chunked_binary.hpp
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/*************************************************************************
*
* Copyright 2019 Realm Inc.
*
* 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 REALM_NOINST_CHUNKED_BINARY_HPP
#define REALM_NOINST_CHUNKED_BINARY_HPP
#include <realm/binary_data.hpp>
#include <realm/column_binary.hpp>
#include <realm/table.hpp>
#include <realm/util/buffer_stream.hpp>
#include <realm/impl/input_stream.hpp>
namespace realm {
/// ChunkedBinaryData manages a vector of BinaryData. It is used to facilitate
/// extracting large binaries from binary columns and tables.
class ChunkedBinaryData {
public:
ChunkedBinaryData() {}
ChunkedBinaryData(const BinaryData& bd)
: m_begin{bd}
{
}
ChunkedBinaryData(const BinaryIterator& bd)
: m_begin{bd}
{
}
ChunkedBinaryData(const BinaryColumn& col, size_t index)
: m_begin{&col, index}
{
}
/// size() returns the number of bytes in the chunked binary.
/// FIXME: This operation is O(n).
size_t size() const noexcept;
/// is_null returns true if the chunked binary has zero chunks or if
/// the first chunk points to the nullptr.
bool is_null() const;
/// FIXME: O(n)
char operator[](size_t index) const;
std::string hex_dump(const char* separator = " ", int min_digits = -1) const;
void write_to(util::ResettableExpandableBufferOutputStream& out) const;
/// copy_to() copies the chunked binary data to \a buffer of size
/// \a buffer_size starting at \a offset in the ChunkedBinary.
/// copy_to() copies until the end of \a buffer or the end of
/// the ChunkedBinary whichever comes first.
/// copy_to() returns the number of copied bytes.
size_t copy_to(char* buffer, size_t buffer_size, size_t offset) const;
/// copy_to() allocates a buffer of size() in \a dest and
/// copies the chunked binary data to \a dest.
size_t copy_to(std::unique_ptr<char[]>& dest) const;
/// get_first_chunk() is used in situations
/// where it is known that there is exactly one
/// chunk. This is the case if the ChunkedBinary
/// has been constructed from BinaryData.
BinaryData get_first_chunk() const;
private:
BinaryIterator m_begin;
friend class ChunkedBinaryInputStream;
};
class ChunkedBinaryInputStream : public _impl::NoCopyInputStream {
public:
explicit ChunkedBinaryInputStream(const ChunkedBinaryData& chunks)
: m_it(chunks.m_begin)
{
}
bool next_block(const char*& begin, const char*& end) override
{
BinaryData block = m_it.get_next();
begin = block.data();
end = begin + block.size();
return begin != end;
}
private:
BinaryIterator m_it;
};
} // namespace realm
#endif // REALM_NOINST_CHUNKED_BINARY_HPP