MathsatExpressionAdapter.h

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#pragma once
 
#include "storm-config.h"
 
#include <stack>
 
#ifdef STORM_HAVE_MATHSAT
#include <mathsat.h>
#endif
 
#include "storm/exceptions/ExpressionEvaluationException.h"
#include "storm/exceptions/InvalidArgumentException.h"
#include "storm/exceptions/InvalidTypeException.h"
#include "storm/exceptions/NotImplementedException.h"
#include "storm/storage/expressions/ExpressionManager.h"
#include "storm/storage/expressions/ExpressionVisitor.h"
#include "storm/storage/expressions/Expressions.h"
#include "storm/utility/constants.h"
#include "storm/utility/macros.h"
 
#ifdef STORM_HAVE_MATHSAT
namespace std {
// Define hashing operator for MathSAT's declarations.
template<>
struct hash<msat_decl> {
    size_t operator()(msat_decl const& declaration) const {
        return hash<void*>()(declaration.repr);
    }
};
}  // namespace std
 
// Define equality operator to make hashing work.
bool operator==(msat_decl decl1, msat_decl decl2);
#endif
 
namespace storm {
namespace adapters {
 
#ifdef STORM_HAVE_MATHSAT
 
class MathsatExpressionAdapter : public storm::expressions::ExpressionVisitor {
   public:
    MathsatExpressionAdapter(storm::expressions::ExpressionManager& manager, msat_env& env) : manager(manager), env(env), variableToDeclarationMapping() {
        // Intentionally left empty.
    }

    msat_term translateExpression(storm::expressions::Expression const& expression) {
        additionalConstraints.clear();
        msat_term result = boost::any_cast<msat_term>(expression.getBaseExpression().accept(*this, boost::none));
        if (MSAT_ERROR_TERM(result)) {
            std::string errorMessage(msat_last_error_message(env));
            STORM_LOG_THROW(!MSAT_ERROR_TERM(result), storm::exceptions::ExpressionEvaluationException,
                            "Could not translate expression to MathSAT's format. (Message: " << errorMessage << ").");
        }
 
        return result;
    }

    msat_term translateExpression(storm::expressions::Variable const& variable) {
        STORM_LOG_ASSERT(variable.getManager() == this->manager, "Invalid expression for solver.");
 
        auto const& variableExpressionPair = variableToDeclarationMapping.find(variable);
        if (variableExpressionPair == variableToDeclarationMapping.end()) {
            return msat_make_constant(env, createVariable(variable));
        }
        return msat_make_constant(env, variableExpressionPair->second);
    }
 
    bool hasAdditionalConstraints() const {
        return !additionalConstraints.empty();
    }

    std::vector<msat_term> const& getAdditionalConstraints() const {
        return additionalConstraints;
    }

    storm::expressions::Variable const& getVariable(msat_decl msatVariableDeclaration) const {
        auto const& declarationVariablePair = declarationToVariableMapping.find(msatVariableDeclaration);
        STORM_LOG_ASSERT(declarationVariablePair != declarationToVariableMapping.end(), "Unknown variable declaration.");
        return declarationVariablePair->second;
    }
 
    std::unordered_map<storm::expressions::Variable, msat_decl> const& getAllDeclaredVariables() const {
        return variableToDeclarationMapping;
    }
 
    virtual boost::any visit(storm::expressions::BinaryBooleanFunctionExpression const& expression, boost::any const& data) override {
        msat_term leftResult = boost::any_cast<msat_term>(expression.getFirstOperand()->accept(*this, data));
        msat_term rightResult = boost::any_cast<msat_term>(expression.getSecondOperand()->accept(*this, data));
 
        switch (expression.getOperatorType()) {
            case storm::expressions::BinaryBooleanFunctionExpression::OperatorType::And:
                return msat_make_and(env, leftResult, rightResult);
            case storm::expressions::BinaryBooleanFunctionExpression::OperatorType::Or:
                return msat_make_or(env, leftResult, rightResult);
            case storm::expressions::BinaryBooleanFunctionExpression::OperatorType::Iff:
                return msat_make_iff(env, leftResult, rightResult);
            case storm::expressions::BinaryBooleanFunctionExpression::OperatorType::Implies:
                return msat_make_or(env, msat_make_not(env, leftResult), rightResult);
            default:
                STORM_LOG_THROW(false, storm::exceptions::ExpressionEvaluationException,
                                "Cannot evaluate expression: unknown boolean binary operator '" << static_cast<uint_fast64_t>(expression.getOperatorType())
                                                                                                << "' in expression " << expression << ".");
        }
    }
 
