[clangd] Extract mapper logic from clangd-indexer into a library.

Summary: Soon we can drop support for MR-via-YAML.
I need to modify some out-of-tree versions to use the library, first.

Reviewers: kadircet

Subscribers: mgorny, ilya-biryukov, ioeric, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D52465

6 files changed, 126 insertions, 69 deletions

diff --git a/clang-tools-extra/clangd/CMakeLists.txt b/clang-tools-extra/clangd/CMakeLists.txt
index a8cd64a1039..0894a927ead 100644
--- a/clang-tools-extra/clangd/CMakeLists.txt
+++ b/clang-tools-extra/clangd/CMakeLists.txt
@@ -40,6 +40,7 @@ add_clang_library(clangDaemon
   index/CanonicalIncludes.cpp
   index/FileIndex.cpp
   index/Index.cpp
+  index/IndexAction.cpp
   index/MemIndex.cpp
   index/Merge.cpp
   index/Serialization.cpp
diff --git a/clang-tools-extra/clangd/index/IndexAction.cpp b/clang-tools-extra/clangd/index/IndexAction.cpp
new file mode 100644
index 00000000000..b9dcb6e19c0
--- /dev/null
+++ b/clang-tools-extra/clangd/index/IndexAction.cpp
@@ -0,0 +1,73 @@
+#include "IndexAction.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Index/IndexDataConsumer.h"
+#include "clang/Index/IndexingAction.h"
+#include "clang/Tooling/Tooling.h"
+namespace clang {
+namespace clangd {
+namespace {
+
+// Wraps the index action and reports index data after each translation unit.
+class IndexAction : public WrapperFrontendAction {
+public:
+  IndexAction(std::shared_ptr<SymbolCollector> C,
+              std::unique_ptr<CanonicalIncludes> Includes,
+              const index::IndexingOptions &Opts,
+              std::function<void(SymbolSlab)> &SymbolsCallback)
+      : WrapperFrontendAction(index::createIndexingAction(C, Opts, nullptr)),
+        SymbolsCallback(SymbolsCallback), Collector(C),
+        Includes(std::move(Includes)),
+        PragmaHandler(collectIWYUHeaderMaps(this->Includes.get())) {}
+
+  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
+                                                 StringRef InFile) override {
+    CI.getPreprocessor().addCommentHandler(PragmaHandler.get());
+    return WrapperFrontendAction::CreateASTConsumer(CI, InFile);
+  }
+
+  bool BeginInvocation(CompilerInstance &CI) override {
+    // We want all comments, not just the doxygen ones.
+    CI.getLangOpts().CommentOpts.ParseAllComments = true;
+    return WrapperFrontendAction::BeginInvocation(CI);
+  }
+
+  void EndSourceFileAction() override {
+    WrapperFrontendAction::EndSourceFileAction();
+
+    const auto &CI = getCompilerInstance();
+    if (CI.hasDiagnostics() &&
+        CI.getDiagnostics().hasUncompilableErrorOccurred()) {
+      llvm::errs() << "Skipping TU due to uncompilable errors\n";
+      return;
+    }
+    SymbolsCallback(Collector->takeSymbols());
+  }
+
+private:
+  std::function<void(SymbolSlab)> SymbolsCallback;
+  std::shared_ptr<SymbolCollector> Collector;
+  std::unique_ptr<CanonicalIncludes> Includes;
+  std::unique_ptr<CommentHandler> PragmaHandler;
+};
+
+} // namespace
+
+std::unique_ptr<FrontendAction>
+createStaticIndexingAction(SymbolCollector::Options Opts,
+                           std::function<void(SymbolSlab)> SymbolsCallback) {
+  index::IndexingOptions IndexOpts;
+  IndexOpts.SystemSymbolFilter =
+      index::IndexingOptions::SystemSymbolFilterKind::All;
+  Opts.CollectIncludePath = true;
+  Opts.CountReferences = true;
+  Opts.Origin = SymbolOrigin::Static;
+  auto Includes = llvm::make_unique<CanonicalIncludes>();
+  addSystemHeadersMapping(Includes.get());
+  Opts.Includes = Includes.get();
+  return llvm::make_unique<IndexAction>(
+      std::make_shared<SymbolCollector>(std::move(Opts)), std::move(Includes),
+      IndexOpts, SymbolsCallback);
+};
+
+} // namespace clangd
+} // namespace clang
diff --git a/clang-tools-extra/clangd/index/IndexAction.h b/clang-tools-extra/clangd/index/IndexAction.h
new file mode 100644
index 00000000000..b51bfd2520f
--- /dev/null
+++ b/clang-tools-extra/clangd/index/IndexAction.h
@@ -0,0 +1,32 @@
+//===--- IndexAction.h - Run the indexer as a frontend action ----*- C++-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_INDEX_ACTION_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_INDEX_ACTION_H
+#include "SymbolCollector.h"
+#include "clang/Frontend/FrontendActions.h"
+
+namespace clang {
+namespace clangd {
+
+// Creates an action that indexes translation units and delivers the results
+// for SymbolsCallback (each slab corresponds to one TU).
+//
+// Only a subset of SymbolCollector::Options are respected:
+//   - include paths are always collected, and canonicalized appropriately
+//   - references are always counted
+//   - the symbol origin is always Static
+std::unique_ptr<FrontendAction>
+createStaticIndexingAction(SymbolCollector::Options Opts,
+                           std::function<void(SymbolSlab)> SymbolsCallback);
+
+} // namespace clangd
+} // namespace clang
+
+#endif
diff --git a/clang-tools-extra/clangd/index/Serialization.h b/clang-tools-extra/clangd/index/Serialization.h
index c73ce23b5e5..4240bdb722b 100644
--- a/clang-tools-extra/clangd/index/Serialization.h
+++ b/clang-tools-extra/clangd/index/Serialization.h
@@ -40,23 +40,26 @@ enum class IndexFileFormat {
   YAML, // Human-readable format, suitable for experiments and debugging.
 };
 
