buffered.hpp

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#pragma once
 
/// @file userver/engine/io/buffered.hpp
/// @brief Buffered I/O wrappers
 
#include <functional>
#include <string>
 
#include <userver/compiler/select.hpp>
#include <userver/engine/deadline.hpp>
#include <userver/engine/io/common.hpp>
#include <userver/engine/io/exception.hpp>
#include <userver/utils/fast_pimpl.hpp>
#include <userver/utils/function_ref.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace engine::io {
namespace impl {
 
class Buffer;
 
}  // namespace impl
 
class TerminatorNotFoundException : public IoException {
public:
    TerminatorNotFoundException();
};
 
/// Wrapper for buffered input
class BufferedReader final {
public:
    /// Creates a buffered reader with default buffer size.
    explicit BufferedReader(ReadableBasePtr source);
 
    /// Creates a buffered reader with specified initial buffer size.
    BufferedReader(ReadableBasePtr source, size_t buffer_size);
 
    ~BufferedReader();
 
    BufferedReader(BufferedReader&&) noexcept;
    BufferedReader& operator=(BufferedReader&&) noexcept;
 
    /// Whether the underlying source is valid.
    bool IsValid() const;
 
    /// Reads some bytes from the input stream.
    std::string ReadSome(size_t max_bytes, Deadline deadline = {});
 
    /// @brief Reads the exact number of bytes from the input stream.
    /// @note May return less bytes than requested in case of EOF.
    std::string ReadAll(size_t num_bytes, Deadline deadline = {});
 
    /// @brief Reads a line from the input, skipping empty lines.
    /// @note Does not return line terminators.
    std::string ReadLine(Deadline deadline = {});
 
    /// Reads the stream until the specified character of EOF is encountered.
    std::string ReadUntil(char terminator, Deadline deadline = {});
 
    /// @brief Reads the stream until the predicate returns `true`.
    /// @param pred predicate that will be called for each byte read and EOF.
    /// @param deadline if specified, interrupts reading upon reaching this deadline
    std::string ReadUntil(utils::function_ref<bool(int) const> pred, Deadline deadline = {});
 
    /// Reads one byte from the stream or reports an EOF (-1).
    int Getc(Deadline deadline = {});
 
    /// Returns the first byte of the buffer or EOF (-1).
    int Peek(Deadline deadline = {});
 
    /// Discards the specified number of bytes from the buffer.
    void Discard(size_t num_bytes, Deadline deadline = {});
 
private:
    size_t FillBuffer(Deadline deadline);
 
    ReadableBasePtr source_;
 
    constexpr static std::size_t kBufferSize =
        compiler::SelectSize()  //
            .For64Bit(40)
            .For32Bit(20);
    constexpr static std::size_t kBufferAlignment = alignof(void*);
    utils::FastPimpl<impl::Buffer, kBufferSize, kBufferAlignment, true> buffer_;
};
 
}  // namespace engine::io
 
USERVER_NAMESPACE_END