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#pragma once
#include "base/assert.hpp"
#include "base/macros.hpp"
#include "std/algorithm.hpp"
#include "std/string.hpp"
#include "zlib.h"
namespace coding
{
// Following class is a wrapper around ZLib routines.
//
// *NOTE* All Inflate() and Deflate() methods may return false in case
// of errors. In this case the output sequence may be already
// partially formed, so the user needs to implement their own
// roll-back strategy.
class ZLib
{
public:
enum class Level
{
NoCompression,
BestSpeed,
BestCompression,
DefaultCompression
};
template <typename OutIt>
static bool Deflate(void const * data, size_t size, Level level, OutIt out)
{
if (data == nullptr)
return false;
DeflateProcessor processor(data, size, level);
return Process(processor, out);
}
template <typename OutIt>
static bool Deflate(string const & s, Level level, OutIt out)
{
return Deflate(s.c_str(), s.size(), level, out);
}
template <typename OutIt>
static bool Inflate(void const * data, size_t size, OutIt out)
{
if (data == nullptr)
return false;
InflateProcessor processor(data, size);
return Process(processor, out);
}
template <typename OutIt>
static bool Inflate(string const & s, OutIt out)
{
return Inflate(s.c_str(), s.size(), out);
}
private:
class Processor
{
public:
static size_t constexpr kBufferSize = 1024;
Processor(void const * data, size_t size) noexcept;
virtual ~Processor() noexcept = default;
inline bool IsInit() const noexcept { return m_init; }
bool ConsumedAll() const;
bool BufferIsFull() const;
template <typename OutIt>
void MoveOut(OutIt out)
{
ASSERT(IsInit(), ());
copy(m_buffer, m_buffer + kBufferSize - m_stream.avail_out, out);
m_stream.next_out = m_buffer;
m_stream.avail_out = kBufferSize;
}
protected:
z_stream m_stream;
bool m_init;
unsigned char m_buffer[kBufferSize];
DISALLOW_COPY_AND_MOVE(Processor);
};
class DeflateProcessor final : public Processor
{
public:
DeflateProcessor(void const * data, size_t size, Level level) noexcept;
virtual ~DeflateProcessor() noexcept override;
int Process(int flush);
DISALLOW_COPY_AND_MOVE(DeflateProcessor);
};
class InflateProcessor final : public Processor
{
public:
InflateProcessor(void const * data, size_t size) noexcept;
virtual ~InflateProcessor() noexcept override;
int Process(int flush);
DISALLOW_COPY_AND_MOVE(InflateProcessor);
};
template <typename Processor, typename OutIt>
static bool Process(Processor & processor, OutIt out)
{
if (!processor.IsInit())
return false;
while (true)
{
int const flush = processor.ConsumedAll() ? Z_FINISH : Z_NO_FLUSH;
int const ret = processor.Process(flush);
if (ret != Z_OK && ret != Z_STREAM_END)
return false;
if (processor.BufferIsFull())
processor.MoveOut(out);
if (flush == Z_FINISH && ret == Z_STREAM_END)
break;
}
processor.MoveOut(out);
return true;
}
};
} // namespace coding
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