In buffer name completion, give priority to filename (not dirname) ma…

…tches

First list filename matches, then full path matches to allow fast selection
of buffers in deep hierarchies where queries match the path of every buffers

src/commands.cc

@@ -57,13 +57,46 @@ const PerArgumentCommandCompleter filename_completer({
                                              cursor_pos) }; }
 });
 
-static CandidateList complete_buffer_name(StringView prefix, ByteCount cursor_pos)
+static CandidateList complete_buffer_name(StringView query, ByteCount cursor_pos)
 {
-    auto c = transformed(BufferManager::instance(),
-                         [](const SafePtr<Buffer>& b) -> const String&
-                         { return b->display_name(); });
+    struct RankedMatchAndBuffer : RankedMatch
+    {
+        RankedMatchAndBuffer(const RankedMatch& m, const Buffer* b = nullptr)
+            : RankedMatch{m}, buffer{b} {}
+
+        using RankedMatch::operator==;
+        using RankedMatch::operator<;
+
+        const Buffer* buffer;
+    };
+
+    query = query.substr(0, cursor_pos);
+    Vector<RankedMatchAndBuffer> filename_matches;
+    Vector<RankedMatchAndBuffer> matches;
+    for (const auto& buffer : BufferManager::instance())
+    {
+        StringView bufname = buffer->display_name();
+        if (buffer->flags() & Buffer::Flags::File)
+        {
+            if (RankedMatch match{split_path(bufname).second, query})
+            {
+                filename_matches.emplace_back(match, buffer.get());
+                continue;
+            }
+        }
+        if (RankedMatch match{bufname, query})
+            matches.emplace_back(match, buffer.get());
+    }
+    std::sort(filename_matches.begin(), filename_matches.end());
+    std::sort(matches.begin(), matches.end());
+
+    CandidateList res;
+    for (auto& match : filename_matches)
+        res.push_back(match.buffer->display_name());
+    for (auto& match : matches)
+        res.push_back(match.buffer->display_name());
 
-    return complete(prefix, cursor_pos, c);
+    return res;
 }
 
 const PerArgumentCommandCompleter buffer_completer({