[clangd] Introduce a "Symbol" class.

Summary:
* The "Symbol" class represents a C++ symbol in the codebase, containing all the
  information of a C++ symbol needed by clangd. clangd will use it in clangd's
  AST/dynamic index and global/static index (code completion and code
  navigation).
* The SymbolCollector (another IndexAction) will be used to recollect the
  symbols when the source file is changed (for ASTIndex), or to generate
  all C++ symbols for the whole project.

In the long term (when index-while-building is ready), clangd should share a
same "Symbol" structure and IndexAction with index-while-building, but
for now we want to have some stuff working in clangd.

Reviewers: ioeric, sammccall, ilya-biryukov, malaperle

Reviewed By: sammccall

Subscribers: malaperle, klimek, mgorny, cfe-commits

Differential Revision: https://reviews.llvm.org/D40897

llvm-svn: 320486

1 files changed, 49 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/index/Index.cpp b/clang-tools-extra/clangd/index/Index.cpp
new file mode 100644
index 00000000000..1914cf57df2
--- /dev/null
+++ b/clang-tools-extra/clangd/index/Index.cpp
@@ -0,0 +1,49 @@
+//===--- Index.cpp -----------------------------------------------*- C++-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Index.h"
+
+#include "llvm/Support/SHA1.h"
+
+namespace clang {
+namespace clangd {
+
+namespace {
+ArrayRef<uint8_t> toArrayRef(StringRef S) {
+  return {reinterpret_cast<const uint8_t *>(S.data()), S.size()};
+}
+} // namespace
+
+SymbolID::SymbolID(llvm::StringRef USR)
+    : HashValue(llvm::SHA1::hash(toArrayRef(USR))) {}
+
+SymbolSlab::const_iterator SymbolSlab::begin() const {
+  return Symbols.begin();
+}
+
+SymbolSlab::const_iterator SymbolSlab::end() const {
+  return Symbols.end();
+}
+
+SymbolSlab::const_iterator SymbolSlab::find(const SymbolID& SymID) const {
+  return Symbols.find(SymID);
+}
+
+void SymbolSlab::freeze() {
+  Frozen = true;
+}
+
+void SymbolSlab::insert(Symbol S) {
+  assert(!Frozen &&
+         "Can't insert a symbol after the slab has been frozen!");
+  Symbols[S.ID] = std::move(S);
+}
+
+} // namespace clangd
+} // namespace clang