rdf_parsers.opa

/*
    Copyright © 2011 MLstate

    This file is part of OPA.

    OPA is free software: you can redistribute it and/or modify it under the
    terms of the GNU Affero General Public License, version 3, as published by
    the Free Software Foundation.

    OPA is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for
    more details.

    You should have received a copy of the GNU Affero General Public License
    along with OPA.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * Parsers for rdf modules
 *
 * This file provides parsers for several rdf format.
 *
 * @author Anthonin Bonnefoy, 2011
 * @category api
 * @destination public
 */


/**
 *  Parser for the nt rdf format used for base dump
 */
NtParser = {{

  @private any = parser t=((!Rule.white_space .)+) -> Text.to_string(t)
  @private sep = parser Rule.ws -> void

  @private parse_nt = parser
    | sep res=any sep pre=any sep val=any sep "." sep -> (res, pre,val)

  @private parse_nts = parser
    | lst={Rule.parse_list(parse_nt, sep)} -> lst

  try_parse(dump):option(Rdf.base) = Parser.try_parse(parse_nts, dump)

}}

/**
 *  Parser for a rdf query
 */
QueryParser = {{

  @private any = parser t=((!Rule.white_space ![{}] .)+) -> Text.to_string(t)
  @private sep = Rule.ws

  @private uri_value= parser
    | "<" t=((!Rule.white_space !". " !"}" !">" .)+) ">" -> Text.to_string(t)

  @private parse_prefix = parser
    | "PREFIX" sep pref=any sep value=uri_value -> (pref, value)

  @private parse_variable = parser
    | sep "?" var=any sep -> var

  @private parse_select = parser
    | "SELECT" sep "*" sep -> { all }
    | "SELECT" sep vars={ Rule.parse_list_non_empty(parse_variable, sep) } sep -> { vars = vars }

  @private parse_where_value = parser
    | t=((!Rule.white_space !". " !"}" .)+) -> Text.to_string(t)

  @private parse_where_element = parser
    | sep var=parse_variable sep -> { var = var }
    | sep value=parse_where_value sep -> { value = value }

  @private parse_where_tuple = parser
    | t={Rule.rep(3, parse_where_element)} -> t

  @private where_element_separator = parser
    | sep "." sep -> void

  @private parse_where = parser
    | "WHERE" sep "\{" wheres={Rule.parse_list_non_empty(parse_where_tuple, where_element_separator)} where_element_separator? "}" sep -> wheres

  @private parse_query = parser
    | sep
      prefix={Rule.parse_list(parse_prefix, sep)} sep
      select=parse_select sep
      where=parse_where .*
      -> { ~prefix; ~select; ~where }

  try_parse(query):option(Rdf.query) = Parser.try_parse(parse_query, query)
}}