Gets vertical skylines from grob stencils

scm/lily.scm

 ;;;; This file is part of LilyPond, the GNU music typesetter.
 ;;;;
 ;;;; Copyright (C) 1998--2012 Jan Nieuwenhuizen <janneke@gnu.org>
 ;;;; Han-Wen Nienhuys <hanwen@xs4all.nl>
 ;;;;
 ;;;; LilyPond 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 of the License, or
 ;;;; (at your option) any later version.
 ;;;;
@@ skipping 578 matching lines @@
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; debug memory leaks
 
 (define gc-dumping
   #f)
 
 (define gc-protect-stat-count
   0)
 
+;; Undead objects that should be ignored after the first time round
+(define gc-zombies
+  (make-weak-key-hash-table 0))
+
 (define-public (dump-live-object-stats outfile)
   (for-each (lambda (x)
               (format outfile "~a: ~a\n" (car x) (cdr x)))
             (sort (gc-live-object-stats)
                   (lambda (x y)
                     (string<? (car x) (car y))))))
 
 (define-public (dump-gc-protects)
   (set! gc-protect-stat-count (1+ gc-protect-stat-count))
   (let* ((protects (sort (hash-table->alist (ly:protects))
@@ skipping 28 matching lines @@
           (ly:progress "Live object statistics: GC'ing\n")
           (ly:reset-all-fonts)
           (gc)
           (gc)
           (ly:progress "Asserting dead objects\n")
           (ly:set-option 'debug-gc-assert-parsed-dead #t)
           (gc)
           (ly:set-option 'debug-gc-assert-parsed-dead #f)
           (for-each
            (lambda (x)
-             (ly:programming-error "Parsed object should be dead: ~a" x))
+             (if (not (hashq-ref gc-zombies x))
+                 (begin
+                   (ly:programming-error "Parsed object should be dead: ~a" x)
+                   (hashq-set! gc-zombies x #t))))
            (ly:parsed-undead-list!))
           (set! stats (gc-live-object-stats))
           (ly:progress "Dumping live object statistics.\n")
           (dump-live-object-stats outfile)))
     (newline outfile)
     (let* ((stats (gc-stats)))
       (for-each (lambda (sym)
                   (format outfile "~a ~a ~a\n"
                           gc-protect-stat-count
                           sym
@@ skipping 226 matching lines @@
             (ly:exit 0 #f)))))
 
 (define (gui-no-files-handler)
   (let* ((ly (string-append (ly:effective-prefix) "/ly/"))
          ;; FIXME: soft-code, localize
          (welcome-ly (string-append ly "Welcome_to_LilyPond.ly"))
          (cmd (get-editor-command welcome-ly 0 0 0)))
     (ly:message (_ "Invoking `~a'...\n") cmd)
     (system cmd)
     (ly:exit 1 #f)))