//
// Created by lenfrex on 2023/5/7.
//

#ifndef LEXER_CPP_GRAMMAR_H
#define LEXER_CPP_GRAMMAR_H

#include <ostream>
#include "vector"
#include "string"
#include "set"
#include "map"

typedef std::string Express;

// 单个产生式的select集合
typedef std::pair<Express, std::set<char>> ExpressSelectSet;

// 多个产生式的Select集合set，同一个非终止符的所有推导式的select集合
typedef std::set<ExpressSelectSet> SelectSet;

typedef std::map<char, std::string> TableRow;

// 文法定义
class Grammar {
private:

    char startChar;

    // 非终止符，vn
    std::set<char> nonTerminals = std::set<char>();;

    // 终止符，vt
    std::set<char> terminals = std::set<char>();;

    // 文法产生式
    std::map<char, std::set<Express>> productionsMap;

    std::map<char, std::set<char>> firstSet = std::map<char, std::set<char>>();
    std::map<char, std::set<char>> followSet = std::map<char, std::set<char>>();
    std::map<char, SelectSet> selectSet = std::map<char, SelectSet>();

    std::map<char, TableRow> analysisTable = std::map<char, std::map<char, std::string>>();

    bool ll1Grammar = false;

    void calcFirstSetForNonTerminal(char nonTerminal);

    // 计算first集合
    void generateFirstSet();

    // 获取当前总的follow集合元素数量
    int getTotalFollowSize();

    // 计算follow集合
    void generateFollowSet();

    // follow集合预处理
    void followPreProcess();

    // follow集合完善处理
    void followFinalProcess();

    // 计算select集合
    void generateSelectSet();

    // 检查当前是否为LL1文法
    bool isLL1Grammar();

    // 构建预测分析表
    void buildAnalysisTable();

public:
    [[nodiscard]] const std::set<char> &getNonTerminals() const;

    [[nodiscard]] const std::set<char> &getTerminals() const;

    [[nodiscard]] const std::map<char, std::set<Express>> &getGrammarExpresses() const;

    Grammar(const std::string &nonTerminalString, const std::string &terminalString,
            const std::set<std::string> &productionTexts, char startChar);

    [[nodiscard]] char getStartChar() const;

    [[nodiscard]] const std::map<char, std::set<Express>> &getProductionsMap() const;

    [[nodiscard]] const std::map<char, std::set<char>> &getFirstSet() const;

    [[nodiscard]] const std::map<char, std::set<char>> &getFollowSet() const;

    [[nodiscard]] const std::map<char, SelectSet> &getSelectSet() const;

    [[nodiscard]] const std::map<char, TableRow> &getAnalysisTable() const;

    [[nodiscard]] bool isLl1Grammar() const;

    friend std::ostream &operator<<(std::ostream &os, const Grammar &grammar);

  static bool canDeducedEmpty(const std::set<std::string> &productions);
};

// 文法不支持异常
class NotSupportedGrammarException : public std::exception {
private:
    const std::string msg;
public:
    [[nodiscard]] const char *what() const _GLIBCXX_TXN_SAFE_DYN _GLIBCXX_NOTHROW override {
        return msg.data();
    };

public:
    explicit NotSupportedGrammarException(std::string msg) : msg(std::move(msg)) {};

    [[nodiscard]] const std::string &getMsg() const {
        return msg;
    };
};

#endif //LEXER_CPP_GRAMMAR_H