diff --git a/src/buffer_manager.cc b/src/buffer_manager.cc
index 400c9f5b..943a2085 100644
--- a/src/buffer_manager.cc
+++ b/src/buffer_manager.cc
@@ -3,6 +3,7 @@
 #include "assert.hh"
 #include "buffer.hh"
 #include "client_manager.hh"
+#include "containers.hh"
 #include "exception.hh"
 #include "file.hh"
 #include "string.hh"
@@ -117,27 +118,19 @@ void BufferManager::backup_modified_buffers()
 CandidateList BufferManager::complete_buffer_name(StringView prefix,
                                                   ByteCount cursor_pos)
 {
-    auto real_prefix = prefix.substr(0, cursor_pos);
-    const bool include_dirs = contains(real_prefix, '/');
-    CandidateList result;
-    CandidateList subsequence_result;
-    for (auto& buffer : m_buffers)
-    {
+    const bool include_dirs = contains(prefix.substr(0, cursor_pos), '/');
+    auto c = transformed(m_buffers,
+                         [include_dirs](const safe_ptr<Buffer>& buffer) -> String {
         String name = buffer->display_name();
-        StringView match_name = name;
         if (not include_dirs and buffer->flags() & Buffer::Flags::File)
         {
             ByteCount pos = name.find_last_of('/');
             if (pos != (int)String::npos)
-                match_name = name.substr(pos+1);
+                return name.substr(pos+1);
         }
-
-        if (prefix_match(match_name, real_prefix))
-            result.push_back(name);
-        if (subsequence_match(name, real_prefix))
-            subsequence_result.push_back(name);
-    }
-    return result.empty() ? subsequence_result : result;
+        return name;
+    });
+    return complete(prefix, cursor_pos, c, prefix_match, subsequence_match);
 }
 
 void BufferManager::clear_buffer_trash()
diff --git a/src/client_manager.cc b/src/client_manager.cc
index 66b4bf62..213cc23f 100644
--- a/src/client_manager.cc
+++ b/src/client_manager.cc
@@ -2,6 +2,7 @@
 
 #include "buffer_manager.hh"
 #include "command_manager.hh"
+#include "containers.hh"
 #include "event_manager.hh"
 #include "face_registry.hh"
 #include "file.hh"
@@ -172,19 +173,8 @@ void ClientManager::clear_mode_trashes() const
 CandidateList ClientManager::complete_client_name(StringView prefix,
                                                   ByteCount cursor_pos) const
 {
-    auto real_prefix = prefix.substr(0, cursor_pos);
-    CandidateList result;
-    CandidateList subsequence_result;
-    for (auto& client : m_clients)
-    {
-        const String& name = client->context().name();
-
-        if (prefix_match(name, real_prefix))
-            result.push_back(name);
-        if (subsequence_match(name, real_prefix))
-            subsequence_result.push_back(name);
-    }
-    return result.empty() ? subsequence_result : result;
+    auto c = transformed(m_clients, [](const std::unique_ptr<Client>& c){ return c->context().name(); });
+    return complete(prefix, cursor_pos, c, prefix_match, subsequence_match);
 }
 
 }
diff --git a/src/completion.hh b/src/completion.hh
index afaf6fbc..e978d0ac 100644
--- a/src/completion.hh
+++ b/src/completion.hh
@@ -53,5 +53,43 @@ inline Completions offset_pos(Completions completion, ByteCount offset)
              std::move(completion.candidates) };
 }
 
+namespace detail
+{
+    template<typename Str, typename Func>
+    void do_matches(Str&& str, StringView prefix,
+                    CandidateList* res, Func match_func)
+    {
+        if (match_func(str, prefix))
+            res->push_back(str);
+    }
+
+    template<typename Str, typename Func, typename... Rest>
+    void do_matches(Str&& str, StringView prefix,
+                    CandidateList* res, Func match_func, Rest... rest)
+    {
+        do_matches(str, prefix, res, match_func);
+        do_matches(str, prefix, res+1, rest...);
+    }
+}
+
+template<typename Container, typename... MatchFunc>
+CandidateList complete(StringView prefix, ByteCount cursor_pos,
+                       const Container& container, MatchFunc... match_func)
+{
+    CandidateList res[sizeof...(match_func)];
+    auto real_prefix = prefix.substr(0, cursor_pos);
+    for (const auto& elem : container)
+        detail::do_matches(elem, real_prefix, res, match_func...);
+    auto it = find_if(res, [](CandidateList& c) { return not c.empty(); });
+    return it == end(res) ? CandidateList{} : std::move(*it);
+}
+
+template<typename Container>
+CandidateList complete(StringView prefix, ByteCount cursor_pos,
+                       const Container& container)
+{
+    return complete(prefix, cursor_pos, container, prefix_match);
+}
+
 }
 #endif // completion_hh_INCLUDED
diff --git a/src/face_registry.cc b/src/face_registry.cc
index d99937c6..367b99b4 100644
--- a/src/face_registry.cc
+++ b/src/face_registry.cc
@@ -2,6 +2,7 @@
 
