codon/compiler/util/peglib.h

//
//  peglib.h
//
//  Copyright (c) 2020 Yuji Hirose. All rights reserved.
//  MIT License
//
// clang-format off

#pragma once

#include <algorithm>
#include <any>
#include <cassert>
#include <cctype>
#if __has_include(<charconv>)
#include <charconv>
#endif
#include <cstring>
#include <functional>
#include <initializer_list>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <mutex>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#if !defined(__cplusplus) || __cplusplus < 201703L
#error "Requires complete C++17 support"
#endif

namespace peg {

/*-----------------------------------------------------------------------------
 *  scope_exit
 *---------------------------------------------------------------------------*/

// This is based on
// "http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4189".

template <typename EF> struct scope_exit {
  explicit scope_exit(EF &&f)
      : exit_function(std::move(f)), execute_on_destruction{true} {}

  scope_exit(scope_exit &&rhs)
      : exit_function(std::move(rhs.exit_function)),
        execute_on_destruction{rhs.execute_on_destruction} {
    rhs.release();
  }

  ~scope_exit() {
    if (execute_on_destruction) { this->exit_function(); }
  }

  void release() { this->execute_on_destruction = false; }

private:
  scope_exit(const scope_exit &) = delete;
  void operator=(const scope_exit &) = delete;
  scope_exit &operator=(scope_exit &&) = delete;

  EF exit_function;
  bool execute_on_destruction;
};

/*-----------------------------------------------------------------------------
 *  UTF8 functions
 *---------------------------------------------------------------------------*/

inline size_t codepoint_length(const char *s8, size_t l) {
  if (l) {
    auto b = static_cast<uint8_t>(s8[0]);
    if ((b & 0x80) == 0) {
      return 1;
    } else if ((b & 0xE0) == 0xC0 && l >= 2) {
      return 2;
    } else if ((b & 0xF0) == 0xE0 && l >= 3) {
      return 3;
    } else if ((b & 0xF8) == 0xF0 && l >= 4) {
      return 4;
    }
  }
  return 0;
}

inline size_t codepoint_count(const char *s8, size_t l) {
  size_t count = 0;
  for (size_t i = 0; i < l; i += codepoint_length(s8 + i, l - i)) {
    count++;
  }
  return count;
}

inline size_t encode_codepoint(char32_t cp, char *buff) {
  if (cp < 0x0080) {
    buff[0] = static_cast<char>(cp & 0x7F);
    return 1;
  } else if (cp < 0x0800) {
    buff[0] = static_cast<char>(0xC0 | ((cp >> 6) & 0x1F));
    buff[1] = static_cast<char>(0x80 | (cp & 0x3F));
    return 2;
  } else if (cp < 0xD800) {
    buff[0] = static_cast<char>(0xE0 | ((cp >> 12) & 0xF));
    buff[1] = static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
    buff[2] = static_cast<char>(0x80 | (cp & 0x3F));
    return 3;
  } else if (cp < 0xE000) {
    // D800 - DFFF is invalid...
    return 0;
  } else if (cp < 0x10000) {
    buff[0] = static_cast<char>(0xE0 | ((cp >> 12) & 0xF));
    buff[1] = static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
    buff[2] = static_cast<char>(0x80 | (cp & 0x3F));
    return 3;
  } else if (cp < 0x110000) {
    buff[0] = static_cast<char>(0xF0 | ((cp >> 18) & 0x7));
    buff[1] = static_cast<char>(0x80 | ((cp >> 12) & 0x3F));
    buff[2] = static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
    buff[3] = static_cast<char>(0x80 | (cp & 0x3F));
    return 4;
  }
  return 0;
}

inline std::string encode_codepoint(char32_t cp) {
  char buff[4];
  auto l = encode_codepoint(cp, buff);
  return std::string(buff, l);
}

inline bool decode_codepoint(const char *s8, size_t l, size_t &bytes,
                             char32_t &cp) {
  if (l) {
    auto b = static_cast<uint8_t>(s8[0]);
    if ((b & 0x80) == 0) {
      bytes = 1;
      cp = b;
      return true;
    } else if ((b & 0xE0) == 0xC0) {
      if (l >= 2) {
        bytes = 2;
        cp = ((static_cast<char32_t>(s8[0] & 0x1F)) << 6) |
             (static_cast<char32_t>(s8[1] & 0x3F));
        return true;
      }
    } else if ((b & 0xF0) == 0xE0) {
      if (l >= 3) {
        bytes = 3;
        cp = ((static_cast<char32_t>(s8[0] & 0x0F)) << 12) |
             ((static_cast<char32_t>(s8[1] & 0x3F)) << 6) |
             (static_cast<char32_t>(s8[2] & 0x3F));
        return true;
      }
    } else if ((b & 0xF8) == 0xF0) {
      if (l >= 4) {
        bytes = 4;
        cp = ((static_cast<char32_t>(s8[0] & 0x07)) << 18) |
             ((static_cast<char32_t>(s8[1] & 0x3F)) << 12) |
             ((static_cast<char32_t>(s8[2] & 0x3F)) << 6) |
             (static_cast<char32_t>(s8[3] & 0x3F));
        return true;
      }
    }
  }
  return false;
}

inline size_t decode_codepoint(const char *s8, size_t l, char32_t &cp) {
  size_t bytes;
  if (decode_codepoint(s8, l, bytes, cp)) { return bytes; }
  return 0;
}

inline char32_t decode_codepoint(const char *s8, size_t l) {
  char32_t cp = 0;
  decode_codepoint(s8, l, cp);
  return cp;
}

inline std::u32string decode(const char *s8, size_t l) {
  std::u32string out;
  size_t i = 0;
  while (i < l) {
    auto beg = i++;
    while (i < l && (s8[i] & 0xc0) == 0x80) {
      i++;
    }
    out += decode_codepoint(&s8[beg], (i - beg));
  }
  return out;
}

template <typename T> const char *u8(const T *s) {
  return reinterpret_cast<const char *>(s);
}

/*-----------------------------------------------------------------------------
 *  escape_characters
 *---------------------------------------------------------------------------*/

inline std::string escape_characters(const char *s, size_t n) {
  std::string str;
  for (size_t i = 0; i < n; i++) {
    auto c = s[i];
    switch (c) {
    case '\n': str += "\\n"; break;
    case '\r': str += "\\r"; break;
    case '\t': str += "\\t"; break;
    default: str += c; break;
    }
  }
  return str;
}

inline std::string escape_characters(std::string_view sv) {
  return escape_characters(sv.data(), sv.size());
}

/*-----------------------------------------------------------------------------
 *  resolve_escape_sequence
 *---------------------------------------------------------------------------*/

inline bool is_hex(char c, int &v) {
  if ('0' <= c && c <= '9') {
    v = c - '0';
    return true;
  } else if ('a' <= c && c <= 'f') {
    v = c - 'a' + 10;
    return true;
  } else if ('A' <= c && c <= 'F') {
    v = c - 'A' + 10;
    return true;
  }
  return false;
}

inline bool is_digit(char c, int &v) {
  if ('0' <= c && c <= '9') {
    v = c - '0';
    return true;
  }
  return false;
}

inline std::pair<int, size_t> parse_hex_number(const char *s, size_t n,
                                               size_t i) {
  int ret = 0;
  int val;
  while (i < n && is_hex(s[i], val)) {
    ret = static_cast<int>(ret * 16 + val);
    i++;
  }
  return std::pair(ret, i);
}

inline std::pair<int, size_t> parse_octal_number(const char *s, size_t n,
                                                 size_t i) {
  int ret = 0;
  int val;
  while (i < n && is_digit(s[i], val)) {
    ret = static_cast<int>(ret * 8 + val);
    i++;
  }
  return std::pair(ret, i);
}

inline std::string resolve_escape_sequence(const char *s, size_t n) {
  std::string r;
  r.reserve(n);

  size_t i = 0;
  while (i < n) {
    auto ch = s[i];
    if (ch == '\\') {
      i++;
      if (i == n) { throw std::runtime_error("Invalid escape sequence..."); }
      switch (s[i]) {
      case 'n':
        r += '\n';
        i++;
        break;
      case 'r':
        r += '\r';
        i++;
        break;
      case 't':
        r += '\t';
        i++;
        break;
      case '\'':
        r += '\'';
        i++;
        break;
      case '"':
        r += '"';
        i++;
        break;
      case '[':
        r += '[';
        i++;
        break;
      case ']':
        r += ']';
        i++;
        break;
      case '\\':
        r += '\\';
        i++;
        break;
      case 'x':
      case 'u': {
        char32_t cp;
        std::tie(cp, i) = parse_hex_number(s, n, i + 1);
        r += encode_codepoint(cp);
        break;
      }
      default: {
        char32_t cp;
        std::tie(cp, i) = parse_octal_number(s, n, i);
        r += encode_codepoint(cp);
        break;
      }
      }
    } else {
      r += ch;
      i++;
    }
  }
  return r;
}

/*-----------------------------------------------------------------------------
 *  token_to_number_ - This function should be removed eventually
 *---------------------------------------------------------------------------*/

template <typename T> T token_to_number_(std::string_view sv) {
  T n = 0;
#if __has_include(<charconv>)
  if constexpr (!std::is_floating_point<T>::value) {
    std::from_chars(sv.data(), sv.data() + sv.size(), n);
#else
  if constexpr (false) {
#endif
  } else {
    auto s = std::string(sv);
    std::istringstream ss(s);
    ss >> n;
  }
  return n;
}

/*-----------------------------------------------------------------------------
 *  Trie
 *---------------------------------------------------------------------------*/

class Trie {
public:
  Trie() = default;
  Trie(const Trie &) = default;

  Trie(const std::vector<std::string> &items) {
    for (const auto &item : items) {
      for (size_t len = 1; len <= item.size(); len++) {
        auto last = len == item.size();
        std::string_view sv(item.data(), len);
        auto it = dic_.find(sv);
        if (it == dic_.end()) {
          dic_.emplace(sv, Info{last, last});
        } else if (last) {
          it->second.match = true;
        } else {
          it->second.done = false;
        }
      }
    }
  }

  size_t match(const char *text, size_t text_len) const {
    size_t match_len = 0;
    auto done = false;
    size_t len = 1;
    while (!done && len <= text_len) {
      std::string_view sv(text, len);
      auto it = dic_.find(sv);
      if (it == dic_.end()) {
        done = true;
      } else {
        if (it->second.match) { match_len = len; }
        if (it->second.done) { done = true; }
      }
      len += 1;
    }
    return match_len;
  }

private:
  struct Info {
    bool done;
    bool match;
  };

  // TODO: Use unordered_map when heterogeneous lookup is supported in C++20
  // std::unordered_map<std::string, Info> dic_;
  std::map<std::string, Info, std::less<>> dic_;
};

/*-----------------------------------------------------------------------------
 *  PEG
 *---------------------------------------------------------------------------*/

/*
 * Line information utility function
 */
inline std::pair<size_t, size_t> line_info(const char *start, const char *cur) {
  auto p = start;
  auto col_ptr = p;
  auto no = 1;

  while (p < cur) {
    if (*p == '\n') {
      no++;
      col_ptr = p + 1;
    }
    p++;
  }

  auto col = codepoint_count(col_ptr, p - col_ptr) + 1;

  return std::pair(no, col);
}

/*
 * String tag
 */
inline constexpr unsigned int str2tag_core(const char *s, size_t l,
                                           unsigned int h) {
  return (l == 0) ? h
                  : str2tag_core(s + 1, l - 1,
                                 (h * 33) ^ static_cast<unsigned char>(*s));
}

inline constexpr unsigned int str2tag(std::string_view sv) {
  return str2tag_core(sv.data(), sv.size(), 0);
}

namespace udl {

inline constexpr unsigned int operator"" _(const char *s, size_t l) {
  return str2tag_core(s, l, 0);
}

