Class: ShEx::Algebra::Shape

Inherits:
Operator show all
Includes:
ShapeExpression
Defined in:
lib/shex/algebra/shape.rb

Constant Summary collapse

NAME = 
:shape

Constants inherited from Operator

Operator::ARITY

Instance Attribute Summary collapse

Attributes inherited from Operator

#id, #logger, #operands, #options, #schema

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ShapeExpression

#validate_expressions!, #validate_self_references!

Methods inherited from Operator

#base_uri, #closed?, #dup, #each_descendant, #eql?, #expression, #expressions, #find, #focus, #focus=, #initialize, #inspect, #iri, iri, #json_type, #matched, #matched=, #message, #message=, #not_matched, #not_satisfied, #operand, #parent, #parent=, #references, #satisfied, #satisfied=, #satisfy, #semact?, #semantic_actions, #serialize_value, #status, #structure_error, #to_h, #to_json, #to_sxp, #to_sxp_bin, #triple_expression?, #unmatched, #unmatched=, #unsatisfied, #unsatisfied=, #value, value

Constructor Details

This class inherits a constructor from ShEx::Algebra::Operator

Instance Attribute Details

#matchables ⇒ Array<RDF::Statement>

Let matchables be the triples in outs whose predicate appears in a TripleConstraint in expression. If expression is absent, matchables = Ø (the empty set).

Returns:

  • (Array<RDF::Statement>) 


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# File 'lib/shex/algebra/shape.rb', line 15

def matchables
  @matchables
end

#outs ⇒ Array<RDF::Statement>

Let outs be the arcsOut in remainder: outs = remainder ∩ arcsOut(G, n).

Returns:

  • (Array<RDF::Statement>) 


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# File 'lib/shex/algebra/shape.rb', line 10

def outs
  @outs
end

#unmatchables ⇒ Array<RDF::Statement>

Let unmatchables be the triples in outs which are not in matchables. matchables ∪ unmatchables = outs.

Returns:

  • (Array<RDF::Statement>) 


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# File 'lib/shex/algebra/shape.rb', line 20

def unmatchables
  @unmatchables
end

Class Method Details

.from_shexj(operator, **options) ⇒ Operator

Creates an operator instance from a parsed ShExJ representation

Returns:

Raises:

  • (ArgumentError) 


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# File 'lib/shex/algebra/shape.rb', line 26

def self.from_shexj(operator, **options)
  raise ArgumentError unless operator.is_a?(Hash) && operator['type'] == "Shape"
  super
end

Instance Method Details

#satisfies?(focus, depth: 0) ⇒ Boolean, ShapeExpression

The satisfies semantics for a Shape depend on a matches function defined below. For a node n, shape S, graph G, and shapeMap m, satisfies(n, S, G, m).

Parameters:

  • focus (RDF::Resource)
  • depth (Integer) (defaults to: 0) —

    for logging

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

    Other, operand-specific options

Returns:

  • (Boolean)
  • (ShapeExpression) —

    with matched and satisfied accessors for matched triples and sub-expressions

Raises:

  • (ShEx::NotMatched) —

    with expression accessor to access matched and unmatched statements along with satisfied and unsatisfied operations.



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# File 'lib/shex/algebra/shape.rb', line 35

def satisfies?(focus, depth: 0)
  # neigh(G, n) is the neighbourhood of the node n in the graph G.
  #
  #    neigh(G, n) = arcsOut(G, n) ∪ arcsIn(G, n)
  arcs_in = schema.graph.query({object: focus}).to_a.sort_by(&:to_sxp)
  arcs_out = schema.graph.query({subject: focus}).to_a.sort_by(&:to_sxp)
  neigh = (arcs_in + arcs_out).uniq

  # `matched` is the subset of statements which match `expression`.
  status("arcsIn: #{arcs_in.count}, arcsOut: #{arcs_out.count}", depth: depth)
  matched_expression = case expression
  when RDF::Resource
    ref.matches(arcs_in, arcs_out, depth: depth + 1)
  when TripleExpression
    expression.matches(arcs_in, arcs_out, depth: depth + 1)
  end
  matched = Array(matched_expression && matched_expression.matched)

  # `remainder` is the set of unmatched statements
  remainder = neigh - matched

  # Let `outs` be the `arcsOut` in `remainder`: `outs = remainder ∩ arcsOut(G, n)`.
  @outs = remainder.select {|s| s.subject == focus}

  # Let `matchables` be the triples in `outs` whose predicate appears in a `TripleConstraint` in `expression`. If `expression` is absent, `matchables = Ø` (the empty set).
  predicates = expression ? expression.triple_constraints.map(&:predicate).uniq : []
  @matchables = outs.select {|s| predicates.include?(s.predicate)}

  # Let `unmatchables` be the triples in `outs` which are not in `matchables`.
  @unmatchables = outs - matchables

  # No matchable can be matched by any TripleConstraint in expression
  unmatched = matchables.select do |statement|
    expression.triple_constraints.any? do |expr|
      begin
        statement.predicate == expr.predicate && expr.matches([], [statement], depth: depth + 1)
      rescue ShEx::NotMatched
        false # Expected not to match
      end
    end if expression
  end
  unless unmatched.empty?
    not_satisfied "Statements remain matching TripleConstraints",
                  matched: matched,
                  unmatched: unmatched,
                  satisfied: expression,
                  depth: depth
  end

  # There is no triple in matchables whose predicate does not appear in extra.
  unmatched = matchables.reject {|st| extra.include?(st.predicate)}
  unless unmatched.empty?
    not_satisfied "Statements remains with predicate #{unmatched.map(&:predicate).compact.join(',')} not in extra",
                  matched: matched,
                  unmatched: unmatched,
                  satisfied: expression,
                  depth: depth
  end

  # closed is false or unmatchables is empty.
  not_satisfied "Unmatchables remain on a closed shape", depth: depth unless !closed? || unmatchables.empty?

  # Presumably, to be satisfied, there must be some triples in matches
  semantic_actions.each do |op|
    op.satisfies?(matched, matched: matched, depth: depth + 1)
  end unless matched.empty?

  # FIXME: also record matchables, outs and others?
  satisfy focus: focus, matched: matched, depth: depth
rescue ShEx::NotMatched => e
  not_satisfied e.message, focus: focus, unsatisfied: e.expression, depth: depth
end

#validate! ⇒ Operator

expression must be a TripleExpression and must not reference itself recursively.

Returns:

Raises:



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# File 'lib/shex/algebra/shape.rb', line 113

def validate!
  case expression
  when nil, TripleExpression
  when RDF::Resource
    ref = schema.find(expression)
    ref.is_a?(TripleExpression) ||
    structure_error("#{json_type} must reference a TripleExpression: #{ref}")
  else
    structure_error("#{json_type} must be a TripleExpression or reference: #{expression.to_sxp}")
  end
  # FIXME: this runs afoul of otherwise legitamate self-references, through a TripleExpression.
  #!validate_self_references!
  super
end