datalog_atom.hpp

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#pragma once
 
#include <cstddef>
#include <string>
#include <vector>
 
#include "pulsatrix/datalog_term.hpp"
 
namespace pulsatrix::datalog {
 
class Atom {
public:
    Atom(std::string predicate_name, std::vector<Term> terms)
        : predicate_name_(std::move(predicate_name)), terms_(std::move(terms)) {}
 
    [[nodiscard]] const std::string& predicate_name() const { return predicate_name_; }
    [[nodiscard]] const std::vector<Term>& terms() const { return terms_; }
    [[nodiscard]] std::size_t arity() const { return terms_.size(); }
 
    [[nodiscard]] bool is_ground() const {
        for (const Term& term : terms_) {
            if (!term.is_constant()) return false;
        }
        return true;
    }
 
    [[nodiscard]] bool operator==(const Atom& other) const {
        return predicate_name_ == other.predicate_name_ && terms_ == other.terms_;
    }
    [[nodiscard]] bool operator!=(const Atom& other) const { return !(*this == other); }
 
private:
    std::string predicate_name_;
    std::vector<Term> terms_;
};
 
struct AtomHash {
    [[nodiscard]] std::size_t operator()(const Atom& atom) const {
        std::size_t h = std::hash<std::string>{}(atom.predicate_name());
        for (const Term& term : atom.terms()) {
            h ^= (TermHash{}(term) + 0x9e3779b9U + (h << 6) + (h >> 2));
        }
        return h;
    }
};
 
}  // namespace pulsatrix::datalog