} // namespace udl

/*
 * Semantic values
 */
struct SemanticValues : public std::vector<std::any> {
  // Input text
  const char *path = nullptr;
  const char *ss = nullptr;
  std::function<const std::vector<size_t> &()> source_line_index;

  // Matched string
  std::string_view sv() const { return sv_; }

  // Definition name
  const std::string &name() const { return name_; }

  std::vector<unsigned int> tags;

  // Line number and column at which the matched string is
  std::pair<size_t, size_t> line_info() const {
    auto &idx = source_line_index();

    auto cur = static_cast<size_t>(std::distance(ss, sv_.data()));
    auto it = std::lower_bound(
        idx.begin(), idx.end(), cur,
        [](size_t element, size_t value) { return element < value; });

    auto id = static_cast<size_t>(std::distance(idx.begin(), it));
    auto off = cur - (id == 0 ? 0 : idx[id - 1] + 1);
    return std::pair(id + 1, off + 1);
  }

  // Choice count
  size_t choice_count() const { return choice_count_; }

  // Choice number (0 based index)
  size_t choice() const { return choice_; }

  // Tokens
  std::vector<std::string_view> tokens;

  std::string_view token(size_t id = 0) const {
    if (tokens.empty()) { return sv_; }
    assert(id < tokens.size());
    return tokens[id];
  }

  // Token conversion
  std::string token_to_string(size_t id = 0) const {
    return std::string(token(id));
  }

  template <typename T> T token_to_number() const {
    return token_to_number_<T>(token());
  }

  // Transform the semantic value vector to another vector
  template <typename T>
  std::vector<T> transform(size_t beg = 0,
                           size_t end = static_cast<size_t>(-1)) const {
    std::vector<T> r;
    end = (std::min)(end, size());
    for (size_t i = beg; i < end; i++) {
      r.emplace_back(std::any_cast<T>((*this)[i]));
    }
    return r;
  }

  using std::vector<std::any>::iterator;
  using std::vector<std::any>::const_iterator;
  using std::vector<std::any>::size;
  using std::vector<std::any>::empty;
  using std::vector<std::any>::assign;
  using std::vector<std::any>::begin;
  using std::vector<std::any>::end;
  using std::vector<std::any>::rbegin;
  using std::vector<std::any>::rend;
  using std::vector<std::any>::operator[];
  using std::vector<std::any>::at;
  using std::vector<std::any>::resize;
  using std::vector<std::any>::front;
  using std::vector<std::any>::back;
  using std::vector<std::any>::push_back;
  using std::vector<std::any>::pop_back;
  using std::vector<std::any>::insert;
  using std::vector<std::any>::erase;
  using std::vector<std::any>::clear;
  using std::vector<std::any>::swap;
  using std::vector<std::any>::emplace;
  using std::vector<std::any>::emplace_back;

private:
  friend class Context;
  friend class Sequence;
  friend class PrioritizedChoice;
  friend class Holder;
  friend class PrecedenceClimbing;

  std::string_view sv_;
  size_t choice_count_ = 0;
  size_t choice_ = 0;
  std::string name_;
};

/*
 * Semantic action
 */
template <typename F, typename... Args> std::any call(F fn, Args &&... args) {
  using R = decltype(fn(std::forward<Args>(args)...));
  if constexpr (std::is_void<R>::value) {
    fn(std::forward<Args>(args)...);
    return std::any();
  } else if constexpr (std::is_same<typename std::remove_cv<R>::type,
                                    std::any>::value) {
    return fn(std::forward<Args>(args)...);
  } else {
    return std::any(fn(std::forward<Args>(args)...));
  }
}

template <typename T>
struct argument_count : argument_count<decltype(&T::operator())> {};
template <typename R, typename... Args>
struct argument_count<R (*)(Args...)>
    : std::integral_constant<unsigned, sizeof...(Args)> {};
template <typename R, typename C, typename... Args>
struct argument_count<R (C::*)(Args...)>
    : std::integral_constant<unsigned, sizeof...(Args)> {};
template <typename R, typename C, typename... Args>
struct argument_count<R (C::*)(Args...) const>
    : std::integral_constant<unsigned, sizeof...(Args)> {};

class Action {
public:
  Action() = default;
  Action(Action &&rhs) = default;
  template <typename F> Action(F fn) : fn_(make_adaptor(fn)) {}
  template <typename F> void operator=(F fn) { fn_ = make_adaptor(fn); }
  Action &operator=(const Action &rhs) = default;

  operator bool() const { return bool(fn_); }

  std::any operator()(SemanticValues &vs, std::any &dt) const {
    return fn_(vs, dt);
  }

private:
  using Fty = std::function<std::any(SemanticValues &vs, std::any &dt)>;

  template <typename F> Fty make_adaptor(F fn) {
    if constexpr (argument_count<F>::value == 1) {
      return [fn](auto &vs, auto & /*dt*/) { return call(fn, vs); };
    } else {
      return [fn](auto &vs, auto &dt) { return call(fn, vs, dt); };
    }
  }

  Fty fn_;
};

/*
 * Semantic predicate
 */
// Note: 'parse_error' exception class should be be used in sematic action
// handlers to reject the rule.
struct parse_error {
  parse_error() = default;
  parse_error(const char *s) : s_(s) {}
  const char *what() const { return s_.empty() ? nullptr : s_.data(); }

private:
  std::string s_;
};

/*
 * Parse result helper
 */
inline bool success(size_t len) { return len != static_cast<size_t>(-1); }

inline bool fail(size_t len) { return len == static_cast<size_t>(-1); }

/*
 * Log
 */
using Log = std::function<void(size_t, size_t, const std::string &)>;

/*
 * ErrorInfo
 */
struct ErrorInfo {
  const char *error_pos = nullptr;
  std::vector<std::pair<const char *, bool>> expected_tokens;
  const char *message_pos = nullptr;
  std::string message;
  mutable const char *last_output_pos = nullptr;

  void clear() {
    error_pos = nullptr;
    expected_tokens.clear();
    message_pos = nullptr;
    message.clear();
  }

  void add(const char *token, bool is_literal) {
    for (const auto &[t, l] : expected_tokens) {
      if (t == token && l == is_literal) { return; }
    }
    expected_tokens.push_back(std::make_pair(token, is_literal));
  }

  void output_log(const Log &log, const char *s, size_t n) const {
    if (message_pos) {
      if (message_pos > last_output_pos) {
        last_output_pos = message_pos;
        auto line = line_info(s, message_pos);
        std::string msg;
        if (auto unexpected_token = heuristic_error_token(s, n, message_pos);
            !unexpected_token.empty()) {
          msg = replace_all(message, "%t", unexpected_token);

          auto unexpected_char = unexpected_token.substr(
              0, codepoint_length(unexpected_token.data(),
                                  unexpected_token.size()));

          msg = replace_all(msg, "%c", unexpected_char);
        } else {
          msg = message;
        }
        log(line.first, line.second, msg);
      }
    } else if (error_pos) {
      if (error_pos > last_output_pos) {
        last_output_pos = error_pos;
        auto line = line_info(s, error_pos);

        std::string msg;
        if (expected_tokens.empty()) {
          msg = "syntax error.";
        } else {
          msg = "syntax error";

          // unexpected token
          if (auto unexpected_token = heuristic_error_token(s, n, error_pos);
              !unexpected_token.empty()) {
            msg += ", unexpected '";
            msg += unexpected_token;
            msg += "'";
          }

          auto first_item = true;
          size_t i = 0;
          while (i < expected_tokens.size()) {
            auto [token, is_literal] =
                expected_tokens[expected_tokens.size() - i - 1];

            // Skip rules start with '_'
            if (!is_literal && token[0] != '_') {
              msg += (first_item ? ", expecting " : ", ");
              if (is_literal) {
                msg += "'";
                msg += token;
                msg += "'";
              } else {
                msg += "<";
                msg += token;
                msg += ">";
              }
              first_item = false;
            }

            i++;
          }
          msg += ".";
        }

        log(line.first, line.second, msg);
      }
    }
  }

private:
  int cast_char(char c) const { return static_cast<unsigned char>(c); }

  std::string heuristic_error_token(const char *s, size_t n,
                                    const char *pos) const {
    auto len = n - std::distance(s, pos);
    if (len) {
      size_t i = 0;
      auto c = cast_char(pos[i++]);
      if (!std::ispunct(c) && !std::isspace(c)) {
        while (i < len && !std::ispunct(cast_char(pos[i])) &&
               !std::isspace(cast_char(pos[i]))) {
          i++;
        }
      }

      size_t count = 8;
      size_t j = 0;
      while (count > 0 && j < i) {
        j += codepoint_length(&pos[j], i - j);
        count--;
      }

      return escape_characters(pos, j);
    }
    return std::string();
  }

  std::string replace_all(std::string str, const std::string &from,
                          const std::string &to) const {
    size_t pos = 0;
    while ((pos = str.find(from, pos)) != std::string::npos) {
      str.replace(pos, from.length(), to);
      pos += to.length();
    }
    return str;
  }
};

/*
 * Context
 */
class Context;
class Ope;
class Definition;

using TracerEnter = std::function<void(const Ope &name, const char *s, size_t n,
                                       const SemanticValues &vs,
                                       const Context &c, const std::any &dt)>;

using TracerLeave = std::function<void(
    const Ope &ope, const char *s, size_t n, const SemanticValues &vs,
    const Context &c, const std::any &dt, size_t)>;

class Context {
public:
  const char *path;
  const char *s;
  const size_t l;
  std::vector<size_t> source_line_index;

  ErrorInfo error_info;
  bool recovered = false;

  std::vector<std::shared_ptr<SemanticValues>> value_stack;
  size_t value_stack_size = 0;

  std::vector<Definition *> rule_stack;
  std::vector<std::vector<std::shared_ptr<Ope>>> args_stack;

  size_t in_token_boundary_count = 0;

  std::shared_ptr<Ope> whitespaceOpe;
  bool in_whitespace = false;

  std::shared_ptr<Ope> wordOpe;

  std::vector<std::map<std::string_view, std::string>> capture_scope_stack;
  size_t capture_scope_stack_size = 0;

  std::vector<bool> cut_stack;

  const size_t def_count;
  const bool enablePackratParsing;
  std::vector<bool> cache_registered;
  std::vector<bool> cache_success;

  std::map<std::pair<size_t, size_t>, std::tuple<size_t, std::any>>
      cache_values;

  TracerEnter tracer_enter;
  TracerLeave tracer_leave;

  Log log;

