llvm/llvm/include/llvm/ADT/CombinationGenerator.h

//===-- llvm/ADT/CombinationGenerator.h ------------------------*- 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
/// Combination generator.
///
/// Example: given input {{0, 1}, {2}, {3, 4}} it will produce the following
/// combinations: {0, 2, 3}, {0, 2, 4}, {1, 2, 3}, {1, 2, 4}.
///
/// It is useful to think of input as vector-of-vectors, where the
/// outer vector is the variable space, and inner vector is choice space.
/// The number of choices for each variable can be different.
///
/// As for implementation, it is useful to think of this as a weird number,
/// where each digit (==variable) may have different base (==number of choices).
/// Thus modelling of 'produce next combination' is exactly analogous to the
/// incrementing of an number - increment lowest digit (pick next choice for the
/// variable), and if it wrapped to the beginning then increment next digit.
///
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_COMBINATIONGENERATOR_H
#define LLVM_ADT_COMBINATIONGENERATOR_H

#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLFunctionalExtras.h"
#include "llvm/ADT/SmallVector.h"
#include <cassert>
#include <cstring>

namespace llvm {

template <typename choice_type, typename choices_storage_type,
          int variable_smallsize>
class CombinationGenerator { … };

} // namespace llvm

#endif