 #include "containers.hh"
 #include "exception.hh"
+#include "containers.hh"
 
 namespace Kakoune
 {
@@ -80,16 +81,12 @@ void FaceRegistry::register_alias(const String& name, const String& facedesc,
 }
 
 CandidateList FaceRegistry::complete_alias_name(StringView prefix,
-                                                 ByteCount cursor_pos) const
+                                                ByteCount cursor_pos) const
 {
-    CandidateList res;
-    auto real_prefix = prefix.substr(0, cursor_pos);
-    for (auto& alias : m_aliases)
-    {
-        if (prefix_match(alias.first, real_prefix))
-            res.push_back(alias.first);
-    }
-    return res;
+    using ValueType = std::pair<String, FaceOrAlias>;
+    return complete(prefix, cursor_pos,
+                    transformed(m_aliases,
+                                [](const ValueType& v){ return v.first; }));
 }
 
 FaceRegistry::FaceRegistry()
diff --git a/src/function_registry.hh b/src/function_registry.hh
index 5f3732ba..cf0ea46e 100644
--- a/src/function_registry.hh
+++ b/src/function_registry.hh
@@ -5,6 +5,7 @@
 #include "id_map.hh"
 #include "string.hh"
 #include "exception.hh"
+#include "containers.hh"
 
 namespace Kakoune
 {
@@ -35,7 +36,8 @@ public:
 
     CandidateList complete_name(StringView prefix, ByteCount cursor_pos)
     {
-        return m_functions.complete_id(prefix, cursor_pos);
+        auto c = transformed(m_functions, id_map<FunctionType>::get_id);
+        return complete(prefix, cursor_pos, c);
     }
 
 private:
diff --git a/src/highlighter_group.cc b/src/highlighter_group.cc
index 20058708..ecaafa95 100644
--- a/src/highlighter_group.cc
+++ b/src/highlighter_group.cc
@@ -48,11 +48,12 @@ Completions HighlighterGroup::complete_child(StringView path, ByteCount cursor_p
         return offset_pos(hl.complete_child(path.substr(offset), cursor_pos - offset, group), offset);
     }
 
-    auto condition = [=](const HighlighterMap::value_type& hl)
-    {
-        return not group or hl.second->has_children();
-    };
-    return { 0, 0, m_highlighters.complete_id_if(path, cursor_pos, condition) };
+    using ValueType = HighlighterMap::value_type;
+    auto c = transformed(filtered(m_highlighters,
+                                  [=](const ValueType& hl)
+                                  { return not group or hl.second->has_children(); }),
+                         HighlighterMap::get_id);
+    return { 0, 0, complete(path, cursor_pos, c) };
 }
 
 }
diff --git a/src/highlighters.cc b/src/highlighters.cc
index 4f999230..a60f70f3 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -3,6 +3,7 @@
 #include "assert.hh"
 #include "buffer_utils.hh"
 #include "context.hh"
+#include "containers.hh"
 #include "display_buffer.hh"
 #include "face_registry.hh"
 #include "highlighter_group.hh"
@@ -957,7 +958,8 @@ public:
             return offset_pos(hl.complete_child(path.substr(offset), cursor_pos - offset, group), offset);
         }
 
