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llvm-mirror/include/llvm/ADT/StringSet.h
Jordan Rose fa21e7962b ADT: Save a word in every StringSet entry
Add a specialization to StringMap (actually StringMapEntry) for a
value type of NoneType (the type of llvm::None), and use it for
StringSet. This'll save us a word from every entry in a StringSet,
used for alignment with the size_t that stores the string length.

I could have gone all the way to some kind of empty base class
optimization, but that seemed like overkill. Someone can consider
adding that in the future, though.

https://reviews.llvm.org/D68586

llvm-svn: 374440
2019-10-10 20:22:53 +00:00

59 lines
1.7 KiB
C++

//===- StringSet.h - The LLVM Compiler Driver -------------------*- 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
//
//===----------------------------------------------------------------------===//
//
// StringSet - A set-like wrapper for the StringMap.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_STRINGSET_H
#define LLVM_ADT_STRINGSET_H
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Allocator.h"
#include <cassert>
#include <initializer_list>
#include <utility>
namespace llvm {
/// StringSet - A wrapper for StringMap that provides set-like functionality.
template <class AllocatorTy = MallocAllocator>
class StringSet : public StringMap<NoneType, AllocatorTy> {
using base = StringMap<NoneType, AllocatorTy>;
public:
StringSet() = default;
StringSet(std::initializer_list<StringRef> S) {
for (StringRef X : S)
insert(X);
}
explicit StringSet(AllocatorTy A) : base(A) {}
std::pair<typename base::iterator, bool> insert(StringRef Key) {
assert(!Key.empty());
return base::insert(std::make_pair(Key, None));
}
template <typename InputIt>
void insert(const InputIt &Begin, const InputIt &End) {
for (auto It = Begin; It != End; ++It)
base::insert(std::make_pair(*It, None));
}
template <typename ValueTy>
std::pair<typename base::iterator, bool>
insert(const StringMapEntry<ValueTy> &MapEntry) {
return insert(MapEntry.getKey());
}
};
} // end namespace llvm
#endif // LLVM_ADT_STRINGSET_H