ll1_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 "grammar.hpp"
#include <span>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
 
class LL1Parser {

    using ll1_table = std::unordered_map<
        std::string, std::unordered_map<std::string, std::vector<production>>>;
 
  public:
    LL1Parser() = default;
    explicit LL1Parser(Grammar gr);

    bool CreateLL1Table();

    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);

    std::unordered_set<std::string>
    PredictionSymbols(const std::string&              antecedent,
                      const std::vector<std::string>& consequent);

    ll1_table ll1_t_;

    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_;
};