>From a729ef1b8b1905cb6c2ec73cc9b54e2e9453a2b3 Mon Sep 17 00:00:00 2001
From: Mark H Weaver <address@hidden>
Date: Thu, 10 Feb 2011 18:03:14 -0500
Subject: [PATCH] Added internal C function to extract from values object

* libguile/values.c (scm_i_extract_values_2): New internal function
  that extracts two values from a values object.

* libguile/values.h: Added prototype.
---
 libguile/values.c |   18 ++++++++++++++++++
 libguile/values.h |    2 ++
 2 files changed, 20 insertions(+), 0 deletions(-)

diff --git a/libguile/values.c b/libguile/values.c
index 967fcd6..b9fe4cc 100644
--- a/libguile/values.c
+++ b/libguile/values.c
@@ -35,6 +35,24 @@
 
 SCM scm_values_vtable;
 
+/* OBJ must be a values object containing exactly two values.
+   scm_i_extract_values_2 puts those two values into *p1 and *p2.  */
+void
+scm_i_extract_values_2 (SCM obj, SCM *p1, SCM *p2)
+{
+  SCM values;
+
+  SCM_ASSERT_TYPE (SCM_VALUESP (obj), obj, SCM_ARG1,
+		   "scm_i_extract_values_2", "values");
+  values = scm_struct_ref (obj, SCM_INUM0);
+  if (!scm_is_null_or_nil (SCM_CDDR (values)))
+    scm_wrong_type_arg_msg
+      ("scm_i_extract_values_2", SCM_ARG1, obj,
+       "a values object containing exactly two values");
+  *p1 = SCM_CAR (values);
+  *p2 = SCM_CADR (values);
+}
+
 static SCM
 print_values (SCM obj, SCM pwps)
 {
diff --git a/libguile/values.h b/libguile/values.h
index 0750aec..65ad8a1 100644
--- a/libguile/values.h
+++ b/libguile/values.h
@@ -30,6 +30,8 @@ SCM_API SCM scm_values_vtable;
 #define SCM_VALUESP(x) (SCM_STRUCTP (x)\
                         && scm_is_eq (scm_struct_vtable (x), scm_values_vtable))
 
+SCM_INTERNAL void scm_i_extract_values_2 (SCM obj, SCM *p1, SCM *p2);
+
 SCM_API SCM scm_values (SCM args);
 SCM_INTERNAL void scm_init_values (void);
 
-- 
1.5.6.5