Recommit "[ClangTidy] Add UsingInserter and NamespaceAliaser"

Summary: This adds helper classes to add using declaractions and namespace aliases to function bodies. These help making function calls to deeply nested functions concise (e.g. when calling helpers in a refactoring)

Patch by Julian Bangert!

Reviewers: alexfh, hokein

Subscribers: beanz, mgorny, cfe-commits

Differential Revision: https://reviews.llvm.org/D24997

llvm-svn: 284368

1 files changed, 52 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
new file mode 100644
index 00000000000..e56d69d3d79
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/utils/NamespaceAliaser.h
@@ -0,0 +1,52 @@
+//===---------- NamespaceAliaser.h - clang-tidy ---------------------------===//
+//
+//                     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_CLANG_TIDY_NAMESPACEALIASER_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_NAMESPACEALIASER_H
+
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/SourceManager.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringMap.h"
+#include <map>
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+// This class creates function-level namespace aliases.
+class NamespaceAliaser {
+public:
+  explicit NamespaceAliaser(const SourceManager &SourceMgr);
+  // Adds a namespace alias for \p Namespace valid near \p
+  // Statement. Picks the first available name from \p Abbreviations.
+  // Returns ``llvm::None`` if an alias already exists or there is an error.
+  llvm::Optional<FixItHint>
+  createAlias(ASTContext &Context, const Stmt &Statement,
+              llvm::StringRef Namespace,
+              const std::vector<std::string> &Abbreviations);
+
+  // Get an alias name for \p Namespace valid at \p Statement. Returns \p
+  // Namespace if there is no alias.
+  std::string getNamespaceName(ASTContext &Context, const Stmt &Statement,
+                               llvm::StringRef Namespace) const;
+
+private:
+  const SourceManager &SourceMgr;
+  llvm::DenseMap<const FunctionDecl *, llvm::StringMap<std::string>>
+      AddedAliases;
+};
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_NAMESPACEALIASER_H