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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef avro_AvroTraits_hh__
#define avro_AvroTraits_hh__
#include "Config.hh"
#include "Types.hh"
#include <cstdint>
#include <type_traits>
/** @file
*
* This header contains type traits and similar utilities used by the library.
*/
namespace avro {
/**
* Define an is_serializable trait for types we can serialize natively.
* New types will need to define the trait as well.
*/
template<typename T>
struct is_serializable : public std::false_type {};
template<typename T>
struct is_promotable : public std::false_type {};
template<typename T>
struct type_to_avro {
static const Type type = AVRO_NUM_TYPES;
};
/**
* Check if a \p T is a complete type i.e. it is defined as opposed to just
* declared.
*
* is_defined<T>::value will be true or false depending on whether T is a
* complete type or not respectively.
*/
template<class T>
struct is_defined {
typedef char yes[1];
typedef char no[2];
template<class U>
static yes &test(char (*)[sizeof(U)]) { throw 0; };
template<class U>
static no &test(...) { throw 0; };
static const bool value = sizeof(test<T>(0)) == sizeof(yes);
};
/**
* Similar to is_defined, but used to check if T is not defined.
*
* is_not_defined<T>::value will be true or false depending on whether T is an
* incomplete type or not respectively.
*/
template<class T>
struct is_not_defined {
typedef char yes[1];
typedef char no[2];
template<class U>
static yes &test(char (*)[sizeof(U)]) { throw 0; };
template<class U>
static no &test(...) { throw 0; };
static const bool value = sizeof(test<T>(0)) == sizeof(no);
};
#define DEFINE_PRIMITIVE(CTYPE, AVROTYPE) \
template<> \
struct is_serializable<CTYPE> : public std::true_type {}; \
\
template<> \
struct type_to_avro<CTYPE> { \
static const Type type = AVROTYPE; \
};
#define DEFINE_PROMOTABLE_PRIMITIVE(CTYPE, AVROTYPE) \
template<> \
struct is_promotable<CTYPE> : public std::true_type {}; \
\
DEFINE_PRIMITIVE(CTYPE, AVROTYPE)
DEFINE_PROMOTABLE_PRIMITIVE(int32_t, AVRO_INT)
DEFINE_PROMOTABLE_PRIMITIVE(int64_t, AVRO_LONG)
DEFINE_PROMOTABLE_PRIMITIVE(float, AVRO_FLOAT)
DEFINE_PRIMITIVE(double, AVRO_DOUBLE)
DEFINE_PRIMITIVE(bool, AVRO_BOOL)
DEFINE_PRIMITIVE(Null, AVRO_NULL)
DEFINE_PRIMITIVE(std::string, AVRO_STRING)
DEFINE_PRIMITIVE(std::vector<uint8_t>, AVRO_BYTES)
} // namespace avro
#endif
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