Class: SPARQL::Algebra::Operator::Move

Inherits:
Operator
  • Object
show all
Includes:
Update
Defined in:
lib/sparql/algebra/operator/move.rb

Overview

The SPARQL UPDATE move operator.

The MOVE operation is a shortcut for moving all data from an input graph into a destination graph. The input graph is removed after insertion and data from the destination graph, if any, is removed before insertion.

[36] Move ::= 'MOVE' 'SILENT'? GraphOrDefault 'TO' GraphOrDefault

Examples:

SPARQL Grammar

MOVE SILENT GRAPH <http://www.example.com/g1> TO DEFAULT

SSE

(update
 (move silent <http://www.example.com/g1> default))

See Also:

Constant Summary collapse

NAME = 
[:move]

Instance Method Summary collapse

Methods included from Update

#empty?, #graph_name=, #unshift, #variables

Instance Method Details

#execute(queryable, **options) ⇒ RDF::Queryable

Executes this upate on the given writable graph or repository.

Parameters:

  • queryable (RDF::Queryable) —

    the graph or repository to write

  • options (Hash{Symbol => Object}) —

    any additional keyword options

Options Hash (**options):

  • debug (Boolean) —

    Query execution debugging

Returns:

Raises:

  • (IOError) —

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

See Also:



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# File 'lib/sparql/algebra/operator/move.rb', line 38

def execute(queryable, **options)
  debug(options) {"Move"}
  silent = operands.first == :silent
  operands.shift if silent

  src_name, dest_name = operands[-2..-1]
  raise ArgumentError, "move expected two operands, got #{operands.length}" unless operands.length == 2
  raise ArgumentError, "move from must be IRI or :default" unless src_name == :default || src_name.is_a?(RDF::URI)
  raise ArgumentError, "move to must be IRI or :default" unless dest_name == :default || dest_name.is_a?(RDF::URI)
  src = queryable.enum_graph.detect {|g| g.to_s == src_name.to_s}

  if src.nil?
    raise IOError, "move operation source does not exist" unless silent
  elsif dest_name == src_name
    # No operation
  else
    dest = queryable.enum_graph.detect {|g| g.to_s == dest_name.to_s}
    
    # Clear destination first
    dest.clear! if dest

    # Copy statements using destination graph
    src.each do |statement|
      statement = statement.dup
      statement.graph_name = (dest_name unless dest_name == :default)
      queryable << statement
    end

    # Clear source
    src.clear!
  end
  queryable
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/move.rb', line 77

def to_sparql(**options)
  *args, last = operands.dup
  args += [:TO, last]
  
  "MOVE " + args.to_sparql(**options)
end