    virtual boost::any visit(storm::expressions::BinaryNumericalFunctionExpression const& expression, boost::any const& data) override {
        msat_term leftResult = boost::any_cast<msat_term>(expression.getFirstOperand()->accept(*this, data));
        msat_term rightResult = boost::any_cast<msat_term>(expression.getSecondOperand()->accept(*this, data));
 
        msat_term result = leftResult;
        int_fast64_t exponent;
        int_fast64_t modulus;
        storm::expressions::Variable freshAuxiliaryVariable;
        msat_term modVariable;
        msat_term lower;
        msat_term upper;
        typename storm::NumberTraits<storm::GmpRationalNumber>::IntegerType gmpModulus;
        switch (expression.getOperatorType()) {
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Plus:
                return msat_make_plus(env, leftResult, rightResult);
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Minus:
                return msat_make_plus(env, leftResult, msat_make_times(env, msat_make_number(env, "-1"), rightResult));
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Times:
                return msat_make_times(env, leftResult, rightResult);
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Divide:
                return msat_make_divide(env, leftResult, rightResult);
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Min:
                return msat_make_term_ite(env, msat_make_leq(env, leftResult, rightResult), leftResult, rightResult);
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Max:
                return msat_make_term_ite(env, msat_make_leq(env, leftResult, rightResult), rightResult, leftResult);
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Power:
                exponent = expression.getSecondOperand()->evaluateAsInt();
                STORM_LOG_THROW(exponent >= 0, storm::exceptions::ExpressionEvaluationException, "Cannot evaluate expression with negative exponent.");
                --exponent;
                if (exponent > 0) {
                    for (; exponent > 0; --exponent) {
                        result = msat_make_times(env, result, leftResult);
                    }
                }
                return result;
            case storm::expressions::BinaryNumericalFunctionExpression::OperatorType::Modulo:
                modulus = expression.getSecondOperand()->evaluateAsInt();
                STORM_LOG_THROW(modulus > 0, storm::exceptions::ExpressionEvaluationException, "Cannot evaluate expression with negative modulus.");
 
                freshAuxiliaryVariable = manager.declareFreshVariable(manager.getIntegerType(), true);
                modVariable = msat_make_constant(env, createVariable(freshAuxiliaryVariable));
 
                gmpModulus = typename storm::NumberTraits<storm::GmpRationalNumber>::IntegerType(static_cast<unsigned>(modulus));
 
                // Create the constraint that fixes the value of the fresh variable.
                additionalConstraints.push_back(msat_make_int_modular_congruence(env, gmpModulus.get_mpz_t(), modVariable, leftResult));
 
                // Create the constraint that limits the value of the modulo operation to 0 <= val <= modulus-1.
                lower = msat_make_number(env, "-1");
                upper = msat_make_number(env, std::to_string(modulus - 1).c_str());
                additionalConstraints.push_back(
                    msat_make_and(env, msat_make_not(env, msat_make_leq(env, modVariable, lower)), msat_make_leq(env, modVariable, upper)));
                return modVariable;
            default:
                STORM_LOG_THROW(false, storm::exceptions::ExpressionEvaluationException,
                                "Cannot evaluate expression: unknown numerical binary operator '" << static_cast<uint_fast64_t>(expression.getOperatorType())
                                                                                                  << "' in expression " << expression << ".");
        }
    }
 
    virtual boost::any visit(storm::expressions::BinaryRelationExpression const& expression, boost::any const& data) override {
        msat_term leftResult = boost::any_cast<msat_term>(expression.getFirstOperand()->accept(*this, data));
        msat_term rightResult = boost::any_cast<msat_term>(expression.getSecondOperand()->accept(*this, data));
 
        switch (expression.getRelationType()) {
            case storm::expressions::RelationType::Equal:
                if (expression.getFirstOperand()->getType().isBooleanType() && expression.getSecondOperand()->getType().isBooleanType()) {
                    return msat_make_iff(env, leftResult, rightResult);
                } else {
                    return msat_make_equal(env, leftResult, rightResult);
                }
            case storm::expressions::RelationType::NotEqual:
                if (expression.getFirstOperand()->getType().isBooleanType() && expression.getSecondOperand()->getType().isBooleanType()) {
                    return msat_make_not(env, msat_make_iff(env, leftResult, rightResult));
                } else {
                    return msat_make_not(env, msat_make_equal(env, leftResult, rightResult));
                }
            case storm::expressions::RelationType::Less:
                return msat_make_and(env, msat_make_not(env, msat_make_equal(env, leftResult, rightResult)), msat_make_leq(env, leftResult, rightResult));
            case storm::expressions::RelationType::LessOrEqual:
                return msat_make_leq(env, leftResult, rightResult);
            case storm::expressions::RelationType::Greater:
                return msat_make_not(env, msat_make_leq(env, leftResult, rightResult));
            case storm::expressions::RelationType::GreaterOrEqual:
                return msat_make_or(env, msat_make_equal(env, leftResult, rightResult), msat_make_not(env, msat_make_leq(env, leftResult, rightResult)));
            default:
                STORM_LOG_THROW(false, storm::exceptions::ExpressionEvaluationException,
                                "Cannot evaluate expression: unknown boolean binary operator '" << static_cast<uint_fast64_t>(expression.getRelationType())
                                                                                                << "' in expression " << expression << ".");
        }
    }
 
