Class: LD::Patch::Algebra::Delete

Inherits:
SPARQL::Algebra::Operator::Unary
  • Object
show all
Includes:
SPARQL::Algebra::Evaluatable, SPARQL::Algebra::Update
Defined in:
lib/ld/patch/algebra/delete.rb

Overview

The LD Patch delete operator (incuding deleteExisting).

The Add operation is used to delete triples from the target graph with or without checking to see if the exist already.

Examples:

(add ((<a> <b> <c>)))

Constant Summary collapse

NAME = 
:delete

Instance Method Summary collapse

Instance Method Details

#execute(queryable, options = {}) ⇒ RDF::Query::Solutions

Executes this upate on the given writable graph or repository.

Parameters:

  • queryable (RDF::Queryable) —

    the graph or repository to write

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

    any additional options

Options Hash (options):

  • :existing (Boolean) —

    Specifies that triples must already exist in the target graph

Returns:

  • (RDF::Query::Solutions) —

    A single solution including passed bindings with var bound to the solution.

Raises:

  • (Error) —

    If existing is specified, and any triple is not found in the traget graph, or if unbound variables are used.

See Also:



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# File 'lib/ld/patch/algebra/delete.rb', line 30

def execute(queryable, options = {})
  debug(options) {"Delete"}
  bindings = options.fetch(:bindings)
  solution = bindings.first

  # Bind variables to triples
  triples = operand(0).dup.replace_vars! do |var|
    case var
    when RDF::Query::Pattern
      s = var.bind(solution)
      raise LD::Patch::Error.new("Operand uses unbound pattern #{var.inspect}", code: 400) if s.variable?
      s
    when RDF::Query::Variable
      raise LD::Patch::Error.new("Operand uses unbound variable #{var.inspect}", code: 400) unless solution.bound?(var)
      solution[var]
    end
  end

  # If `:new` is specified, verify that no triple in triples exists in queryable
  if @options[:existing]
    triples.each do |triple|
      raise LD::Patch::Error, "Target graph does not contain triple #{triple.to_ntriples}" unless queryable.has_statement?(triple)
    end
  end

  queryable.delete(*triples)
  bindings
end