slr1_parser.hpp

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/*
 * SyntaxTutor - Interactive Tutorial About Syntax Analyzers
 * Copyright (C) 2025 Jose R. (jose-rzm)
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
#pragma once
#include <map>
#include <span>
#include <string>
#include <unordered_set>
 
#include "grammar.hpp"
#include "lr0_item.hpp"
#include "state.hpp"

class SLR1Parser {
  public:
    enum class Action { Shift, Reduce, Accept, Empty };

    struct s_action {
        const Lr0Item* item;
        Action         action;
    };

    using action_table =
        std::map<unsigned int, std::map<std::string, SLR1Parser::s_action>>;

    using transition_table =
        std::map<unsigned int, std::map<std::string, unsigned int>>;
 
    SLR1Parser() = default;
    explicit SLR1Parser(Grammar gr);

    std::unordered_set<Lr0Item> AllItems() const;

    void Closure(std::unordered_set<Lr0Item>& items);

    void ClosureUtil(std::unordered_set<Lr0Item>& items, unsigned int size,
                     std::unordered_set<std::string>& visited);

    std::unordered_set<Lr0Item> Delta(const std::unordered_set<Lr0Item>& items,
                                      const std::string&                 str);

    bool SolveLRConflicts(const state& st);

    void First(std::span<const std::string>     rule,
               std::unordered_set<std::string>& result);

    void ComputeFirstSets();

    void ComputeFollowSets();

    std::unordered_set<std::string> Follow(const std::string& arg);

    void MakeInitialState();

    bool MakeParser();

    std::string PrintItems(const std::unordered_set<Lr0Item>& items) const;

    Grammar gr_;

    std::unordered_map<std::string, std::unordered_set<std::string>>
        first_sets_;

    std::unordered_map<std::string, std::unordered_set<std::string>>
        follow_sets_;

    action_table actions_;

    transition_table transitions_;

    std::unordered_set<state> states_;
};