  Context(const char *path, const char *s, size_t l, size_t def_count,
          std::shared_ptr<Ope> whitespaceOpe, std::shared_ptr<Ope> wordOpe,
          bool enablePackratParsing, TracerEnter tracer_enter,
          TracerLeave tracer_leave, Log log)
      : path(path), s(s), l(l), whitespaceOpe(whitespaceOpe), wordOpe(wordOpe),
        def_count(def_count), enablePackratParsing(enablePackratParsing),
        cache_registered(enablePackratParsing ? def_count * (l + 1) : 0),
        cache_success(enablePackratParsing ? def_count * (l + 1) : 0),
        tracer_enter(tracer_enter), tracer_leave(tracer_leave), log(log) {

    args_stack.resize(1);

    push_capture_scope();
  }

  ~Context() { assert(!value_stack_size); }

  Context(const Context &) = delete;
  Context(Context &&) = delete;
  Context operator=(const Context &) = delete;

  template <typename T>
  void packrat(const char *a_s, bool enable_memoize, size_t def_id, size_t &len, std::any &val,
               T fn) {
    if (!enablePackratParsing || !enable_memoize) {
      fn(val);
      return;
    }

    auto col = a_s - s;
    auto idx = def_count * static_cast<size_t>(col) + def_id;

    if (cache_registered[idx]) {
      if (cache_success[idx]) {
        auto key = std::pair(col, def_id);
        std::tie(len, val) = cache_values[key];
        return;
      } else {
        len = static_cast<size_t>(-1);
        return;
      }
    } else {
      fn(val);
      cache_registered[idx] = true;
      cache_success[idx] = success(len);
      if (success(len)) {
        auto key = std::pair(col, def_id);
        cache_values[key] = std::pair(len, val);
      }
      return;
    }
  }

  SemanticValues &push() {
    assert(value_stack_size <= value_stack.size());
    if (value_stack_size == value_stack.size()) {
      value_stack.emplace_back(std::make_shared<SemanticValues>());
    } else {
      auto &vs = *value_stack[value_stack_size];
      if (!vs.empty()) {
        vs.clear();
        if (!vs.tags.empty()) { vs.tags.clear(); }
      }
      vs.sv_ = std::string_view();
      vs.choice_count_ = 0;
      vs.choice_ = 0;
      if (!vs.tokens.empty()) { vs.tokens.clear(); }
    }

    auto &vs = *value_stack[value_stack_size++];
    vs.path = path;
    vs.ss = s;
    vs.source_line_index = [&]() -> const std::vector<size_t> & {
      if (source_line_index.empty()) {
        for (size_t pos = 0; pos < l; pos++) {
          if (s[pos] == '\n') { source_line_index.push_back(pos); }
        }
        source_line_index.push_back(l);
      }
      return source_line_index;
    };

    return vs;
  }

  void pop() { value_stack_size--; }

  void push_args(std::vector<std::shared_ptr<Ope>> &&args) {
    args_stack.emplace_back(args);
  }

  void pop_args() { args_stack.pop_back(); }

  const std::vector<std::shared_ptr<Ope>> &top_args() const {
    return args_stack[args_stack.size() - 1];
  }

  void push_capture_scope() {
    assert(capture_scope_stack_size <= capture_scope_stack.size());
    if (capture_scope_stack_size == capture_scope_stack.size()) {
      capture_scope_stack.emplace_back(
          std::map<std::string_view, std::string>());
    } else {
      auto &cs = capture_scope_stack[capture_scope_stack_size];
      if (!cs.empty()) { cs.clear(); }
    }
    capture_scope_stack_size++;
  }

  void pop_capture_scope() { capture_scope_stack_size--; }

  void shift_capture_values() {
    assert(capture_scope_stack.size() >= 2);
    auto curr = &capture_scope_stack[capture_scope_stack_size - 1];
    auto prev = curr - 1;
    for (const auto &[k, v] : *curr) {
      (*prev)[k] = v;
    }
  }

  void set_error_pos(const char *a_s, const char *literal = nullptr);

  // void trace_enter(const char *name, const char *a_s, size_t n,
  void trace_enter(const Ope &ope, const char *a_s, size_t n,
                   SemanticValues &vs, std::any &dt) const;
  // void trace_leave(const char *name, const char *a_s, size_t n,
  void trace_leave(const Ope &ope, const char *a_s, size_t n,
                   SemanticValues &vs, std::any &dt, size_t len) const;
  bool is_traceable(const Ope &ope) const;

  mutable size_t next_trace_id = 0;
  mutable std::list<size_t> trace_ids;
};

/*
 * Parser operators
 */
class Ope {
public:
  struct Visitor;

  virtual ~Ope() = default;
  size_t parse(const char *s, size_t n, SemanticValues &vs, Context &c,
               std::any &dt) const;
  virtual size_t parse_core(const char *s, size_t n, SemanticValues &vs,
                            Context &c, std::any &dt) const = 0;
  virtual void accept(Visitor &v) = 0;

  std::string code; // Store code in blocks ({ })
};

class Sequence : public Ope {
public:
  template <typename... Args>
  Sequence(const Args &... args)
      : opes_{static_cast<std::shared_ptr<Ope>>(args)...} {}
  Sequence(const std::vector<std::shared_ptr<Ope>> &opes) : opes_(opes) {}
  Sequence(std::vector<std::shared_ptr<Ope>> &&opes) : opes_(opes) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    auto &chldsv = c.push();
    auto pop_se = scope_exit([&]() { c.pop(); });
    size_t i = 0;
    for (const auto &ope : opes_) {
      const auto &rule = *ope;
      auto len = rule.parse(s + i, n - i, chldsv, c, dt);
      if (fail(len)) { return len; }
      i += len;
    }
    if (!chldsv.empty()) {
      for (size_t j = 0; j < chldsv.size(); j++) {
        vs.emplace_back(std::move(chldsv[j]));
      }
    }
    if (!chldsv.tags.empty()) {
      for (size_t j = 0; j < chldsv.tags.size(); j++) {
        vs.tags.emplace_back(std::move(chldsv.tags[j]));
      }
    }
    vs.sv_ = chldsv.sv_;
    if (!chldsv.tokens.empty()) {
      for (size_t j = 0; j < chldsv.tokens.size(); j++) {
        vs.tokens.emplace_back(std::move(chldsv.tokens[j]));
      }
    }
    return i;
  }

  void accept(Visitor &v) override;

  std::vector<std::shared_ptr<Ope>> opes_;
};

class PrioritizedChoice : public Ope {
public:
  template <typename... Args>
  PrioritizedChoice(bool for_label, const Args &... args)
      : opes_{static_cast<std::shared_ptr<Ope>>(args)...},
        for_label_(for_label) {}
  PrioritizedChoice(const std::vector<std::shared_ptr<Ope>> &opes)
      : opes_(opes) {}
  PrioritizedChoice(std::vector<std::shared_ptr<Ope>> &&opes) : opes_(opes) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    size_t len = static_cast<size_t>(-1);

    if (!for_label_) { c.cut_stack.push_back(false); }

    size_t id = 0;
    for (const auto &ope : opes_) {
      if (!c.cut_stack.empty()) { c.cut_stack.back() = false; }

      auto &chldsv = c.push();
      c.push_capture_scope();

      auto se = scope_exit([&]() {
        c.pop();
        c.pop_capture_scope();
      });

      len = ope->parse(s, n, chldsv, c, dt);

      if (success(len)) {
        if (!chldsv.empty()) {
          for (size_t i = 0; i < chldsv.size(); i++) {
            vs.emplace_back(std::move(chldsv[i]));
          }
        }
        if (!chldsv.tags.empty()) {
          for (size_t i = 0; i < chldsv.tags.size(); i++) {
            vs.tags.emplace_back(std::move(chldsv.tags[i]));
          }
        }
        vs.sv_ = chldsv.sv_;
        vs.choice_count_ = opes_.size();
        vs.choice_ = id;
        if (!chldsv.tokens.empty()) {
          for (size_t i = 0; i < chldsv.tokens.size(); i++) {
            vs.tokens.emplace_back(std::move(chldsv.tokens[i]));
          }
        }
        c.shift_capture_values();
        break;
      } else if (!c.cut_stack.empty() && c.cut_stack.back()) {
        break;
      }

      id++;
    }

    if (!for_label_) { c.cut_stack.pop_back(); }

    return len;
  }

  void accept(Visitor &v) override;

  size_t size() const { return opes_.size(); }

  std::vector<std::shared_ptr<Ope>> opes_;
  bool for_label_ = false;
};

class Repetition : public Ope {
public:
  Repetition(const std::shared_ptr<Ope> &ope, size_t min, size_t max)
      : ope_(ope), min_(min), max_(max) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    size_t count = 0;
    size_t i = 0;
    while (count < min_) {
      c.push_capture_scope();
      auto se = scope_exit([&]() { c.pop_capture_scope(); });
      const auto &rule = *ope_;
      auto len = rule.parse(s + i, n - i, vs, c, dt);
      if (success(len)) {
        c.shift_capture_values();
      } else {
        return len;
      }
      i += len;
      count++;
    }

    while (n - i > 0 && count < max_) {
      c.push_capture_scope();
      auto se = scope_exit([&]() { c.pop_capture_scope(); });
      auto save_sv_size = vs.size();
      auto save_tok_size = vs.tokens.size();
      const auto &rule = *ope_;
      auto len = rule.parse(s + i, n - i, vs, c, dt);
      if (success(len)) {
        c.shift_capture_values();
      } else {
        if (vs.size() != save_sv_size) {
          vs.erase(vs.begin() + static_cast<std::ptrdiff_t>(save_sv_size));
          vs.tags.erase(vs.tags.begin() +
                        static_cast<std::ptrdiff_t>(save_sv_size));
        }
        if (vs.tokens.size() != save_tok_size) {
          vs.tokens.erase(vs.tokens.begin() +
                          static_cast<std::ptrdiff_t>(save_tok_size));
        }
        break;
      }
      i += len;
      count++;
    }
    return i;
  }

  void accept(Visitor &v) override;

  bool is_zom() const {
    return min_ == 0 && max_ == std::numeric_limits<size_t>::max();
  }

  static std::shared_ptr<Repetition> zom(const std::shared_ptr<Ope> &ope) {
    return std::make_shared<Repetition>(ope, 0,
                                        std::numeric_limits<size_t>::max());
  }

  static std::shared_ptr<Repetition> oom(const std::shared_ptr<Ope> &ope) {
    return std::make_shared<Repetition>(ope, 1,
                                        std::numeric_limits<size_t>::max());
  }

  static std::shared_ptr<Repetition> opt(const std::shared_ptr<Ope> &ope) {
    return std::make_shared<Repetition>(ope, 0, 1);
  }

  std::shared_ptr<Ope> ope_;
  size_t min_;
  size_t max_;
};

class AndPredicate : public Ope {
public:
  AndPredicate(const std::shared_ptr<Ope> &ope) : ope_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues & /*vs*/,
                    Context &c, std::any &dt) const override {
    auto &chldsv = c.push();
    c.push_capture_scope();
    auto se = scope_exit([&]() {
      c.pop();
      c.pop_capture_scope();
    });
    const auto &rule = *ope_;
    auto len = rule.parse(s, n, chldsv, c, dt);
    if (success(len)) {
      return 0;
    } else {
      return len;
    }
  }

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
};

class NotPredicate : public Ope {
public:
  NotPredicate(const std::shared_ptr<Ope> &ope) : ope_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues & /*vs*/,
                    Context &c, std::any &dt) const override {
    auto &chldsv = c.push();
    c.push_capture_scope();
    auto se = scope_exit([&]() {
      c.pop();
      c.pop_capture_scope();
    });
    auto len = ope_->parse(s, n, chldsv, c, dt);
    if (success(len)) {
      c.set_error_pos(s);
      return static_cast<size_t>(-1);
    } else {
      return 0;
    }
  }

