Class: SPARQL::Algebra::Operator::Desc

Inherits:
Asc show all
Defined in:
lib/sparql/algebra/operator/desc.rb

Overview

The SPARQL descending sort operator.

[24] OrderCondition ::= ( ( 'ASC' | 'DESC' ) BrackettedExpression ) | ( Constraint | Var )

Examples:

SPARQL Grammar

PREFIX foaf:    <http://xmlns.com/foaf/0.1/>
SELECT ?name
WHERE { ?x foaf:name ?name }
ORDER BY DESC(?name)

SSE

(prefix ((foaf: <http://xmlns.com/foaf/0.1/>))
  (project (?name)
    (order ((desc ?name))
      (bgp (triple ?x foaf:name ?name)))))

See Also:

Constant Summary collapse

NAME = 
:desc

Constants inherited from Unary

Unary::ARITY

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 inherited from Asc

#evaluate

Methods included from Evaluatable

#apply, #evaluate, #memoize, #replace_aggregate!, #replace_vars!

Methods inherited from Unary

#initialize

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

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Provides order to descendant query.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/desc.rb', line 31

def to_sparql(**options)
  "DESC(#{operands.last.to_sparql(**options)})"
end