json/include/nlohmann/detail/exceptions.hpp

#pragma once

#include <exception> // exception
#include <stdexcept> // runtime_error
#include <string> // to_string
#include <vector> // vector

#include <nlohmann/detail/value_t.hpp>
#include <nlohmann/detail/string_escape.hpp>
#include <nlohmann/detail/input/position_t.hpp>
#include <nlohmann/detail/macro_scope.hpp>

namespace nlohmann
{
namespace detail
{
////////////////
// exceptions //
////////////////

/// @brief general exception of the @ref basic_json class
/// @sa https://json.nlohmann.me/api/basic_json/exception/
class exception : public std::exception
{
  public:
    /// returns the explanatory string
    const char* what() const noexcept override
    {
        return m.what();
    }

    /// the id of the exception
    const int id; // NOLINT(cppcoreguidelines-non-private-member-variables-in-classes)

  protected:
    JSON_HEDLEY_NON_NULL(3)
    exception(int id_, const char* what_arg) : id(id_), m(what_arg) {} // NOLINT(bugprone-throw-keyword-missing)

    static std::string name(const std::string& ename, int id_)
    {
        return "[json.exception." + ename + "." + std::to_string(id_) + "] ";
    }

    template<typename BasicJsonType>
    static std::string diagnostics(const BasicJsonType& leaf_element)
    {
#if JSON_DIAGNOSTICS
        std::vector<std::string> tokens;
        for (const auto* current = &leaf_element; current->m_parent != nullptr; current = current->m_parent)
        {
            switch (current->m_parent->type())
            {
                case value_t::array:
                {
                    for (std::size_t i = 0; i < current->m_parent->m_value.array->size(); ++i)
                    {
                        if (&current->m_parent->m_value.array->operator[](i) == current)
                        {
                            tokens.emplace_back(std::to_string(i));
                            break;
                        }
                    }
                    break;
                }

                case value_t::object:
                {
                    for (const auto& element : *current->m_parent->m_value.object)
                    {
                        if (&element.second == current)
                        {
                            tokens.emplace_back(element.first.c_str());
                            break;
                        }
                    }
                    break;
                }

                case value_t::null: // LCOV_EXCL_LINE
                case value_t::string: // LCOV_EXCL_LINE
                case value_t::boolean: // LCOV_EXCL_LINE
                case value_t::number_integer: // LCOV_EXCL_LINE
                case value_t::number_unsigned: // LCOV_EXCL_LINE
                case value_t::number_float: // LCOV_EXCL_LINE
                case value_t::binary: // LCOV_EXCL_LINE
                case value_t::discarded: // LCOV_EXCL_LINE
                default:   // LCOV_EXCL_LINE
                    break; // LCOV_EXCL_LINE
            }
        }

        if (tokens.empty())
        {
            return "";
        }

        return "(" + std::accumulate(tokens.rbegin(), tokens.rend(), std::string{},
                                     [](const std::string & a, const std::string & b)
        {
            return a + "/" + detail::escape(b);
        }) + ") ";
#else
        static_cast<void>(leaf_element);
        return "";
#endif
    }

  private:
    /// an exception object as storage for error messages
    std::runtime_error m;
};

/// @brief exception indicating a parse error
/// @sa https://json.nlohmann.me/api/basic_json/parse_error/
class parse_error : public exception
{
  public:
    /*!
    @brief create a parse error exception
    @param[in] id_       the id of the exception
    @param[in] pos       the position where the error occurred (or with
                         chars_read_total=0 if the position cannot be
                         determined)
    @param[in] what_arg  the explanatory string
    @return parse_error object
    */
    template<typename BasicJsonType>
    static parse_error create(int id_, const position_t& pos, const std::string& what_arg, const BasicJsonType& context)
    {
        std::string w = exception::name("parse_error", id_) + "parse error" +
                        position_string(pos) + ": " + exception::diagnostics(context) + what_arg;
        return {id_, pos.chars_read_total, w.c_str()};
    }

    template<typename BasicJsonType>
    static parse_error create(int id_, std::size_t byte_, const std::string& what_arg, const BasicJsonType& context)
    {
        std::string w = exception::name("parse_error", id_) + "parse error" +
                        (byte_ != 0 ? (" at byte " + std::to_string(byte_)) : "") +
                        ": " + exception::diagnostics(context) + what_arg;
        return {id_, byte_, w.c_str()};
    }

    /*!
    @brief byte index of the parse error

    The byte index of the last read character in the input file.

    @note For an input with n bytes, 1 is the index of the first character and
          n+1 is the index of the terminating null byte or the end of file.
          This also holds true when reading a byte vector (CBOR or MessagePack).
    */
    const std::size_t byte;

  private:
    parse_error(int id_, std::size_t byte_, const char* what_arg)
        : exception(id_, what_arg), byte(byte_) {}

    static std::string position_string(const position_t& pos)
    {
        return " at line " + std::to_string(pos.lines_read + 1) +
               ", column " + std::to_string(pos.chars_read_current_line);
    }
};

/// @brief exception indicating errors with iterators
/// @sa https://json.nlohmann.me/api/basic_json/invalid_iterator/
class invalid_iterator : public exception
{
  public:
    template<typename BasicJsonType>
    static invalid_iterator create(int id_, const std::string& what_arg, const BasicJsonType& context)
    {
        std::string w = exception::name("invalid_iterator", id_) + exception::diagnostics(context) + what_arg;
        return {id_, w.c_str()};
    }

  private:
    JSON_HEDLEY_NON_NULL(3)
    invalid_iterator(int id_, const char* what_arg)
        : exception(id_, what_arg) {}
};

/// @brief exception indicating executing a member function with a wrong type
/// @sa https://json.nlohmann.me/api/basic_json/type_error/
class type_error : public exception
{
  public:
    template<typename BasicJsonType>
    static type_error create(int id_, const std::string& what_arg, const BasicJsonType& context)
    {
        std::string w = exception::name("type_error", id_) + exception::diagnostics(context) + what_arg;
        return {id_, w.c_str()};
    }

  private:
    JSON_HEDLEY_NON_NULL(3)
    type_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
};

/// @brief exception indicating access out of the defined range
/// @sa https://json.nlohmann.me/api/basic_json/out_of_range/
class out_of_range : public exception
{
  public:
    template<typename BasicJsonType>
    static out_of_range create(int id_, const std::string& what_arg, const BasicJsonType& context)
    {
        std::string w = exception::name("out_of_range", id_) + exception::diagnostics(context) + what_arg;
        return {id_, w.c_str()};
    }

  private:
    JSON_HEDLEY_NON_NULL(3)
    out_of_range(int id_, const char* what_arg) : exception(id_, what_arg) {}
};

/// @brief exception indicating other library errors
/// @sa https://json.nlohmann.me/api/basic_json/other_error/
class other_error : public exception
{
  public:
    template<typename BasicJsonType>
    static other_error create(int id_, const std::string& what_arg, const BasicJsonType& context)
    {
        std::string w = exception::name("other_error", id_) + exception::diagnostics(context) + what_arg;
        return {id_, w.c_str()};
    }

  private:
    JSON_HEDLEY_NON_NULL(3)
    other_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
};

}  // namespace detail
}  // namespace nlohmann