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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <cstring>
#include <type_traits>
#include "mongo/base/data_type.h"
#include "mongo/base/error_codes.h"
#include "mongo/platform/endian.h"
namespace mongo {
template <typename T>
struct IsEndian : std::false_type {};
#define MAKE_ENDIAN(name, loadFunc, storeFunc) \
template <typename T> \
struct name { \
using value_type = T; \
name() : value(T{}) {} \
name(T t) : value(t) {} \
T value; \
\
operator T() const { \
return value; \
} \
\
static auto load(T t) -> decltype(loadFunc(t)) { \
return loadFunc(t); \
} \
\
static auto store(T t) -> decltype(storeFunc(t)) { \
return storeFunc(t); \
} \
}; \
\
template <typename T> \
name<T> tag##name(T t) { \
return t; \
} \
\
template <typename T> \
struct IsEndian<name<T>> : std::true_type {};
/**
* BigEndian and LittleEndian offer support for using natively encoded types
* and reading/writing them as big endian or little endian through char ptrs.
*
* The Reverse variants assume the pointed to bytes are natively encoded and
* return big or little endian encoded types. I.e. you probably shouldn't use
* them with floats and should be wary of using them with signed types.
*/
MAKE_ENDIAN(BigEndian, endian::bigToNative, endian::nativeToBig)
MAKE_ENDIAN(LittleEndian, endian::littleToNative, endian::nativeToLittle)
MAKE_ENDIAN(ReverseBigEndian, endian::nativeToBig, endian::bigToNative)
MAKE_ENDIAN(ReverseLittleEndian, endian::nativeToLittle, endian::littleToNative)
template <typename T>
struct DataType::Handler<T, typename std::enable_if<IsEndian<T>::value>::type> {
static void unsafeLoad(T* t, const char* ptr, size_t* advanced) {
if (t) {
DataType::unsafeLoad(&t->value, ptr, advanced);
t->value = T::load(t->value);
} else {
DataType::unsafeLoad(decltype(&t->value){nullptr}, ptr, advanced);
}
}
static Status load(
T* t, const char* ptr, size_t length, size_t* advanced, std::ptrdiff_t debug_offset) {
if (t) {
Status x = DataType::load(&t->value, ptr, length, advanced, debug_offset);
if (x.isOK()) {
t->value = T::load(t->value);
}
return x;
} else {
return DataType::load(
decltype(&t->value){nullptr}, ptr, length, advanced, debug_offset);
}
}
static void unsafeStore(const T& t, char* ptr, size_t* advanced) {
DataType::unsafeStore(T::store(t.value), ptr, advanced);
}
static Status store(
const T& t, char* ptr, size_t length, size_t* advanced, std::ptrdiff_t debug_offset) {
return DataType::store(T::store(t.value), ptr, length, advanced, debug_offset);
}
static typename T::value_type defaultConstruct() {
return DataType::defaultConstruct<typename T::value_type>();
}
};
} // namespace mongo
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