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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_BOUNDED_WRITER_H_
#define LIBNOP_INCLUDE_NOP_UTILITY_BOUNDED_WRITER_H_
#include <cstddef>
#include <cstdint>
#include <iterator>
#include <nop/base/encoding.h>
#include <nop/base/handle.h>
#include <nop/base/utility.h>
namespace nop {
// BoundedWriter is a writer type that wraps another writer pointer and tracks
// the number of bytes written. Writer operations are transparently passed to
// the underlying writer unless the requested operation would exceed the size
// limit set at construction. BufferWriter can also pad the output up to the
// size limit in situations that require specific output payload size.
template <typename Writer>
class BoundedWriter {
public:
constexpr BoundedWriter() = default;
constexpr BoundedWriter(const BoundedWriter&) = default;
constexpr BoundedWriter(Writer* writer, std::size_t size)
: writer_{writer}, size_{size} {}
constexpr BoundedWriter& operator=(const BoundedWriter&) = default;
constexpr Status<void> Prepare(std::size_t size) {
if (index_ + size > size_)
return ErrorStatus::WriteLimitReached;
else
return writer_->Prepare(size);
}
constexpr Status<void> Write(std::uint8_t byte) {
if (index_ < size_) {
auto status = writer_->Write(byte);
if (!status)
return status;
index_ += 1;
return {};
} else {
return ErrorStatus::WriteLimitReached;
}
}
template <typename T, typename Enabel = EnableIfArithmetic<T>>
constexpr Status<void> Write(const T* begin, const 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;
if (length_bytes > (size_ - index_))
return ErrorStatus::WriteLimitReached;
auto status = writer_->Write(begin, end);
if (!status)
return status;
index_ += length_bytes;
return {};
}
constexpr Status<void> Skip(std::size_t padding_bytes,
std::uint8_t padding_value = 0x00) {
if (padding_bytes > (size_ - index_))
return ErrorStatus::WriteLimitReached;
auto status = writer_->Skip(padding_bytes, padding_value);
if (!status)
return status;
index_ += padding_bytes;
return {};
}
// Fills out any remaining bytes with the given padding value.
constexpr Status<void> WritePadding(std::uint8_t padding_value = 0x00) {
const std::size_t padding_bytes = size_ - index_;
auto status = writer_->Skip(padding_bytes, padding_value);
if (!status)
return status;
index_ += padding_bytes;
return {};
}
template <typename HandleType>
constexpr Status<HandleType> PushHandle(const HandleType& handle) {
return writer_->PushHandle(handle);
}
constexpr std::size_t size() const { return index_; }
constexpr std::size_t capacity() const { return size_; }
private:
Writer* writer_{nullptr};
std::size_t size_{0};
std::size_t index_{0};
};
} // namespace nop
#endif // LIBNOP_INCLUDE_NOP_UTILITY_BOUNDED_WRITER_H_
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