Class: SPARQL::Algebra::Operator::Lang
- Inherits:
-
Unary
- Object
- SPARQL::Algebra::Operator
- Unary
- SPARQL::Algebra::Operator::Lang
- Includes:
- Evaluatable
- Defined in:
- lib/sparql/algebra/operator/lang.rb
Overview
The SPARQL lang
operator.
[121] BuiltInCall ::= … | ‘LANG’ ‘(’ Expression ‘)’
Constant Summary collapse
- NAME =
:lang
Constants inherited from Unary
Constants inherited from SPARQL::Algebra::Operator
Constants included from Expression
Instance Attribute Summary
Attributes inherited from SPARQL::Algebra::Operator
Instance Method Summary collapse
-
#apply(literal, **options) ⇒ RDF::Literal
Returns the language tag of the operand, if it has one.
-
#to_sparql(**options) ⇒ String
Returns a partial SPARQL grammar for this operator.
Methods included from Evaluatable
#evaluate, #memoize, #replace_aggregate!, #replace_vars!
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
#apply(literal, **options) ⇒ RDF::Literal
Returns the language tag of the operand, if it has one.
If the operand has no language tag, returns ""
.
37 38 39 40 41 42 |
# File 'lib/sparql/algebra/operator/lang.rb', line 37 def apply(literal, **) case literal when RDF::Literal then RDF::Literal(literal.language.to_s) else raise TypeError, "expected an RDF::Literal, but got #{literal.inspect}" end end |
#to_sparql(**options) ⇒ String
Returns a partial SPARQL grammar for this operator.
49 50 51 |
# File 'lib/sparql/algebra/operator/lang.rb', line 49 def to_sparql(**) "lang(" + operands.first.to_sparql(**) + ")" end |