Class: SPARQL::Algebra::Operator::SHA256

Inherits:
Unary show all
Includes:
Evaluatable
Defined in:
lib/sparql/algebra/operator/sha256.rb

Overview

The SPARQL logical sha256 operator.

Returns the SHA256 checksum, as a hex digit string, calculated on the UTF-8 representation of the simple literal or lexical form of the xsd:string. Hex digits SHOULD be in lower case.

[121] BuiltInCall ::= ... | 'SHA256' '(' Expression ')'

Examples:

SPARQL Grammar

PREFIX : <http://example.org/>
SELECT (SHA256(?l) AS ?hash) WHERE {
 :s1 :str ?l
}

SSE

(prefix ((: <http://example.org/>))
  (project (?hash)
    (extend ((?hash (sha256 ?l)))
      (bgp (triple :s1 :str ?l)))))

See Also:

Constant Summary collapse

NAME = 
:sha256

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 included from Evaluatable

#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

#apply(operand, **options) ⇒ RDF::Literal

Returns the SHA256 checksum, as a hex digit string, calculated on the UTF-8 representation of the simple literal or lexical form of the xsd:string. Hex digits should be in lower case.

Parameters:

  • operand (RDF::Literal) —

    the operand

Returns:

  • (RDF::Literal)

Raises:

  • (TypeError) —

    if the operand is not a simple literal



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# File 'lib/sparql/algebra/operator/sha256.rb', line 37

def apply(operand, **options)
  raise TypeError, "expected an RDF::Literal, but got #{operand.inspect}" unless operand.literal?
  raise TypeError, "expected simple literal or xsd:string, but got #{operand.inspect}" unless (operand.datatype || RDF::XSD.string) == RDF::XSD.string
  RDF::Literal(Digest::SHA256.new.hexdigest(operand.to_s))
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/sha256.rb', line 48

def to_sparql(**options)
  "SHA256(" + operands.to_sparql(**options) + ")"
end