From ae0495dda1032c3994c770d727c65b46e702459c Mon Sep 17 00:00:00 2001
From: David Kastrup <dak@gnu.org>
Date: Sun, 11 Mar 2012 14:48:51 +0100
Subject: [PATCH] Implement ly:output-find-context-def

---
 lily/context-def.cc         | 12 ++++++++++++
 lily/include/context-def.hh |  1 +
 lily/output-def-scheme.cc   | 27 +++++++++++++++++++++++++++
 3 files changed, 40 insertions(+)

diff --git a/lily/context-def.cc b/lily/context-def.cc
index 9c988f4da9..d4f3dc3433 100644
--- a/lily/context-def.cc
+++ b/lily/context-def.cc
@@ -374,6 +374,18 @@ Context_def::lookup (SCM sym) const
   return SCM_UNDEFINED;
 }
 
+bool
+Context_def::is_alias (SCM sym) const
+{
+  if (scm_is_eq (sym, ly_symbol2scm ("Bottom")))
+    return !scm_is_pair (get_accepted (SCM_EOL));
+
+  if (scm_is_eq (sym, get_context_name ()))
+    return true;
+
+  return scm_is_true (scm_c_memq (sym, context_aliases_));
+}
+
 LY_DEFINE (ly_context_def_lookup, "ly:context-def-lookup",
 	   2, 1, 0, (SCM def, SCM sym, SCM val),
            "Return the value of @var{sym} in output definition @var{def}"
diff --git a/lily/include/context-def.hh b/lily/include/context-def.hh
index 8f4218745b..2fddd980b7 100644
--- a/lily/include/context-def.hh
+++ b/lily/include/context-def.hh
@@ -57,6 +57,7 @@ public:
   SCM get_translator_group_type () const { return translator_group_type_; }
   void set_acceptor (SCM accepts, bool add);
   SCM lookup (SCM sym) const;
+  bool is_alias (SCM sym) const;
 
   VIRTUAL_COPY_CONSTRUCTOR (Context_def, Context_def);
 
diff --git a/lily/output-def-scheme.cc b/lily/output-def-scheme.cc
index 43d5b64105..a2e1e34513 100644
--- a/lily/output-def-scheme.cc
+++ b/lily/output-def-scheme.cc
@@ -91,6 +91,8 @@ LY_DEFINE (ly_output_description, "ly:output-description",
 	   1, 0, 0, (SCM output_def),
 	   "Return the description of translators in @var{output-def}.")
 {
+  LY_ASSERT_SMOB (Output_def, output_def, 1);
+
   Output_def *id = unsmob_output_def (output_def);
 
   SCM al = ly_module_2_alist (id->scope_);
@@ -105,6 +107,31 @@ LY_DEFINE (ly_output_description, "ly:output-description",
   return ell;
 }
 
+LY_DEFINE (ly_output_find_context_def, "ly:output-find-context-def",
+	   1, 1, 0, (SCM output_def, SCM context_name),
+	   "Return an alist of all context defs (matching @var{context-name}"
+	   "if given) in @var{output-def}.")
+{
+  LY_ASSERT_SMOB (Output_def, output_def, 1);
+  if (!SCM_UNBNDP (context_name))
+    LY_ASSERT_TYPE (ly_is_symbol, context_name, 2);
+
+  Output_def *id = unsmob_output_def (output_def);
+
+  SCM al = ly_module_2_alist (id->scope_);
+  SCM ell = SCM_EOL;
+  for (SCM s = al; scm_is_pair (s); s = scm_cdr (s))
+    {
+      SCM p = scm_car (s);
+      Context_def *td = unsmob_context_def (scm_cdr (p));
+      if (td && scm_is_eq (scm_car (p), td->get_context_name ())
+	  && (SCM_UNBNDP (context_name) || td->is_alias (context_name)))
+	ell = scm_cons (p, ell);
+    }
+  return ell;
+}
+
+
 LY_DEFINE (ly_output_def_p, "ly:output-def?",
 	   1, 0, 0, (SCM def),
 	   "Is @var{def} an output definition?")
-- 
2.39.5