verilator/src/V3TSP.h

// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Implementation of Christofides' algorithm to
//              approximate the solution to the traveling salesman problem.
//
// Code available from: https://verilator.org
//
//*************************************************************************
//
// Copyright 2003-2021 by Wilson Snyder. This program is free software; you
// can redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
//
//*************************************************************************

#ifndef VERILATOR_V3TSP_H_
#define VERILATOR_V3TSP_H_

#include "config_build.h"
#include "verilatedos.h"

#include "V3Error.h"

namespace V3TSP {
// Perform a "Traveling Salesman Problem" optimizing sort
// on any type you like -- so long as inherits from TspStateBase.

class TspStateBase VL_NOT_FINAL {
public:
    // This is the cost function that the TSP sort will minimize.
    // All costs in V3TSP are int, chosen to match the type of
    // V3GraphEdge::weight() which will reflect each edge's cost.
    virtual int cost(const TspStateBase* otherp) const = 0;

    // This operator< must place a meaningless, arbitrary, but
    // stable order on all TspStateBase's. It's used only to
    // key maps so that iteration is stable, without relying
    // on pointer values that could lead to nondeterminism.
    virtual bool operator<(const TspStateBase& otherp) const = 0;

    virtual ~TspStateBase() = default;
};

using StateVec = std::vector<const TspStateBase*>;

// Given an unsorted set of TspState's, sort them to minimize
// the transition cost for walking the sorted list.
void tspSort(const StateVec& states, StateVec* resultp);

void selfTest();
}  // namespace V3TSP

#endif  // Guard