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
};

class Dictionary : public Ope, public std::enable_shared_from_this<Dictionary> {
public:
  Dictionary(const std::vector<std::string> &v) : trie_(v) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override;

  void accept(Visitor &v) override;

  Trie trie_;
};

class LiteralString : public Ope,
                      public std::enable_shared_from_this<LiteralString> {
public:
  LiteralString(std::string &&s, bool ignore_case)
      : lit_(s), ignore_case_(ignore_case), is_word_(false) {}

  LiteralString(const std::string &s, bool ignore_case)
      : lit_(s), ignore_case_(ignore_case), is_word_(false) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override;

  void accept(Visitor &v) override;

  std::string lit_;
  bool ignore_case_;
  mutable std::once_flag init_is_word_;
  mutable bool is_word_;
};

class CharacterClass : public Ope,
                       public std::enable_shared_from_this<CharacterClass> {
public:
  CharacterClass(const std::string &s, bool negated) : negated_(negated) {
    auto chars = decode(s.data(), s.length());
    auto i = 0u;
    while (i < chars.size()) {
      if (i + 2 < chars.size() && chars[i + 1] == '-') {
        auto cp1 = chars[i];
        auto cp2 = chars[i + 2];
        ranges_.emplace_back(std::pair(cp1, cp2));
        i += 3;
      } else {
        auto cp = chars[i];
        ranges_.emplace_back(std::pair(cp, cp));
        i += 1;
      }
    }
    assert(!ranges_.empty());
  }

  CharacterClass(const std::vector<std::pair<char32_t, char32_t>> &ranges,
                 bool negated)
      : ranges_(ranges), negated_(negated) {
    assert(!ranges_.empty());
  }

  size_t parse_core(const char *s, size_t n, SemanticValues & /*vs*/,
                    Context &c, std::any & /*dt*/) const override {
    if (n < 1) {
      c.set_error_pos(s);
      return static_cast<size_t>(-1);
    }

    char32_t cp = 0;
    auto len = decode_codepoint(s, n, cp);

    for (const auto &range : ranges_) {
      if (range.first <= cp && cp <= range.second) {
        if (negated_) {
          c.set_error_pos(s);
          return static_cast<size_t>(-1);
        } else {
          return len;
        }
      }
    }

    if (negated_) {
      return len;
    } else {
      c.set_error_pos(s);
      return static_cast<size_t>(-1);
    }
  }

  void accept(Visitor &v) override;

  std::vector<std::pair<char32_t, char32_t>> ranges_;
  bool negated_;
};

class Character : public Ope, public std::enable_shared_from_this<Character> {
public:
  Character(char ch) : ch_(ch) {}

  size_t parse_core(const char *s, size_t n, SemanticValues & /*vs*/,
                    Context &c, std::any & /*dt*/) const override {
    if (n < 1 || s[0] != ch_) {
      c.set_error_pos(s);
      return static_cast<size_t>(-1);
    }
    return 1;
  }

  void accept(Visitor &v) override;

  char ch_;
};

class AnyCharacter : public Ope,
                     public std::enable_shared_from_this<AnyCharacter> {
public:
  size_t parse_core(const char *s, size_t n, SemanticValues & /*vs*/,
                    Context &c, std::any & /*dt*/) const override {
    auto len = codepoint_length(s, n);
    if (len < 1) {
      c.set_error_pos(s);
      return static_cast<size_t>(-1);
    }
    return len;
  }

  void accept(Visitor &v) override;
};

class CaptureScope : public Ope {
public:
  CaptureScope(const std::shared_ptr<Ope> &ope) : ope_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    c.push_capture_scope();
    auto se = scope_exit([&]() { c.pop_capture_scope(); });
    const auto &rule = *ope_;
    auto len = rule.parse(s, n, vs, c, dt);
    return len;
  }

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
};

class Capture : public Ope {
public:
  using MatchAction = std::function<void(const char *s, size_t n, Context &c)>;

  Capture(const std::shared_ptr<Ope> &ope, MatchAction ma)
      : ope_(ope), match_action_(ma) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    const auto &rule = *ope_;
    auto len = rule.parse(s, n, vs, c, dt);
    if (success(len) && match_action_) { match_action_(s, len, c); }
    return len;
  }

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
  MatchAction match_action_;
};

class TokenBoundary : public Ope {
public:
  TokenBoundary(const std::shared_ptr<Ope> &ope) : ope_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override;

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
};

class Ignore : public Ope {
public:
  Ignore(const std::shared_ptr<Ope> &ope) : ope_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues & /*vs*/,
                    Context &c, std::any &dt) const override {
    const auto &rule = *ope_;
    auto &chldsv = c.push();
    auto se = scope_exit([&]() { c.pop(); });
    return rule.parse(s, n, chldsv, c, dt);
  }

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
};

using Parser = std::function<size_t(const char *s, size_t n, SemanticValues &vs,
                                    std::any &dt)>;

class User : public Ope {
public:
  User(Parser fn) : fn_(fn) {}
  size_t parse_core(const char *s, size_t n, SemanticValues &vs,
                    Context & /*c*/, std::any &dt) const override {
    assert(fn_);
    return fn_(s, n, vs, dt);
  }
  void accept(Visitor &v) override;
  std::function<size_t(const char *s, size_t n, SemanticValues &vs,
                       std::any &dt)>
      fn_;
};

class WeakHolder : public Ope {
public:
  WeakHolder(const std::shared_ptr<Ope> &ope) : weak_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    auto ope = weak_.lock();
    assert(ope);
    const auto &rule = *ope;
    return rule.parse(s, n, vs, c, dt);
  }

  void accept(Visitor &v) override;

  std::weak_ptr<Ope> weak_;
};

class Holder : public Ope {
public:
  Holder(Definition *outer) : outer_(outer) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override;

  void accept(Visitor &v) override;

  std::any reduce(SemanticValues &vs, std::any &dt) const;

  const char *trace_name() const;

  std::shared_ptr<Ope> ope_;
  Definition *outer_;
  mutable std::string trace_name_;

  friend class Definition;
};

using Grammar = std::unordered_map<std::string, Definition>;

class Reference : public Ope, public std::enable_shared_from_this<Reference> {
public:
  Reference(const Grammar &grammar, const std::string &name, const char *s,
            bool is_macro, const std::vector<std::shared_ptr<Ope>> &args)
      : grammar_(grammar), name_(name), s_(s), is_macro_(is_macro), args_(args),
        rule_(nullptr), iarg_(0) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override;

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> get_core_operator() const;

  const Grammar &grammar_;
  const std::string name_;
  const char *s_;

  const bool is_macro_;
  const std::vector<std::shared_ptr<Ope>> args_;

  Definition *rule_;
  size_t iarg_;
};

class Whitespace : public Ope {
public:
  Whitespace(const std::shared_ptr<Ope> &ope) : ope_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    if (c.in_whitespace) { return 0; }
    c.in_whitespace = true;
    auto se = scope_exit([&]() { c.in_whitespace = false; });
    const auto &rule = *ope_;
    return rule.parse(s, n, vs, c, dt);
  }

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
};

class BackReference : public Ope {
public:
  BackReference(std::string &&name) : name_(name) {}

  BackReference(const std::string &name) : name_(name) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override;

  void accept(Visitor &v) override;

  std::string name_;
};

class PrecedenceClimbing : public Ope {
public:
  using BinOpeInfo = std::map<std::string_view, std::pair<size_t, char>>;

  PrecedenceClimbing(const std::shared_ptr<Ope> &atom,
                     const std::shared_ptr<Ope> &binop, const BinOpeInfo &info,
                     const Definition &rule)
      : atom_(atom), binop_(binop), info_(info), rule_(rule) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override {
    return parse_expression(s, n, vs, c, dt, 0);
  }

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> atom_;
  std::shared_ptr<Ope> binop_;
  BinOpeInfo info_;
  const Definition &rule_;

private:
  size_t parse_expression(const char *s, size_t n, SemanticValues &vs,
                          Context &c, std::any &dt, size_t min_prec) const;

  Definition &get_reference_for_binop(Context &c) const;
};

class Recovery : public Ope {
public:
  Recovery(const std::shared_ptr<Ope> &ope) : ope_(ope) {}

  size_t parse_core(const char *s, size_t n, SemanticValues &vs, Context &c,
                    std::any &dt) const override;

  void accept(Visitor &v) override;

  std::shared_ptr<Ope> ope_;
};

class Cut : public Ope, public std::enable_shared_from_this<Cut> {
public:
  size_t parse_core(const char * /*s*/, size_t /*n*/, SemanticValues & /*vs*/,
                    Context &c, std::any & /*dt*/) const override {
    c.cut_stack.back() = true;
    return 0;
  }

  void accept(Visitor &v) override;
};

/*
 * Factories
 */
template <typename... Args> std::shared_ptr<Ope> seq(Args &&... args) {
  return std::make_shared<Sequence>(static_cast<std::shared_ptr<Ope>>(args)...);
}

template <typename... Args> std::shared_ptr<Ope> cho(Args &&... args) {
  return std::make_shared<PrioritizedChoice>(
      false, static_cast<std::shared_ptr<Ope>>(args)...);
}

template <typename... Args> std::shared_ptr<Ope> cho4label_(Args &&... args) {
  return std::make_shared<PrioritizedChoice>(
      true, static_cast<std::shared_ptr<Ope>>(args)...);
}

inline std::shared_ptr<Ope> zom(const std::shared_ptr<Ope> &ope) {
  return Repetition::zom(ope);
}

inline std::shared_ptr<Ope> oom(const std::shared_ptr<Ope> &ope) {
  return Repetition::oom(ope);
}

inline std::shared_ptr<Ope> opt(const std::shared_ptr<Ope> &ope) {
  return Repetition::opt(ope);
}

inline std::shared_ptr<Ope> rep(const std::shared_ptr<Ope> &ope, size_t min,
                                size_t max) {
  return std::make_shared<Repetition>(ope, min, max);
}

inline std::shared_ptr<Ope> apd(const std::shared_ptr<Ope> &ope) {
  return std::make_shared<AndPredicate>(ope);
}

inline std::shared_ptr<Ope> npd(const std::shared_ptr<Ope> &ope) {
  return std::make_shared<NotPredicate>(ope);
}

inline std::shared_ptr<Ope> dic(const std::vector<std::string> &v) {
  return std::make_shared<Dictionary>(v);
}

inline std::shared_ptr<Ope> lit(std::string &&s) {
  return std::make_shared<LiteralString>(s, false);
}

inline std::shared_ptr<Ope> liti(std::string &&s) {
  return std::make_shared<LiteralString>(s, true);
}

inline std::shared_ptr<Ope> cls(const std::string &s) {
  return std::make_shared<CharacterClass>(s, false);
}

inline std::shared_ptr<Ope>
cls(const std::vector<std::pair<char32_t, char32_t>> &ranges) {
  return std::make_shared<CharacterClass>(ranges, false);
}

inline std::shared_ptr<Ope> ncls(const std::string &s) {
  return std::make_shared<CharacterClass>(s, true);
}

inline std::shared_ptr<Ope>
ncls(const std::vector<std::pair<char32_t, char32_t>> &ranges) {
  return std::make_shared<CharacterClass>(ranges, true);
}

inline std::shared_ptr<Ope> chr(char dt) {
  return std::make_shared<Character>(dt);
}

