CastExceptions.h

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// Copyright 2018-2019, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  Header
 * @author Ryan Pavlik <ryan.pavlik@collabora.com>
 */

#pragma once

#ifdef XRTRAITS_USE_EXCEPTIONS
// Internal Includes
#include "BaseExceptions.h" // IWYU pragma: export

// Library Includes
// - none

// Standard Includes
#include <cstddef> // for std::nullptr_t

namespace xrtraits {
namespace exceptions {

    /*!
     * Exception thrown when we can't perform a given tagged cast to
     * a reference type due to type field mismatch or null input.
     *
     * Only thrown on xr_tagged_dynamic_cast or xr_tagged_risky_cast
     * to a reference type, because a reference is logically never
     * null so a mismatch can't be handled by returning nullptr.
     * Input of a nullptr gets a slightly different what() message
     * but is the same exception as thrown when the input is a
     * reference to or a non-null pointer to an object with a
     * non-matching `type` member.
     *
     * @ingroup exceptions
     */
    struct bad_tagged_cast : xr_runtime_error
    {
        /*!
         * Constructor used for a tag mismatch with non-null
         * input.
         */
        bad_tagged_cast(XrStructureType destTag,
                        XrStructureType sourceTag,
                        const char* castType);

        /*!
         * Constructor used for nullptr input.
         */
        bad_tagged_cast(XrStructureType destTag, std::nullptr_t,
                        const char* castType);
    };

} // namespace exceptions
} // namespace xrtraits

#endif // XRTRAITS_USE_EXCEPTIONS