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