inline std::shared_ptr<Ope> dot() { return std::make_shared<AnyCharacter>(); }

inline std::shared_ptr<Ope> csc(const std::shared_ptr<Ope> &ope) {
  return std::make_shared<CaptureScope>(ope);
}

inline std::shared_ptr<Ope> cap(const std::shared_ptr<Ope> &ope,
                                Capture::MatchAction ma) {
  return std::make_shared<Capture>(ope, ma);
}

inline std::shared_ptr<Ope> tok(const std::shared_ptr<Ope> &ope) {
  return std::make_shared<TokenBoundary>(ope);
}

inline std::shared_ptr<Ope> ign(const std::shared_ptr<Ope> &ope) {
  return std::make_shared<Ignore>(ope);
}

inline std::shared_ptr<Ope>
usr(std::function<size_t(const char *s, size_t n, SemanticValues &vs,
                         std::any &dt)>
        fn) {
  return std::make_shared<User>(fn);
}

inline std::shared_ptr<Ope> ref(const Grammar &grammar, const std::string &name,
                                const char *s = "", bool is_macro = false,
                                const std::vector<std::shared_ptr<Ope>> &args = {}) {
  return std::make_shared<Reference>(grammar, name, s, is_macro, args);
}

inline std::shared_ptr<Ope> wsp(const std::shared_ptr<Ope> &ope) {
  return std::make_shared<Whitespace>(std::make_shared<Ignore>(ope));
}

inline std::shared_ptr<Ope> bkr(std::string &&name) {
  return std::make_shared<BackReference>(name);
}

inline std::shared_ptr<Ope> pre(const std::shared_ptr<Ope> &atom,
                                const std::shared_ptr<Ope> &binop,
                                const PrecedenceClimbing::BinOpeInfo &info,
                                const Definition &rule) {
  return std::make_shared<PrecedenceClimbing>(atom, binop, info, rule);
}

inline std::shared_ptr<Ope> rec(const std::shared_ptr<Ope> &ope) {
  return std::make_shared<Recovery>(ope);
}

inline std::shared_ptr<Ope> cut() { return std::make_shared<Cut>(); }

/*
 * Visitor
 */
struct Ope::Visitor {
  virtual ~Visitor() {}
  virtual void visit(Sequence &) {}
  virtual void visit(PrioritizedChoice &) {}
  virtual void visit(Repetition &) {}
  virtual void visit(AndPredicate &) {}
  virtual void visit(NotPredicate &) {}
  virtual void visit(Dictionary &) {}
  virtual void visit(LiteralString &) {}
  virtual void visit(CharacterClass &) {}
  virtual void visit(Character &) {}
  virtual void visit(AnyCharacter &) {}
  virtual void visit(CaptureScope &) {}
  virtual void visit(Capture &) {}
  virtual void visit(TokenBoundary &) {}
  virtual void visit(Ignore &) {}
  virtual void visit(User &) {}
  virtual void visit(WeakHolder &) {}
  virtual void visit(Holder &) {}
  virtual void visit(Reference &) {}
  virtual void visit(Whitespace &) {}
  virtual void visit(BackReference &) {}
  virtual void visit(PrecedenceClimbing &) {}
  virtual void visit(Recovery &) {}
  virtual void visit(Cut &) {}
};

struct IsReference : public Ope::Visitor {
  void visit(Reference &) override { is_reference_ = true; }

  static bool check(Ope &ope) {
    IsReference vis;
    ope.accept(vis);
    return vis.is_reference_;
  }

private:
  bool is_reference_ = false;
};

struct TraceOpeName : public Ope::Visitor {
  void visit(Sequence &) override { name_ = "Sequence"; }
  void visit(PrioritizedChoice &) override { name_ = "PrioritizedChoice"; }
  void visit(Repetition &) override { name_ = "Repetition"; }
  void visit(AndPredicate &) override { name_ = "AndPredicate"; }
  void visit(NotPredicate &) override { name_ = "NotPredicate"; }
  void visit(Dictionary &) override { name_ = "Dictionary"; }
  void visit(LiteralString &) override { name_ = "LiteralString"; }
  void visit(CharacterClass &) override { name_ = "CharacterClass"; }
  void visit(Character &) override { name_ = "Character"; }
  void visit(AnyCharacter &) override { name_ = "AnyCharacter"; }
  void visit(CaptureScope &) override { name_ = "CaptureScope"; }
  void visit(Capture &) override { name_ = "Capture"; }
  void visit(TokenBoundary &) override { name_ = "TokenBoundary"; }
  void visit(Ignore &) override { name_ = "Ignore"; }
  void visit(User &) override { name_ = "User"; }
  void visit(WeakHolder &) override { name_ = "WeakHolder"; }
  void visit(Holder &ope) override { name_ = ope.trace_name(); }
  void visit(Reference &) override { name_ = "Reference"; }
  void visit(Whitespace &) override { name_ = "Whitespace"; }
  void visit(BackReference &) override { name_ = "BackReference"; }
  void visit(PrecedenceClimbing &) override { name_ = "PrecedenceClimbing"; }
  void visit(Recovery &) override { name_ = "Recovery"; }
  void visit(Cut &) override { name_ = "Cut"; }

  static std::string get(Ope &ope) {
    TraceOpeName vis;
    ope.accept(vis);
    return vis.name_;
  }

private:
  const char *name_ = nullptr;
};

struct AssignIDToDefinition : public Ope::Visitor {
  void visit(Sequence &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(Repetition &ope) override { ope.ope_->accept(*this); }
  void visit(AndPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(NotPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(CaptureScope &ope) override { ope.ope_->accept(*this); }
  void visit(Capture &ope) override { ope.ope_->accept(*this); }
  void visit(TokenBoundary &ope) override { ope.ope_->accept(*this); }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(WeakHolder &ope) override { ope.weak_.lock()->accept(*this); }
  void visit(Holder &ope) override;
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override { ope.ope_->accept(*this); }
  void visit(PrecedenceClimbing &ope) override;
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }

  std::unordered_map<void *, size_t> ids;
};

struct IsLiteralToken : public Ope::Visitor {
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      if (!IsLiteralToken::check(*op)) { return; }
    }
    result_ = true;
  }

  void visit(Dictionary &) override { result_ = true; }
  void visit(LiteralString &) override { result_ = true; }

  static bool check(Ope &ope) {
    IsLiteralToken vis;
    ope.accept(vis);
    return vis.result_;
  }

private:
  bool result_ = false;
};

struct TokenChecker : public Ope::Visitor {
  void visit(Sequence &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(Repetition &ope) override { ope.ope_->accept(*this); }
  void visit(CaptureScope &ope) override { ope.ope_->accept(*this); }
  void visit(Capture &ope) override { ope.ope_->accept(*this); }
  void visit(TokenBoundary &) override { has_token_boundary_ = true; }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(WeakHolder &) override { has_rule_ = true; }
  void visit(Holder &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override { ope.ope_->accept(*this); }
  void visit(PrecedenceClimbing &ope) override { ope.atom_->accept(*this); }
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }

  static bool is_token(Ope &ope) {
    if (IsLiteralToken::check(ope)) { return true; }

    TokenChecker vis;
    ope.accept(vis);
    return vis.has_token_boundary_ || !vis.has_rule_;
  }

private:
  bool has_token_boundary_ = false;
  bool has_rule_ = false;
};

struct FindLiteralToken : public Ope::Visitor {
  void visit(LiteralString &ope) override { token_ = ope.lit_.c_str(); }
  void visit(TokenBoundary &ope) override { ope.ope_->accept(*this); }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }

  static const char *token(Ope &ope) {
    FindLiteralToken vis;
    ope.accept(vis);
    return vis.token_;
  }

private:
  const char *token_ = nullptr;
};

struct DetectLeftRecursion : public Ope::Visitor {
  DetectLeftRecursion(const std::string &name) : name_(name) {}

  void visit(Sequence &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (done_) {
        break;
      } else if (error_s) {
        done_ = true;
        break;
      }
    }
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (error_s) {
        done_ = true;
        break;
      }
    }
  }
  void visit(Repetition &ope) override {
    ope.ope_->accept(*this);
    done_ = ope.min_ > 0;
  }
  void visit(AndPredicate &ope) override {
    ope.ope_->accept(*this);
    done_ = false;
  }
  void visit(NotPredicate &ope) override {
    ope.ope_->accept(*this);
    done_ = false;
  }
  void visit(Dictionary &) override { done_ = true; }
  void visit(LiteralString &ope) override { done_ = !ope.lit_.empty(); }
  void visit(CharacterClass &) override { done_ = true; }
  void visit(Character &) override { done_ = true; }
  void visit(AnyCharacter &) override { done_ = true; }
  void visit(CaptureScope &ope) override { ope.ope_->accept(*this); }
  void visit(Capture &ope) override { ope.ope_->accept(*this); }
  void visit(TokenBoundary &ope) override { ope.ope_->accept(*this); }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(User &) override { done_ = true; }
  void visit(WeakHolder &ope) override { ope.weak_.lock()->accept(*this); }
  void visit(Holder &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override { ope.ope_->accept(*this); }
  void visit(BackReference &) override { done_ = true; }
  void visit(PrecedenceClimbing &ope) override { ope.atom_->accept(*this); }
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }
  void visit(Cut &) override { done_ = true; }

  const char *error_s = nullptr;

private:
  std::string name_;
  std::set<std::string> refs_;
  bool done_ = false;
};

struct HasEmptyElement : public Ope::Visitor {
  HasEmptyElement(std::list<std::pair<const char *, std::string>> &refs)
      : refs_(refs) {}

  void visit(Sequence &ope) override {
    auto save_is_empty = false;
    const char *save_error_s = nullptr;
    std::string save_error_name;
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (!is_empty) { return; }
      save_is_empty = is_empty;
      save_error_s = error_s;
      save_error_name = error_name;
      is_empty = false;
      error_name.clear();
    }
    is_empty = save_is_empty;
    error_s = save_error_s;
    error_name = save_error_name;
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (is_empty) { return; }
    }
  }
  void visit(Repetition &ope) override {
    if (ope.min_ == 0) {
      set_error();
    } else {
      ope.ope_->accept(*this);
    }
  }
  void visit(AndPredicate &) override { set_error(); }
  void visit(NotPredicate &) override { set_error(); }
  void visit(LiteralString &ope) override {
    if (ope.lit_.empty()) { set_error(); }
  }
  void visit(CaptureScope &ope) override { ope.ope_->accept(*this); }
  void visit(Capture &ope) override { ope.ope_->accept(*this); }
  void visit(TokenBoundary &ope) override { ope.ope_->accept(*this); }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(WeakHolder &ope) override { ope.weak_.lock()->accept(*this); }
  void visit(Holder &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override { ope.ope_->accept(*this); }
  void visit(PrecedenceClimbing &ope) override { ope.atom_->accept(*this); }
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }

  bool is_empty = false;
  const char *error_s = nullptr;
  std::string error_name;

private:
  void set_error() {
    is_empty = true;
    tie(error_s, error_name) = refs_.back();
  }
  std::list<std::pair<const char *, std::string>> &refs_;
};

struct DetectInfiniteLoop : public Ope::Visitor {
  DetectInfiniteLoop(const char *s, const std::string &name) {
    refs_.emplace_back(s, name);
  }

