.. ******************************************************************************
.. * Copyright 2021 Intel Corporation
.. *
.. * Licensed 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
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.. *******************************************************************************/

.. highlight:: cpp
.. default-domain:: cpp

.. _api_csv-data-source:

---------------
CSV data source
---------------

Refer to :ref:`Developer Guide: CSV data source <csv-data-source>`.

Programming Interface
---------------------
All types and functions in this section are declared in the
``oneapi::dal::csv`` namespace and be available via inclusion of the
``oneapi/dal/io/csv.hpp`` header file.

::

   enum class read_options : std::uint64_t {
      none = 0,
      parse_header = 1 << 0
   };

   constexpr char default_delimiter = ',';
   constexpr read_options default_read_options = read_options::none;

   class data_source {
   public:
      data_source(const char *file_name,
                  char delimiter = default_delimiter,
                  read_options opts = default_read_options);

      data_source(const std::string &file_name,
                  char delimiter = default_delimiter,
                  read_options opts = default_read_options);

      std::string get_file_name() const;
      char get_delimiter() const;
      read_options get_read_options() const;
   };

.. namespace:: oneapi::dal::csv
.. class:: data_source

   .. function:: data_source(const char *file_name, char delimiter = default_delimiter, read_options opts = default_read_options)

      Creates a new instance of a CSV data source with the given
      :cpp:expr:`file_name`, :cpp:expr:`delimiter` and read options :cpp:expr:`opts` flag.

   .. function:: data_source(const std::string &file_name, char delimiter = default_delimiter, read_options opts = default_read_options)

      Creates a new instance of a CSV data source with the given
      :cpp:expr:`file_name`, :cpp:expr:`delimiter` and read options :cpp:expr:`opts` flag.

   .. member:: std::string file_name = ""

      A string that contains the name of the file with the dataset to read.

      Getter
         | ``std::string get_filename() const``

   .. member:: char delimiter = default_delimiter

      A character that represents the delimiter between separate features in the
      input file.

      Getter
         | ``char get_delimter() const``

   .. member:: read_options options = default_read_options

      Value that stores read options to be applied during reading of the input
      file. Enabled ``parse_header`` option indicates that the first line in the
      input file is processed as a header record with features names.

      Getter
         | ``read_options get_read_options() const``


Reading :cpp:expr:`oneapi::dal::read<Object>(...)`
-------------------------------------------------------

Args
~~~~
::

   template <typename Object>
   class read_args {
   public:
      read_args();
   };

.. namespace:: oneapi::dal::csv
.. class:: template <typename Object> \
           read_args

   .. function:: read_args()

      Creates args for the read operation with the default attribute
      values.

Operation
~~~~~~~~~

:cpp:expr:`oneapi::dal::table` is the only supported value of the :code:`Object`
template parameter for :cpp:expr:`read` operation with CSV data source.

.. namespace:: oneapi::dal
.. function:: template <typename Object, typename DataSource> \
              Object read(const DataSource& ds)

   :tparam Object: |short_name| object type that is produced as a result of
                   reading from the data source.
   :tparam DataSource: CSV data source :cpp:expr:`csv::data_source`.

Usage example
-------------

.. include:: ../../../includes/data-management/csv-data-source-usage-example.rst