[glom/no_raw_loops2: 3/4] Add and use Utils::copy_if().

[Murray Cumming <murrayc src gnome org>]

commit bcd487aeec94e65a69a5632d5bfadd87e3a87641
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Feb 10 15:04:36 2016 +0100

    Add and use Utils::copy_if().

 glom/libglom/algorithms_utils.h |   10 ++++++++++
 glom/libglom/privs.cc           |   15 ++++++---------
 2 files changed, 16 insertions(+), 9 deletions(-)
---
diff --git a/glom/libglom/algorithms_utils.h b/glom/libglom/algorithms_utils.h
index 0a79dbc..bcf2883 100644
--- a/glom/libglom/algorithms_utils.h
+++ b/glom/libglom/algorithms_utils.h
@@ -92,6 +92,16 @@ copy(T_container_input input, T_container_output& output)
     std::back_inserter(output));
 }
 
+template<typename T_container_input, typename T_container_output, typename T_callable>
+void
+copy_if(T_container_input input, T_container_output& output, T_callable f)
+{
+  std::copy_if(
+    std::begin(input), std::end(input),
+    std::back_inserter(output),
+    f);
+}
+
 } //namespace Utils
 
 } //namespace Glom
diff --git a/glom/libglom/privs.cc b/glom/libglom/privs.cc
index 98c771e..5d6f002 100644
--- a/glom/libglom/privs.cc
+++ b/glom/libglom/privs.cc
@@ -398,16 +398,13 @@ Privs::type_vec_strings Privs::get_groups_of_user(const Glib::ustring& user)
   type_vec_strings result;
 
   //Look at each group:
-  type_vec_strings groups = get_database_groups();
-  for(const auto& group : groups)
-  {
-    //See whether the user is in this group:
-    if(get_user_is_in_group(user, group))
-    {
-      //Add the group to the result:
-      result.emplace_back(group);
+  const auto groups = get_database_groups();
+  Utils::copy_if(groups, result,
+    [&user](const auto& group) {
+      //See whether the user is in this group:
+      return get_user_is_in_group(user, group);
     }
-  }
+  );
 
   return result;
 }