lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.h

   1 //===-- CxxModuleHandler.h --------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CXXMODULEHANDLER_H
  10 #define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CXXMODULEHANDLER_H
  11
  12 #include "clang/AST/ASTImporter.h"
  13 #include "clang/Sema/Sema.h"
  14 #include "llvm/ADT/StringSet.h"
  15 #include <optional>
  16
  17 namespace lldb_private {
  18
  19 /// Handles importing decls into an ASTContext with an attached C++ module.
  20 ///
  21 /// This class searches a C++ module (which must be attached to the target
  22 /// ASTContext) for an equivalent decl to the one that should be imported.
  23 /// If the decl that is found in the module is a suitable replacement
  24 /// for the decl that should be imported, the module decl will be treated as
  25 /// the result of the import process.
  26 ///
  27 /// If the Decl that should be imported is a template specialization
  28 /// that doesn't exist yet in the target ASTContext (e.g. `std::vector<int>`),
  29 /// then this class tries to create the template specialization in the target
  30 /// ASTContext. This is only possible if the CxxModuleHandler can determine
  31 /// that instantiating this template is safe to do, e.g. because the target
  32 /// decl is a container class from the STL.
  33 class CxxModuleHandler {
  34   /// The ASTImporter that should be used to import any Decls which aren't
  35   /// directly handled by this class itself.
  36   clang::ASTImporter *m_importer = nullptr;
  37
  38   /// The Sema instance of the target ASTContext.
  39   clang::Sema *m_sema = nullptr;
  40
  41   /// List of template names this class currently supports. These are the
  42   /// template names inside the 'std' namespace such as 'vector' or 'list'.
  43   llvm::StringSet<> m_supported_templates;
  44
  45   /// Tries to manually instantiate the given foreign template in the target
  46   /// context (designated by m_sema).
  47   std::optional<clang::Decl *> tryInstantiateStdTemplate(clang::Decl *d);
  48
  49 public:
  50   CxxModuleHandler() = default;
  51   CxxModuleHandler(clang::ASTImporter &importer, clang::ASTContext *target);
  52
  53   /// Attempts to import the given decl into the target ASTContext by
  54   /// deserializing it from the 'std' module. This function returns a Decl if a
  55   /// Decl has been deserialized from the 'std' module. Otherwise this function
  56   /// returns nothing.
  57   std::optional<clang::Decl *> Import(clang::Decl *d);
  58
  59   /// Returns true iff this instance is capable of importing any declarations
  60   /// in the target ASTContext.
  61   bool isValid() const { return m_sema != nullptr; }
  62 };
  63
  64 } // namespace lldb_private
  65
  66 #endif // LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CXXMODULEHANDLER_H