    virtual boost::any visit(storm::expressions::IfThenElseExpression const& expression, boost::any const& data) override {
        msat_term conditionResult = boost::any_cast<msat_term>(expression.getCondition()->accept(*this, data));
        msat_term thenResult = boost::any_cast<msat_term>(expression.getThenExpression()->accept(*this, data));
        msat_term elseResult = boost::any_cast<msat_term>(expression.getElseExpression()->accept(*this, data));
 
        // MathSAT does not allow ite with boolean arguments, so we have to encode it ourselves.
        if (expression.getThenExpression()->hasBooleanType() && expression.getElseExpression()->hasBooleanType()) {
            return msat_make_and(env, msat_make_or(env, msat_make_not(env, conditionResult), thenResult), msat_make_or(env, conditionResult, elseResult));
        } else {
            return msat_make_term_ite(env, conditionResult, thenResult, elseResult);
        }
    }
 
    virtual boost::any visit(storm::expressions::BooleanLiteralExpression const& expression, boost::any const&) override {
        return expression.getValue() ? msat_make_true(env) : msat_make_false(env);
    }
 
    virtual boost::any visit(storm::expressions::RationalLiteralExpression const& expression, boost::any const&) override {
        std::stringstream fractionStream;
        fractionStream << expression.getValue();
        return msat_make_number(env, fractionStream.str().c_str());
    }
 
    virtual boost::any visit(storm::expressions::IntegerLiteralExpression const& expression, boost::any const&) override {
        return msat_make_number(env, std::to_string(static_cast<int>(expression.getValue())).c_str());
    }
 
    virtual boost::any visit(storm::expressions::UnaryBooleanFunctionExpression const& expression, boost::any const& data) override {
        msat_term childResult = boost::any_cast<msat_term>(expression.getOperand()->accept(*this, data));
 
        switch (expression.getOperatorType()) {
            case storm::expressions::UnaryBooleanFunctionExpression::OperatorType::Not:
                return msat_make_not(env, childResult);
                break;
            default:
                STORM_LOG_THROW(false, storm::exceptions::ExpressionEvaluationException,
                                "Cannot evaluate expression: unknown boolean unary operator: '" << static_cast<uint_fast64_t>(expression.getOperatorType())
                                                                                                << "' in expression " << expression << ".");
        }
    }
 
    virtual boost::any visit(storm::expressions::UnaryNumericalFunctionExpression const& expression, boost::any const& data) override {
        msat_term childResult = boost::any_cast<msat_term>(expression.getOperand()->accept(*this, data));
 
        switch (expression.getOperatorType()) {
            case storm::expressions::UnaryNumericalFunctionExpression::OperatorType::Minus:
                return msat_make_times(env, msat_make_number(env, "-1"), childResult);
            case storm::expressions::UnaryNumericalFunctionExpression::OperatorType::Floor:
                return msat_make_floor(env, childResult);
            case storm::expressions::UnaryNumericalFunctionExpression::OperatorType::Ceil:
                // Mathsat does not support ceil... but ceil(x) = -floor(-x)  wheeii \o/
                return msat_make_times(env, msat_make_number(env, "-1"), msat_make_floor(env, msat_make_times(env, msat_make_number(env, "-1"), childResult)));
            default:
                STORM_LOG_THROW(false, storm::exceptions::ExpressionEvaluationException,
                                "Cannot evaluate expression: unknown numerical unary operator: '" << static_cast<uint_fast64_t>(expression.getOperatorType())
                                                                                                  << "' in expression " << expression << ".");
        }
    }
 
    virtual boost::any visit(storm::expressions::VariableExpression const& expression, boost::any const&) override {
        return translateExpression(expression.getVariable());
    }
 