+// Holds the contents of an index file that was read.
+struct IndexFileIn {
+  llvm::Optional<SymbolSlab> Symbols;
+};
+// Parse an index file. The input must be a RIFF container chunk.
+llvm::Expected<IndexFileIn> readIndexFile(llvm::StringRef);
+
 // Specifies the contents of an index file to be written.
 struct IndexFileOut {
   const SymbolSlab *Symbols;
   // TODO: Support serializing symbol occurrences.
   // TODO: Support serializing Dex posting lists.
   IndexFileFormat Format = IndexFileFormat::RIFF;
-};
-// Serializes an index file. (This is a RIFF container chunk).
-llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const IndexFileOut &O);
 
-// Holds the contents of an index file that was read.
-struct IndexFileIn {
-  llvm::Optional<SymbolSlab> Symbols;
-  IndexFileFormat Format;
+  IndexFileOut() = default;
+  IndexFileOut(const IndexFileIn &I)
+      : Symbols(I.Symbols ? I.Symbols.getPointer() : nullptr) {}
 };
-// Parse an index file. The input must be a RIFF container chunk.
-llvm::Expected<IndexFileIn> readIndexFile(llvm::StringRef);
+// Serializes an index file.
+llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const IndexFileOut &O);
 
 std::string toYAML(const Symbol &);
 // Returned symbol is backed by the YAML input.
diff --git a/clang-tools-extra/clangd/index/SymbolCollector.h b/clang-tools-extra/clangd/index/SymbolCollector.h
index db0e3074ecf..1994183c21e 100644
--- a/clang-tools-extra/clangd/index/SymbolCollector.h
+++ b/clang-tools-extra/clangd/index/SymbolCollector.h
@@ -6,6 +6,8 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOL_COLLECTOR_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_SYMBOL_COLLECTOR_H
 
 #include "CanonicalIncludes.h"
 #include "Index.h"
@@ -122,3 +124,4 @@ private:
 
