abnf-parser/include/abnf/grammar.h

#pragma once

#include <initializer_list>
#include <limits>
#include <map>
#include <string>
#include <vector>

#include <abnf/detail/iless.h>
#include <abnf/forward.h>

namespace abnf {

struct rule {
  rule() = default;
  rule(rule_part part);
  rule(rule_part_like auto && part);
  rule(std::initializer_list<rule_part> rules);

  friend bool operator==(rule const & lhs, rule const & rhs);

  std::vector<rule_part> rules;
};

struct literal {
  explicit literal(std::string_view lit);

  friend bool operator==(literal const &, literal const &) = default;

  std::string value;
};

struct reference {
  explicit reference(std::string_view ref);

  friend bool operator==(reference const &, reference const &) = default;

  std::string value;
};

struct char_range { // TODO: UTF8/Codepoint handling
  char_range() = default;
  char_range(int val) : first(val), last(val) {}
  char_range(int first, int last) : first(first), last(last) {}

  friend bool operator==(char_range const &, char_range const &) = default;

  int first;
  int last;
};

struct repeated {
  friend bool operator==(repeated const &, repeated const &) = default;

  rule rule;
  size_t min = 0;
  size_t max = std::numeric_limits<size_t>::max();
};

struct one_of {
  explicit one_of(rule_part part) : rules{part} {}
  one_of(std::initializer_list<rule> rules) : rules(rules) {}
  one_of(std::initializer_list<rule_part> rules)
      : rules(rules.begin(), rules.end()) {}

  friend bool operator==(one_of const &, one_of const &) = default;

  std::vector<rule> rules;
};

inline bool operator==(rule const & lhs, rule const & rhs) {
  return lhs.rules == rhs.rules;
}

class grammar {
public:
  using rule_store = std::map<std::string, rule, detail::iless>;

private:
  struct satisfies_result;

public:
  grammar(std::string_view name, rule base_rule, rule_store rules = {})
      : name_(name), base_rule_(std::move(base_rule)),
        rules_(std::move(rules)) {}

  bool satisfies(std::string_view text) const;

private:
  grammar() = default;

  satisfies_result satisfies(std::string_view & text, rule const & rule) const;
  satisfies_result satisfies(std::string_view text, auto const & lit) const;

  friend bool operator==(grammar const &, grammar const &) = default;

private:
  friend std::ostream & operator<<(std::ostream &, grammar const &);
  friend grammar parse(std::istream &);

  std::string name_;
  rule base_rule_;
  // TODO: Default Rules of ABNF
  static rule_store const s_default_rules_;
  rule_store rules_;
};

rule::rule(rule_part_like auto && part)
    : rule(rule_part(std::forward<decltype(part)>(part))) {}
}