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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 <tuple>
#include <type_traits>
#include "mongo/base/data_type.h"
#include "mongo/base/error_codes.h"
#include "mongo/base/status_with.h"
#include "mongo/platform/endian.h"
#include "mongo/util/mongoutils/str.h"
namespace mongo {
class ConstDataRange {
public:
// begin and end should point to the first and one past last bytes in
// the range you wish to view.
//
// debug_offset provides a way to indicate that the ConstDataRange is
// located at an offset into some larger logical buffer. By setting it
// to a non-zero value, you'll change the Status messages that are
// returned on failure to be offset by the amount passed to this
// constructor.
ConstDataRange(const char* begin, const char* end, std::ptrdiff_t debug_offset = 0)
: _begin(begin), _end(end), _debug_offset(debug_offset) {
invariant(end >= begin);
}
ConstDataRange(const char* begin, std::size_t length, std::ptrdiff_t debug_offset = 0)
: ConstDataRange(begin, begin + length, debug_offset) {}
const char* data() const {
return _begin;
}
size_t length() const {
return _end - _begin;
}
bool empty() const {
return length() == 0;
}
template <typename T>
Status read(T* t, size_t offset = 0) const {
if (offset > length()) {
return makeOffsetStatus(offset);
}
return DataType::load(
t, _begin + offset, length() - offset, nullptr, offset + _debug_offset);
}
template <typename T>
StatusWith<T> read(std::size_t offset = 0) const {
T t(DataType::defaultConstruct<T>());
Status s = read(&t, offset);
if (s.isOK()) {
return StatusWith<T>(std::move(t));
} else {
return StatusWith<T>(std::move(s));
}
}
friend bool operator==(const ConstDataRange& lhs, const ConstDataRange& rhs) {
return std::tie(lhs._begin, lhs._end) == std::tie(rhs._begin, rhs._end);
}
friend bool operator!=(const ConstDataRange& lhs, const ConstDataRange& rhs) {
return !(lhs == rhs);
}
protected:
const char* _begin;
const char* _end;
std::ptrdiff_t _debug_offset;
Status makeOffsetStatus(size_t offset) const;
};
class DataRange : public ConstDataRange {
public:
typedef char* bytes_type;
DataRange(bytes_type begin, bytes_type end, std::ptrdiff_t debug_offset = 0)
: ConstDataRange(begin, end, debug_offset) {}
DataRange(bytes_type begin, std::size_t length, std::ptrdiff_t debug_offset = 0)
: ConstDataRange(begin, length, debug_offset) {}
template <typename T>
Status write(const T& value, std::size_t offset = 0) {
if (offset > length()) {
return makeOffsetStatus(offset);
}
return DataType::store(value,
const_cast<char*>(_begin + offset),
length() - offset,
nullptr,
offset + _debug_offset);
}
};
struct DataRangeTypeHelper {
static Status makeStoreStatus(size_t t_length, size_t length, std::ptrdiff_t debug_offset);
};
// Enable for classes derived from ConstDataRange
template <typename T>
struct DataType::Handler<T,
typename std::enable_if<std::is_base_of<ConstDataRange, T>::value>::type> {
static Status load(
T* t, const char* ptr, size_t length, size_t* advanced, std::ptrdiff_t debug_offset) {
if (t) {
// Assuming you know what you're doing at the read above this
// is fine. Either you're reading into a readable buffer, so
// ptr started off non-const, or the const_cast will feed back
// to const char* taking Const variants. So it'll get tossed
// out again.
*t = T(const_cast<char*>(ptr), const_cast<char*>(ptr) + length);
}
if (advanced) {
*advanced = length;
}
return Status::OK();
}
static Status store(
const T& t, char* ptr, size_t length, size_t* advanced, std::ptrdiff_t debug_offset) {
if (t.length() > length) {
return DataRangeTypeHelper::makeStoreStatus(t.length(), length, debug_offset);
}
if (ptr) {
std::memcpy(ptr, t.data(), t.length());
}
if (advanced) {
*advanced = t.length();
}
return Status::OK();
}
static T defaultConstruct() {
return T(nullptr, nullptr);
}
};
} // namespace mongo
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