    storm::expressions::Expression translateExpression(msat_term const& term) {
        if (msat_term_is_and(env, term)) {
            return translateExpression(msat_term_get_arg(term, 0)) && translateExpression(msat_term_get_arg(term, 1));
        } else if (msat_term_is_or(env, term)) {
            return translateExpression(msat_term_get_arg(term, 0)) || translateExpression(msat_term_get_arg(term, 1));
        } else if (msat_term_is_iff(env, term)) {
            return storm::expressions::iff(translateExpression(msat_term_get_arg(term, 0)), translateExpression(msat_term_get_arg(term, 1)));
        } else if (msat_term_is_not(env, term)) {
            return !translateExpression(msat_term_get_arg(term, 0));
        } else if (msat_term_is_plus(env, term)) {
            return translateExpression(msat_term_get_arg(term, 0)) + translateExpression(msat_term_get_arg(term, 1));
        } else if (msat_term_is_times(env, term)) {
            return translateExpression(msat_term_get_arg(term, 0)) * translateExpression(msat_term_get_arg(term, 1));
        } else if (msat_term_is_equal(env, term)) {
            return translateExpression(msat_term_get_arg(term, 0)) == translateExpression(msat_term_get_arg(term, 1));
        } else if (msat_term_is_leq(env, term)) {
            return translateExpression(msat_term_get_arg(term, 0)) <= translateExpression(msat_term_get_arg(term, 1));
        } else if (msat_term_is_true(env, term)) {
            return manager.boolean(true);
        } else if (msat_term_is_false(env, term)) {
            return manager.boolean(false);
        } else if (msat_term_is_constant(env, term)) {
            char* name = msat_decl_get_name(msat_term_get_decl(term));
            std::string nameString(name);
            storm::expressions::Expression result = manager.getVariableExpression(nameString.substr(0, nameString.find('/')));
            msat_free(name);
            return result;
        } else if (msat_term_is_number(env, term)) {
            char* termAsCString = msat_term_repr(term);
            std::string termString(termAsCString);
            msat_free(termAsCString);
            if (msat_is_integer_type(env, msat_term_get_type(term))) {
                return manager.integer(std::stoll(msat_term_repr(term)));
            } else if (msat_is_rational_type(env, msat_term_get_type(term))) {
                return manager.rational(storm::utility::convertNumber<storm::RationalNumber>(termString));
            }
        } else if (msat_term_is_term_ite(env, term)) {
            return storm::expressions::ite(translateExpression(msat_term_get_arg(term, 0)), translateExpression(msat_term_get_arg(term, 1)),
                                           translateExpression(msat_term_get_arg(term, 2)));
        }
 
        // If all other cases did not apply, we cannot represent the term in our expression framework.
        char* termAsCString = msat_term_repr(term);
        std::string termString(termAsCString);
        msat_free(termAsCString);
        STORM_LOG_THROW(false, storm::exceptions::ExpressionEvaluationException, "Cannot translate expression: unknown term: '" << termString << "'.");
    }
 
   private:
    msat_decl createVariable(storm::expressions::Variable const& variable) {
        msat_decl msatDeclaration;
        if (variable.getType().isBooleanType()) {
            msatDeclaration = msat_declare_function(env, variable.getName().c_str(), msat_get_bool_type(env));
        } else if (variable.getType().isIntegerType()) {
            msatDeclaration = msat_declare_function(env, variable.getName().c_str(), msat_get_integer_type(env));
        } else if (variable.getType().isBitVectorType()) {
            msatDeclaration = msat_declare_function(env, variable.getName().c_str(), msat_get_bv_type(env, variable.getType().getWidth()));
        } else if (variable.getType().isRationalType()) {
            msatDeclaration = msat_declare_function(env, variable.getName().c_str(), msat_get_rational_type(env));
        } else {
            STORM_LOG_THROW(false, storm::exceptions::InvalidTypeException,
                            "Encountered variable '" << variable.getName() << "' with unknown type while trying to create solver variables.");
        }
        variableToDeclarationMapping.insert(std::make_pair(variable, msatDeclaration));
        declarationToVariableMapping.insert(std::make_pair(msatDeclaration, variable));
        return msatDeclaration;
    }
 
    // The expression manager to use.
    storm::expressions::ExpressionManager& manager;
 
    // The MathSAT environment used.
    msat_env& env;
 
    // A vector of constraints that need to be kept separate, because they were only implicitly part of an
    // assertion that was added.
    std::vector<msat_term> additionalConstraints;
 
    // A mapping of variable names to their declaration in the MathSAT environment.
    std::unordered_map<storm::expressions::Variable, msat_decl> variableToDeclarationMapping;
 
    // A mapping from MathSAT variable declarations to our variables.
    std::unordered_map<msat_decl, storm::expressions::Variable> declarationToVariableMapping;
};
#endif
}  // namespace adapters
}  // namespace storm