Class: SPARQL::Algebra::Operator::Sequence

Inherits:
Operator
  • Object
show all
Includes:
Update
Defined in:
lib/sparql/algebra/operator/sequence.rb

Overview

The SPARQL UPDATE sequence operator.

Sequences through each operand.

[103] CollectionPath ::= '(' GraphNodePath+ ')'

See Also:

Constant Summary collapse

NAME = 
:sequence

Instance Method Summary collapse

Methods included from Update

#empty?, #graph_name=, #unshift, #variables

Instance Method Details

#execute(queryable, **options) {|solution| ... } ⇒ Object

Basically a JOIN across multiple operands

Parameters:

  • queryable (RDF::Queryable) —

    the graph or repository to write

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

    any additional keyword options

Options Hash (**options):

  • debug (Boolean) —

    Query execution debugging

Yields:

  • (solution) —

    each matching solution

Yield Parameters:

Yield Returns:

  • (void) —

    ignored

See Also:



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# File 'lib/sparql/algebra/operator/sequence.rb', line 31

def execute(queryable, **options, &block)
  debug(options) {"Sequence #{operands.to_sse}"}

  last = queryable.query(operands.shift, **options.merge(depth: options[:depth].to_i + 1))
  debug(options) {"(sequence)=>(last) #{last.map(&:to_h).to_sse}"}

  operands.each do |op|
    this = queryable.query(op, **options.merge(depth: options[:depth].to_i + 1))
    debug(options) {"(sequence)=>(this) #{this.map(&:to_h).to_sse}"}

    last = last.map do |s1|
      this.map do |s2|
        s2.merge(s1) if s2.compatible?(s1)
      end
    end.flatten.compact
    debug(options) {"(sequence)=>(next) #{last.map(&:to_h).to_sse}"}
  end

  @solutions = RDF::Query::Solutions.new(last)
  debug(options) {"(sequence)=> #{@solutions.map(&:to_h).to_sse}"}
  @solutions.each(&block) if block_given?
  @solutions
end

#to_sparql(**options) ⇒ String

Returns a partial SPARQL grammar for this operator.

Returns:

  • (String) 


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# File 'lib/sparql/algebra/operator/sequence.rb', line 60

def to_sparql(**options)
  str = "{\n" + operands.to_sparql(top_level: false, **options) + "\n}"
  Operator.to_sparql(str, **options)
end