c_glib/arrow-glib/readable.cpp

/*
 * 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.
 */

#include <arrow/api.h>

#include <arrow-glib/buffer.hpp>
#include <arrow-glib/error.hpp>
#include <arrow-glib/readable.hpp>

G_BEGIN_DECLS

/**
 * SECTION: readable
 * @title: GArrowReadable
 * @short_description: Input interface
 *
 * #GArrowReadable is an interface for input. Input must be
 * readable.
 */

G_DEFINE_INTERFACE(GArrowReadable,
                   garrow_readable,
                   G_TYPE_OBJECT)

static void
garrow_readable_default_init (GArrowReadableInterface *iface)
{
  iface->buffer_new_raw = garrow_buffer_new_raw;
}

/**
 * garrow_readable_read:
 * @readable: A #GArrowReadable.
 * @n_bytes: The number of bytes to be read.
 * @error: (nullable): Return location for a #GError or %NULL.
 *
 * Returns: (transfer full) (nullable): #GArrowBuffer that has read
 *   data on success, %NULL if there was an error.
 */
GArrowBuffer *
garrow_readable_read(GArrowReadable *readable,
                     gint64 n_bytes,
                     GError **error)
{
  const auto arrow_readable = garrow_readable_get_raw(readable);

  auto arrow_buffer = arrow_readable->Read(n_bytes);
  if (garrow::check(error, arrow_buffer, "[readable][read]")) {
    auto *iface = GARROW_READABLE_GET_IFACE(readable);
    return iface->buffer_new_raw(&(arrow_buffer.ValueOrDie()));
  } else {
    return NULL;
  }
}

/**
 * garrow_readable_read_bytes:
 * @readable: A #GArrowReadable.
 * @n_bytes: The number of bytes to be read.
 * @error: (nullable): Return location for a #GError or %NULL.
 *
 * Returns: (transfer full) (nullable): #GBytes that has read data on
 * success, %NULL if there was an error.
 *
 * Since: 0.17.0
 */
GBytes *
garrow_readable_read_bytes(GArrowReadable *readable,
                           gint64 n_bytes,
                           GError **error)
{
  const auto arrow_readable = garrow_readable_get_raw(readable);

  auto arrow_buffer_result = arrow_readable->Read(n_bytes);
  if (!garrow::check(error, arrow_buffer_result, "[readable][read-bytes]")) {
    return NULL;
  }
  auto arrow_cpu_buffer_result =
    arrow::Buffer::ViewOrCopy(*arrow_buffer_result,
                              arrow::default_cpu_memory_manager());
  if (!garrow::check(error,
                     arrow_cpu_buffer_result,
                     "[readable][read-bytes][view-or-copy]")) {
    return NULL;
  }
  auto arrow_cpu_buffer = *arrow_cpu_buffer_result;
  return g_bytes_new(arrow_cpu_buffer->data(),
                     arrow_cpu_buffer->size());
}

G_END_DECLS

std::shared_ptr<arrow::io::Readable>
garrow_readable_get_raw(GArrowReadable *readable)
{
  auto *iface = GARROW_READABLE_GET_IFACE(readable);
  return iface->get_raw(readable);
}