From ce593af7561f08610bb21e0c9e00bfba2807fe25 Mon Sep 17 00:00:00 2001
From: Neil Puttock <n.puttock@gmail.com>
Date: Tue, 23 Nov 2010 22:12:46 +0000
Subject: [PATCH] Add ly:grob-array->list; use in live-elements-list for
 InstrumentName.

* lily/grob-array-scheme.cc (ly_grob_array_2_list):

  new exported function

* lily/grob-array.cc (grob_array_to_list):

  new function: convert Grob_array to Scheme list

* scm/output-lib.scm (system-start-text::calc-y-offset):

  simplify live-elements-list using filter! and ly:grob-array->list
---
 lily/grob-array-scheme.cc  | 10 ++++++++++
 lily/grob-array.cc         | 13 +++++++++++++
 lily/include/grob-array.hh |  1 +
 scm/output-lib.scm         | 16 ++++------------
 4 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/lily/grob-array-scheme.cc b/lily/grob-array-scheme.cc
index d99cb58a90..7518d2e2f5 100644
--- a/lily/grob-array-scheme.cc
+++ b/lily/grob-array-scheme.cc
@@ -49,3 +49,13 @@ LY_DEFINE (ly_grob_array_ref, "ly:grob-array-ref",
   return me->grob (i)->self_scm ();
 }
 
+LY_DEFINE (ly_grob_array_2_list, "ly:grob-array->list",
+	   1, 0, 0,
+	   (SCM grob_arr),
+	   "Return the elements of @var{grob-arr} as a Scheme list.")
+{
+  Grob_array *me = unsmob_grob_array (grob_arr);
+  LY_ASSERT_SMOB (Grob_array, grob_arr, 1);
+
+  return grob_array_to_list (me);
+}
diff --git a/lily/grob-array.cc b/lily/grob-array.cc
index 1cebe0e458..4084e0fa75 100644
--- a/lily/grob-array.cc
+++ b/lily/grob-array.cc
@@ -129,3 +129,16 @@ grob_list_to_grob_array (SCM lst)
   return arr_scm;
 }
 
+SCM
+grob_array_to_list (Grob_array *array)
+{
+  SCM list = SCM_EOL;
+  SCM *tail = &list;
+
+  for (vsize i = 0; i < array->size (); i++)
+    {
+      *tail = scm_cons (array->grob (i)->self_scm (), SCM_EOL);
+      tail = SCM_CDRLOC (*tail);
+    }
+  return list;
+}
diff --git a/lily/include/grob-array.hh b/lily/include/grob-array.hh
index cb2d2f56c1..6e49dabb56 100644
--- a/lily/include/grob-array.hh
+++ b/lily/include/grob-array.hh
@@ -53,6 +53,7 @@ DECLARE_UNSMOB (Grob_array, grob_array);
 
 vector<Grob*> const &ly_scm2link_array (SCM x);
 SCM grob_list_to_grob_array (SCM lst);
+SCM grob_array_to_list (Grob_array *array);
 
 #endif /* GROB_ARRAY_HH */
 
diff --git a/scm/output-lib.scm b/scm/output-lib.scm
index 716f36a735..6c10913d38 100644
--- a/scm/output-lib.scm
+++ b/scm/output-lib.scm
@@ -859,18 +859,10 @@ between the two text elements."
 (define-public (system-start-text::calc-y-offset grob)
 
   (define (live-elements-list me)
-    (let* ((elements (ly:grob-object me 'elements))
-	   (elts-length (ly:grob-array-length elements))
-	   (live-elements '()))
-
-      (let get-live ((len elts-length))
-	(if (> len 0)
-	    (let ((elt (ly:grob-array-ref elements (1- len))))
-
-	      (if (grob::is-live? elt)
-		  (set! live-elements (cons elt live-elements)))
-	      (get-live (1- len)))))
-      live-elements))
+    (let ((elements (ly:grob-object me 'elements)))
+
+      (filter! grob::is-live?
+               (ly:grob-array->list elements))))
 
   (let* ((left-bound (ly:spanner-bound grob LEFT))
 	 (live-elts (live-elements-list grob))
-- 
2.39.2