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// Copyright (c) 2016 The WebM project authors. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
#ifndef INCLUDE_WEBM_ISTREAM_READER_H_
#define INCLUDE_WEBM_ISTREAM_READER_H_
#include <cstdint>
#include <cstdlib>
#include <istream>
#include <memory>
#include <type_traits>
#include "./reader.h"
#include "./status.h"
/**
\file
A `Reader` implementation that reads from a `std::istream`.
*/
namespace webm {
/**
A `Reader` implementation that can read from `std::istream`-based resources.
*/
class IstreamReader : public Reader {
public:
/**
Constructs a new, empty reader.
*/
IstreamReader() = default;
/**
Constructs a new reader, using the provided `std::istream` as the data
source.
Ownership of the stream is taken, and it will be moved into a new internal
instance.
\param istream The stream to use as a data source. Must be an rvalue
reference derived from `std::istream`.
*/
template <typename T>
explicit IstreamReader(T&& istream) : istream_(new T(std::move(istream))) {}
/**
Constructs a new reader by moving the provided reader into the new reader.
\param other The source reader to move. After moving, it will be reset to an
empty stream.
*/
IstreamReader(IstreamReader&& other);
/**
Moves the provided reader into this reader.
\param other The source reader to move. After moving, it will be reset to an
empty stream. May be equal to `*this`, in which case this is a no-op.
\return `*this`.
*/
IstreamReader& operator=(IstreamReader&& other);
Status Read(std::size_t num_to_read, std::uint8_t* buffer,
std::uint64_t* num_actually_read) override;
Status Skip(std::uint64_t num_to_skip,
std::uint64_t* num_actually_skipped) override;
std::uint64_t Position() const override;
/**
Constructs a new reader and its data source in place.
`T` must be derived from `std::istream` and constructible from the provided
arguments.
\param args Arguments that will be forwarded to the `T`'s constructor.
\return A new `IstreamReader` backed by the underlying data source equivalent
to `T(std::forward<Args>(args)...`.
*/
template <typename T, typename... Args>
static IstreamReader Emplace(Args&&... args) {
IstreamReader reader;
reader.istream_.reset(new T(std::forward<Args>(args)...));
return reader;
}
private:
std::unique_ptr<std::istream> istream_;
std::uint64_t position_ = 0;
};
} // namespace webm
#endif // INCLUDE_WEBM_ISTREAM_READER_H_
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