//===- ModuleLoader.h - Module Loader Interface -----------------*- C++ -*-===//

//

// 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 ModuleLoader interface, which is responsible for

//  loading named modules.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LEX_MODULELOADER_H

#define LLVM_CLANG_LEX_MODULELOADER_H

#include "clang/Basic/LLVM.h"

#include "clang/Basic/Module.h"

#include "clang/Basic/SourceLocation.h"

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/PointerIntPair.h"

#include "llvm/ADT/StringRef.h"

#include <utility>

namespace clang {

class GlobalModuleIndex;

class IdentifierInfo;

/// A sequence of identifier/location pairs used to describe a particular

/// module or submodule, e.g., std.vector.

using ModuleIdPath = ArrayRef<std::pair<IdentifierInfo *, SourceLocation>>;

/// Describes the result of attempting to load a module.

class ModuleLoadResult {

public:

  enum LoadResultKind {

    // We either succeeded or failed to load the named module.

    Normal,

    // The module exists, but does not actually contain the named submodule.

    // This should only happen if the named submodule was inferred from an

    // umbrella directory, but not actually part of the umbrella header.

    MissingExpected,

    // The module exists but cannot be imported due to a configuration mismatch.

    ConfigMismatch,

  };

  llvm::PointerIntPair<Module *, 2, LoadResultKind> Storage;

  ModuleLoadResult() = default;

  ModuleLoadResult(Module *M) : Storage(M, Normal) {}

  ModuleLoadResult(LoadResultKind Kind) : Storage(nullptr, Kind) {}

  operator Module *() const { return Storage.getPointer(); }

  /// Determines whether this is a normal return, whether or not loading the

  /// module was successful.

  bool isNormal() const { return Storage.getInt() == Normal; }

  /// Determines whether the module, which failed to load, was

  /// actually a submodule that we expected to see (based on implying the

  /// submodule from header structure), but didn't materialize in the actual

  /// module.

  bool isMissingExpected() const { return Storage.getInt() == MissingExpected; }

  /// Determines whether the module failed to load due to a configuration

  /// mismatch with an explicitly-named .pcm file from the command line.

  bool isConfigMismatch() const { return Storage.getInt() == ConfigMismatch; }

};

/// Abstract interface for a module loader.

///

/// This abstract interface describes a module loader, which is responsible

/// for resolving a module name (e.g., "std") to an actual module file, and

/// then loading that module.

class ModuleLoader {

  // Building a module if true.

  bool BuildingModule;

public:

  explicit ModuleLoader(bool BuildingModule = false)

      : BuildingModule(BuildingModule) {}

  virtual ~ModuleLoader();

  /// Returns true if this instance is building a module.

  bool buildingModule() const {

    return BuildingModule;

  }

  /// Flag indicating whether this instance is building a module.

  void setBuildingModule(bool BuildingModuleFlag) {

    BuildingModule = BuildingModuleFlag;

  }

  /// Attempt to load the given module.

  ///

  /// This routine attempts to load the module described by the given

  /// parameters.  If there is a module cache, this may implicitly compile the

  /// module before loading it.

  ///

  /// \param ImportLoc The location of the 'import' keyword.

  ///

  /// \param Path The identifiers (and their locations) of the module

  /// "path", e.g., "std.vector" would be split into "std" and "vector".

  ///

  /// \param Visibility The visibility provided for the names in the loaded

  /// module.

  ///

  /// \param IsInclusionDirective Indicates that this module is being loaded

  /// implicitly, due to the presence of an inclusion directive. Otherwise,

  /// it is being loaded due to an import declaration.

  ///

  /// \returns If successful, returns the loaded module. Otherwise, returns

  /// NULL to indicate that the module could not be loaded.

  virtual ModuleLoadResult loadModule(SourceLocation ImportLoc,

                                      ModuleIdPath Path,

                                      Module::NameVisibilityKind Visibility,

                                      bool IsInclusionDirective) = 0;

  /// Attempt to create the given module from the specified source buffer.

  /// Does not load the module or make any submodule visible; for that, use

  /// loadModule and makeModuleVisible.

  ///

  /// \param Loc The location at which to create the module.

  /// \param ModuleName The name of the module to create.

  /// \param Source The source of the module: a (preprocessed) module map.

  virtual void createModuleFromSource(SourceLocation Loc, StringRef ModuleName,

                                      StringRef Source) = 0;

  /// Make the given module visible.

  virtual void makeModuleVisible(Module *Mod,

                                 Module::NameVisibilityKind Visibility,

                                 SourceLocation ImportLoc) = 0;

  /// Load, create, or return global module.

  /// This function returns an existing global module index, if one

  /// had already been loaded or created, or loads one if it

  /// exists, or creates one if it doesn't exist.

  /// Also, importantly, if the index doesn't cover all the modules

  /// in the module map, it will be update to do so here, because

  /// of its use in searching for needed module imports and

  /// associated fixit messages.

  /// \param TriggerLoc The location for what triggered the load.

  /// \returns Returns null if load failed.

  virtual GlobalModuleIndex *loadGlobalModuleIndex(

                                                SourceLocation TriggerLoc) = 0;

  /// Check global module index for missing imports.

  /// \param Name The symbol name to look for.

  /// \param TriggerLoc The location for what triggered the load.

  /// \returns Returns true if any modules with that symbol found.

  virtual bool lookupMissingImports(StringRef Name,

                                    SourceLocation TriggerLoc) = 0;

  bool HadFatalFailure = false;

};

/// A module loader that doesn't know how to create or load modules.

class TrivialModuleLoader : public ModuleLoader {

public:

  ModuleLoadResult loadModule(SourceLocation ImportLoc, ModuleIdPath Path,

                              Module::NameVisibilityKind Visibility,

                              bool IsInclusionDirective) override {

    return {};

  }

  void createModuleFromSource(SourceLocation ImportLoc, StringRef ModuleName,

                              StringRef Source) override {}

  void makeModuleVisible(Module *Mod, Module::NameVisibilityKind Visibility,

                         SourceLocation ImportLoc) override {}

  GlobalModuleIndex *loadGlobalModuleIndex(SourceLocation TriggerLoc) override {

    return nullptr;

  }

  bool lookupMissingImports(StringRef Name,

                            SourceLocation TriggerLoc) override {

    return false;

  }

};

} // namespace clang

#endif // LLVM_CLANG_LEX_MODULELOADER_H