Class: SPARQL::Algebra::Operator::Reverse
- Inherits:
-
Unary
- Object
- SPARQL::Algebra::Operator
- Unary
- SPARQL::Algebra::Operator::Reverse
- Includes:
- Query
- Defined in:
- lib/sparql/algebra/operator/reverse.rb
Overview
The SPARQL Property Path reverse
(NegatedPropertySet) operator.
[92] PathEltOrInverse ::= PathElt | ‘^’ PathElt
Constant Summary collapse
- NAME =
:reverse
Constants inherited from Unary
Constants inherited from SPARQL::Algebra::Operator
Constants included from Expression
Instance Attribute Summary
Attributes included from Query
Attributes inherited from SPARQL::Algebra::Operator
Instance Method Summary collapse
-
#execute(queryable, **options) {|solution| ... } ⇒ Object
Equivliant to:.
-
#to_sparql(**options) ⇒ String
Returns a partial SPARQL grammar for this operator.
Methods included from Query
#each_solution, #empty?, #failed?, #graph_name=, #matched?, #query_yields_boolean?, #query_yields_solutions?, #query_yields_statements?, #unshift, #variables
Methods inherited from Unary
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::Unary
Instance Method Details
#execute(queryable, **options) {|solution| ... } ⇒ Object
Equivliant to:
(path (:a (reverse :p) :b)) => (bgp (:b :p :a))
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# File 'lib/sparql/algebra/operator/reverse.rb', line 53 def execute(queryable, **, &block) debug() {"Reverse #{operands.to_sse}"} subject, object = [:subject], [:object] # Solutions where predicate exists query = if operand.is_a?(RDF::Term) RDF::Query.new do |q| q.pattern [object, operand, subject] end else operand(0) end queryable.query(query, **.merge( subject: object, object: subject, depth: [:depth].to_i + 1 ), &block) end |
#to_sparql(**options) ⇒ String
Returns a partial SPARQL grammar for this operator.
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# File 'lib/sparql/algebra/operator/reverse.rb', line 78 def to_sparql(**) "^(" + operands.first.to_sparql(**) + ')' end |