Better order of the completion items.

src/clang_complete.cc

@@ -46,6 +46,18 @@ unsigned GetCompletionPriority(const CXCompletionString& str,
   return priority;
 }
 
+bool CompareLsCompletionItem(const lsCompletionItem &item1,
+                             const lsCompletionItem &item2)
+{
+  if (item1.pos_ != item2.pos_)
+    return item1.pos_ < item2.pos_;
+  if (item1.priority_ != item2.priority_)
+    return item1.priority_ < item2.priority_;
+  if (item1.label.length() != item2.label.length())
+    return item1.label.length() < item2.label.length();
+  return item1.label < item2.label;
+}
+
 template <typename T>
 char* tofixedbase64(T input, char* out) {
   const char* digits =
@@ -464,15 +476,22 @@ void CompletionQueryMain(ClangCompleteManager* completion_manager) {
             ls_completion_item.documentation = ToString(
                 clang_getCompletionBriefComment(result.CompletionString));
 
-            char buf[16];
-            ls_completion_item.sortText =
-                tofixedbase64(GetCompletionPriority(result.CompletionString,
-                                                    result.CursorKind,
-                                                    ls_completion_item.label),
-                              buf);
+            ls_completion_item.pos_ =
+                ls_completion_item.label.find(request->existing_text);
+
+            ls_completion_item.priority_ =
+                GetCompletionPriority(result.CompletionString, result.CursorKind,
+                                      ls_completion_item.label);
 
             ls_result.push_back(ls_completion_item);
           }
+
+          // order all items and set |sortText|
+          std::sort(ls_result.begin(), ls_result.end(), CompareLsCompletionItem);
+          char buf[16];
+          for (size_t i = 0; i < ls_result.size(); ++i)
+            ls_result[i].sortText = tofixedbase64(i, buf);
+
           timer.ResetAndPrint("[complete] Building " +
                               std::to_string(ls_result.size()) +
                               " completion results");
@@ -569,6 +588,7 @@ ClangCompleteManager::~ClangCompleteManager() {}
 
 void ClangCompleteManager::CodeComplete(
     const lsTextDocumentPositionParams& completion_location,
+    const std::string &existing_text,
     const OnComplete& on_complete) {
   completion_request_.WithLock(
       [&](std::unique_ptr<CompletionRequest>& request_storage) {
@@ -579,6 +599,7 @@ void ClangCompleteManager::CodeComplete(
         // Make the request send out code completion information.
         request_storage->document = completion_location.textDocument;
         request_storage->position = completion_location.position;
+        request_storage->existing_text = existing_text;
         request_storage->on_complete = on_complete;
       });
 }

src/clang_complete.h

@@ -57,6 +57,7 @@ struct ClangCompleteManager {
   struct CompletionRequest {
     lsTextDocumentIdentifier document;
     optional<lsPosition> position;
+    std::string existing_text;
     OnComplete on_complete;  // May be null/empty.
     bool emit_diagnostics = false;
   };
@@ -71,6 +72,7 @@ struct ClangCompleteManager {
   // Start a code completion at the given location. |on_complete| will run when
   // completion results are available. |on_complete| may run on any thread.
   void CodeComplete(const lsTextDocumentPositionParams& completion_location,
+                    const std::string &existing_text,
                     const OnComplete& on_complete);
   // Request a diagnostics update.
   void DiagnosticsUpdate(const lsTextDocumentIdentifier& document);

src/language_server_api.h

@@ -356,6 +356,10 @@ struct lsCompletionItem {
   // A human-readable string that represents a doc-comment.
   std::string documentation;
 
+  // Internal information to order candidates.
+  std::string::size_type pos_;
+  unsigned priority_;
+
   // A string that shoud be used when comparing this item
   // with other items. When `falsy` the label is used.
   std::string sortText;

src/messages/text_document_completion.cc

@@ -69,15 +69,16 @@ void FilterCompletionResponse(Out_TextDocumentComplete* complete_response,
 
   // find the exact text
   const bool found = !complete_text.empty() &&
-                     std::find_if(items.begin(), items.end(),
+                     std::any_of(items.begin(), items.end(),
                                  [&](const lsCompletionItem& item) {
-                                    return item.label == complete_text;
-                                  }) != items.end();
+                                   return item.pos_ == 0 &&
+                                       item.label.length() == complete_text.length();
+                                 });
   // If found, remove all candidates that do not start with it.
   if (found) {
     items.erase(std::remove_if(items.begin(), items.end(),
                                [&](const lsCompletionItem& item) {
-                                 return item.label.find(complete_text) != 0;
+                                 return item.pos_ != 0;
                                }),
                 items.end());
   }
@@ -242,7 +243,7 @@ struct TextDocumentCompletionHandler : MessageHandler {
           callback(global_code_complete_cache->cached_results_,
                    true /*is_cached_result*/);
         });
-        clang_complete->CodeComplete(request->params, freshen_global);
+        clang_complete->CodeComplete(request->params, existing_completion, freshen_global);
       } else if (non_global_code_complete_cache->IsCacheValid(
                      request->params)) {
         non_global_code_complete_cache->WithLock([&]() {
@@ -250,7 +251,7 @@ struct TextDocumentCompletionHandler : MessageHandler {
                    true /*is_cached_result*/);
         });
       } else {
-        clang_complete->CodeComplete(request->params, callback);
+        clang_complete->CodeComplete(request->params, existing_completion, callback);
       }
     }
   }

src/messages/text_document_signature_help.cc

@@ -160,7 +160,7 @@ struct TextDocumentSignatureHelpHandler : MessageHandler {
         callback(signature_cache->cached_results_, true /*is_cached_result*/);
       });
     } else {
-      clang_complete->CodeComplete(params, std::move(callback));
+      clang_complete->CodeComplete(params, search, std::move(callback));
     }
   }
 };