From: David Kastrup <dak@gnu.org>
Date: Fri, 25 Sep 2015 07:40:17 +0000 (+0200)
Subject: Issue 4620/2: Add ly:pure-call and ly:unpure-call functions
X-Git-Tag: release/2.19.29-1~38
X-Git-Url: https://git.donarmstrong.com/lilypond.git?a=commitdiff_plain;h=ebc17304f454a3debdc791e3bc7bb829d8b33b00;p=lilypond.git

Issue 4620/2: Add ly:pure-call and ly:unpure-call functions
---

diff --git a/lily/unpure-pure-container.cc b/lily/unpure-pure-container.cc
index 81bba591e4..0e389d4bcd 100644
--- a/lily/unpure-pure-container.cc
+++ b/lily/unpure-pure-container.cc
@@ -87,3 +87,40 @@ Unpure_pure_container::print_smob (SCM port, scm_print_state *) const
   scm_puts (" >", port);
   return 1;
 }
+
+LY_DEFINE (ly_pure_call, "ly:pure-call",
+           4, 0, 1, (SCM data, SCM grob, SCM start, SCM end, SCM rest),
+           "Convert property @var{data} (unpure-pure container or procedure)"
+           " to value in a pure context defined by @var{grob},"
+           " @var{start}, @var{end}, and possibly @var{rest} arguments.")
+{
+  if (Unpure_pure_container *upc = unsmob<Unpure_pure_container> (data))
+    {
+      // Avoid gratuitous creation of an Unpure_pure_call
+      if (upc->is_unchanging ())
+        data = upc->unpure_part ();
+      else
+        {
+          data = upc->pure_part ();
+          if (ly_is_procedure (data))
+            return scm_apply_3 (data, grob, start, end, rest);
+          return data;
+        }
+    }
+  if (ly_is_procedure (data))
+    return scm_apply_1 (data, grob, rest);
+  return data;
+}
+
+LY_DEFINE (ly_unpure_call, "ly:unpure-call",
+           2, 0, 1, (SCM data, SCM grob, SCM rest),
+           "Convert property @var{data} (unpure-pure container or procedure)"
+           " to value in an unpure context defined by @var{grob}"
+           " and possibly @var{rest} arguments.")
+{
+  if (Unpure_pure_container *upc = unsmob<Unpure_pure_container> (data))
+    data = upc->unpure_part ();
+  if (ly_is_procedure (data))
+    return scm_apply_1 (data, grob, rest);
+  return data;
+}