[clangd] Introduced Logger interface.

Summary: This fixes a bunch of logging-related FIXMEs.

Reviewers: bkramer, krasimir, malaperle

Reviewed By: malaperle

Subscribers: malaperle, klimek, cfe-commits, mgorny

Differential Revision: https://reviews.llvm.org/D37972

llvm-svn: 313730

1 files changed, 41 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/Logger.h b/clang-tools-extra/clangd/Logger.h
new file mode 100644
index 00000000000..7cf05561433
--- /dev/null
+++ b/clang-tools-extra/clangd/Logger.h
@@ -0,0 +1,41 @@
+//===--- Logger.h - Logger interface for clangd ------------------*- 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_LOGGER_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANGD_LOGGER_H
+
+#include "llvm/ADT/Twine.h"
+
+namespace clang {
+namespace clangd {
+
+/// Interface to allow custom logging in clangd.
+class Logger {
+public:
+  virtual ~Logger() = default;
+
+  /// Implementations of this method must be thread-safe.
+  virtual void log(const llvm::Twine &Message) = 0;
+};
+
+/// Logger implementation that ignores all messages.
+class EmptyLogger : public Logger {
+public:
+  static EmptyLogger &getInstance();
+
+  void log(const llvm::Twine &Message) override;
+
+private:
+  EmptyLogger() = default;
+};
+
+} // namespace clangd
+} // namespace clang
+
+#endif