//===--- FileUnit.h - The contents of a module ------------------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//

#ifndef SWIFT_AST_FILEUNIT_H
#define SWIFT_AST_FILEUNIT_H

#include "swift/AST/Module.h"

namespace swift {
static inline unsigned alignOfFileUnit();

/// A container for module-scope declarations that itself provides a scope; the
/// smallest unit of code organization.
///
/// FileUnit is an abstract base class; its subclasses represent different
/// sorts of containers that can each provide a set of decls, e.g. a source
/// file. A module can contain several file-units.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wnon-virtual-dtor"
class FileUnit : public DeclContext {
#pragma clang diagnostic pop
  virtual void anchor();

  // FIXME: Stick this in a PointerIntPair.
  const FileUnitKind Kind;

protected:
  FileUnit(FileUnitKind kind, ModuleDecl &M)
    : DeclContext(DeclContextKind::FileUnit, &M), Kind(kind) {
  }

public:
  FileUnitKind getKind() const {
    return Kind;
  }

  /// Look up a (possibly overloaded) value set at top-level scope
  /// (but with the specified access path, which may come from an import decl)
  /// within this file.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  virtual void lookupValue(DeclName name, NLKind lookupKind,
                           SmallVectorImpl<ValueDecl*> &result) const = 0;

  /// Look up a local type declaration by its mangled name.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  virtual TypeDecl *lookupLocalType(StringRef MangledName) const {
    return nullptr;
  }

  /// Look up an opaque return type by the mangled name of the declaration
  /// that defines it.
  virtual OpaqueTypeDecl *lookupOpaqueResultType(StringRef MangledName) {
    return nullptr;
  }

  /// Directly look for a nested type declared within this module inside the
  /// given nominal type (including any extensions).
  ///
  /// This is a fast-path hack to avoid circular dependencies in deserialization
  /// and the Clang importer.
  ///
  /// Private and fileprivate types should not be returned by this lookup.
  virtual TypeDecl *lookupNestedType(Identifier name,
                                     const NominalTypeDecl *parent) const {
    return nullptr;
  }

  /// Find ValueDecls in the module and pass them to the given consumer object.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  virtual void lookupVisibleDecls(ModuleDecl::AccessPathTy accessPath,
                                  VisibleDeclConsumer &consumer,
                                  NLKind lookupKind) const {}

  /// Finds all class members defined in this file.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  virtual void lookupClassMembers(ModuleDecl::AccessPathTy accessPath,
                                  VisibleDeclConsumer &consumer) const {}

  /// Finds class members defined in this file with the given name.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  virtual void lookupClassMember(ModuleDecl::AccessPathTy accessPath,
                                 DeclName name,
                                 SmallVectorImpl<ValueDecl*> &results) const {}

  /// Find all Objective-C methods with the given selector.
  virtual void lookupObjCMethods(
                 ObjCSelector selector,
                 SmallVectorImpl<AbstractFunctionDecl *> &results) const = 0;

  /// Returns the comment attached to the given declaration.
  ///
  /// This function is an implementation detail for comment serialization.
  /// If you just want to get a comment attached to a decl, use
  /// \c Decl::getRawComment() or \c Decl::getBriefComment().
  virtual Optional<CommentInfo>
  getCommentForDecl(const Decl *D) const {
    return None;
  }

  virtual Optional<StringRef>
  getGroupNameForDecl(const Decl *D) const {
    return None;
  }

  virtual Optional<StringRef>
  getSourceFileNameForDecl(const Decl *D) const {
    return None;
  }

  virtual Optional<unsigned>
  getSourceOrderForDecl(const Decl *D) const {
    return None;
  }

  virtual Optional<StringRef>
  getGroupNameByUSR(StringRef USR) const {
    return None;
  }

  virtual void collectAllGroups(std::vector<StringRef> &Names) const {}

  /// Returns an implementation-defined "discriminator" for \p D, which
  /// distinguishes \p D from other declarations in the same module with the
  /// same name.
  ///
  /// Since this value is used in name mangling, it should be a valid ASCII-only
  /// identifier.
  virtual Identifier
  getDiscriminatorForPrivateValue(const ValueDecl *D) const = 0;

  /// Finds all top-level decls in this file.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  /// The order of the results is not guaranteed to be meaningful.
  virtual void getTopLevelDecls(SmallVectorImpl<Decl*> &results) const {}


  /// Finds all precedence group decls in this file.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  /// The order of the results is not guaranteed to be meaningful.
  virtual void
  getPrecedenceGroups(SmallVectorImpl<PrecedenceGroupDecl*> &Results) const {}

  /// Finds all local type decls in this file.
  ///
  /// This does a simple local lookup, not recursively looking through imports.
  /// The order of the results is not guaranteed to be meaningful.
  virtual void getLocalTypeDecls(SmallVectorImpl<TypeDecl*> &results) const {}

  virtual void
  getOpaqueReturnTypeDecls(SmallVectorImpl<OpaqueTypeDecl*> &results) const {}

  /// Adds all top-level decls to the given vector.
  ///
  /// This includes all decls that should be displayed to clients of the module.
  /// The order of the results is not guaranteed to be meaningful.
  ///
  /// This can differ from \c getTopLevelDecls, e.g. it returns decls from a
  /// shadowed clang module.
  virtual void getDisplayDecls(SmallVectorImpl<Decl*> &results) const {
    getTopLevelDecls(results);
  }

  /// Looks up which modules are imported by this file.
  ///
  /// \p filter controls whether public, private, or any imports are included
  /// in this list.
  virtual void
  getImportedModules(SmallVectorImpl<ModuleDecl::ImportedModule> &imports,
                     ModuleDecl::ImportFilter filter) const {}

