minifi-api/include/minifi-cpp/io/InputStream.h

/**
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <array>
#include <cstddef>
#include <stdexcept>
#include <vector>
#include <string>
#include "Stream.h"
#include "minifi-cpp/utils/Id.h"

namespace org::apache::nifi::minifi::io {

class InputStream : public virtual Stream {
 public:
  [[nodiscard]] virtual size_t size() const = 0;
  /**
   * Reads a byte array from the stream. Use isError (Stream.h) to check for errors.
   * @param out_buffer reference in which will set the result
   * @param len length to read
   * @return resulting read size or STREAM_ERROR on error or static_cast<size_t>(-2) on EAGAIN
   **/
  virtual size_t read(std::span<std::byte> out_buffer) = 0;

  /**
   * Read string from stream. Use isError (Stream.h) to check for errors.
   * @param str reference string
   * @return resulting read size or STREAM_ERROR on error or static_cast<size_t>(-2) on EAGAIN
   **/
  size_t read(std::string &str, bool widen = false);

  /**
   * Read a bool from stream. Use isError (Stream.h) to check for errors.
   * @param value reference to the output
   * @return resulting read size or STREAM_ERROR on error or static_cast<size_t>(-2) on EAGAIN
   **/
  size_t read(bool& value);

  /**
   * Read a uuid from stream. Use isError (Stream.h) to check for errors.
   * @param value reference to the output
   * @return resulting read size or STREAM_ERROR on error or static_cast<size_t>(-2) on EAGAIN
   **/
  size_t read(utils::Identifier& value);

  /**
   * Reads sizeof(Integral) bytes from the stream. Use isError (Stream.h) to check for errors.
   * @param value reference in which will set the result
   * @return resulting read size or STREAM_ERROR on error or static_cast<size_t>(-2) on EAGAIN
   **/
  template<typename Integral, typename = std::enable_if_t<std::is_unsigned<Integral>::value && !std::is_same<Integral, bool>::value>>
  size_t read(Integral& value) {
    std::array<std::byte, sizeof(Integral)> buf;
    if (read(buf) != sizeof(Integral)) {
      return io::STREAM_ERROR;
    }

    value = 0;
    for (std::size_t byteIdx = 0; byteIdx < sizeof(Integral); ++byteIdx) {
      value += static_cast<Integral>(buf[byteIdx]) << (8 * (sizeof(Integral) - 1) - 8 * byteIdx);
    }

    return sizeof(Integral);
  }

  std::optional<std::byte> readByte();
};

}  // namespace org::apache::nifi::minifi::io