class SPARQL::Algebra::Operator::DeleteWhere

The SPARQL UPDATE `deleteWhere` operator.

The DELETE WHERE operation is a shortcut form for the DELETE/INSERT operation where bindings matched by the WHERE clause are used to define the triples in a graph that will be deleted.

@example

(deleteWhere ((triple :a foaf:knows ?b))

@see www.w3.org/TR/sparql11-update/#deleteWhere

Constants

NAME

Public Instance Methods

execute(queryable, **options) click to toggle source

Query the operand, and delete all statements created by binding each solution to the patterns

@param [RDF::Queryable] queryable

the graph or repository to write

@param [Hash{Symbol => Object}] options

any additional keyword options

@option options [Boolean] debug

Query execution debugging

@return [RDF::Queryable]

Returns queryable.

@raise [IOError]

If `from` does not exist, unless the `silent` operator is present

@see www.w3.org/TR/sparql11-update/

# File lib/sparql/algebra/operator/delete_where.rb, line 32
def execute(queryable, **options)
  # Operands are an array of patterns and Queries (when named).
  # Create a new query made up all patterns
  patterns = operand.inject([]) do |memo, op|
    if op.respond_to?(:statements)
      memo += op.statements.to_a
    else
      memo << op
    end
    memo
  end
  query = RDF::Query.new(*patterns, **{}) # FIXME: added hash argument needed until Statement#to_hash removed.
  debug(options) {"DeleteWhere query #{query.to_sse}"}
  query.execute(queryable, depth: options[:depth].to_i + 1, **options) do |solution|
    debug(options) {"DeleteWhere solution #{solution.to_sse}"}
    query.each_statement do |pattern|
      pattern = pattern.dup.bind(solution)
      debug(options) {"DeleteWhere pattern #{pattern.to_sse}"}
      queryable.delete(RDF::Statement.from(pattern)) if pattern.bound? || pattern.constant?
    end
  end
  queryable
end