//===- clang/Basic/DirectoryEntry.h - Directory references ------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Defines interfaces for clang::DirectoryEntry and clang::DirectoryEntryRef.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_BASIC_DIRECTORYENTRY_H
#define LLVM_CLANG_BASIC_DIRECTORYENTRY_H
#include "clang/Basic/CustomizableOptional.h"
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/ErrorOr.h"
#include <optional>
#include <utility>
namespace clang {
namespace FileMgr {
template <class RefTy> class MapEntryOptionalStorage;
} // end namespace FileMgr
/// Cached information about one directory (either on disk or in
/// the virtual file system).
class DirectoryEntry {
DirectoryEntry() = default;
DirectoryEntry(const DirectoryEntry &) = delete;
DirectoryEntry &operator=(const DirectoryEntry &) = delete;
friend class FileManager;
friend class FileEntryTestHelper;
// FIXME: We should not be storing a directory entry name here.
StringRef Name; // Name of the directory.
public:
StringRef getName() const { return Name; }
};
/// A reference to a \c DirectoryEntry that includes the name of the directory
/// as it was accessed by the FileManager's client.
class DirectoryEntryRef {
public:
const DirectoryEntry &getDirEntry() const { return *ME->getValue(); }
StringRef getName() const { return ME->getKey(); }
/// Hash code is based on the DirectoryEntry, not the specific named
/// reference.
friend llvm::hash_code hash_value(DirectoryEntryRef Ref) {
return llvm::hash_value(&Ref.getDirEntry());
}
using MapEntry = llvm::StringMapEntry<llvm::ErrorOr<DirectoryEntry &>>;
const MapEntry &getMapEntry() const { return *ME; }
/// Check if RHS referenced the file in exactly the same way.
bool isSameRef(DirectoryEntryRef RHS) const { return ME == RHS.ME; }
DirectoryEntryRef() = delete;
DirectoryEntryRef(const MapEntry &ME) : ME(&ME) {}
/// Allow DirectoryEntryRef to degrade into 'const DirectoryEntry*' to
/// facilitate incremental adoption.
///
/// The goal is to avoid code churn due to dances like the following:
/// \code
/// // Old code.
/// lvalue = rvalue;
///
/// // Temporary code from an incremental patch.
/// lvalue = &rvalue.getDirectoryEntry();
///
/// // Final code.
/// lvalue = rvalue;
/// \endcode
///
/// FIXME: Once DirectoryEntryRef is "everywhere" and DirectoryEntry::getName
/// has been deleted, delete this implicit conversion.
operator const DirectoryEntry *() const { return &getDirEntry(); }
private:
friend class FileMgr::MapEntryOptionalStorage<DirectoryEntryRef>;
struct optional_none_tag {};
// Private constructor for use by OptionalStorage.
DirectoryEntryRef(optional_none_tag) : ME(nullptr) {}
bool hasOptionalValue() const { return ME; }
friend struct llvm::DenseMapInfo<DirectoryEntryRef>;
struct dense_map_empty_tag {};
struct dense_map_tombstone_tag {};
// Private constructors for use by DenseMapInfo.
DirectoryEntryRef(dense_map_empty_tag)
: ME(llvm::DenseMapInfo<const MapEntry *>::getEmptyKey()) {}
DirectoryEntryRef(dense_map_tombstone_tag)
: ME(llvm::DenseMapInfo<const MapEntry *>::getTombstoneKey()) {}
bool isSpecialDenseMapKey() const {
return isSameRef(DirectoryEntryRef(dense_map_empty_tag())) ||
isSameRef(DirectoryEntryRef(dense_map_tombstone_tag()));
}
const MapEntry *ME;
};
using OptionalDirectoryEntryRef = CustomizableOptional<DirectoryEntryRef>;
namespace FileMgr {
/// Customized storage for refs derived from map entires in FileManager, using
/// the private optional_none_tag to keep it to the size of a single pointer.
template <class RefTy> class MapEntryOptionalStorage {
using optional_none_tag = typename RefTy::optional_none_tag;
RefTy MaybeRef;
public:
MapEntryOptionalStorage() : MaybeRef(optional_none_tag()) {}
template <class... ArgTypes>
explicit MapEntryOptionalStorage(std::in_place_t, ArgTypes &&...Args)
: MaybeRef(std::forward<ArgTypes>(Args)...) {}
void reset() { MaybeRef = optional_none_tag(); }
bool has_value() const { return MaybeRef.hasOptionalValue(); }
RefTy &value() & {
assert(has_value());
return MaybeRef;
}
RefTy const &value() const & {
assert(has_value());
return MaybeRef;
}
RefTy &&value() && {
assert(has_value());
return std::move(MaybeRef);
}
template <class... Args> void emplace(Args &&...args) {
MaybeRef = RefTy(std::forward<Args>(args)...);
}
MapEntryOptionalStorage &operator=(RefTy Ref) {
MaybeRef = Ref;
return *this;
}
};
} // end namespace FileMgr
namespace optional_detail {
/// Customize OptionalStorage<DirectoryEntryRef> to use DirectoryEntryRef and
/// its optional_none_tag to keep it the size of a single pointer.