  void visit(Sequence &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (has_error) { return; }
    }
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (has_error) { return; }
    }
  }
  void visit(Repetition &ope) override {
    if (ope.max_ == std::numeric_limits<size_t>::max()) {
      HasEmptyElement vis(refs_);
      ope.ope_->accept(vis);
      if (vis.is_empty) {
        has_error = true;
        error_s = vis.error_s;
        error_name = vis.error_name;
      }
    } else {
      ope.ope_->accept(*this);
    }
  }
  void visit(AndPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(NotPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(CaptureScope &ope) override { ope.ope_->accept(*this); }
  void visit(Capture &ope) override { ope.ope_->accept(*this); }
  void visit(TokenBoundary &ope) override { ope.ope_->accept(*this); }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(WeakHolder &ope) override { ope.weak_.lock()->accept(*this); }
  void visit(Holder &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override { ope.ope_->accept(*this); }
  void visit(PrecedenceClimbing &ope) override { ope.atom_->accept(*this); }
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }

  bool has_error = false;
  const char *error_s = nullptr;
  std::string error_name;

private:
  std::list<std::pair<const char *, std::string>> refs_;
};

struct ReferenceChecker : public Ope::Visitor {
  ReferenceChecker(const Grammar &grammar,
                   const std::vector<std::string> &params)
      : grammar_(grammar), params_(params) {}

  void visit(Sequence &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(Repetition &ope) override { ope.ope_->accept(*this); }
  void visit(AndPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(NotPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(CaptureScope &ope) override { ope.ope_->accept(*this); }
  void visit(Capture &ope) override { ope.ope_->accept(*this); }
  void visit(TokenBoundary &ope) override { ope.ope_->accept(*this); }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(WeakHolder &ope) override { ope.weak_.lock()->accept(*this); }
  void visit(Holder &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override { ope.ope_->accept(*this); }
  void visit(PrecedenceClimbing &ope) override { ope.atom_->accept(*this); }
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }

  std::unordered_map<std::string, const char *> error_s;
  std::unordered_map<std::string, std::string> error_message;
  std::unordered_set<std::string> referenced;

private:
  const Grammar &grammar_;
  const std::vector<std::string> &params_;
};

struct LinkReferences : public Ope::Visitor {
  LinkReferences(Grammar &grammar, const std::vector<std::string> &params)
      : grammar_(grammar), params_(params) {}

  void visit(Sequence &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
    }
  }
  void visit(Repetition &ope) override { ope.ope_->accept(*this); }
  void visit(AndPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(NotPredicate &ope) override { ope.ope_->accept(*this); }
  void visit(CaptureScope &ope) override { ope.ope_->accept(*this); }
  void visit(Capture &ope) override { ope.ope_->accept(*this); }
  void visit(TokenBoundary &ope) override { ope.ope_->accept(*this); }
  void visit(Ignore &ope) override { ope.ope_->accept(*this); }
  void visit(WeakHolder &ope) override { ope.weak_.lock()->accept(*this); }
  void visit(Holder &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override { ope.ope_->accept(*this); }
  void visit(PrecedenceClimbing &ope) override { ope.atom_->accept(*this); }
  void visit(Recovery &ope) override { ope.ope_->accept(*this); }

private:
  Grammar &grammar_;
  const std::vector<std::string> &params_;
};

struct FindReference : public Ope::Visitor {
  FindReference(const std::vector<std::shared_ptr<Ope>> &args,
                const std::vector<std::string> &params)
      : args_(args), params_(params) {}

  void visit(Sequence &ope) override {
    std::vector<std::shared_ptr<Ope>> opes;
    for (auto o : ope.opes_) {
      o->accept(*this);
      opes.push_back(found_ope);
    }
    found_ope = std::make_shared<Sequence>(opes);
  }
  void visit(PrioritizedChoice &ope) override {
    std::vector<std::shared_ptr<Ope>> opes;
    for (auto o : ope.opes_) {
      o->accept(*this);
      opes.push_back(found_ope);
    }
    found_ope = std::make_shared<PrioritizedChoice>(opes);
  }
  void visit(Repetition &ope) override {
    ope.ope_->accept(*this);
    found_ope = rep(found_ope, ope.min_, ope.max_);
  }
  void visit(AndPredicate &ope) override {
    ope.ope_->accept(*this);
    found_ope = apd(found_ope);
  }
  void visit(NotPredicate &ope) override {
    ope.ope_->accept(*this);
    found_ope = npd(found_ope);
  }
  void visit(Dictionary &ope) override { found_ope = ope.shared_from_this(); }
  void visit(LiteralString &ope) override {
    found_ope = ope.shared_from_this();
  }
  void visit(CharacterClass &ope) override {
    found_ope = ope.shared_from_this();
  }
  void visit(Character &ope) override { found_ope = ope.shared_from_this(); }
  void visit(AnyCharacter &ope) override { found_ope = ope.shared_from_this(); }
  void visit(CaptureScope &ope) override {
    ope.ope_->accept(*this);
    found_ope = csc(found_ope);
  }
  void visit(Capture &ope) override {
    ope.ope_->accept(*this);
    found_ope = cap(found_ope, ope.match_action_);
  }
  void visit(TokenBoundary &ope) override {
    ope.ope_->accept(*this);
    found_ope = tok(found_ope);
  }
  void visit(Ignore &ope) override {
    ope.ope_->accept(*this);
    found_ope = ign(found_ope);
  }
  void visit(WeakHolder &ope) override { ope.weak_.lock()->accept(*this); }
  void visit(Holder &ope) override { ope.ope_->accept(*this); }
  void visit(Reference &ope) override;
  void visit(Whitespace &ope) override {
    ope.ope_->accept(*this);
    found_ope = wsp(found_ope);
  }
  void visit(PrecedenceClimbing &ope) override {
    ope.atom_->accept(*this);
    found_ope = csc(found_ope);
  }
  void visit(Recovery &ope) override {
    ope.ope_->accept(*this);
    found_ope = rec(found_ope);
  }
  void visit(Cut &ope) override { found_ope = ope.shared_from_this(); }

  std::shared_ptr<Ope> found_ope;

private:
  const std::vector<std::shared_ptr<Ope>> &args_;
  const std::vector<std::string> &params_;
};

struct IsPrioritizedChoice : public Ope::Visitor {
  void visit(PrioritizedChoice &) override { result_ = true; }

  static bool check(Ope &ope) {
    IsPrioritizedChoice vis;
    ope.accept(vis);
    return vis.result_;
  }

private:
  bool result_ = false;
};

/*
 * Keywords
 */
static const char *WHITESPACE_DEFINITION_NAME = "%whitespace";
static const char *WORD_DEFINITION_NAME = "%word";
static const char *RECOVER_DEFINITION_NAME = "%recover";

/*
 * Definition
 */
class Definition {
public:
  struct Result {
    bool ret;
    bool recovered;
    size_t len;
    ErrorInfo error_info;
  };

  Definition() : holder_(std::make_shared<Holder>(this)) {}

  Definition(const Definition &rhs) : name(rhs.name), holder_(rhs.holder_) {
    holder_->outer_ = this;
  }

  Definition(const std::shared_ptr<Ope> &ope)
      : holder_(std::make_shared<Holder>(this)) {
    *this <= ope;
  }

  operator std::shared_ptr<Ope>() {
    return std::make_shared<WeakHolder>(holder_);
  }

  Definition &operator<=(const std::shared_ptr<Ope> &ope) {
    holder_->ope_ = ope;
    return *this;
  }

  Result parse(const char *s, size_t n, const char *path = nullptr,
               Log log = nullptr) const {
    SemanticValues vs;
    std::any dt;
    return parse_core(s, n, vs, dt, path, log);
  }

  Result parse(const char *s, const char *path = nullptr,
               Log log = nullptr) const {
    auto n = strlen(s);
    return parse(s, n, path, log);
  }

  Result parse(const char *s, size_t n, std::any &dt,
               const char *path = nullptr, Log log = nullptr) const {
    SemanticValues vs;
    return parse_core(s, n, vs, dt, path, log);
  }

  Result parse(const char *s, std::any &dt, const char *path = nullptr,
               Log log = nullptr) const {
    auto n = strlen(s);
    return parse(s, n, dt, path, log);
  }

  template <typename T>
  Result parse_and_get_value(const char *s, size_t n, T &val,
                             const char *path = nullptr,
                             Log log = nullptr) const {
    SemanticValues vs;
    std::any dt;
    auto r = parse_core(s, n, vs, dt, path, log);
    if (r.ret && !vs.empty() && vs.front().has_value()) {
      val = std::any_cast<T>(vs[0]);
    }
    return r;
  }

  template <typename T>
  Result parse_and_get_value(const char *s, T &val, const char *path = nullptr,
                             Log log = nullptr) const {
    auto n = strlen(s);
    return parse_and_get_value(s, n, val, path, log);
  }

  template <typename T>
  Result parse_and_get_value(const char *s, size_t n, std::any &dt, T &val,
                             const char *path = nullptr,
                             Log log = nullptr) const {
    SemanticValues vs;
    auto r = parse_core(s, n, vs, dt, path, log);
    if (r.ret && !vs.empty() && vs.front().has_value()) {
      val = std::any_cast<T>(vs[0]);
    }
    return r;
  }

  template <typename T>
  Result parse_and_get_value(const char *s, std::any &dt, T &val,
                             const char *path = nullptr,
                             Log log = nullptr) const {
    auto n = strlen(s);
    return parse_and_get_value(s, n, dt, val, path, log);
  }

  void operator=(Action a) { action = a; }

  template <typename T> Definition &operator,(T fn) {
    operator=(fn);
    return *this;
  }

  Definition &operator~() {
    ignoreSemanticValue = true;
    return *this;
  }

  void accept(Ope::Visitor &v) { holder_->accept(v); }

  std::shared_ptr<Ope> get_core_operator() const { return holder_->ope_; }

  bool is_token() const {
    std::call_once(is_token_init_, [this]() {
      is_token_ = TokenChecker::is_token(*get_core_operator());
    });
    return is_token_;
  }

  std::string name;
  const char *s_ = nullptr;

  size_t id = 0;
  Action action;
  std::function<void(const char *s, size_t n, std::any &dt)> enter;
  std::function<void(const char *s, size_t n, size_t matchlen, std::any &value,
                     std::any &dt)>
      leave;
  bool ignoreSemanticValue = false;
  std::shared_ptr<Ope> whitespaceOpe;
  std::shared_ptr<Ope> wordOpe;
  bool enablePackratParsing = false;
  bool enable_memoize = true;
  bool is_macro = false;
  std::vector<std::string> params;
  TracerEnter tracer_enter;
  TracerLeave tracer_leave;
  bool disable_action = false;

  std::string error_message;
  bool no_ast_opt = false;

private:
  friend class Reference;
  friend class ParserGenerator;

  Definition &operator=(const Definition &rhs);
  Definition &operator=(Definition &&rhs);

  void initialize_definition_ids() const {
    std::call_once(definition_ids_init_, [&]() {
      AssignIDToDefinition vis;
      holder_->accept(vis);
      if (whitespaceOpe) { whitespaceOpe->accept(vis); }
      if (wordOpe) { wordOpe->accept(vis); }
      definition_ids_.swap(vis.ids);
    });
  }

  Result parse_core(const char *s, size_t n, SemanticValues &vs, std::any &dt,
                    const char *path, Log log) const {
    initialize_definition_ids();

    std::shared_ptr<Ope> ope = holder_;
    if (whitespaceOpe) { ope = std::make_shared<Sequence>(whitespaceOpe, ope); }

