First attempt to include the semantic highlight feature, introduced in specification 3.16.0.

CMakeLists.txt

@@ -235,6 +235,7 @@ target_sources(ccls PRIVATE
   src/messages/textDocument_hover.cc
   src/messages/textDocument_references.cc
   src/messages/textDocument_rename.cc
+  src/messages/textDocument_semanticToken.cc
   src/messages/textDocument_signatureHelp.cc
   src/messages/workspace.cc
 )

src/message_handler.cc

@@ -188,6 +188,7 @@ MessageHandler::MessageHandler() {
   bind("textDocument/rename", &MessageHandler::textDocument_rename);
   bind("textDocument/signatureHelp", &MessageHandler::textDocument_signatureHelp);
   bind("textDocument/typeDefinition", &MessageHandler::textDocument_typeDefinition);
+  bind("textDocument/semanticTokens/full", &MessageHandler::textDocument_semanticTokensFull);
   bind("workspace/didChangeConfiguration", &MessageHandler::workspace_didChangeConfiguration);
   bind("workspace/didChangeWatchedFiles", &MessageHandler::workspace_didChangeWatchedFiles);
   bind("workspace/didChangeWorkspaceFolders", &MessageHandler::workspace_didChangeWorkspaceFolders);

src/message_handler.hh

@@ -48,6 +48,10 @@ struct TextDocumentPositionParam {
   TextDocumentIdentifier textDocument;
   Position position;
 };
+struct SemanticTokensParams {
+  TextDocumentIdentifier textDocument;
+};
+REFLECT_STRUCT(SemanticTokensParams, textDocument);
 struct TextDocumentEdit {
   VersionedTextDocumentIdentifier textDocument;
   std::vector<TextEdit> edits;
@@ -287,6 +291,7 @@ private:
   void textDocument_rename(RenameParam &, ReplyOnce &);
   void textDocument_signatureHelp(TextDocumentPositionParam &, ReplyOnce &);
   void textDocument_typeDefinition(TextDocumentPositionParam &, ReplyOnce &);
+  void textDocument_semanticTokensFull(SemanticTokensParams &, ReplyOnce &);
   void workspace_didChangeConfiguration(EmptyParam &);
   void workspace_didChangeWatchedFiles(DidChangeWatchedFilesParam &);
   void workspace_didChangeWorkspaceFolders(DidChangeWorkspaceFoldersParam &);

src/messages/initialize.cc

@@ -25,6 +25,47 @@
 namespace ccls {
 using namespace llvm;
 
+std::vector<const char *> SEMANTIC_TOKENS = {
+  "unknown",
+
+  "file",
+  "module",
+  "namespace",
+  "package",
+  "class",
+  "method",
+  "property",
+  "field",
+  "constructor",
+  "enum",
+  "interface",
+  "function",
+  "variable",
+  "constant",
+  "string",
+  "number",
+  "boolean",
+  "array",
+  "object",
+  "key",
+  "null",
+  "enumMember",
+  "struct",
+  "event",
+  "operator",
+  "typeParameter",
+  "typeAlias", //252 => 27
+  "parameter",
+  "staticMethod",
+  "macro"
+};
+
+std::vector<const char *> SEMANTIC_MODIFIERS = {
+    "declaration", //1
+    "definition",  //2
+    "static"       //4
+};
+
 extern std::vector<std::string> g_init_options;
 
 namespace {
@@ -89,6 +130,13 @@ struct ServerCap {
     std::vector<const char *> commands = {ccls_xref};
   } executeCommandProvider;
   Config::ServerCap::Workspace workspace;
+  struct SemanticTokenProvider {
+      struct SemanticTokensLegend {
+          std::vector<const char *> tokenTypes = SEMANTIC_TOKENS;
+          std::vector<const char *> tokenModifiers = SEMANTIC_MODIFIERS;
+      } legend;
+      bool full = true;
+  } semanticTokensProvider;
 };
 REFLECT_STRUCT(ServerCap::CodeActionOptions, codeActionKinds);
 REFLECT_STRUCT(ServerCap::CodeLensOptions, resolveProvider);
@@ -109,7 +157,9 @@ REFLECT_STRUCT(ServerCap, textDocumentSync, hoverProvider, completionProvider,
                documentRangeFormattingProvider,
                documentOnTypeFormattingProvider, renameProvider,
                documentLinkProvider, foldingRangeProvider,
-               executeCommandProvider, workspace);
+               executeCommandProvider, workspace, semanticTokensProvider);
+REFLECT_STRUCT(ServerCap::SemanticTokenProvider, legend, full);
+REFLECT_STRUCT(ServerCap::SemanticTokenProvider::SemanticTokensLegend, tokenTypes, tokenModifiers);
 
 struct DynamicReg {
   bool dynamicRegistration = false;

