[gimp/gimp-2-10] app: add gimp_list_compare()

[Ell <ell src gnome org>]

commit 4dd3e73aaac65e18972358caa6b3ef924f14547f
Author: Ell <ell_se yahoo com>
Date:   Thu May 30 01:37:32 2019 -0400

    app: add gimp_list_compare()
    
    ... which lexicographically (shallowly) compares a pair of GLists.
    
    (cherry picked from commit c4ce70a2d3054f811ea046577d8f79192f74f75a)

 app/core/gimp-utils.c | 23 +++++++++++++++++++++++
 app/core/gimp-utils.h |  3 +++
 2 files changed, 26 insertions(+)
---
diff --git a/app/core/gimp-utils.c b/app/core/gimp-utils.c
index 8be6c3c5d8..74b7410c4d 100644
--- a/app/core/gimp-utils.c
+++ b/app/core/gimp-utils.c
@@ -858,6 +858,29 @@ gimp_ascii_strtod (const gchar  *nptr,
   return TRUE;
 }
 
+gint
+gimp_list_compare (GList *list1,
+                   GList *list2)
+{
+  while (list1 && list2)
+    {
+      if (list1->data < list2->data)
+        return -1;
+      else if (list1->data > list2->data)
+        return +1;
+
+      list1 = g_list_next (list1);
+      list2 = g_list_next (list2);
+    }
+
+  if (! list1)
+    return -1;
+  else if (! list2)
+    return +1;
+
+  return 0;
+}
+
 
 /*  debug stuff  */
 
diff --git a/app/core/gimp-utils.h b/app/core/gimp-utils.h
index 956216e82b..761c73ef31 100644
--- a/app/core/gimp-utils.h
+++ b/app/core/gimp-utils.h
@@ -98,6 +98,9 @@ gboolean     gimp_ascii_strtod                     (const gchar     *nptr,
                                                     gchar          **endptr,
                                                     gdouble         *result);
 
+gint         gimp_list_compare                     (GList           *list1,
+                                                    GList           *list2);
+
 GimpImage  * gimp_create_image_from_buffer         (Gimp            *gimp,
                                                     GeglBuffer      *buffer,
                                                     const gchar     *image_name);