1 files changed, 141 insertions, 0 deletions
diff --git a/clang/lib/AST/ASTImporterLookupTable.cpp b/clang/lib/AST/ASTImporterLookupTable.cpp
new file mode 100644
index 000000000000..7390329d4ed8
--- /dev/null
+++ b/clang/lib/AST/ASTImporterLookupTable.cpp
@@ -0,0 +1,141 @@
+//===- ASTImporterLookupTable.cpp - ASTImporter specific lookup -----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the ASTImporterLookupTable class which implements a
+//  lookup procedure for the import mechanism.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTImporterLookupTable.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/RecursiveASTVisitor.h"
+
+namespace clang {
+
+namespace {
+
+struct Builder : RecursiveASTVisitor<Builder> {
+  ASTImporterLookupTable &LT;
+  Builder(ASTImporterLookupTable &LT) : LT(LT) {}
+  bool VisitNamedDecl(NamedDecl *D) {
+    LT.add(D);
+    return true;
+  }
+  // In most cases the FriendDecl contains the declaration of the befriended
+  // class as a child node, so it is discovered during the recursive
+  // visitation. However, there are cases when the befriended class is not a
+  // child, thus it must be fetched explicitly from the FriendDecl, and only
+  // then can we add it to the lookup table.
+  bool VisitFriendDecl(FriendDecl *D) {
+    if (D->getFriendType()) {
+      QualType Ty = D->getFriendType()->getType();
+      if (isa<ElaboratedType>(Ty))
+        Ty = cast<ElaboratedType>(Ty)->getNamedType();
+      // A FriendDecl with a dependent type (e.g. ClassTemplateSpecialization)
+      // always has that decl as child node.
+      // However, there are non-dependent cases which does not have the
+      // type as a child node. We have to dig up that type now.
+      if (!Ty->isDependentType()) {
+        if (const auto *RTy = dyn_cast<RecordType>(Ty))
+          LT.add(RTy->getAsCXXRecordDecl());
+        else if (const auto *SpecTy = dyn_cast<TemplateSpecializationType>(Ty))
+          LT.add(SpecTy->getAsCXXRecordDecl());
+        else if (isa<TypedefType>(Ty)) {
+          // We do not put friend typedefs to the lookup table because
+          // ASTImporter does not organize typedefs into redecl chains.
+        } else {
+          llvm_unreachable("Unhandled type of friend class");
+        }
+      }
+    }
+    return true;
+  }
+
+  // Override default settings of base.
+  bool shouldVisitTemplateInstantiations() const { return true; }
+  bool shouldVisitImplicitCode() const { return true; }
+};
+
+} // anonymous namespace
+
+ASTImporterLookupTable::ASTImporterLookupTable(TranslationUnitDecl &TU) {
+  Builder B(*this);
+  B.TraverseDecl(&TU);
+}
+
+void ASTImporterLookupTable::add(DeclContext *DC, NamedDecl *ND) {
+  DeclList &Decls = LookupTable[DC][ND->getDeclName()];
+  // Inserts if and only if there is no element in the container equal to it.
+  Decls.insert(ND);
+}
+
+void ASTImporterLookupTable::remove(DeclContext *DC, NamedDecl *ND) {
+  DeclList &Decls = LookupTable[DC][ND->getDeclName()];
+  bool EraseResult = Decls.remove(ND);
+  (void)EraseResult;
+  assert(EraseResult == true && "Trying to remove not contained Decl");
+}
+
+void ASTImporterLookupTable::add(NamedDecl *ND) {
+  assert(ND);
+  DeclContext *DC = ND->getDeclContext()->getPrimaryContext();
+  add(DC, ND);
+  DeclContext *ReDC = DC->getRedeclContext()->getPrimaryContext();
+  if (DC != ReDC)
+    add(ReDC, ND);
+}
+
+void ASTImporterLookupTable::remove(NamedDecl *ND) {
+  assert(ND);
+  DeclContext *DC = ND->getDeclContext()->getPrimaryContext();
+  remove(DC, ND);
+  DeclContext *ReDC = DC->getRedeclContext()->getPrimaryContext();
+  if (DC != ReDC)
+    remove(ReDC, ND);
+}
+
+ASTImporterLookupTable::LookupResult
+ASTImporterLookupTable::lookup(DeclContext *DC, DeclarationName Name) const {
+  auto DCI = LookupTable.find(DC->getPrimaryContext());
+  if (DCI == LookupTable.end())
+    return {};
+
+  const auto &FoundNameMap = DCI->second;
+  auto NamesI = FoundNameMap.find(Name);
+  if (NamesI == FoundNameMap.end())
+    return {};
+
+  return NamesI->second;
+}
+
+void ASTImporterLookupTable::dump(DeclContext *DC) const {
+  auto DCI = LookupTable.find(DC->getPrimaryContext());
+  if (DCI == LookupTable.end())
+    llvm::errs() << "empty\n";
+  const auto &FoundNameMap = DCI->second;
+  for (const auto &Entry : FoundNameMap) {
+    DeclarationName Name = Entry.first;
+    llvm::errs() << "==== Name: ";
+    Name.dump();
+    const DeclList& List = Entry.second;
+    for (NamedDecl *ND : List) {
+      ND->dump();
+    }
+  }
+}
+
+void ASTImporterLookupTable::dump() const {
+  for (const auto &Entry : LookupTable) {
+    DeclContext *DC = Entry.first;
+    StringRef Primary = DC->getPrimaryContext() ? " primary" : "";
+    llvm::errs() << "== DC:" << cast<Decl>(DC) << Primary << "\n";
+    dump(DC);
+  }
+}
+
+} // namespace clang