Class: SPARQL::Algebra::Operator::Alt
- Inherits:
-
Binary
- Object
- SPARQL::Algebra::Operator
- Binary
- SPARQL::Algebra::Operator::Alt
- Includes:
- Query
- Defined in:
- lib/sparql/algebra/operator/alt.rb
Overview
The SPARQL Property Path alt
(Alternative Property Path) operator.
Let P and Q be property path expressions.
eval(Path(X, alt(P,Q), Y)) = Union(eval(Path(X, P, Y)), eval(Path(X, Q, Y)))
[89] PathAlternative ::= PathSequence ( ‘|’ PathSequence )*
Constant Summary collapse
- NAME =
:alt
Constants inherited from Binary
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
Equivalent 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 Binary
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::Binary
Instance Method Details
#execute(queryable, **options) {|solution| ... } ⇒ Object
Equivalent to:
(path x (alt :p :q) y) => (union (bgp (x :p y)) (bgp (x :q y)))
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# File 'lib/sparql/algebra/operator/alt.rb', line 51 def execute(queryable, **, &block) subject, object = [:subject], [:object] debug() {"Alt #{[subject, operands, object].to_sse}"} # Solutions where predicate exists qa = if operand(0).is_a?(RDF::Term) RDF::Query.new do |q| q.pattern [subject, operand(0), object] end else operand(0) end qb = if operand(1).is_a?(RDF::Term) RDF::Query.new do |q| q.pattern [subject, operand(1), object] end else operand(1) end query = Union.new(qa, qb) queryable.query(query, **.merge(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/alt.rb', line 81 def to_sparql(**) "(#{operands.first.to_sparql(**)}|#{operands.last.to_sparql(**)})" end |