ll1_parser.hpp

#pragma once
#include "grammar.hpp"
#include <deque>
#include <queue>
#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(Grammar gr, std::string text_file, bool table_format = true);

    LL1Parser(const std::string& grammar_file, std::string text_file,
              bool table_format = true);

    explicit LL1Parser(const std::string& grammar_file,
                       bool               table_format = true);

    bool Parse();

    bool MatchTerminal(const std::string& top_symbol,
                       const std::string& current_symbol);

    bool ProcessNonTerminal(const std::string& top_symbol,
                            const std::string& current_symbol);

    void PrintTable();

    void PrintStackTrace();

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

    void ComputeFirstSets();

    void ComputeFollowSets();

    bool UpdateFollow(const std::string& symbol, const std::string& lhs,
                      const production& rhs, size_t i);

    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);

    bool CreateLL1Table();

    void PrintTableUsingTabulate();

    const size_t kTraceSize{5};

    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_;

    std::stack<std::string> symbol_stack_;

    std::deque<std::string> trace_;

    std::string grammar_file_;

    std::string text_file_;

    bool print_table_format_{true};
};