Class: SPARQL::Algebra::Operator::In

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

Overview

The SPARQL GraphPattern in operator.

[114] RelationalExpression ::= NumericExpression ('IN' ExpressionList)?

Examples:

SPARQL Grammar

ASK { FILTER(2 IN (1, 2, 3)) }

SSE

(ask (filter (in 2 1 2 3) (bgp)))

See Also:

Constant Summary collapse

NAME = 
:in

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 Evaluatable

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

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?, 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

#evaluate(bindings, **options) ⇒ RDF::Literal::Boolean

The IN operator tests whether the RDF term on the left-hand side is found in the values of list of expressions on the right-hand side. The test is done with "=" operator, which tests for the same value, as determined by the operator mapping.

A list of zero terms on the right-hand side is legal.

Errors in comparisons cause the IN expression to raise an error if the RDF term being tested is not found elsewhere in the list of terms.

The IN operator is equivalent to the SPARQL expression:

(lhs = expression1) || (lhs = expression2) || ...

Examples:


2 IN (1, 2, 3) #=> true
2 IN () #=> false
2 IN (<http://example/iri>, "str", 2.0) #=> true
2 IN (1/0, 2) #=> true
2 IN (2, 1/0) #=> true
2 IN (3, 1/0) #=> raises an error

Parameters:

  • bindings (RDF::Query::Solution) —

    a query solution containing zero or more variable bindings

  • options (Hash{Symbol => Object}) —

    ({}) options passed from query

Returns:

  • (RDF::Literal::Boolean) —

    true or false

Raises:

  • (TypeError) —

    if term is not found and any operand raises an error



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# File 'lib/sparql/algebra/operator/in.rb', line 46

def evaluate(bindings, **options)
  lhs = operands.first.evaluate(bindings, **options)
  error_found = false
  found = operands[1..-1].any? do |op|
    begin
      lhs == op.evaluate(bindings, **options.merge(depth: options[:depth].to_i + 1))
    rescue TypeError
      error_found = true
    end
  end
  case
  when found then RDF::Literal::TRUE
  when error_found then raise TypeError
  else RDF::Literal::FALSE
  end
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/in.rb', line 68

def to_sparql(**options)
  "(" + operands.first.to_sparql(**options) +
  " IN (" +
  operands[1..-1].map {|e| e.to_sparql(**options)}.join(", ") +
  "))"
end