llvm/llvm/include/llvm/ADT/StringMapEntry.h

//===- StringMapEntry.h - String Hash table map 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file defines the StringMapEntry class - it is intended to be a low
/// dependency implementation detail of StringMap that is more suitable for
/// inclusion in public headers than StringMap.h itself is.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_STRINGMAPENTRY_H
#define LLVM_ADT_STRINGMAPENTRY_H

#include "llvm/ADT/StringRef.h"
#include <optional>

namespace llvm {

/// StringMapEntryBase - Shared base class of StringMapEntry instances.
class StringMapEntryBase { … };

// Define out-of-line to dissuade inlining.
template <typename AllocatorTy>
void *StringMapEntryBase::allocateWithKey(size_t EntrySize, size_t EntryAlign,
                                          StringRef Key,
                                          AllocatorTy &Allocator) { … }

/// StringMapEntryStorage - Holds the value in a StringMapEntry.
///
/// Factored out into a separate base class to make it easier to specialize.
/// This is primarily intended to support StringSet, which doesn't need a value
/// stored at all.
template <typename ValueTy>
class StringMapEntryStorage : public StringMapEntryBase { … };

template <>
class StringMapEntryStorage<std::nullopt_t> : public StringMapEntryBase { … };

/// StringMapEntry - This is used to represent one value that is inserted into
/// a StringMap.  It contains the Value itself and the key: the string length
/// and data.
template <typename ValueTy>
class StringMapEntry final : public StringMapEntryStorage<ValueTy> { … };

// Allow structured bindings on StringMapEntry.
template <std::size_t Index, typename ValueTy>
decltype(auto) get(const StringMapEntry<ValueTy> &E) { … }

} // end namespace llvm

namespace std {
tuple_size<llvm::StringMapEntry<ValueTy>>;

tuple_element<I, llvm::StringMapEntry<ValueTy>>;
} // namespace std

#endif // LLVM_ADT_STRINGMAPENTRY_H