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#pragma once
#include "buffer.h"
#include <util/generic/ptr.h>
#include <util/generic/strbuf.h>
#include <util/system/types.h>
#include <util/system/yassert.h>
#include <cstddef>
#include <memory>
class IInputStream;
class IZeroCopyInput;
namespace NYsonPull {
namespace NInput {
//! \brief Input stream adaptor interface.
//!
//! Represents a model of a chunked input data stream.
class IStream {
input_buffer buffer_;
bool at_end_ = false;
public:
virtual ~IStream() = default;
bool at_end() const {
return at_end_;
}
input_buffer& buffer() noexcept {
return buffer_;
}
const input_buffer& buffer() const noexcept {
return buffer_;
}
void fill_buffer() {
while (buffer_.is_empty() && !at_end()) {
at_end_ = do_fill_buffer() == result::at_end;
}
}
protected:
enum class result {
have_more_data, //! May continue reading
at_end, //! Reached end of stream
};
//! \brief Read next chunk of data.
//!
//! The implementation is to discard the buffer contents
//! and reset the buffer to a next chunk of data.
//! End-of-stream condition is to be reported via return value.
//!
//! Read is assumed to always succeed unless it throws an exception.
virtual result do_fill_buffer() = 0;
};
//! \brief Read data from a contiguous memory block (i.e. a string)
//!
//! Does not take ownership on memory.
THolder<IStream> FromMemory(TStringBuf data);
//! \brief Read data from C FILE* object.
//!
//! Does not take ownership on file object.
//! Data is buffered internally regardless of file buffering.
THolder<IStream> FromStdioFile(FILE* file, size_t buffer_size = 65536);
//! \brief Read data from POSIX file descriptor.
//!
//! Does not take ownership on streambuf.
THolder<IStream> FromPosixFd(int fd, size_t buffer_size = 65536);
THolder<IStream> FromZeroCopyInput(IZeroCopyInput* input);
THolder<IStream> FromInputStream(IInputStream* input, size_t buffer_size = 65536);
}
}
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