SftToBddTransformator.h

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#pragma once
 
#include <memory>
#include <vector>
 
#include "storm-dft/storage/DFT.h"
#include "storm-dft/storage/SylvanBddManager.h"
#include "storm-dft/utility/RelevantEvents.h"
#include "storm/exceptions/NotSupportedException.h"
#include "storm/utility/bitoperations.h"
 
namespace storm::dft {
namespace transformations {
 
template<typename ValueType>
class SftToBddTransformator {
   public:
    using Bdd = sylvan::Bdd;
 
    SftToBddTransformator(std::shared_ptr<storm::dft::storage::DFT<ValueType>> dft,
                          std::shared_ptr<storm::dft::storage::SylvanBddManager> sylvanBddManager = std::make_shared<storm::dft::storage::SylvanBddManager>(),
                          storm::dft::utility::RelevantEvents relevantEvents = {})
        : dft{std::move(dft)}, sylvanBddManager{std::move(sylvanBddManager)}, relevantEvents{relevantEvents} {
        // create Variables for the BEs
        for (auto const& i : this->dft->getBasicElements()) {
            // Filter constantBeTrigger
            if (i->name() != "constantBeTrigger") {
                variables.push_back(this->sylvanBddManager->createVariable(i->name()));
            }
        }
    }
 
    Bdd const& transformTopLevel() {
        auto const tlName{dft->getTopLevelElement()->name()};
        if (relevantEventBdds.empty()) {
            relevantEventBdds[tlName] = translate(dft->getTopLevelElement());
        }
        // else relevantEventBdds is not empty and we maintain the invariant
        // that the toplevel event is in there
        STORM_LOG_ASSERT(relevantEventBdds.count(tlName) == 1, "Not all relevantEvents where transformed into BDDs.");
 
        return relevantEventBdds[tlName];
    }
 
    std::map<std::string, Bdd> const& transformRelevantEvents() {
        if (relevantEventBdds.empty()) {
            relevantEventBdds[dft->getTopLevelElement()->name()] = translate(dft->getTopLevelElement());
        }
 
        // we maintain the invariant that if relevantEventBdds is not empty
        // then we have calculated all relevant bdds
        STORM_LOG_ASSERT(relevantEventBdds.size() == relevantEvents.count(getDFT()), "Not all relevantEvents where transformed into BDDs.");
 
        return relevantEventBdds;
    }
 
    std::vector<uint32_t> const& getDdVariables() const noexcept {
        return variables;
    }
 
    std::shared_ptr<storm::dft::storage::DFT<ValueType>> getDFT() const noexcept {
        return dft;
    }
 
    std::shared_ptr<storm::dft::storage::SylvanBddManager> getSylvanBddManager() const noexcept {
        return sylvanBddManager;
    }
 
   private:
    std::map<std::string, Bdd> relevantEventBdds{};
    std::vector<uint32_t> variables{};
    std::shared_ptr<storm::dft::storage::DFT<ValueType>> dft;
    std::shared_ptr<storm::dft::storage::SylvanBddManager> sylvanBddManager;
    storm::dft::utility::RelevantEvents relevantEvents;
 
    Bdd translate(std::shared_ptr<storm::dft::storage::elements::DFTElement<ValueType> const> element) {
        auto isRelevant{relevantEvents.isRelevant(element->name())};
        if (isRelevant) {
            auto const it{relevantEventBdds.find(element->name())};
            if (it != relevantEventBdds.end()) {
                return it->second;
            }
        }
 
        Bdd rBdd;
        if (element->isGate()) {
            rBdd = translate(std::dynamic_pointer_cast<storm::dft::storage::elements::DFTGate<ValueType> const>(element));
        } else if (element->isBasicElement()) {
            rBdd = translate(std::dynamic_pointer_cast<storm::dft::storage::elements::DFTBE<ValueType> const>(element));
        } else {
            STORM_LOG_THROW(false, storm::exceptions::NotSupportedException,
                            "Element of type \"" << element->typestring() << "\" is not supported. Probably not a SFT.");
            rBdd = sylvanBddManager->getZero();
        }
 
        if (isRelevant) {
            // rBdd can't be in relevantEventBdds
            // as we would've returned
            // at the start of the function
            relevantEventBdds[element->name()] = rBdd;
        }
 
        return rBdd;
    }
 
    Bdd translate(std::shared_ptr<storm::dft::storage::elements::DFTGate<ValueType> const> gate) {
        if (gate->type() == storm::dft::storage::elements::DFTElementType::AND) {
            // used only in conjunctions therefore neutral element -> 1
            auto tmpBdd{sylvanBddManager->getOne()};
            for (auto const& child : gate->children()) {
                tmpBdd &= translate(child);
            }
            return tmpBdd;
        } else if (gate->type() == storm::dft::storage::elements::DFTElementType::OR) {
            // used only in disjunctions therefore neutral element -> 0
            auto tmpBdd{sylvanBddManager->getZero()};
            for (auto const& child : gate->children()) {
                tmpBdd |= translate(child);
            }
            return tmpBdd;
        } else if (gate->type() == storm::dft::storage::elements::DFTElementType::VOT) {
            return translate(std::dynamic_pointer_cast<storm::dft::storage::elements::DFTVot<ValueType> const>(gate));
        }
        STORM_LOG_THROW(false, storm::exceptions::NotSupportedException, "Gate of type \"" << gate->typestring() << "\" is not supported. Probably not a SFT.");
        return sylvanBddManager->getZero();
    }
 
    Bdd translate(std::shared_ptr<storm::dft::storage::elements::DFTVot<ValueType> const> vot) {
        std::vector<Bdd> bdds;
        bdds.reserve(vot->children().size());
 
        for (auto const& child : vot->children()) {
            bdds.push_back(translate(child));
        }
 
        auto const rval{translateVot(0, vot->threshold(), bdds)};
        return rval;
    }
 
    Bdd translateVot(size_t const currentIndex, size_t const threshold, std::vector<Bdd> const& bdds) const {
        if (threshold == 0) {
            return sylvanBddManager->getOne();
        } else if (currentIndex >= bdds.size()) {
            return sylvanBddManager->getZero();
        }
 
        auto const notChosenBdd{translateVot(currentIndex + 1, threshold, bdds)};
        auto const chosenBdd{translateVot(currentIndex + 1, threshold - 1, bdds)};
 
        return bdds[currentIndex].Ite(chosenBdd, notChosenBdd);
    }
 
    Bdd translate(std::shared_ptr<storm::dft::storage::elements::DFTBE<ValueType> const> const basicElement) {
        return sylvanBddManager->getPositiveLiteral(basicElement->name());
    }
};
 
}  // namespace transformations
}  // namespace storm::dft