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/*
* Copyright 2017 The Native Object Protocols Authors
*
* Licensed 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
*
* http://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 LIBNOP_INCLUDE_NOP_UTILITY_BUFFER_READER_H_
#define LIBNOP_INCLUDE_NOP_UTILITY_BUFFER_READER_H_
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <nop/base/encoding.h>
#include <nop/base/utility.h>
namespace nop {
// An efficient reader type that supports runtime serialization from a byte
// buffer. This reader improves efficiency by only performing bounds checks in
// the Ensure() method. This type is safe for use with the library-provided
// Deserializer types, which predicate serialization on the result of Ensure().
// Use PedanticBufferReader if your use case interacts with the reader directly
// and you need bounds checking in the Read() and Skip() methods.
class BufferReader {
public:
BufferReader() = default;
BufferReader(const BufferReader&) = default;
template <std::size_t Size>
BufferReader(const std::uint8_t (&buffer)[Size])
: buffer_{buffer}, size_{Size} {}
BufferReader(const std::uint8_t* buffer, std::size_t size)
: buffer_{buffer}, size_{size} {}
BufferReader(const void* buffer, std::size_t size)
: buffer_{static_cast<const std::uint8_t*>(buffer)}, size_{size} {}
BufferReader& operator=(const BufferReader&) = default;
Status<void> Ensure(std::size_t size) {
if (size_ - index_ < size)
return ErrorStatus::ReadLimitReached;
else
return {};
}
Status<void> Read(std::uint8_t* byte) { return Read(byte, byte + 1); }
template <typename T, typename Enable = EnableIfArithmetic<T>>
Status<void> Read(T* begin, T* end) {
const std::size_t element_size = sizeof(T);
const std::size_t length = end - begin;
const std::size_t length_bytes = length * element_size;
std::memcpy(begin, &buffer_[index_], length_bytes);
index_ += length_bytes;
return {};
}
Status<void> Skip(std::size_t padding_bytes) {
index_ += padding_bytes;
return {};
}
bool empty() const { return index_ == size_; }
std::size_t remaining() const { return size_ - index_; }
std::size_t capacity() const { return size_; }
private:
const std::uint8_t* buffer_{nullptr};
std::size_t size_{0};
std::size_t index_{0};
};
} // namespace nop
#endif // LIBNOP_INCLUDE_NOP_UTILITY_BUFFER_READER_H_
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