Formula.h

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/*
 * This file is part of KnowRob, please consult
 * https://github.com/knowrob/knowrob for license details.
 */
 
#ifndef KNOWROB_FORMULA_H_
#define KNOWROB_FORMULA_H_
 
#include <memory>
#include <ostream>
#include "knowrob/Printable.h"
 
namespace knowrob {
    enum class FormulaType {
        // A formula of the form `P(t_1,..,t_n)` where each ti is a term
        // and "P" is a n-ary predicate symbol (or functor).
        PREDICATE,
        // A formula of the form `phi_1 AND ... AND phi_n` where each phi_i is a formula.
        CONJUNCTION,
        // A formula of the form `phi_1 OR ... OR phi_n` where each phi_i is a formula.
        DISJUNCTION,
        NEGATION,
        IMPLICATION,
        MODAL
    };
 
    class Formula : public Printable {
    public:
        explicit Formula(const FormulaType &type);
 
        virtual ~Formula() = default;
 
        bool operator==(const Formula &other) const;
 
        FormulaType type() const { return type_; }
 
        bool isAtomic() const;
 
        bool isGround() const { return isGround_; }
 
        bool isTop() const;
 
        bool isBottom() const;
 
    protected:
        const FormulaType type_;
        bool isGround_ = true;
 
        virtual bool isEqual(const Formula &other) const = 0;
    };
 
    class FormulaLabel {
    public:
        FormulaLabel() = default;
 
        virtual ~FormulaLabel() = default;
 
        bool operator==(const FormulaLabel &other);
 
    protected:
        virtual bool isEqual(const FormulaLabel &other) const = 0;
    };
 
    // alias declaration
    using FormulaPtr = std::shared_ptr<Formula>;
    using FormulaLabelPtr = std::shared_ptr<FormulaLabel>;
}
 
#endif //KNOWROB_FORMULA_H_