src/messages/textDocument_semanticToken.cc

@@ -0,0 +1,259 @@
+// Copyright 2017-2020 ccls Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include "indexer.hh"
+#include "message_handler.hh"
+#include "pipeline.hh"
+#include "sema_manager.hh"
+
+#include <clang/Sema/Sema.h>
+#include <algorithm>
+#include <stdexcept>
+#include <string>
+
+#include <iostream>
+
+MAKE_HASHABLE(ccls::SymbolIdx, t.usr, t.kind);
+
+namespace ccls {
+using namespace clang;
+
+namespace {
+struct SemanticTokens {
+  std::vector<int> data;
+};
+REFLECT_STRUCT(SemanticTokens, data);
+
+struct CclsSemanticHighlightSymbol {
+  int id = 0;
+  SymbolKind parentKind;
+  SymbolKind kind;
+  uint8_t storage;
+  std::vector<std::pair<lsRange, Role>> lsRangeAndRoles;
+};
+
+struct ScanLineEvent {
+  Position pos;
+  Position end_pos; // Second key when there is a tie for insertion events.
+  int id;
+  CclsSemanticHighlightSymbol *symbol;
+  Role role;
+  bool operator<(const ScanLineEvent &o) const {
+    // See the comments below when insertion/deletion events are inserted.
+    if (!(pos == o.pos))
+      return pos < o.pos;
+    if (!(o.end_pos == end_pos))
+      return o.end_pos < end_pos;
+    // This comparison essentially order Macro after non-Macro,
+    // So that macros will not be rendered as Var/Type/...
+    if (symbol->kind != o.symbol->kind)
+      return symbol->kind < o.symbol->kind;
+    // If symbol A and B occupy the same place, we want one to be placed
+    // before the other consistantly.
+    return symbol->id < o.symbol->id;
+  }
+};
+
+}
+
+void MessageHandler::textDocument_semanticTokensFull(
+        SemanticTokensParams &param, ReplyOnce &reply) {
+  std::string path = param.textDocument.uri.getPath();
+  WorkingFile *wfile = wfiles->getFile(path);
+  if (!wfile) {
+    reply.notOpened(path);
+    return;
+  }
+
+  QueryFile *file = findFile(path);
+  if (!file) {
+    reply.notOpened(path); //TODO
+    return;
+  }
+
+  SemanticTokens result;
+
+  static GroupMatch match(g_config->highlight.whitelist,
+                          g_config->highlight.blacklist);
+  assert(file->def);
+  if (wfile->buffer_content.size() > g_config->highlight.largeFileSize ||
+      !match.matches(file->def->path)) {
+    reply.notOpened(path); //TODO
+    return; //TODO?
+  }
+
+  // Group symbols together.
+  std::unordered_map<SymbolIdx, CclsSemanticHighlightSymbol> grouped_symbols;
+  for (auto [sym, refcnt] : file->symbol2refcnt) {
+    if (refcnt <= 0) //TODO: unused?
+      continue;
+    std::string_view detailed_name;
+    SymbolKind parent_kind = SymbolKind::Unknown;
+    SymbolKind kind = SymbolKind::Unknown;
+    uint8_t storage = SC_None;
+    int idx;
+    // This switch statement also filters out symbols that are not highlighted.
+    switch (sym.kind) {
+    case Kind::Func: {
+      idx = db->func_usr[sym.usr];
+      const QueryFunc &func = db->funcs[idx];
+      const QueryFunc::Def *def = func.anyDef();
+      if (!def)
+        continue; // applies to for loop
+      // Don't highlight overloadable operators or implicit lambda ->
+      // std::function constructor.
+      std::string_view short_name = def->name(false);
+      if (short_name.compare(0, 8, "operator") == 0)
+        continue; // applies to for loop
+      kind = def->kind;
+      storage = def->storage;
+      detailed_name = short_name;
+      parent_kind = def->parent_kind;
+
+      // Check whether the function name is actually there.
+      // If not, do not publish the semantic highlight.
+      // E.g. copy-initialization of constructors should not be highlighted
+      // but we still want to keep the range for jumping to definition.
+      std::string_view concise_name =
+          detailed_name.substr(0, detailed_name.find('<'));
+      uint16_t start_line = sym.range.start.line;
+      int16_t start_col = sym.range.start.column;
+      if (start_line >= wfile->index_lines.size())
+        continue;
+      std::string_view line = wfile->index_lines[start_line];
+      sym.range.end.line = start_line;
+      if (!(start_col + concise_name.size() <= line.size() &&
+            line.compare(start_col, concise_name.size(), concise_name) == 0))
+        continue;
+      sym.range.end.column = start_col + concise_name.size();
+      break;
+    }
+    case Kind::Type: {
+      idx = db->type_usr[sym.usr];
+      const QueryType &type = db->types[idx];
+      for (auto &def : type.def) {
