tempest/src/storm/storage/expressions/VariableSetPredicateSplitter.cpp

#include "storm/storage/expressions/VariableSetPredicateSplitter.h"

#include "storm/storage/expressions/Expressions.h"

#include "storm/utility/macros.h"
#include "storm/exceptions/InvalidArgumentException.h"

namespace storm {
    namespace expressions {
        
        VariableSetPredicateSplitter::VariableSetPredicateSplitter(std::set<storm::expressions::Variable> const& irrelevantVariables) : irrelevantVariables(irrelevantVariables) {
            // Intentionally left empty.
        }
        
        std::vector<storm::expressions::Expression> VariableSetPredicateSplitter::split(storm::expressions::Expression const& expression) {
            STORM_LOG_THROW(expression.hasBooleanType(), storm::exceptions::InvalidArgumentException, "Expected predicate of boolean type.");
            
            // Gather all atoms.
            resultPredicates.clear();
            expression.accept(*this, boost::none);
            
            // Remove all boolean literals from the atoms.
            std::vector<storm::expressions::Expression> expressionsToKeep;
            for (auto const& atom : resultPredicates) {
                if (!atom.isTrue() && !atom.isFalse()) {
                    expressionsToKeep.push_back(atom);
                }
            }
            resultPredicates = std::move(expressionsToKeep);
            
            return resultPredicates;
        }
        
        boost::any VariableSetPredicateSplitter::visit(IfThenElseExpression const& expression, boost::any const&) {
            std::set<storm::expressions::Variable> conditionVariables;
            expression.getCondition()->gatherVariables(conditionVariables);
            bool conditionOnlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), conditionVariables.begin(), conditionVariables.end());
            
            std::set<storm::expressions::Variable> tmp;
            std::set_intersection(conditionVariables.begin(), conditionVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool conditionHasIrrelevantVariables = !tmp.empty();
            
            std::set<storm::expressions::Variable> thenVariables;
            expression.getThenExpression()->gatherVariables(thenVariables);
            bool thenOnlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), thenVariables.begin(), thenVariables.end());

            tmp.clear();
            std::set_intersection(thenVariables.begin(), thenVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool thenHasIrrelevantVariables = !tmp.empty();

            std::set<storm::expressions::Variable> elseVariables;
            expression.getElseExpression()->gatherVariables(elseVariables);
            bool elseOnlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), elseVariables.begin(), elseVariables.end());

            tmp.clear();
            std::set_intersection(elseVariables.begin(), elseVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool elseHasIrrelevantVariables = !tmp.empty();

            if (conditionHasIrrelevantVariables || thenHasIrrelevantVariables || elseHasIrrelevantVariables) {
                STORM_LOG_THROW(conditionOnlyIrrelevantVariables && thenOnlyIrrelevantVariables && elseOnlyIrrelevantVariables, storm::exceptions::InvalidArgumentException, "Cannot split expression based on variable set as variables of different type are related.");
            } else {
                resultPredicates.push_back(expression.toExpression());
            }
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(BinaryBooleanFunctionExpression const& expression, boost::any const& data) {
            std::set<storm::expressions::Variable> leftContainedVariables;
            expression.getFirstOperand()->gatherVariables(leftContainedVariables);
            bool leftOnlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), leftContainedVariables.begin(), leftContainedVariables.end());
            
            std::set<storm::expressions::Variable> tmp;
            std::set_intersection(leftContainedVariables.begin(), leftContainedVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool leftHasIrrelevantVariables = !tmp.empty();
            
            std::set<storm::expressions::Variable> rightContainedVariables;
            expression.getSecondOperand()->gatherVariables(rightContainedVariables);
            bool rightOnlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), rightContainedVariables.begin(), rightContainedVariables.end());
            
            tmp.clear();
            std::set_intersection(rightContainedVariables.begin(), rightContainedVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool rightHasIrrelevantVariables = !tmp.empty();
            
            if (leftOnlyIrrelevantVariables && rightOnlyIrrelevantVariables) {
                return boost::any();
            }
            
            if (!leftHasIrrelevantVariables && !rightHasIrrelevantVariables) {
                resultPredicates.push_back(expression.toExpression());
            }
            
            if (!leftHasIrrelevantVariables) {
                resultPredicates.push_back(expression.getFirstOperand()->toExpression());
            } else if (!leftOnlyIrrelevantVariables) {
                return expression.getFirstOperand()->accept(*this, data);
            }
            
            if (!rightHasIrrelevantVariables) {
                resultPredicates.push_back(expression.getSecondOperand()->toExpression());
            } else if (!rightOnlyIrrelevantVariables) {
                return expression.getSecondOperand()->accept(*this, data);
            }
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(BinaryNumericalFunctionExpression const& expression, boost::any const&) {
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(BinaryRelationExpression const& expression, boost::any const&) {
            std::set<storm::expressions::Variable> leftContainedVariables;
            expression.getFirstOperand()->gatherVariables(leftContainedVariables);
            bool leftOnlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), leftContainedVariables.begin(), leftContainedVariables.end());
            
            std::set<storm::expressions::Variable> tmp;
            std::set_intersection(leftContainedVariables.begin(), leftContainedVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool leftHasIrrelevantVariables = !tmp.empty();

            std::set<storm::expressions::Variable> rightContainedVariables;
            expression.getSecondOperand()->gatherVariables(rightContainedVariables);
            bool rightOnlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), rightContainedVariables.begin(), rightContainedVariables.end());
            
            tmp.clear();
            std::set_intersection(rightContainedVariables.begin(), rightContainedVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool rightHasIrrelevantVariables = !tmp.empty();

            if (!leftHasIrrelevantVariables && !rightHasIrrelevantVariables) {
                resultPredicates.push_back(expression.toExpression());
            } else {
                STORM_LOG_THROW(leftOnlyIrrelevantVariables && rightOnlyIrrelevantVariables, storm::exceptions::InvalidArgumentException, "Cannot abstract from variable set in expression as it mixes variables of different types.");
            }
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(VariableExpression const& expression, boost::any const&) {
            if (expression.hasBooleanType() && irrelevantVariables.find(expression.getVariable()) == irrelevantVariables.end()) {
                resultPredicates.push_back(expression.toExpression());
            }
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(UnaryBooleanFunctionExpression const& expression, boost::any const& data) {
            std::set<storm::expressions::Variable> containedVariables;
            expression.gatherVariables(containedVariables);
            bool onlyIrrelevantVariables = std::includes(irrelevantVariables.begin(), irrelevantVariables.end(), containedVariables.begin(), containedVariables.end());
            
            if (onlyIrrelevantVariables) {
                return boost::any();
            }
            
            std::set<storm::expressions::Variable> tmp;
            std::set_intersection(containedVariables.begin(), containedVariables.end(), irrelevantVariables.begin(), irrelevantVariables.end(), std::inserter(tmp, tmp.begin()));
            bool hasIrrelevantVariables = !tmp.empty();

            if (hasIrrelevantVariables) {
                expression.getOperand()->accept(*this, data);
            } else {
                resultPredicates.push_back(expression.toExpression());
            }
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(UnaryNumericalFunctionExpression const&, boost::any const&) {
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(BooleanLiteralExpression const&, boost::any const&) {
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(IntegerLiteralExpression const&, boost::any const&) {
            return boost::any();
        }
        
        boost::any VariableSetPredicateSplitter::visit(RationalLiteralExpression const&, boost::any const&) {
            return boost::any();
        }
        
    }
}