mysql-server/libs/mysql/serialization/field_definition.h
2025-03-05 14:31:37 +07:00

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// Copyright (c) 2023, 2024, Oracle and/or its affiliates.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0,
// as published by the Free Software Foundation.
//
// This program is designed to work with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation. The authors of MySQL hereby grant you an additional
// permission to link the program and your derivative works with the
// separately licensed software that they have either included with
// the program or referenced in the documentation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License, version 2.0, for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
#ifndef MYSQL_SERIALIZATION_FIELD_DEFINITION_H
#define MYSQL_SERIALIZATION_FIELD_DEFINITION_H
#include <functional>
#include "mysql/serialization/field_functor.h"
#include "mysql/serialization/serializable_type_tags.h"
#include "mysql/serialization/serialization_types.h"
#include "mysql/serialization/unknown_field_policy.h"
/// @file
/// Experimental API header
/// @addtogroup GroupLibsMysqlSerialization
/// @{
namespace mysql::serialization {
/// @brief Field definition provided by classes implementing Serializable
/// interface
template <class Field_type, Field_size defined_field_size = sizeof(Field_type)>
class Field_definition {
public:
using Tag = Field_definition_tag;
using Field_type_ref = std::reference_wrapper<Field_type>;
/// @brief Constructs field definition object
/// @param[in] field Reference to described field object
/// externally, serializer may ignore this value or use it to hide some fields
/// @param[in] encode_predicate Function that is called for optional fields,
/// defines whether field will be encoded
/// @param[in] unknown_field_policy What decoder should do in case this
/// field definition is unknown to the decoder (error / ignore)
/// @param[in] field_missing_functor Function that is called for this
/// field in case it is not available in encoded data
Field_definition(Field_type &field, Field_encode_predicate encode_predicate,
Unknown_field_policy unknown_field_policy,
Field_missing_functor field_missing_functor)
: Field_definition(field, encode_predicate, unknown_field_policy) {
m_field_missing_functor = field_missing_functor;
}
/// @brief Constructs field definition object
/// @param[in] field Reference to described field object
/// @param[in] unknown_field_policy What decoder should do in case this
/// field definition is unknown to the decoder (error / ignore)
Field_definition(
Field_type &field,
Unknown_field_policy unknown_field_policy = Unknown_field_policy::ignore)
: m_ref(field), m_unknown_field_policy(unknown_field_policy) {
m_encode_predicate = Field_encode_predicate([]() -> bool { return true; });
m_field_missing_functor = Field_missing_functor([]() -> void {});
}
/// @brief Constructs field definition object
/// @param[in] field Reference to described field object
/// @param[in] unknown_field_policy What decoder should do in case this
/// field definition is unknown to the decoder (error / ignore)
/// @param[in] encode_predicate Function that is called for optional fields,
/// defines whether field will be encoded
Field_definition(
Field_type &field, Field_encode_predicate encode_predicate,
Unknown_field_policy unknown_field_policy = Unknown_field_policy::ignore)
: Field_definition(field, unknown_field_policy) {
m_encode_predicate = encode_predicate;
}
/// @brief Constructs field definition object
/// @param[in] field Reference to described field object
/// @param[in] field_missing_functor Function that is called for this
/// field in case it is not available in encoded data
Field_definition(Field_type &field,
Field_missing_functor field_missing_functor)
: Field_definition(field) {
m_field_missing_functor = field_missing_functor;
}
Field_type &get_ref() { return m_ref.get(); }
const Field_type &get_ref() const { return m_ref.get(); }
/// @brief Runs "field missing functor" in case field is not available in the
/// provided encoded data
void run_field_missing() const { m_field_missing_functor(); }
/// @brief Runs encode predicate functor
/// @retval true Encode field
/// @retval false Do not encode field
bool run_encode_predicate() const { return m_encode_predicate(); }
/// @brief Indicates whether this field can be ignored by decoders that
/// do not know this field
/// @retval true Decoders that do not recognize this field may ignore it
/// @retval false Decoders that do not recognize this field should generate
/// an error if they find this field in the packet
bool is_field_ignorable() const {
return m_unknown_field_policy == Unknown_field_policy::ignore;
}
protected:
Field_type_ref m_ref; ///< Field object reference
/// Defines what a decoder should do if the field is present but the decoder
/// is a version that does not know how to interpret the field.
/// Typically the encoder writes this information to the packet as a
/// directive that instructs old decoders or third-party decoders how to
/// handle the field, if the message definition that they are aware of
/// does not include the field.
Unknown_field_policy m_unknown_field_policy = Unknown_field_policy::ignore;
/// Defines whether field will be encoded
Field_encode_predicate m_encode_predicate;
/// Function that is called for this field during decoding in case
/// field is missing in the encoded message
Field_missing_functor m_field_missing_functor;
};
} // namespace mysql::serialization
/// @}
#endif // MYSQL_SERIALIZATION_FIELD_DEFINITION_H