Kieren MacMillan <kie...@kierenmacmillan.info> writes:
> Hi Jean,
>
>> Well, it's not too hard to implement them.
>
> In the hopes that it’s also not too hard for Super-Jean to implement anchors…
> ;)
>
> Is there a world in which one could write something like
>
> global = {
> \anchor #'intro
> s1*8
> \anchor #'verse
> s1*8
> \anchor #'chorus
> s1*8
> }
>
> and then
>
> chorusMusic = {
> \gotoAnchor #'chorus
> c'1
> }
>
> would make a whole note c' appear in the 17th measure of the score?
It takes an iterator to wait an unspecified amount of time, and those
can only be written in C++ right now.
There actually is some ancient local branch in my repository with a
sketch of an idea, but it likely doesn't work at all for anything.
But maybe it gives someone an idea...
>From 4f86263cb78f33ad56706f0f9b6668622c417870 Mon Sep 17 00:00:00 2001
From: David Kastrup <d...@gnu.org>
Date: Fri, 17 Jul 2015 17:23:17 +0200
Subject: [PATCH] Create a wait music function.
---
lily/wait-iterator.cc | 112 +++++++++++++++++++++++++++++++++++++
ly/music-functions-init.ly | 11 ++++
scm/define-music-types.scm | 6 ++
3 files changed, 129 insertions(+)
create mode 100644 lily/wait-iterator.cc
diff --git a/lily/wait-iterator.cc b/lily/wait-iterator.cc
new file mode 100644
index 0000000000..939ba34c9b
--- /dev/null
+++ b/lily/wait-iterator.cc
@@ -0,0 +1,112 @@
+/*
+ This file is part of LilyPond, the GNU music typesetter.
+
+ Copyright (C) 2016 David Kastrup <d...@gnu.org>
+
+ 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.
+
+ LilyPond 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 LilyPond. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "lily-guile.hh"
+#include "context.hh"
+#include "input.hh"
+#include "international.hh"
+#include "moment.hh"
+#include "music.hh"
+#include "music-iterator.hh"
+
+class Wait_iterator : public Music_wrapper_iterator
+{
+ bool triggered_;
+ SCM procedure_;
+protected:
+ virtual void derived_mark () const;
+ virtual Moment pending_moment () const;
+ virtual void process (Moment);
+ virtual bool ok () const;
+ virtual bool run_always () const;
+public:
+ Wait_iterator ();
+ DECLARE_SCHEME_CALLBACK (constructor, ());
+ virtual void construct_children ();
+};
+
+Wait_iterator::Wait_iterator ()
+ : triggered_ (false), procedure_ (SCM_UNDEFINED)
+{
+}
+
+void
+Wait_iterator::derived_mark () const
+{
+ scm_gc_mark (procedure_);
+}
+
+Moment
+Wait_iterator::pending_moment () const
+{
+ if (triggered_)
+ return Moment (0);
+ Moment m;
+ m.set_infinite (1);
+ return m;
+}
+
+bool
+Wait_iterator::run_always () const
+{
+ return triggered
+ || !Music_wrapper_iterator::ok ()
+ || Music_wrapper_iterator::run_always ();
+}
+
+void
+Wait_iterator::process (Moment m)
+{
+ if (triggered_)
+ return;
+ if (scm_is_true (scm_call_1 (procedure_, get_outlet ()->self_scm ())))
+ {
+ triggered_ = true;
+ return;
+ }
+ if (!Music_wrapper_iterator::ok ())
+ {
+ Music_wrapper_iterator::construct_children ();
+ if (!Music_wrapper_iterator::ok ())
+ return;
+ }
+ Music_wrapper_iterator::process (m);
+}
+
+bool
+Wait_iterator::ok () const
+{
+ return !triggered_;
+}
+
+void
+Wait_iterator::construct_children ()
+{
+ procedure_ = get_music ()->get_property ("procedure");
+ if (!ly_is_procedure (procedure_))
+ {
+ get_music ()->origin ()->warning (_ ("Bad procedure"));
+ triggered_ = true;
+ return;
+ }
+
+ Music_iterator::construct_children ();
+}
+
+IMPLEMENT_CTOR_CALLBACK (Wait_iterator)
diff --git a/ly/music-functions-init.ly b/ly/music-functions-init.ly
index aaea08d83f..b74fc11a14 100644
--- a/ly/music-functions-init.ly
+++ b/ly/music-functions-init.ly
@@ -2226,6 +2226,17 @@ vshape =
ease of tweaking."
(once (propertyTweak 'show-control-points #t (shape offsets item))))
+waitFor =
+#(define-music-function (music) (ly:music?)
+ (_i "Wait for the occurence of the given @var{music} in the
+current context. Use it, for example, as
+@example
+\\context Score \\waitFor \\mark "A"
+@end example
+")
+ (make-music 'WaitMusic
+ 'element music))
+
withMusicProperty =
#(define-music-function (sym val music)
(symbol? scheme? ly:music?)
diff --git a/scm/define-music-types.scm b/scm/define-music-types.scm
index e61667de3c..97b7b93e7e 100644
--- a/scm/define-music-types.scm
+++ b/scm/define-music-types.scm
@@ -913,6 +913,12 @@ brackets start and stop.")
(start-callback . ,ly:music-wrapper::start-callback)
(types . (volta-specification music-wrapper-music))
))
+
+ (WaitMusic
+ . ((description . "Waits for the given event.")
+ (iterator-ctor . ,ly:wait-iterator::constructor)
+ (types . (wait-music))
+ ))
))
(set! music-descriptions
--
2.37.2
--
David Kastrup
