[clangd] Add limit extension on completion and workspace-symbols

This overrides the --limit-results command-line flag, and is not constrained
by it.
See clangd/clangd#707

Differential Revision: https://reviews.llvm.org/D97801

Author: sam-mccall

clang-tools-extra/clangd/ClangdLSPServer.cpp

@@ -780,7 +780,7 @@ void ClangdLSPServer::onWorkspaceSymbol(
     const WorkspaceSymbolParams &Params,
     Callback<std::vector<SymbolInformation>> Reply) {
   Server->workspaceSymbols(
-      Params.query, Opts.CodeComplete.Limit,
+      Params.query, Params.limit.getValueOr(Opts.CodeComplete.Limit),
       [Reply = std::move(Reply),
        this](llvm::Expected<std::vector<SymbolInformation>> Items) mutable {
         if (!Items)
@@ -1031,21 +1031,24 @@ void ClangdLSPServer::onCompletion(const CompletionParams &Params,
     vlog("ignored auto-triggered completion, preceding char did not match");
     return Reply(CompletionList());
   }
-  Server->codeComplete(
-      Params.textDocument.uri.file(), Params.position, Opts.CodeComplete,
-      [Reply = std::move(Reply),
-       this](llvm::Expected<CodeCompleteResult> List) mutable {
-        if (!List)
-          return Reply(List.takeError());
-        CompletionList LSPList;
-        LSPList.isIncomplete = List->HasMore;
-        for (const auto &R : List->Completions) {
-          CompletionItem C = R.render(Opts.CodeComplete);
-          C.kind = adjustKindToCapability(C.kind, SupportedCompletionItemKinds);
-          LSPList.items.push_back(std::move(C));
-        }
-        return Reply(std::move(LSPList));
-      });
+  auto Opts = this->Opts.CodeComplete;
+  if (Params.limit && *Params.limit >= 0)
+    Opts.Limit = *Params.limit;
+  Server->codeComplete(Params.textDocument.uri.file(), Params.position, Opts,
+                       [Reply = std::move(Reply), Opts,
+                        this](llvm::Expected<CodeCompleteResult> List) mutable {
+                         if (!List)
+                           return Reply(List.takeError());
+                         CompletionList LSPList;
+                         LSPList.isIncomplete = List->HasMore;
+                         for (const auto &R : List->Completions) {
+                           CompletionItem C = R.render(Opts);
+                           C.kind = adjustKindToCapability(
+                               C.kind, SupportedCompletionItemKinds);
+                           LSPList.items.push_back(std::move(C));
+                         }
+                         return Reply(std::move(LSPList));
+                       });
 }
 
 void ClangdLSPServer::onSignatureHelp(const TextDocumentPositionParams &Params,

clang-tools-extra/clangd/Protocol.cpp

@@ -750,7 +750,8 @@ llvm::raw_ostream &operator<<(llvm::raw_ostream &O, const SymbolDetails &S) {
 bool fromJSON(const llvm::json::Value &Params, WorkspaceSymbolParams &R,
               llvm::json::Path P) {
   llvm::json::ObjectMapper O(Params, P);
-  return O && O.map("query", R.query);
+  return O && O.map("query", R.query) &&
+         mapOptOrNull(Params, "limit", R.limit, P);
 }
 
 llvm::json::Value toJSON(const Command &C) {
@@ -851,7 +852,8 @@ bool fromJSON(const llvm::json::Value &Params, CompletionContext &R,
 
 bool fromJSON(const llvm::json::Value &Params, CompletionParams &R,
               llvm::json::Path P) {
-  if (!fromJSON(Params, static_cast<TextDocumentPositionParams &>(R), P))
+  if (!fromJSON(Params, static_cast<TextDocumentPositionParams &>(R), P) ||
+      !mapOptOrNull(Params, "limit", R.limit, P))
     return false;
   if (auto *Context = Params.getAsObject()->get("context"))
     return fromJSON(*Context, R.context, P.field("context"));

clang-tools-extra/clangd/Protocol.h

@@ -1056,8 +1056,13 @@ bool operator==(const SymbolDetails &, const SymbolDetails &);
 
 /// The parameters of a Workspace Symbol Request.
 struct WorkspaceSymbolParams {
-  /// A non-empty query string
+  /// A query string to filter symbols by.
+  /// Clients may send an empty string here to request all the symbols.
   std::string query;
+
+  /// Max results to return, overriding global default. 0 means no limit.
+  /// Clangd extension.
+  llvm::Optional<int> limit;
 };
 bool fromJSON(const llvm::json::Value &, WorkspaceSymbolParams &,
               llvm::json::Path);
@@ -1106,6 +1111,10 @@ bool fromJSON(const llvm::json::Value &, CompletionContext &, llvm::json::Path);
 
 struct CompletionParams : TextDocumentPositionParams {
   CompletionContext context;
+
+  /// Max results to return, overriding global default. 0 means no limit.
+  /// Clangd extension.
+  llvm::Optional<int> limit;
 };
 bool fromJSON(const llvm::json::Value &, CompletionParams &, llvm::json::Path);