-        return { 0, 0, m_groups.complete_id(path, cursor_pos) };
+        auto container = transformed(m_groups, id_map<HighlighterGroup>::get_id);
+        return { 0, 0, complete(path, cursor_pos, container) };
     }
 
     static HighlighterAndId create(HighlighterParameters params)
diff --git a/src/hook_manager.cc b/src/hook_manager.cc
index 70e1c8eb..2fe8bf5c 100644
--- a/src/hook_manager.cc
+++ b/src/hook_manager.cc
@@ -1,5 +1,6 @@
 #include "hook_manager.hh"
 
+#include "containers.hh"
 #include "context.hh"
 #include "debug.hh"
 #include "regex.hh"
@@ -26,8 +27,8 @@ CandidateList HookManager::complete_hook_group(StringView prefix, ByteCount pos_
     CandidateList res;
     for (auto& list : m_hook)
     {
-        auto candidates = list.second.complete_id(prefix, pos_in_token);
-        for (auto& c : candidates)
+        auto container = transformed(list.second, id_map<HookFunc>::get_id);
+        for (auto& c : complete(prefix, pos_in_token, container))
         {
             if (!contains(res, c))
                 res.push_back(c);
diff --git a/src/hook_manager.hh b/src/hook_manager.hh
index 5aa52b2f..7a8b9ab7 100644
--- a/src/hook_manager.hh
+++ b/src/hook_manager.hh
@@ -2,6 +2,7 @@
 #define hook_manager_hh_INCLUDED
 
 #include "id_map.hh"
+#include "completion.hh"
 #include "unordered_map.hh"
 
 namespace Kakoune
diff --git a/src/id_map.hh b/src/id_map.hh
index a15903c1..7496a21a 100644
--- a/src/id_map.hh
+++ b/src/id_map.hh
@@ -2,7 +2,6 @@
 #define id_map_hh_INCLUDED
 
 #include "containers.hh"
-#include "completion.hh"
 #include "string.hh"
 
 #include <vector>
@@ -63,30 +62,7 @@ public:
         m_content.erase(it, end());
     }
 
-    template<typename Condition>
-    CandidateList complete_id_if(StringView prefix,
-                                 ByteCount cursor_pos,
-                                 Condition condition) const
-    {
-        auto real_prefix = prefix.substr(0, cursor_pos);
-        CandidateList result;
-        for (auto& value : m_content)
-        {
-            if (not condition(value))
-                continue;
-
-            if (prefix_match(value.first, real_prefix))
-                result.push_back(value.first);
-        }
-        return result;
-    }
-
-    CandidateList complete_id(StringView prefix,
-                              ByteCount cursor_pos) const
-    {
-        return complete_id_if(
-            prefix, cursor_pos, [](const value_type&) { return true; });
-    }
+    static const String& get_id(const value_type& v) { return v.first; }
 
     bool empty() const { return m_content.empty(); }
 
diff --git a/src/ncurses_ui.cc b/src/ncurses_ui.cc
index 0a7dbf38..3b4d5b09 100644
--- a/src/ncurses_ui.cc
+++ b/src/ncurses_ui.cc
@@ -1,5 +1,6 @@
 #include "ncurses_ui.hh"
 
+#include "containers.hh"
 #include "display_buffer.hh"
 #include "event_manager.hh"
 #include "keys.hh"
diff --git a/src/option_manager.hh b/src/option_manager.hh
index c8fb1d5f..c1f9bd12 100644
--- a/src/option_manager.hh
+++ b/src/option_manager.hh
@@ -6,7 +6,6 @@
 #include "exception.hh"
 #include "flags.hh"
 #include "option_types.hh"
-#include "utils.hh"
 #include "regex.hh"
 
 namespace Kakoune
diff --git a/src/register_manager.cc b/src/register_manager.cc
index f9d36ae3..fb4baf81 100644
--- a/src/register_manager.cc
+++ b/src/register_manager.cc
@@ -1,8 +1,8 @@
 #include "register_manager.hh"
 
 #include "assert.hh"
-#include "id_map.hh"
 #include "exception.hh"
+#include "id_map.hh"
 
 namespace Kakoune
 {
diff --git a/src/scope.hh b/src/scope.hh
index 0fb99f8d..5cc63b28 100644
--- a/src/scope.hh
+++ b/src/scope.hh
@@ -5,6 +5,7 @@
 #include "hook_manager.hh"
 #include "keymap_manager.hh"
 #include "option_manager.hh"
+#include "utils.hh"
 
 namespace Kakoune
 {