    Context cxt(path, s, n, definition_ids_.size(), whitespaceOpe, wordOpe,
                enablePackratParsing, tracer_enter, tracer_leave, log);

    auto len = ope->parse(s, n, vs, cxt, dt);
    return Result{success(len), cxt.recovered, len, cxt.error_info};
  }

  std::shared_ptr<Holder> holder_;
  mutable std::once_flag is_token_init_;
  mutable bool is_token_ = false;
  mutable std::once_flag assign_id_to_definition_init_;
  mutable std::once_flag definition_ids_init_;
  mutable std::unordered_map<void *, size_t> definition_ids_;
};

/*
 * Implementations
 */

inline size_t parse_literal(const char *s, size_t n, SemanticValues &vs,
                            Context &c, std::any &dt, const std::string &lit,
                            std::once_flag &init_is_word, bool &is_word,
                            bool ignore_case) {
  size_t i = 0;
  for (; i < lit.size(); i++) {
    if (i >= n || (ignore_case ? (std::tolower(s[i]) != std::tolower(lit[i]))
                               : (s[i] != lit[i]))) {
      c.set_error_pos(s, lit.c_str());
      return static_cast<size_t>(-1);
    }
  }

  // Word check
  if (c.wordOpe) {
    std::call_once(init_is_word, [&]() {
      SemanticValues dummy_vs;
      Context dummy_c(nullptr, c.s, c.l, 0, nullptr, nullptr, false, nullptr,
                      nullptr, nullptr);
      std::any dummy_dt;

      auto len =
          c.wordOpe->parse(lit.data(), lit.size(), dummy_vs, dummy_c, dummy_dt);
      is_word = success(len);
    });

    if (is_word) {
      SemanticValues dummy_vs;
      Context dummy_c(nullptr, c.s, c.l, 0, nullptr, nullptr, false, nullptr,
                      nullptr, nullptr);
      std::any dummy_dt;

      NotPredicate ope(c.wordOpe);
      auto len = ope.parse(s + i, n - i, dummy_vs, dummy_c, dummy_dt);
      if (fail(len)) { return len; }
      i += len;
    }
  }

  // Skip whiltespace
  if (!c.in_token_boundary_count) {
    if (c.whitespaceOpe) {
      auto len = c.whitespaceOpe->parse(s + i, n - i, vs, c, dt);
      if (fail(len)) { return len; }
      i += len;
    }
  }

  return i;
}

inline void Context::set_error_pos(const char *a_s, const char *literal) {
  if (log) {
    if (error_info.error_pos <= a_s) {
      if (error_info.error_pos < a_s) {
        error_info.error_pos = a_s;
        error_info.expected_tokens.clear();
      }
      if (literal) {
        error_info.add(literal, true);
      } else if (!rule_stack.empty()) {
        auto rule = rule_stack.back();
        auto ope = rule->get_core_operator();
        if (auto token = FindLiteralToken::token(*ope);
            token && token[0] != '\0') {
          error_info.add(token, true);
        } else {
          error_info.add(rule->name.c_str(), false);
        }
      }
    }
  }
}

inline void Context::trace_enter(const Ope &ope, const char *a_s, size_t n,
                                 SemanticValues &vs, std::any &dt) const {
  trace_ids.push_back(next_trace_id++);
  tracer_enter(ope, a_s, n, vs, *this, dt);
}

inline void Context::trace_leave(const Ope &ope, const char *a_s, size_t n,
                                 SemanticValues &vs, std::any &dt,
                                 size_t len) const {
  tracer_leave(ope, a_s, n, vs, *this, dt, len);
  trace_ids.pop_back();
}

inline bool Context::is_traceable(const Ope &ope) const {
  if (tracer_enter && tracer_leave) {
    return !IsReference::check(const_cast<Ope &>(ope));
  }
  return false;
}

inline size_t Ope::parse(const char *s, size_t n, SemanticValues &vs,
                         Context &c, std::any &dt) const {
  if (c.is_traceable(*this)) {
    c.trace_enter(*this, s, n, vs, dt);
    auto len = parse_core(s, n, vs, c, dt);
    c.trace_leave(*this, s, n, vs, dt, len);
    return len;
  }
  return parse_core(s, n, vs, c, dt);
}

inline size_t Dictionary::parse_core(const char *s, size_t n,
                                     SemanticValues & /*vs*/, Context &c,
                                     std::any & /*dt*/) const {
  auto len = trie_.match(s, n);
  if (len > 0) { return len; }
  c.set_error_pos(s);
  return static_cast<size_t>(-1);
}

inline size_t LiteralString::parse_core(const char *s, size_t n,
                                        SemanticValues &vs, Context &c,
                                        std::any &dt) const {
  return parse_literal(s, n, vs, c, dt, lit_, init_is_word_, is_word_,
                       ignore_case_);
}

inline size_t TokenBoundary::parse_core(const char *s, size_t n,
                                        SemanticValues &vs, Context &c,
                                        std::any &dt) const {
  size_t len;
  {
    c.in_token_boundary_count++;
    auto se = scope_exit([&]() { c.in_token_boundary_count--; });
    len = ope_->parse(s, n, vs, c, dt);
  }

  if (success(len)) {
    vs.tokens.emplace_back(std::string_view(s, len));

    if (!c.in_token_boundary_count) {
      if (c.whitespaceOpe) {
        auto l = c.whitespaceOpe->parse(s + len, n - len, vs, c, dt);
        if (fail(l)) { return l; }
        len += l;
      }
    }
  }
  return len;
}

inline size_t Holder::parse_core(const char *s, size_t n, SemanticValues &vs,
                                 Context &c, std::any &dt) const {
  if (!ope_) {
    throw std::logic_error("Uninitialized definition ope was used...");
  }

  // Macro reference
  if (outer_->is_macro) {
    c.rule_stack.push_back(outer_);
    auto len = ope_->parse(s, n, vs, c, dt);
    c.rule_stack.pop_back();
    return len;
  }

  size_t len;
  std::any val;

  c.packrat(s, outer_->enable_memoize, outer_->id, len, val, [&](std::any &a_val) {
    if (outer_->enter) { outer_->enter(s, n, dt); }

    auto se2 = scope_exit([&]() {
      c.pop();
      if (outer_->leave) { outer_->leave(s, n, len, a_val, dt); }
    });

    auto &chldsv = c.push();

    c.rule_stack.push_back(outer_);
    len = ope_->parse(s, n, chldsv, c, dt);
    c.rule_stack.pop_back();

    // Invoke action
    if (success(len)) {
      chldsv.sv_ = std::string_view(s, len);
      chldsv.name_ = outer_->name;

      if (!IsPrioritizedChoice::check(*ope_)) {
        chldsv.choice_count_ = 0;
        chldsv.choice_ = 0;
      }

      try {
        a_val = reduce(chldsv, dt);
      } catch (const parse_error &e) {
        if (c.log) {
          if (e.what()) {
            if (c.error_info.message_pos < s) {
              c.error_info.message_pos = s;
              c.error_info.message = e.what();
            }
          }
        }
        len = static_cast<size_t>(-1);
      }
    }
  });

  if (success(len)) {
    if (!outer_->ignoreSemanticValue) {
      vs.emplace_back(std::move(val));
      vs.tags.emplace_back(str2tag(outer_->name));
    }
  }

  return len;
}

inline std::any Holder::reduce(SemanticValues &vs, std::any &dt) const {
  if (outer_->action && !outer_->disable_action) {
    return outer_->action(vs, dt);
  } else if (vs.empty()) {
    return std::any();
  } else {
    return std::move(vs.front());
  }
}

inline const char *Holder::trace_name() const {
  if (trace_name_.empty()) { trace_name_ = "[" + outer_->name + "]"; }
  return trace_name_.data();
}

inline size_t Reference::parse_core(const char *s, size_t n, SemanticValues &vs,
                                    Context &c, std::any &dt) const {
  if (rule_) {
    // Reference rule
    if (rule_->is_macro) {
      // Macro
      FindReference vis(c.top_args(), c.rule_stack.back()->params);

      // Collect arguments
      std::vector<std::shared_ptr<Ope>> args;
      for (auto arg : args_) {
        arg->accept(vis);
        args.emplace_back(std::move(vis.found_ope));
      }

      c.push_args(std::move(args));
      auto se = scope_exit([&]() { c.pop_args(); });
      auto ope = get_core_operator();
      return ope->parse(s, n, vs, c, dt);
    } else {
      // Definition
      c.push_args(std::vector<std::shared_ptr<Ope>>());
      auto se = scope_exit([&]() { c.pop_args(); });
      auto ope = get_core_operator();
      return ope->parse(s, n, vs, c, dt);
    }
  } else {
    // Reference parameter in macro
    const auto &args = c.top_args();
    return args[iarg_]->parse(s, n, vs, c, dt);
  }
}

inline std::shared_ptr<Ope> Reference::get_core_operator() const {
  return rule_->holder_;
}

inline size_t BackReference::parse_core(const char *s, size_t n,
                                        SemanticValues &vs, Context &c,
                                        std::any &dt) const {
  auto size = static_cast<int>(c.capture_scope_stack_size);
  for (auto i = size - 1; i >= 0; i--) {
    auto index = static_cast<size_t>(i);
    const auto &cs = c.capture_scope_stack[index];
    if (cs.find(name_) != cs.end()) {
      const auto &lit = cs.at(name_);
      std::once_flag init_is_word;
      auto is_word = false;
      return parse_literal(s, n, vs, c, dt, lit, init_is_word, is_word, false);
    }
  }
  throw std::runtime_error("Invalid back reference...");
}

inline Definition &
PrecedenceClimbing::get_reference_for_binop(Context &c) const {
  if (rule_.is_macro) {
    // Reference parameter in macro
    const auto &args = c.top_args();
    auto iarg = dynamic_cast<Reference &>(*binop_).iarg_;
    auto arg = args[iarg];
    return *dynamic_cast<Reference &>(*arg).rule_;
  }

  return *dynamic_cast<Reference &>(*binop_).rule_;
}

inline size_t PrecedenceClimbing::parse_expression(const char *s, size_t n,
                                                   SemanticValues &vs,
                                                   Context &c, std::any &dt,
                                                   size_t min_prec) const {
  auto len = atom_->parse(s, n, vs, c, dt);
  if (fail(len)) { return len; }

  std::string tok;
  auto &rule = get_reference_for_binop(c);
  auto action = std::move(rule.action);

  rule.action = [&](SemanticValues &vs2, std::any &dt2) {
    tok = vs2.token();
    if (action) {
      return action(vs2, dt2);
    } else if (!vs2.empty()) {
      return vs2[0];
    }
    return std::any();
  };
  auto action_se = scope_exit([&]() { rule.action = std::move(action); });

  auto i = len;
  while (i < n) {
    std::vector<std::any> save_values(vs.begin(), vs.end());
    auto save_tokens = vs.tokens;

    auto chv = c.push();
    auto chl = binop_->parse(s + i, n - i, chv, c, dt);
    c.pop();

    if (fail(chl)) { break; }

    auto it = info_.find(tok);
    if (it == info_.end()) { break; }

    auto level = std::get<0>(it->second);
    auto assoc = std::get<1>(it->second);

    if (level < min_prec) { break; }

    vs.emplace_back(std::move(chv[0]));
    i += chl;

    auto next_min_prec = level;
    if (assoc == 'L') { next_min_prec = level + 1; }

    chv = c.push();
    chl = parse_expression(s + i, n - i, chv, c, dt, next_min_prec);
    c.pop();

    if (fail(chl)) {
      vs.assign(save_values.begin(), save_values.end());
      vs.tokens = save_tokens;
      i = chl;
      break;
    }

    vs.emplace_back(std::move(chv[0]));
    i += chl;

    std::any val;
    if (rule_.action) {
      vs.sv_ = std::string_view(s, i);
      val = rule_.action(vs, dt);
    } else if (!vs.empty()) {
      val = vs[0];
    }
    vs.clear();
    vs.emplace_back(std::move(val));
  }

  return i;
}

inline size_t Recovery::parse_core(const char *s, size_t n,
                                   SemanticValues & /*vs*/, Context &c,
                                   std::any & /*dt*/) const {
  const auto &rule = dynamic_cast<Reference &>(*ope_);