  /// \see ModuleDecl::getImportedModulesForLookup
  virtual void getImportedModulesForLookup(
      SmallVectorImpl<ModuleDecl::ImportedModule> &imports) const {
    return getImportedModules(imports, ModuleDecl::ImportFilterKind::Public);
  }

  /// Generates the list of libraries needed to link this file, based on its
  /// imports.
  virtual void
  collectLinkLibraries(ModuleDecl::LinkLibraryCallback callback) const {}

  /// True if this file contains the main class for the module.
  bool hasMainClass() const {
    return getMainClass();
  }
  virtual ClassDecl *getMainClass() const {
    assert(hasEntryPoint());
    return nullptr;
  }
  virtual bool hasEntryPoint() const {
    return false;
  }

  /// Returns the associated clang module if one exists.
  virtual const clang::Module *getUnderlyingClangModule() const {
    return nullptr;
  }

  /// Returns the name to use when referencing entities in this file.
  ///
  /// Usually this is the module name itself, but certain Clang features allow
  /// substituting another name instead.
  virtual StringRef getExportedModuleName() const {
    return getParentModule()->getName().str();
  }

  /// Traverse the decls within this file.
  ///
  /// \returns true if traversal was aborted, false if it completed
  /// successfully.
  virtual bool walk(ASTWalker &walker);

  // Efficiency override for DeclContext::getParentModule().
  ModuleDecl *getParentModule() const {
    return const_cast<ModuleDecl *>(cast<ModuleDecl>(getParent()));
  }

  static bool classof(const DeclContext *DC) {
    return DC->getContextKind() == DeclContextKind::FileUnit;
  }

private:
  // Make placement new and vanilla new/delete illegal for FileUnits.
  void *operator new(size_t Bytes) throw() = delete;
  void *operator new(size_t Bytes, void *Mem) throw() = delete;
  void operator delete(void *Data) throw() = delete;

public:
  // Only allow allocation of FileUnits using the allocator in ASTContext
  // or by doing a placement new.
  void *operator new(size_t Bytes, ASTContext &C,
                     unsigned Alignment = alignOfFileUnit());
};

static inline unsigned alignOfFileUnit() {
  return alignof(FileUnit&);
}

/// This represents the compiler's implicitly generated declarations in the
/// Builtin module.
class BuiltinUnit final : public FileUnit {
public:
  class LookupCache;

private:
  std::unique_ptr<LookupCache> Cache;
  LookupCache &getCache() const;

  friend ASTContext;
  ~BuiltinUnit() = default;

public:
  explicit BuiltinUnit(ModuleDecl &M);

  virtual void lookupValue(DeclName name, NLKind lookupKind,
                           SmallVectorImpl<ValueDecl*> &result) const override;

  /// Find all Objective-C methods with the given selector.
  void lookupObjCMethods(
         ObjCSelector selector,
         SmallVectorImpl<AbstractFunctionDecl *> &results) const override;

  Identifier
  getDiscriminatorForPrivateValue(const ValueDecl *D) const override {
    llvm_unreachable("no private values in the Builtin module");
  }

  static bool classof(const FileUnit *file) {
    return file->getKind() == FileUnitKind::Builtin;
  }

  static bool classof(const DeclContext *DC) {
    return isa<FileUnit>(DC) && classof(cast<FileUnit>(DC));
  }
};

/// Represents an externally-loaded file of some kind.
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wnon-virtual-dtor"
class LoadedFile : public FileUnit {
#pragma clang diagnostic pop
protected:
  LoadedFile(FileUnitKind Kind, ModuleDecl &M) noexcept
    : FileUnit(Kind, M) {
    assert(classof(this) && "invalid kind");
  }
public:
  /// Returns an arbitrary string representing the storage backing this file.
  ///
  /// This is usually a filesystem path.
  virtual StringRef getFilename() const;

  virtual StringRef getFilenameForPrivateDecl(const ValueDecl *decl) const {
    return StringRef();
  }

  /// Look up an operator declaration.
  ///
  /// \param name The operator name ("+", ">>", etc.)
  ///
  /// \param fixity One of PrefixOperator, InfixOperator, or PostfixOperator.
  virtual OperatorDecl *lookupOperator(Identifier name, DeclKind fixity) const {
    return nullptr;
  }

  /// Look up a precedence group.
  ///
  /// \param name The precedence group name.
  virtual PrecedenceGroupDecl *lookupPrecedenceGroup(Identifier name) const {
    return nullptr;
  }

  /// Returns the Swift module that overlays a Clang module.
  virtual ModuleDecl *getOverlayModule() const { return nullptr; }

  virtual bool isSystemModule() const { return false; }

  /// Retrieve the set of generic signatures stored within this module.
  ///
  /// \returns \c true if this module file supports retrieving all of the
  /// generic signatures, \c false otherwise.
  virtual bool getAllGenericSignatures(
                 SmallVectorImpl<GenericSignature> &genericSignatures) {
    return false;
  }

  static bool classof(const FileUnit *file) {
    return file->getKind() == FileUnitKind::SerializedAST ||
           file->getKind() == FileUnitKind::ClangModule ||
           file->getKind() == FileUnitKind::DWARFModule;
  }
  static bool classof(const DeclContext *DC) {
    return isa<FileUnit>(DC) && classof(cast<FileUnit>(DC));
  }
};


inline FileUnit &ModuleDecl::getMainFile(FileUnitKind expectedKind) const {
  assert(expectedKind != FileUnitKind::Source &&
         "must use specific source kind; see getMainSourceFile");
  assert(!Files.empty() && "No files added yet");
  assert(Files.front()->getKind() == expectedKind);
  return *Files.front();
}

} // end namespace swift

#endif