+        kind = def.kind;
+        detailed_name = def.detailed_name;
+        if (def.spell) {
+          parent_kind = def.parent_kind;
+          break;
+        }
+      }
+      break;
+    }
+    case Kind::Var: {
+      idx = db->var_usr[sym.usr];
+      const QueryVar &var = db->vars[idx];
+      for (auto &def : var.def) {
+        kind = def.kind;
+        storage = def.storage;
+        detailed_name = def.detailed_name;
+        if (def.spell) {
+          parent_kind = def.parent_kind;
+          break;
+        }
+      }
+      break;
+    }
+    default:
+      continue; // applies to for loop
+    }
+
+    if (std::optional<lsRange> loc = getLsRange(wfile, sym.range)) {
+      auto it = grouped_symbols.find(sym);
+      if (it != grouped_symbols.end()) {
+        it->second.lsRangeAndRoles.push_back({*loc, sym.role});
+      } else {
+        CclsSemanticHighlightSymbol symbol;
+        symbol.id = idx;
+        symbol.parentKind = parent_kind;
+        symbol.kind = kind;
+        symbol.storage = storage;
+        symbol.lsRangeAndRoles.push_back({*loc, sym.role});
+        grouped_symbols[sym] = symbol;
+      }
+    }
+  }
+
+  // Make ranges non-overlapping using a scan line algorithm.
+  std::vector<ScanLineEvent> events;
+  int id = 0;
+  for (auto &entry : grouped_symbols) {
+    CclsSemanticHighlightSymbol &symbol = entry.second;
+    for (auto &loc : symbol.lsRangeAndRoles) {
+      // For ranges sharing the same start point, the one with leftmost end
+      // point comes first.
+      events.push_back({loc.first.start, loc.first.end, id, &symbol, loc.second});
+      // For ranges sharing the same end point, their relative order does not
+      // matter, therefore we arbitrarily assign loc.end to them. We use
+      // negative id to indicate a deletion event.
+      events.push_back({loc.first.end, loc.first.end, ~id, &symbol, loc.second});
+      id++;
+    }
+    symbol.lsRangeAndRoles.clear();
+  }
+  std::sort(events.begin(), events.end());
+
+  std::vector<uint8_t> deleted(id, 0);
+  int top = 0;
+  for (size_t i = 0; i < events.size(); i++) {
+    while (top && deleted[events[top - 1].id])
+      top--;
+    // Order [a, b0) after [a, b1) if b0 < b1. The range comes later overrides
+    // the ealier. The order of [a0, b) [a1, b) does not matter.
+    // The order of [a, b) [b, c) does not as long as we do not emit empty
+    // ranges.
+    // Attribute range [events[i-1].pos, events[i].pos) to events[top-1].symbol
+    // .
+    if (top && !(events[i - 1].pos == events[i].pos))
+      events[top - 1].symbol->lsRangeAndRoles.push_back(
+          {{events[i - 1].pos, events[i].pos}, events[i].role});
+    if (events[i].id >= 0)
+      events[top++] = events[i];
+    else
+      deleted[~events[i].id] = 1;
+  }
+
+  // Transform lsRange into pair<int, int> (offset pairs)
+    std::vector<std::pair<std::pair<lsRange, Role>, CclsSemanticHighlightSymbol *>> scratch;
+    for (auto &entry : grouped_symbols) {
+      for (auto &range : entry.second.lsRangeAndRoles)
+        scratch.emplace_back(range, &entry.second);
+      entry.second.lsRangeAndRoles.clear();
+    }
+    std::sort(scratch.begin(), scratch.end(),
+              [](auto &l, auto &r) { return l.first.first.start < r.first.first.start; });
+    int line = 0;
+    int column = 0;
+    for (auto &entry : scratch) {
+      lsRange &r = entry.first.first;
+      if (r.start.line != line) {
+        column = 0;
+      }
+      result.data.push_back(r.start.line - line); line = r.start.line;
+      result.data.push_back(r.start.character - column); column = r.start.character;
+      result.data.push_back(r.end.character - r.start.character);
+      uint8_t kindId;
+      int modifiers = entry.second->storage == SC_Static ? 4 : 0;
+      if (entry.first.second & Role::Declaration) {
+          modifiers |= 1;
+      }
+      if (entry.first.second & Role::Definition) {
+          modifiers |= 2;
+      }
+      if (entry.second->kind == SymbolKind::StaticMethod) {
+          kindId = (uint8_t) SymbolKind::Method;
+          modifiers = 4;
+      } else {
+          kindId = (uint8_t) entry.second->kind;
+          if (kindId > (uint8_t) SymbolKind::StaticMethod)
+              kindId--;
+          if (kindId >= 252) kindId = 27 + kindId - 252;
+      }
+      result.data.push_back(kindId);
+      result.data.push_back(modifiers);
+    }
+
+  reply(result);
+}
+} // namespace ccls