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

#pragma once

#include <map>
#include <stdexcept>
#include <string_view>
#include <vector>

#include <jvalidate/adapter.h>
#include <jvalidate/detail/number.h>
#include <jvalidate/detail/simple_adapter.h>
#include <jvalidate/enum.h>
#include <jvalidate/status.h>

namespace jvalidate::detail {
/**
 * @brief An ArrayAdapter implmenetation for JSON "types" which do not support
 * arrays. This is for example caused when attempting to apply json schema
 * validation to non-json types representation, such as a some forms of
 * PropertyTree implementations.
 *
 * This is specifically provided for making StringAdapter compatible with the
 * Adapter concept.
 */
template <typename CRTP> class UnsupportedArrayAdapter {
public:
  size_t size() const { return 0; }
  CRTP operator[](size_t) const { throw std::runtime_error("stub implementation"); }
  std::vector<CRTP>::const_iterator begin() const { return {}; }
  std::vector<CRTP>::const_iterator end() const { return {}; }
};

/**
 * @brief An ObjectAdapter implmenetation for JSON "types" which do not support
 * objects. This is for example caused when attempting to apply json schema
 * validation to non-json types representation.
 *
 * This is specifically provided for making StringAdapter compatible with the
 * Adapter concept.
 */
template <typename CRTP> class UnsupportedObjectAdapter {
public:
  size_t size() const { return 0; }
  bool contains(std::string_view) const { return false; }
  CRTP operator[](std::string_view) const { throw std::runtime_error("stub implementation"); }
  std::map<std::string, CRTP>::const_iterator begin() const { return {}; }
  std::map<std::string, CRTP>::const_iterator end() const { return {}; }
};

/**
 * @brief An Adapter for strings, required for implmenting propertyNames
 * constraints, which are applied to the keys of a JSON object.
 *
 * Unfortunately requires a large number of stub function implementations in
 * order to satisfy adapter::Adapter AND Adapter concept.
 */
class StringAdapter final : public adapter::Adapter {
public:
  using value_type = std::string_view;

  StringAdapter(std::string_view value) : value_(value) {}

  adapter::Type type() const { return adapter::Type::String; }
  bool as_boolean() const { die("boolean"); }
  int64_t as_integer() const { die("integer"); }
  double as_number() const { die("number"); }
  std::string as_string() const { return std::string(value_); }

  size_t array_size() const { die("array"); }
  UnsupportedArrayAdapter<StringAdapter> as_array() const { die("array"); }
  Status apply_array(adapter::AdapterCallback const &) const { return Status::Noop; }

  size_t object_size() const { die("object"); }
  UnsupportedObjectAdapter<StringAdapter> as_object() const { die("object"); }
  Status apply_object(adapter::ObjectAdapterCallback const &) const { return Status::Noop; }

  bool equals(adapter::Adapter const & rhs, bool strict) const {
    if (std::optional str = rhs.maybe_string(strict)) {
      return str == value_;
    }
    return false;
  }

  std::unique_ptr<adapter::Const const> freeze() const final {
    return std::make_unique<adapter::detail::GenericConst<std::string_view>>(value_);
  }

private:
  [[noreturn]] static void die(std::string expected) {
    throw std::runtime_error("StringAdapter is not an " + expected);
  }

private:
  std::string_view value_;
};

}

template <> struct jvalidate::adapter::AdapterTraits<std::string_view> {
  template <typename> using Adapter = jvalidate::detail::StringAdapter;
  using ConstAdapter = jvalidate::detail::StringAdapter;
};