[glib/wip/chergert/garraylist] arraylist: add g_array_list_first()

[Christian Hergert <chergert src gnome org>]

commit 2f282b9577e83636279b2bb7b6194fdb2ad3af79
Author: Christian Hergert <christian hergert me>
Date:   Sun Sep 13 03:21:30 2015 -0700

    arraylist: add g_array_list_first()

 glib/garraylist.h      |    1 +
 glib/tests/arraylist.c |    3 +++
 2 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/glib/garraylist.h b/glib/garraylist.h
index 43351bf..caf45c3 100644
--- a/glib/garraylist.h
+++ b/glib/garraylist.h
@@ -71,6 +71,7 @@ void         g_array_list_remove_index (GArrayList     *list,
 GLIB_AVAILABLE_IN_2_46
 void         g_array_list_destroy      (GArrayList     *list);
 
+#define g_array_list_first(list) (((list)->len == 0) ? NULL : g_array_list_index((list),0))
 #define g_array_list_last(list) (((list)->len == 0) ? NULL : g_array_list_index((list),(list)->len-1))
 
 G_END_DECLS
diff --git a/glib/tests/arraylist.c b/glib/tests/arraylist.c
index 81712c8..79ab3c5 100644
--- a/glib/tests/arraylist.c
+++ b/glib/tests/arraylist.c
@@ -39,12 +39,15 @@ test_basic (GArrayList *al)
   g_assert (al != NULL);
   g_assert_cmpint (al->len, ==, 0);
 
+  g_assert_cmpint (GPOINTER_TO_SIZE (g_array_list_first(al)), ==, 0);
+
   for (i = 1; i <= 1000; i++)
     {
       g_array_list_add (al, GSIZE_TO_POINTER (i));
       g_assert_cmpint (al->len, ==, i);
     }
 
+  g_assert_cmpint (GPOINTER_TO_SIZE (g_array_list_first(al)), ==, 1);
   g_assert_cmpint (GPOINTER_TO_SIZE (g_array_list_last(al)), ==, 1000);
 
   list = g_array_list_peek (al);