Class: Bmg::Operator::Restrict

Inherits:
Object
  • Object
show all
Includes:
Unary
Defined in:
lib/bmg/operator/restrict.rb

Overview

Restrict operator.

Filters operand’s tuples to those that meet the predicate received at construction.

Constant Summary

Constants included from Algebra

Algebra::METHODS

Instance Attribute Summary

Attributes included from Unary

#operand, #type

Instance Method Summary collapse

Methods included from Unary

#_visit, #operands

Methods included from Bmg::Operator

#inspect, #to_s

Methods included from Relation

#debug, #delete, empty, #empty?, #insert, new, #one, #one_or_nil, #to_json, #update, #visit, #ys_by_x

Methods included from Algebra

#allbut, #autosummarize, #autowrap, #constants, #extend, #image, #project, #rename, #restrict, #spied, #union, #unspied

Constructor Details

#initialize(type, operand, predicate) ⇒ Restrict

Returns a new instance of Restrict.



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# File 'lib/bmg/operator/restrict.rb', line 12

def initialize(type, operand, predicate)
  @type = type
  @operand = operand
  @predicate = predicate
end

Instance Method Details

#each ⇒ Object 



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# File 'lib/bmg/operator/restrict.rb', line 24

def each
  @operand.each do |tuple|
    yield(tuple) if @predicate.evaluate(tuple)
  end
end

#to_ast ⇒ Object 



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# File 'lib/bmg/operator/restrict.rb', line 30

def to_ast
  [ :restrict, operand.to_ast, predicate.sexpr ]
end