llvm/llvm/include/llvm/ADT/PackedVector.h

//===- llvm/ADT/PackedVector.h - Packed values vector -----------*- 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 implements the PackedVector class.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_PACKEDVECTOR_H
#define LLVM_ADT_PACKEDVECTOR_H

#include "llvm/ADT/BitVector.h"
#include <cassert>
#include <limits>

namespace llvm {

template <typename T, unsigned BitNum, typename BitVectorTy, bool isSigned>
class PackedVectorBase;

// This won't be necessary if we can specialize members without specializing
// the parent template.
PackedVectorBase<T, BitNum, BitVectorTy, false>;

PackedVectorBase<T, BitNum, BitVectorTy, true>;

/// Store a vector of values using a specific number of bits for each
/// value. Both signed and unsigned types can be used, e.g
/// @code
///   PackedVector<signed, 2> vec;
/// @endcode
/// will create a vector accepting values -2, -1, 0, 1. Any other value will hit
/// an assertion.
template <typename T, unsigned BitNum, typename BitVectorTy = BitVector>
class PackedVector : public PackedVectorBase<T, BitNum, BitVectorTy,
                                            std::numeric_limits<T>::is_signed> { … };

// Leave BitNum=0 undefined.
PackedVector<T, 0>;

} // end namespace llvm

#endif // LLVM_ADT_PACKEDVECTOR_H