  // Custom error message
  if (c.log) {
    auto label = dynamic_cast<Reference *>(rule.args_[0].get());
    if (label) {
      if (!label->rule_->error_message.empty()) {
        c.error_info.message_pos = s;
        c.error_info.message = label->rule_->error_message;
      }
    }
  }

  // Recovery
  size_t len = static_cast<size_t>(-1);
  {
    auto save_log = c.log;
    c.log = nullptr;
    auto se = scope_exit([&]() { c.log = save_log; });

    SemanticValues dummy_vs;
    std::any dummy_dt;

    len = rule.parse(s, n, dummy_vs, c, dummy_dt);
  }

  if (success(len)) {
    c.recovered = true;

    if (c.log) {
      c.error_info.output_log(c.log, c.s, c.l);
      c.error_info.clear();
    }
  }

  // Cut
  if (!c.cut_stack.empty()) {
    c.cut_stack.back() = true;

    if (c.cut_stack.size() == 1) {
      // TODO: Remove unneeded entries in packrat memoise table
    }
  }

  return len;
}

inline void Sequence::accept(Visitor &v) { v.visit(*this); }
inline void PrioritizedChoice::accept(Visitor &v) { v.visit(*this); }
inline void Repetition::accept(Visitor &v) { v.visit(*this); }
inline void AndPredicate::accept(Visitor &v) { v.visit(*this); }
inline void NotPredicate::accept(Visitor &v) { v.visit(*this); }
inline void Dictionary::accept(Visitor &v) { v.visit(*this); }
inline void LiteralString::accept(Visitor &v) { v.visit(*this); }
inline void CharacterClass::accept(Visitor &v) { v.visit(*this); }
inline void Character::accept(Visitor &v) { v.visit(*this); }
inline void AnyCharacter::accept(Visitor &v) { v.visit(*this); }
inline void CaptureScope::accept(Visitor &v) { v.visit(*this); }
inline void Capture::accept(Visitor &v) { v.visit(*this); }
inline void TokenBoundary::accept(Visitor &v) { v.visit(*this); }
inline void Ignore::accept(Visitor &v) { v.visit(*this); }
inline void User::accept(Visitor &v) { v.visit(*this); }
inline void WeakHolder::accept(Visitor &v) { v.visit(*this); }
inline void Holder::accept(Visitor &v) { v.visit(*this); }
inline void Reference::accept(Visitor &v) { v.visit(*this); }
inline void Whitespace::accept(Visitor &v) { v.visit(*this); }
inline void BackReference::accept(Visitor &v) { v.visit(*this); }
inline void PrecedenceClimbing::accept(Visitor &v) { v.visit(*this); }
inline void Recovery::accept(Visitor &v) { v.visit(*this); }
inline void Cut::accept(Visitor &v) { v.visit(*this); }

inline void AssignIDToDefinition::visit(Holder &ope) {
  auto p = static_cast<void *>(ope.outer_);
  if (ids.count(p)) { return; }
  auto id = ids.size();
  ids[p] = id;
  ope.outer_->id = id;
  ope.ope_->accept(*this);
}

inline void AssignIDToDefinition::visit(Reference &ope) {
  if (ope.rule_) {
    for (auto arg : ope.args_) {
      arg->accept(*this);
    }
    ope.rule_->accept(*this);
  }
}

inline void AssignIDToDefinition::visit(PrecedenceClimbing &ope) {
  ope.atom_->accept(*this);
  ope.binop_->accept(*this);
}

inline void TokenChecker::visit(Reference &ope) {
  if (ope.is_macro_) {
    for (auto arg : ope.args_) {
      arg->accept(*this);
    }
  } else {
    has_rule_ = true;
  }
}

inline void FindLiteralToken::visit(Reference &ope) {
  if (ope.is_macro_) {
    ope.rule_->accept(*this);
    for (auto arg : ope.args_) {
      arg->accept(*this);
    }
  }
}

inline void DetectLeftRecursion::visit(Reference &ope) {
  if (ope.name_ == name_) {
    error_s = ope.s_;
  } else if (!refs_.count(ope.name_)) {
    refs_.insert(ope.name_);
    if (ope.rule_) {
      ope.rule_->accept(*this);
      if (done_ == false) { return; }
    }
  }
  done_ = true;
}

inline void HasEmptyElement::visit(Reference &ope) {
  auto it = std::find_if(refs_.begin(), refs_.end(),
                         [&](const std::pair<const char *, std::string> &ref) {
                           return ope.name_ == ref.second;
                         });
  if (it != refs_.end()) { return; }

  if (ope.rule_) {
    refs_.emplace_back(ope.s_, ope.name_);
    ope.rule_->accept(*this);
    refs_.pop_back();
  }
}

inline void DetectInfiniteLoop::visit(Reference &ope) {
  auto it = std::find_if(refs_.begin(), refs_.end(),
                         [&](const std::pair<const char *, std::string> &ref) {
                           return ope.name_ == ref.second;
                         });
  if (it != refs_.end()) { return; }

  if (ope.rule_) {
    refs_.emplace_back(ope.s_, ope.name_);
    ope.rule_->accept(*this);
    refs_.pop_back();
  }

  if (ope.is_macro_) {
    for (auto arg : ope.args_) {
      arg->accept(*this);
    }
  }
}

inline void ReferenceChecker::visit(Reference &ope) {
  auto it = std::find(params_.begin(), params_.end(), ope.name_);
  if (it != params_.end()) { return; }

  if (!grammar_.count(ope.name_)) {
    error_s[ope.name_] = ope.s_;
    error_message[ope.name_] = "'" + ope.name_ + "' is not defined.";
  } else {
    if (!referenced.count(ope.name_)) { referenced.insert(ope.name_); }
    const auto &rule = grammar_.at(ope.name_);
    if (rule.is_macro) {
      if (!ope.is_macro_ || ope.args_.size() != rule.params.size()) {
        error_s[ope.name_] = ope.s_;
        error_message[ope.name_] = "incorrect number of arguments.";
      }
    } else if (ope.is_macro_) {
      error_s[ope.name_] = ope.s_;
      error_message[ope.name_] = "'" + ope.name_ + "' is not macro.";
    }
    for (auto arg : ope.args_) {
      arg->accept(*this);
    }
  }
}

inline void LinkReferences::visit(Reference &ope) {
  // Check if the reference is a macro parameter
  auto found_param = false;
  for (size_t i = 0; i < params_.size(); i++) {
    const auto &param = params_[i];
    if (param == ope.name_) {
      ope.iarg_ = i;
      found_param = true;
      break;
    }
  }

  // Check if the reference is a definition rule
  if (!found_param && grammar_.count(ope.name_)) {
    auto &rule = grammar_.at(ope.name_);
    ope.rule_ = &rule;
  }

  for (auto arg : ope.args_) {
    arg->accept(*this);
  }
}

inline void FindReference::visit(Reference &ope) {
  for (size_t i = 0; i < args_.size(); i++) {
    const auto &name = params_[i];
    if (name == ope.name_) {
      found_ope = args_[i];
      return;
    }
  }
  found_ope = ope.shared_from_this();
}

/*-----------------------------------------------------------------------------
 *  PEG parser generator
 *---------------------------------------------------------------------------*/

class parser {
public:
  parser() = default;

  operator bool() { return grammar_ != nullptr; }

  bool parse_n(const char *s, size_t n, const char *path = nullptr) const {
    if (grammar_ != nullptr) {
      const auto &rule = (*grammar_)[start_];
      return post_process(s, n, rule.parse(s, n, path, log));
    }
    return false;
  }

  bool parse(std::string_view sv, const char *path = nullptr) const {
    return parse_n(sv.data(), sv.size(), path);
  }

  bool parse_n(const char *s, size_t n, std::any &dt,
               const char *path = nullptr) const {
    if (grammar_ != nullptr) {
      const auto &rule = (*grammar_)[start_];
      return post_process(s, n, rule.parse(s, n, dt, path, log));
    }
    return false;
  }

  bool parse(std::string_view sv, std::any &dt,
             const char *path = nullptr) const {
    return parse_n(sv.data(), sv.size(), dt, path);
  }

  template <typename T>
  bool parse_n(const char *s, size_t n, T &val,
               const char *path = nullptr) const {
    if (grammar_ != nullptr) {
      const auto &rule = (*grammar_)[start_];
      return post_process(s, n, rule.parse_and_get_value(s, n, val, path, log));
    }
    return false;
  }

  template <typename T>
  bool parse(std::string_view sv, T &val, const char *path = nullptr) const {
    return parse_n(sv.data(), sv.size(), val, path);
  }

  template <typename T>
  bool parse_n(const char *s, size_t n, std::any &dt, T &val,
               const char *path = nullptr) const {
    if (grammar_ != nullptr) {
      const auto &rule = (*grammar_)[start_];
      return post_process(s, n,
                          rule.parse_and_get_value(s, n, dt, val, path, log));
    }
    return false;
  }

  template <typename T>
  bool parse(const char *s, std::any &dt, T &val,
             const char *path = nullptr) const {
    auto n = strlen(s);
    return parse_n(s, n, dt, val, path);
  }

  Definition &operator[](const char *s) { return (*grammar_)[s]; }

  const Definition &operator[](const char *s) const { return (*grammar_)[s]; }

  std::vector<std::string> get_rule_names() const {
    std::vector<std::string> rules;
    for (auto &[name, _] : *grammar_) {
      rules.push_back(name);
    }
    return rules;
  }

  void enable_packrat_parsing() {
    if (grammar_ != nullptr) {
      auto &rule = (*grammar_)[start_];
      rule.enablePackratParsing = enablePackratParsing_ && true;
    }
  }

  void enable_trace(TracerEnter tracer_enter, TracerLeave tracer_leave) {
    if (grammar_ != nullptr) {
      auto &rule = (*grammar_)[start_];
      rule.tracer_enter = tracer_enter;
      rule.tracer_leave = tracer_leave;
    }
  }

  Log log;
  std::string preamble_;

  Grammar &grammar() { return *grammar_; }

private:
  bool post_process(const char *s, size_t n,
                    const Definition::Result &r) const {
    auto ret = r.ret && r.len == n;
    if (log && !ret) { r.error_info.output_log(log, s, n); }
    return ret && !r.recovered;
  }

  std::shared_ptr<Grammar> grammar_;
  std::string start_;
  bool enablePackratParsing_ = false;
};

} // namespace peg

// clang-format on