 } // namespace clangd
 } // namespace clang
+#endif
diff --git a/clang-tools-extra/clangd/indexer/IndexerMain.cpp b/clang-tools-extra/clangd/indexer/IndexerMain.cpp
index dbd43cd1952..9136693822d 100644
--- a/clang-tools-extra/clangd/indexer/IndexerMain.cpp
+++ b/clang-tools-extra/clangd/indexer/IndexerMain.cpp
@@ -15,6 +15,7 @@
 #include "RIFF.h"
 #include "index/CanonicalIncludes.h"
 #include "index/Index.h"
+#include "index/IndexAction.h"
 #include "index/Merge.h"
 #include "index/Serialization.h"
 #include "index/SymbolCollector.h"
@@ -86,68 +87,12 @@ public:
   SymbolIndexActionFactory(SymbolsConsumer &Consumer) : Consumer(Consumer) {}
 
   clang::FrontendAction *create() override {
-    // Wraps the index action and reports collected symbols to the execution
-    // context at the end of each translation unit.
-    class WrappedIndexAction : public WrapperFrontendAction {
-    public:
-      WrappedIndexAction(std::shared_ptr<SymbolCollector> C,
-                         std::unique_ptr<CanonicalIncludes> Includes,
-                         const index::IndexingOptions &Opts,
-                         SymbolsConsumer &Consumer)
-          : WrapperFrontendAction(
-                index::createIndexingAction(C, Opts, nullptr)),
-            Consumer(Consumer), Collector(C), Includes(std::move(Includes)),
-            PragmaHandler(collectIWYUHeaderMaps(this->Includes.get())) {}
-
-      std::unique_ptr<ASTConsumer>
-      CreateASTConsumer(CompilerInstance &CI, StringRef InFile) override {
-        CI.getPreprocessor().addCommentHandler(PragmaHandler.get());
-        return WrapperFrontendAction::CreateASTConsumer(CI, InFile);
-      }
-
-      bool BeginInvocation(CompilerInstance &CI) override {
-        // We want all comments, not just the doxygen ones.
-        CI.getLangOpts().CommentOpts.ParseAllComments = true;
-        return WrapperFrontendAction::BeginInvocation(CI);
-      }
-
-      void EndSourceFileAction() override {
-        WrapperFrontendAction::EndSourceFileAction();
-
-        const auto &CI = getCompilerInstance();
-        if (CI.hasDiagnostics() &&
-            CI.getDiagnostics().hasUncompilableErrorOccurred()) {
-          llvm::errs()
-              << "Found uncompilable errors in the translation unit. Igoring "
-                 "collected symbols...\n";
-          return;
-        }
-
-        Consumer.consumeSymbols(Collector->takeSymbols());
-      }
-
-    private:
-      SymbolsConsumer &Consumer;
-      std::shared_ptr<SymbolCollector> Collector;
-      std::unique_ptr<CanonicalIncludes> Includes;
-      std::unique_ptr<CommentHandler> PragmaHandler;
-    };
-
-    index::IndexingOptions IndexOpts;
-    IndexOpts.SystemSymbolFilter =
-        index::IndexingOptions::SystemSymbolFilterKind::All;
-    IndexOpts.IndexFunctionLocals = false;
     auto CollectorOpts = SymbolCollector::Options();
     CollectorOpts.FallbackDir = AssumedHeaderDir;
-    CollectorOpts.CollectIncludePath = true;
-    CollectorOpts.CountReferences = true;
-    CollectorOpts.Origin = SymbolOrigin::Static;
-    auto Includes = llvm::make_unique<CanonicalIncludes>();
-    addSystemHeadersMapping(Includes.get());
-    CollectorOpts.Includes = Includes.get();
-    return new WrappedIndexAction(
-        std::make_shared<SymbolCollector>(std::move(CollectorOpts)),
-        std::move(Includes), IndexOpts, Consumer);
+    return createStaticIndexingAction(
+               CollectorOpts,
+               [&](SymbolSlab S) { Consumer.consumeSymbols(std::move(S)); })
+        .release();
   }
 
   SymbolsConsumer &Consumer;