Class: Bmg::Operator::Matching

Inherits:
Object
  • Object
show all
Includes:
Binary
Defined in:
lib/bmg/operator/matching.rb

Overview

Matching operator.

Filters tuples of left operand to those matching at least one tuple in right operand.

Constant Summary

Constants included from Algebra

Algebra::METHODS

Instance Attribute Summary

Attributes included from Binary

#left, #right, #type

Instance Method Summary collapse

Methods included from Binary

#_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, #group, #image, #matching, #page, #project, #rename, #restrict, #rxmatch, #spied, #union, #unspied

Constructor Details

#initialize(type, left, right, on) ⇒ Matching

Returns a new instance of Matching.



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

def initialize(type, left, right, on)
  @type = type
  @left = left
  @right = right
  @on = on
end

Instance Method Details

#each ⇒ Object 



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# File 'lib/bmg/operator/matching.rb', line 25

def each
  index = Hash.new
  right.each_with_object(index) do |t, index|
    key = tuple_project(t, on)
    index[key] = true
  end
  left.each do |tuple|
    key = tuple_project(tuple, on)
    yield tuple if index.has_key?(key)
  end
end

#to_ast ⇒ Object 



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# File 'lib/bmg/operator/matching.rb', line 37

def to_ast
  [ :matching, left.to_ast, right.to_ast, on ]
end