Class: SPARQL::Algebra::Operator::Copy

Inherits:
SPARQL::Algebra::Operator show all
Includes:
Update
Defined in:
lib/sparql/algebra/operator/copy.rb

Overview

The SPARQL UPDATE copy operator.

The COPY operation is a shortcut for inserting all data from an input graph into a destination graph. Data from the input graph is not affected, but data from the destination graph, if any, is removed before insertion.

[37] Copy ::= ‘COPY’ ‘SILENT’? GraphOrDefault ‘TO’ GraphOrDefault

Examples:

SPARQL Grammar

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

SSE

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

See Also:

Constant Summary collapse

NAME = 
[:copy]

Constants inherited from SPARQL::Algebra::Operator

ARITY, IsURI, URI

Constants included from Expression

Expression::PATTERN_PARENTS

Instance Attribute Summary

Attributes inherited from SPARQL::Algebra::Operator

#operands

Instance Method Summary collapse

Methods included from Update

#graph_name=, #unshift, #variables

Methods inherited from SPARQL::Algebra::Operator

#aggregate?, arity, #base_uri, base_uri, base_uri=, #bind, #boolean, #constant?, #deep_dup, #each_descendant, #eql?, #evaluatable?, evaluate, #executable?, #first_ancestor, for, #initialize, #inspect, #ndvars, #node?, #operand, #optimize, #optimize!, #parent, #parent=, #prefixes, prefixes, prefixes=, #rewrite, #to_binary, to_sparql, #to_sxp, #to_sxp_bin, #validate!, #variable?, #variables, #vars

Methods included from Expression

cast, #constant?, #evaluate, extension, extension?, extensions, for, #invalid?, new, #node?, open, #optimize, #optimize!, parse, register_extension, #to_sxp_bin, #valid?, #validate!, #variable?

Constructor Details

This class inherits a constructor from SPARQL::Algebra::Operator

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/copy.rb', line 37

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

  src_name, dest_name = operands[-2..-1]
  raise ArgumentError, "copy expected two operands, got #{operands.length}" unless operands.length == 2
  raise ArgumentError, "copy from must be IRI or :default" unless src_name == :default || src_name.is_a?(RDF::URI)
  raise ArgumentError, "copy 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, "copy 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_name
    src.each do |statement|
      statement = statement.dup
      statement.graph_name = (dest_name unless dest_name == :default)
      queryable << statement
    end
  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/copy.rb', line 73

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