json-validator/include/jvalidate/detail/pointer.h

#pragma once

#include <compare>
#include <cstdint>
#include <ostream>
#include <string>
#include <string_view>
#include <variant>
#include <vector>

namespace std {
template <typename T> std::strong_ordering operator<=>(T const & lhs, T const & rhs) {
  if (lhs < rhs) {
    return std::strong_ordering::less;
  }
  if (lhs > rhs) {
    return std::strong_ordering::greater;
  }
  return std::strong_ordering::equal;
}
}

namespace jvalidate::detail {

class Pointer {
public:
  Pointer() = default;
  Pointer(std::vector<std::variant<std::string, size_t>> const & tokens) : tokens_(tokens) {}
  Pointer(std::string_view path) {
    for (size_t p = path.find('/'); p != std::string::npos;
         path.remove_prefix(p + 1), p = path.find('/')) {
      std::string token(path.substr(0, p));
      if (token.find_first_not_of("0123456789") == std::string::npos) {
        tokens_.emplace_back(std::stoull(token));
      } else {
        tokens_.emplace_back(token);
      }
    }
  }

  Pointer parent() const { return Pointer({tokens_.begin(), tokens_.end() - 1}); }

  Pointer & operator/=(Pointer const & relative) {
    tokens_.insert(tokens_.end(), relative.tokens_.begin(), relative.tokens_.end());
    return *this;
  }

  Pointer operator/(Pointer const & relative) const { return Pointer(*this) /= relative; }

  Pointer & operator/=(std::string_view key) {
    tokens_.emplace_back(std::string(key));
    return *this;
  }

  Pointer operator/(std::string_view key) const { return Pointer(*this) /= key; }

  Pointer & operator/=(size_t index) {
    tokens_.emplace_back(index);
    return *this;
  }

  Pointer operator/(size_t index) const { return Pointer(*this) /= index; }

  friend std::ostream & operator<<(std::ostream & os, Pointer const & self) {
    for (auto const & elem : self.tokens_) {
      std::visit([&os](auto const & v) { os << '/' << v; }, elem);
    }
    return os;
  }
  auto operator<=>(Pointer const &) const = default;

private:
  std::vector<std::variant<std::string, size_t>> tokens_{};
};
}