[Guile-commits] GNU Guile branch, stable-2.0, updated. v2.0.3-162-g1ceeca0

[Mark H Weaver]

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- Log -----------------------------------------------------------------
commit 1ceeca0a76809248aa974685756e0f05c7f64200
Author: Mark H Weaver <address@hidden>
Date:   Wed Jan 18 17:52:43 2012 -0500

    Add `scm_c_value_ref' to allow access to multiple returned values from C
    
    Based on a patch by Julian Graham <address@hidden>
    
    * libguile/values.c, libguile/values.h (scm_c_value_ref): New function.
    * doc/ref/api-control.texi (Multiple Values): Add documentation.
    * test-suite/standalone/test-scm-values.c: New test program.
    * test-suite/standalone/Makefile.am: Add test-scm-values test.

-----------------------------------------------------------------------

Summary of changes:
 doc/ref/api-control.texi                           |    7 +++
 libguile/values.c                                  |   25 +++++++++
 libguile/values.h                                  |    1 +
 test-suite/standalone/Makefile.am                  |    7 +++
 .../standalone/{test-list.c => test-scm-values.c}  |   52 +++++++++++---------
 5 files changed, 68 insertions(+), 24 deletions(-)
 copy test-suite/standalone/{test-list.c => test-scm-values.c} (50%)

diff --git a/doc/ref/api-control.texi b/doc/ref/api-control.texi
index c1502b0..5596778 100644
--- a/doc/ref/api-control.texi
+++ b/doc/ref/api-control.texi
@@ -785,6 +785,13 @@ the current implementation that object shares structure 
with
 @var{args}, so @var{args} should not be modified subsequently.
 @end deffn
 
address@hidden {C Function} scm_c_value_ref (values, idx)
+Returns the value at the position specified by @var{idx} in
address@hidden  Note that @var{values} will ordinarily be a
+multiple-values object, but it need not be.  Any other object
+represents a single value (itself), and is handled appropriately.
address@hidden deffn
+
 @rnindex call-with-values
 @deffn {Scheme Procedure} call-with-values producer consumer
 Calls its @var{producer} argument with no values and a
diff --git a/libguile/values.c b/libguile/values.c
index ab77731..9c9e5ff 100644
--- a/libguile/values.c
+++ b/libguile/values.c
@@ -67,6 +67,31 @@ print_values (SCM obj, SCM pwps)
   return SCM_UNSPECIFIED;
 }
 
+SCM
+scm_c_value_ref (SCM obj, size_t idx)
+{
+  if (SCM_LIKELY (SCM_VALUESP (obj)))
+    {
+      SCM values = scm_struct_ref (obj, SCM_INUM0);
+      size_t i = idx;
+      while (SCM_LIKELY (scm_is_pair (values)))
+        {
+          if (i == 0)
+            return SCM_CAR (values);
+          values = SCM_CDR (values);
+          i--;
+        }
+    }
+  else if (idx == 0)
+    return obj;
+
+  scm_error (scm_out_of_range_key,
+            "scm_c_value_ref",
+            "Too few values in ~S to access index ~S",
+             scm_list_2 (obj, scm_from_unsigned_integer (idx)),
+             scm_list_1 (scm_from_unsigned_integer (idx)));
+}
+
 SCM_DEFINE (scm_values, "values", 0, 0, 1,
            (SCM args),
            "Delivers all of its arguments to its continuation.  Except for\n"
diff --git a/libguile/values.h b/libguile/values.h
index 65ad8a1..5f79855 100644
--- a/libguile/values.h
+++ b/libguile/values.h
@@ -33,6 +33,7 @@ SCM_API SCM 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_API SCM scm_c_value_ref (SCM values, size_t idx);
 SCM_INTERNAL void scm_init_values (void);
 
 #endif  /* SCM_VALUES_H */
diff --git a/test-suite/standalone/Makefile.am 
b/test-suite/standalone/Makefile.am
index 08d249c..d8cfafa 100644
--- a/test-suite/standalone/Makefile.am
+++ b/test-suite/standalone/Makefile.am
@@ -189,6 +189,13 @@ test_scm_to_latin1_string_LDADD = $(LIBGUILE_LDADD)
 check_PROGRAMS += test-scm-to-latin1-string
 TESTS += test-scm-to-latin1-string
 
+# test-scm-values
+test_scm_values_SOURCES = test-scm-values.c
+test_scm_values_CFLAGS = ${test_cflags}
+test_scm_values_LDADD = $(LIBGUILE_LDADD)
+check_PROGRAMS += test-scm-values
+TESTS += test-scm-values
+
 if HAVE_SHARED_LIBRARIES
 
 # test-extensions
diff --git a/test-suite/standalone/test-list.c 
b/test-suite/standalone/test-scm-values.c
similarity index 50%
copy from test-suite/standalone/test-list.c
copy to test-suite/standalone/test-scm-values.c
index b51a2a1..ece62da 100644
--- a/test-suite/standalone/test-list.c
+++ b/test-suite/standalone/test-scm-values.c
@@ -1,6 +1,4 @@
-/* test-list.c - exercise libguile/list.c functions */
-
-/* Copyright (C) 2006, 2008, 2009, 2010 Free Software Foundation, Inc.
+/* Copyright (C) 2012 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -22,39 +20,45 @@
 # include <config.h>
 #endif
 
+#include <assert.h>
 #include <libguile.h>
-
 #include <stdlib.h>
-#include <stdio.h>
 #include <string.h>
 
-/* pretty trivial, but ensure this entrypoint exists, since it was
-   documented in Guile 1.6 and earlier */
 static void
-test_scm_list (void)
+test_scm_c_value_ref_on_multiple_values ()
 {
-  {
-    if (! scm_is_eq (SCM_EOL, scm_list (SCM_EOL)))
-      {
-        fprintf (stderr, "fail: scm_list SCM_EOL\n");
-        exit (EXIT_FAILURE);
-      }
-  }
+  SCM values = scm_values (scm_list_3 (scm_from_latin1_string ("foo"),
+                                       scm_from_latin1_string ("bar"),
+                                       scm_from_latin1_string ("baz")));
+
+  char *foo = scm_to_latin1_string (scm_c_value_ref (values, 0));
+  char *bar = scm_to_latin1_string (scm_c_value_ref (values, 1));
+  char *baz = scm_to_latin1_string (scm_c_value_ref (values, 2));
+
+  assert (strcmp (foo, "foo") == 0);
+  assert (strcmp (bar, "bar") == 0);
+  assert (strcmp (baz, "baz") == 0);
 
-  {
-    SCM lst = scm_list_2 (scm_from_int (1), scm_from_int (2));
-    if (! scm_is_true (scm_equal_p (lst, scm_list (lst))))
-      {
-        fprintf (stderr, "fail: scm_list '(1 2)\n");
-        exit (EXIT_FAILURE);
-      }
-  }
+  free (foo);
+  free (bar);
+  free (baz);
+}
+
+static void
+test_scm_c_value_ref_on_a_single_value ()
+{
+  SCM value = scm_from_latin1_string ("foo");
+  char *foo = scm_to_latin1_string (scm_c_value_ref (value, 0));
+  assert (strcmp (foo, "foo") == 0);
+  free (foo);
 }
 
 static void
 tests (void *data, int argc, char **argv)
 {
-  test_scm_list ();
+  test_scm_c_value_ref_on_multiple_values ();
+  test_scm_c_value_ref_on_a_single_value ();
 }
 
 int


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