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#pragma once
#include "idatastream.h"
#include <algorithm>
#include <cstdio>
namespace stream
{
namespace detail
{
inline int whence_for_seekdir(SeekableStream::seekdir direction)
{
switch (direction)
{
case SeekableStream::cur:
return SEEK_CUR;
case SeekableStream::end:
return SEEK_END;
default:
break;
}
return SEEK_SET;
}
}
/// \brief A wrapper around a file input stream opened for reading in binary mode. Similar to std::ifstream.
///
/// - Maintains a valid file handle associated with a name passed to the constructor.
/// - Implements SeekableInputStream.
class FileInputStream :
public SeekableInputStream
{
private:
std::FILE* _file;
public:
FileInputStream(const std::string& name) :
_file(!name.empty() ? fopen(name.c_str(), "rb") : nullptr)
{}
~FileInputStream()
{
if (!failed())
{
fclose(_file);
}
}
bool failed() const
{
return _file == nullptr;
}
size_type read(byte_type* buffer, size_type length) override
{
return fread(buffer, 1, length, _file);
}
size_type seek(size_type position) override
{
return fseek(_file, static_cast<long>(position), SEEK_SET);
}
size_type seek(offset_type offset, seekdir direction) override
{
return fseek(_file, offset, detail::whence_for_seekdir(direction));
}
size_type tell() const override
{
return ftell(_file);
}
std::FILE* file()
{
return _file;
}
};
/// \brief A wrapper around a FileInputStream limiting access.
///
/// - Maintains an input stream.
/// - Provides input starting at an offset in the file for a limited range.
class SubFileInputStream :
public InputStream
{
private:
FileInputStream& _istream;
size_type _remaining;
public:
typedef FileInputStream::position_type position_type;
SubFileInputStream(FileInputStream& istream, position_type offset, size_type size) :
_istream(istream),
_remaining(size)
{
_istream.seek(offset);
}
size_type read(byte_type* buffer, size_type length) override
{
size_type result = _istream.read(buffer, std::min(length, _remaining));
_remaining -= result;
return result;
}
};
}
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