header-list))
+	(compfun (cond
+		  ((or (null? (car comp)) (eq? (car comp) #:over))
+		   (lambda (val lim)
+		     (> val lim)))
+		  ((eq? (car comp) #:under)
+		   (lambda (val lim)
+		     (< val lim)))
+		  (else
+		   (runtime-error LOG_CRIT "test-numaddr: unknown comparator "
+				  comp)))))
+    (call-with-current-continuation
+     (lambda (exit)
+       (for-each
+	(lambda (h)
+	  (let ((hdr (cdr h)))
+	    (if hdr
+		(let ((naddr (mu-address-get-count hdr)))
+		  (set! total-count (+ total-count naddr))
+		  (if (compfun total-count count)
+		      (exit #t))))))
+	header-fields)
+       #f))))
+
+;;; Register the test at compile time
+(if sieve-parser
+    (sieve-register-test "numaddr"
+			 test-numaddr
+			 size-comp
+			 (list 'string-list 'number)))