[evolution-data-server/openismus-work-3-8] ECollator: fixed e_collator_collate() to allow NULL strings.

[Tristan Van Berkom <tvb src gnome org>]

commit 62df07eff231bb8ed0d6df90d73a83f069928eee
Author: Tristan Van Berkom <tristanvb openismus com>
Date:   Tue Nov 26 17:12:42 2013 +0900

    ECollator: fixed e_collator_collate() to allow NULL strings.
    
    NULL strings sort below other strings.

 libedataserver/e-collator.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)
---
diff --git a/libedataserver/e-collator.c b/libedataserver/e-collator.c
index 80bb3f6..d6283d4 100644
--- a/libedataserver/e-collator.c
+++ b/libedataserver/e-collator.c
@@ -527,8 +527,8 @@ e_collator_generate_key_for_index (ECollator       *collator,
 /**
  * e_collator_collate:
  * @collator: An #ECollator
- * @str_a: A string to compare
- * @str_b: The string to compare with @str_a
+ * @str_a: (allow none): A string to compare
+ * @str_b: (allow none): The string to compare with @str_a
  * @result: (out): A location to store the comparison result
  * @error: (allow none): A location to store a #GError from the #E_COLLATOR_ERROR domain
  *
@@ -537,6 +537,8 @@ e_collator_generate_key_for_index (ECollator       *collator,
  * The @result will be set to integer less than, equal to, or greater than zero if @str_a is found,
  * respectively, to be less than, to match, or be greater than @str_b.
  *
+ * Either @str_a or @str_b can be %NULL, %NULL strings are considered to sort below other strings.
+ *
  * This function will first ensure that both strings are valid UTF-8.
  *
  * Returns: %TRUE on success, otherwise if %FALSE is returned then @error will be set.
@@ -553,10 +555,13 @@ e_collator_collate (ECollator    *collator,
        gchar *sort_key_a, *sort_key_b;
 
        g_return_val_if_fail (collator != NULL, -1);
-       g_return_val_if_fail (str_a != NULL, -1);
-       g_return_val_if_fail (str_b != NULL, -1);
        g_return_val_if_fail (result != NULL, -1);
 
+       if (!str_a || !str_b) {
+               *result = g_strcmp0 (str_a, str_b);
+               return TRUE;
+       }
+
        sort_key_a = e_collator_generate_key (collator, str_a, error);
        if (!sort_key_a)
                return FALSE;