template <>
class OptionalStorage<clang::DirectoryEntryRef>
: public clang::FileMgr::MapEntryOptionalStorage<clang::DirectoryEntryRef> {
using StorageImpl =
clang::FileMgr::MapEntryOptionalStorage<clang::DirectoryEntryRef>;
public:
OptionalStorage() = default;
template <class... ArgTypes>
explicit OptionalStorage(std::in_place_t, ArgTypes &&...Args)
: StorageImpl(std::in_place_t{}, std::forward<ArgTypes>(Args)...) {}
OptionalStorage &operator=(clang::DirectoryEntryRef Ref) {
StorageImpl::operator=(Ref);
return *this;
}
};
static_assert(sizeof(OptionalDirectoryEntryRef) == sizeof(DirectoryEntryRef),
"OptionalDirectoryEntryRef must avoid size overhead");
static_assert(std::is_trivially_copyable<OptionalDirectoryEntryRef>::value,
"OptionalDirectoryEntryRef should be trivially copyable");
} // end namespace optional_detail
} // namespace clang
namespace llvm {
/// Specialisation of DenseMapInfo for DirectoryEntryRef.
template <> struct DenseMapInfo<clang::DirectoryEntryRef> {
static inline clang::DirectoryEntryRef getEmptyKey() {
return clang::DirectoryEntryRef(
clang::DirectoryEntryRef::dense_map_empty_tag());
}
static inline clang::DirectoryEntryRef getTombstoneKey() {
return clang::DirectoryEntryRef(
clang::DirectoryEntryRef::dense_map_tombstone_tag());
}
static unsigned getHashValue(clang::DirectoryEntryRef Val) {
return hash_value(Val);
}
static bool isEqual(clang::DirectoryEntryRef LHS,
clang::DirectoryEntryRef RHS) {
// Catch the easy cases: both empty, both tombstone, or the same ref.
if (LHS.isSameRef(RHS))
return true;
// Confirm LHS and RHS are valid.
if (LHS.isSpecialDenseMapKey() || RHS.isSpecialDenseMapKey())
return false;
// It's safe to use operator==.
return LHS == RHS;
}
};
} // end namespace llvm
namespace clang {
/// Wrapper around OptionalDirectoryEntryRef that degrades to 'const
/// DirectoryEntry*', facilitating incremental patches to propagate
/// DirectoryEntryRef.
///
/// This class can be used as return value or field where it's convenient for
/// an OptionalDirectoryEntryRef to degrade to a 'const DirectoryEntry*'. The
/// purpose is to avoid code churn due to dances like the following:
/// \code
/// // Old code.
/// lvalue = rvalue;
///
/// // Temporary code from an incremental patch.
/// OptionalDirectoryEntryRef MaybeF = rvalue;
/// lvalue = MaybeF ? &MaybeF.getDirectoryEntry() : nullptr;
///
/// // Final code.
/// lvalue = rvalue;
/// \endcode
///
/// FIXME: Once DirectoryEntryRef is "everywhere" and DirectoryEntry::LastRef
/// and DirectoryEntry::getName have been deleted, delete this class and
/// replace instances with OptionalDirectoryEntryRef.
class OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr
: public OptionalDirectoryEntryRef {
public:
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr() = default;
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr(
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &&) = default;
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr(
const OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &) = default;
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &
operator=(OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &&) = default;
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &
operator=(const OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &) = default;
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr(std::nullopt_t) {}
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr(DirectoryEntryRef Ref)
: OptionalDirectoryEntryRef(Ref) {}
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr(
OptionalDirectoryEntryRef MaybeRef)
: OptionalDirectoryEntryRef(MaybeRef) {}
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &
operator=(std::nullopt_t) {
OptionalDirectoryEntryRef::operator=(std::nullopt);
return *this;
}
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &operator=(DirectoryEntryRef Ref) {
OptionalDirectoryEntryRef::operator=(Ref);
return *this;
}
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr &
operator=(OptionalDirectoryEntryRef MaybeRef) {
OptionalDirectoryEntryRef::operator=(MaybeRef);
return *this;
}
/// Degrade to 'const DirectoryEntry *' to allow DirectoryEntry::LastRef and
/// DirectoryEntry::getName have been deleted, delete this class and replace
/// instances with OptionalDirectoryEntryRef
operator const DirectoryEntry *() const {
return has_value() ? &(*this)->getDirEntry() : nullptr;
}
};
static_assert(std::is_trivially_copyable<
OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr>::value,
"OptionalDirectoryEntryRefDegradesToDirectoryEntryPtr should be "
"trivially copyable");
} // end namespace clang
#endif // LLVM_CLANG_BASIC_DIRECTORYENTRY_H